Operational Guidelines on Plague[2]

8/8/2019 Operational Guidelines on Plague[2]

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Oerational guieline on

plaue surveillane, dianoi,prevention an control


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World Health Organization 2009

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This publiation ontains the olletive views of an international group ofexperts and does not necessarily represent the decisions or the statedpoliy of the World Health Organization.

Printed in India

WHO Library Cataloguing-in-Publication data

World Health Organization, Regional Ofce for South-East Asia.Operational guidelines on plague surveillane, diagnosis, prevention and

ontrol.

1. Plague diagnosis epidemiology prevention and control.

2. Disease Outbreaks. 3. Laboratory Techniques and Procedures.

4. Disaster Planning. 5. Mass Media. 6. Guidelines.

ISBN 978-92-9022-376-4 (NLM classication: WC 350)


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OperationalGuidelinesonPlagueSurveillane,Diagnosis

,Preventionandcontrol

content

Prefae ...............................................................................v

Aknowledgements ............................................................. vii

Introduction1. ...................................................................1

1.1 Historical perspective ............................................... 2

1.2 Current global situation ............................................ 3

1.3 Plague in the WHO South-East Asia Region ................. 4

1.4 Purpose of the revised guideline ................................ 5

Epidemiology2. ..................................................................7

2.1 Infectious agent .......................................................

2.2 The human host ..................................................... 8

2.3 Reservoir................................................................ 9

2.4 Vetor ...................................................................11

2.5 Risk fators ...........................................................12

2.6 Mode of transmission and period of ommuniability....13

2.7 Types of plague ......................................................16

clinial manifestation3. ....................................................18

3.1 Bubonic plague.......................................................18

3.2 Septicaemic plague.................................................19

3.3 Pneumonic plague ..................................................20

3.4 Differential diagnosis...............................................21

Standard case denition4. .................................................22

Laboratory in surveillane and diagnosis5. ..........................24

5.1 Laboratory and surveillance .....................................24

5.2 colletion, storage and transport of samples ..............24

5.3 Laboratory diagnosis of plague .................................30

5.4 Safe handling of infetious materialsin the laboratory .....................................................32

Prevention and ontrol6. ...................................................34

6.1 Surveillance ...........................................................34

6.2 Organization of surveillane ativities ........................35

6.3 Components of surveillance .....................................37


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Oerational guieline on plaue surveillane, dianoi, prevention an control

6.4 Early warnin inal ...... .......... ......... .......... .......... 41

6.5 Roent urveillane an e-ratt in in eaort ...... .... .42

6.6 Health euation an omm unity artiiation .... .... ... 44

6.7 I nteretoral oorination ......... .......... ......... .......... ..45

6.8 Roent ontrol ......... ......... .......... .......... .......... ....... 45

6.9 Vetor ontrol .......... ......... .......... .......... .......... ....... 51

Eiemi rearene7. .. . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . 54

7.1 Identicationofrapidresponseteams . . . . . . . . . . . . . . . . . . . . . .54

7.2 Loiti ......... .......... .......... ......... .......... .......... ...... 54

7.3 Hoital rearene .......... .......... .......... ......... ...... 56

7.4 Manower eveloment .......... ......... .......... .......... .... 56

Managementofanoutbreak8. .. . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . 57

8.1 Identicationofanoutbreak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

8.2 Outbreakinvestigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

8.3 ActivationofCrisisManagementCommittee . . . . . . . . . . . . . . .60

8.4 cae manaement .......... .......... ......... .......... .......... .62

8.5 prohylaxi .......... .......... ......... .......... .......... .......... .65

8.6 Infectioncontrol . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . .66

8.7 I nternat ional Health Reulation (2005)andplaguenotication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71

partnerhi w ith ma meia9. .. . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . 74

Lessonslearntfromplagueoutbreaks10. .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . 79

10.1PlagueoutbreakinSuratandBeed, Maharahtra (Inia), 1994 ......................................79

10.2 pneumoni laue in shim la itrit,Himahal praeh ( Inia), 2002 .......... .......... .......... ..80

References . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . 85

Furt her reain . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .86

Annexe

Methodtocollectbubopus1. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87

Instructionfortheuse2. oftherapidtests . . . . . . . . . . . . . . . . . . . . . . . . . .88

Decisioninstrumentfortheassessmentand3.noticationofeventsthatmayconstituteapublichealthemergencyofinternationalconcern. . . . . . . . . . . .89


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prefae

Plague is one of the important vector-borne zoonotic diseases

that remains endemi in many natural foi around the world,

including some countries of the South-East Asia Region.

Human plague outbreaks have been reported from India

and Indonesia in 2004 and 2007 respectively. Plague evokes

onsiderable fear among people beause of its historial

reputation of killing millions of people. The lessons learned

during the major plague outbreak in 1994 in Surat and theeffective measures taken by the Government of India were

helpful in early detetion and rapid ontainment of the 2004

outbreak. Reent outbreaks have shown that plague may

re-emerge in areas after a long period of silence. There is

need, therefore, for onerted efforts to strengthen plague

surveillane ativity and build adequate apaity for timely

detetion and rapid ontainment of outbreaks should an

outbreak our in previously silent natural foi in all ountries

of the South-East Asia Region.

The need for regional operational guidelines to provide

a omprehensive knowledge and information on plague

epidemiology, surveillane, diagnosis, ase management and

prevention and control was felt for the benet of national

health authorities in all Member ountries. These guidelines

were published by the WHO South-East Asia Region in 2004

and it was neessary to revise and update them in the

context of new case denitions adopted in 2006 and the

enforcement of the International Health Regulations (2005)

from June 2007.

The revised and updated operational guidelines have

been developed through a proess of onsultation and inputs

from a number of experts on plague and public health, both

from within and outside the World Health Organization. As

there is ontinued threat of plague outbreaks in our Region,


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Operational Guidelines on Plague Surveillane, Diagnosis, Prevention and control

effective surveillance of existing natural foci of sylvatic plague

and preparedness at the national, provinial and distrit

levels is important. I am condent that these guidelines willbe useful to those responsible for ommuniable disease

surveillane and response in Member ountries and will

be of immense benet to health ofcials responsible for

emergeny preparedness.

Dr Samlee PliangbanhangRegional Diretor


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Aknowleement

A revised and updated draft doument was prepared by Dr

Gyanendra N. Gongal and Dr K.N. Tewari. The original draft

was peer reviewed extensively by a consortium of technical

experts in various disciplines as listed below at the expert

onsultation meeting held in the Plague Surveillane Unit of

the National Centre for Disease Control, Bengaluru, on 7-8

August 2009. The role of the following at the onsultation

is acknowledged:

Dr Veena Mittal, Joint Director & Head, Incharge,(1)

central Plague Laboratory, National centre for

Disease Control, Delhi, India.

Dr Shyam Lal Biswas, Joint Director & Incharge,(2)

Plague Surveillance Unit, Bengaluru, India.

Drh Wilfried H. Purba, Head of Sub-Directorate(3)

for Zoonotic Diseases, Directorate of VBDC,Directorate-General, Disease Control & Environmental

Health, Ministry of Health, Jakarta, Indonesia.

Dr Si Si Tun, Senior Consultant, 1000-bed General(4)

Hospital, Nay Pyi Taw, Myanmar.

Further tehnial input was also obtained from

Dr Eric Bertherat, WHO HQ, before nalizing the nal draft.

The valuable contribution of Dr Rajesh Bhatia, Regional

Adviser, Blood Safety and Laboratory Technology, in nalizingthe guidelines is gratefully aknowledged.


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Plague is an aute ommuniable disease aused by a

baterium alled Yersinia pestis and transmitted to man by

the bite of infected rat eas. It is primarily a zoonosis, being a

disease of rodents, and humans are affeted inidentally.

Plague has a important plae in history. For enturies

the disease represented disaster for those living in Asia,

Africa and Europe. Because the cause of plague was not

known, plague outbreaks ontributed to massive pani in

places where they appeared; indeed, it continues to invoke

an intense, irrational fear even in an era when antibiotis

and insetiides are available. This disease may have aused

over 200 million deaths in the history of humanity.

Plague is often classied as a problem of the past or an

ancient disease that is not likely to disappear. But continued

outbreaks throughout the world attest to its tenaious

presence. It remains a current threat in many parts of theworld, partiularly in Asia. Following the reappearane of

plague during the 1990s in several countries, plague has

been categorized as a re-emerging disease.

The plague organism is onsidered as a potential

biologial weapon for bioterrorists.

Despite the availability of a number of highly effetive

therapeuti agents, mortality due to plague remains very high

beause most outbreaks our in remote plaes and there

is delay in proper diagnosis and treatment of disease.

1Introution


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Underreporting of plague due to lak of laboratory failities

for diagnostic conrmation is also common. Many countries

have dismantled a surveillane system for plague beause ofa lack of funds and the absence of periodic outbreaks. But

there is a onstant threat of a plague outbreak, partiularly

in plague-endemic areas and known natural foci, and hence

the disease should be made an integral part of the national

publi health surveillane system.

Plague was one of the three diseases reportable under

International Health Regulation (1969). It has a great

signicance under IHR (2005) as a public health emergencyof international onern.

1.1 Hitorial eretive

In the course of history, plague has been responsible for at

least three widespread pandemis with high mortality. The

rst (the Justinian plague) spread around the Mediterranean

Sea in the 6th century of the current Era; the second (the

Black Death) struck Europe in the 14th century; and the

third started in China during the middle of the 19 th entury

and spread throughout the world.

The Black Death caused an estimated 75200 million

deaths, approximately half of them in Asia and Africa

and the other half in Europe1. The Black Death decimated

Medieval Europe, and had a major impact on the continents

soioeonomi development, ulture, art, religion and

politis2,3. The fourteenth entury plague is estimated to

have killed a third of the population of china4.

The third pandemic killed 12.5 million people in India

alone5. Large plague outbreaks occurred during the rst half

of the 20th century in India. Each pandemic was caused by

a different biovar of Y. pestis, respetively, Antiqua (still

found in Africa and Central Asia), Medievalis (currently

limited to Central Asia) and Orientalis (almost worldwide in

its distribution) 6, 7.


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A total of 11 479 cases of human plague and 772 deaths

were reported by 14 countries in Africa, the Americas and

Asia from 2004 to 2008. Four countries reported cases ofhuman plague every year (Democratic Republic of Congo,

Madagascar and Peru and the United States) from 2004

to 2008. The global distribution of natural plague foci is

shown in Fig. 19.

Fiure 1:Global distribution of natural plague foi

(in rodent populations), 1999

Human plague outbreaks have a orrelation with natural

foi of plague in rodents. A small number of Afrian ountries

with well-known natural plague foci reported the highest

number of ases in reent years. Although it is predominantly

a rural disease, there have been outbreaks of plague in

urban populations in Madagasar and the United Republi

of Tanzania. china, Demorati Republi of congo, Libya,

Madagasar, Mongolia, Peru, Uganda, United Republi of

Tanzania and USA reported plague outbreaks in 2009. A

general upward trend in the inidene of human plague has

been observed sine 2005, with a global average inidene

of 2083 cases annually. Recent outbreaks have shown

that plague may re-emerge in areas after a long period of

absene10.


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1.3 plaue in the WHO south-Eat AiaReion

Plague remains endemi in many natural foi around the

world; in the WHO South-East Asia Region, endemic foci

are found in India, Indonesia and Myanmar. Natural foci

of plague exist in parts of Maharashtra, Gujarat, Andhra

Pradesh, Tamil Nadu, Karnataka, Himahal Pradesh and

Uttarakhand in India. There were plague outbreaks in India

in 1954 and 1963, and then again 30 years later in 1994.

A large plague outbreak in India in 1994 was responsible

for a US$ 3 billion loss due to inadequate and delayedresponse at the national level as well as the overreation of

the international ommunity, whih imposed restritions on

international travel and commercial exchanges. A pneumonic

plague outbreak was reported in February 2002 in Himahal

Pradesh. A loalized outbreak of buboni plague ourred

in Dangud village in distrit Uttarkashi, Uttarakhand, in

Otober, 2004.

At present, two active plague foci are known to exist inIndonesia, one located in the Boyolali district of Central Java

and the other in the Pasuruan district of East Java. Both of

these foi have been soures of human plague outbreaks in

the past 40 years. The last plague outbreak was reported in

Pasuruan district of East Java province in February 2007.

Myanmar reported its last human plague outbreak in

1994. Till 1994, Myanmar reported cases virtually every year.

Nepal reported its last plague outbreak in 1968 in Bajhangdistrict of western Nepal. Plague is notiable disease in

Bhutan, India, Indonesia, Maldives, Myanmar and Sri Lanka

and many ountries are preparing to reintrodue plague

surveillane in rodent population.

1.4 puroe of the revie uieline

The purpose of these Operational Guidelines is to help health

personnel and health authorities at any level to:


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update current knowledge about plague;

provide omprehensive information on epidemiology

and standard tehniques in aordane with new

tehniques for diagnosis, ase management,

prevention and ontrol of plague for both sporadi

case(s) and an outbreak;

dene standards in case denition, laboratory

diagnosis, ase management and isolation

preautions in order to meet the needs of pratitioners,

laboratory workers, health-care providers and public

health administrators;provide an overview on surveillance of plague;

detet and ontrol outbreaks of plague as early as

possible;

strengthen the apaity of emergeny response to

outbreaks;

develop an efcient partnership with mass media;

and

share lessons learnt from plague outbreaks.

These guidelines are intended as a technical support to eld

workers. However, these must be modied appropriately and utilized

for development of manuals for eld workers by the national health

authorities. Such modied guidelines should have the approval of

the aroriate authoritie, onform w ith national oliie an law,

an meet loal nee.


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2Epidemiology

Plague is primarily a disease of rodents. The infetion

is maintained in the natural foi of the disease in wild

rodent olonies through transmission between them by

their ea ectoparasites. For the most part, the wild rodent

reservoirs are speies that are suseptible to the infetion

but resistant to the disease. Wild plague exists in its natural

foi independent of human populations and their ativity.

Domesti plague is intimately assoiated with rodents living

with humans and an produe epidemis in both human andanimal populations.

The epidemiology of plague is extremely complex.

Infection depends upon the maintenance of a great variety

of rodents and vetors, whih differ from ountry to ountry

and also over time. Ecological studies point to a multiplicity

of factors concerned in the uctuating balance that exists

between rodents of greater and lesser degree of suseptibility

to the plague baillus, and also in the degree of risk to whihhumans is exposed.

2.1 Infetiou aent

Yersinia pestis, the plague bacillus, is a non-motile, non-acid-

fast, non-spore-forming, and gram-negative coccobacillus

measuring 1.5 by 0.75 microns. When stained with aniline

dyes, the ends of the bacillus take the stain more intensely;

this is known as bipolar staining. True apsules are seen in


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living tissues but less readily seen in ulture. The apsular

material is important for antigeniity and protetivity and

is used for preparation of Fraction I antigen for serologicaltest.

The organism is pathogeni to ommon laboratory

animals like mie, guinea pigs, et. The inoulated animals

die in three to four days. The harateristi oobailli are

seen in large numbers in lms made from lymphnodes,

spleen pulp and heart blood as shown in Fig. 2.

Fiure 2: Plague baterium

Y. pestis belongs to the group of bailli with low resistane

to environmental fators. Sunlight, high temperatures

and desiation have a destrutive effet, and ordinary

disinfetant preparations ontaining hlorine kill it within

ten minutes.

2.2 The human hot

All ages and both sexes are susceptible to plague. Mortality

depends on the type of plague:

Bubonic plague is fatal in about 50%75% of untreated

cases, but perhaps 10%15% when treated.

Septicaemic plague is almost fatal, and perhaps 40%

with treatment.

Pneumonic plague is fatal if not treated within 18%

24% hours of infection.


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2.3 Reervoir

A large number of mammals may be infeted with Y. pestis.

More than 200 animals have been shown to be suseptible. Of

the domesti animals, attle, horses, sheep and pigs are not

known to develop plague. Goats and amels have reportedly

developed linial illness. Rabbits are suseptible to infetion.

Ground squirrels are highly suseptible. cats are severely

affeted by Y. pestis infection; They can develop all three

forms of plague. Dogs seem to be somewhat resistant to Y.

pestis infetion. Dogs may beome infeted without showing

any sign of illness and act as sentinel animals. Sero-testingof arnivores an be an indiator to assess the prevalene of

plague in that area. If they do become ill, the only symptoms

may be fever or lymphadenopathy. All the aforesaid animals

are basially aidental hosts ofY. pestis.

Rodents are the true natural and maintenane hosts

of plague. At least 220 speies of rodents, whih inhabit

mountains, plains, steppes, deserts, cultivated eld and

forests in both temperate and tropial limates, are wellknown to be infeted with plague baillus. Many speies of

rodents (wild and domestic) and other small mammals are

suseptible to infetion but are only oasionally infeted,

and are not neessarily important reservoirs of infetion.

The infetion persists in some rodent speies and a few

other animal hosts. While wild and peri-domestic rodents

are suseptible to the infetion but resistant to the disease,

domesti rodents are suseptible both to the infetion and

the diseasehene the phenomenon of rat falls*.

Among the wild and peri-domestic rodents, the role of

Indian gerbil (Tatera indica) and bandicoot rat (Bandicota

bengalensis) as a natural reservoir of plague is well

established. Among the ommensal rodents, Rattus rattus

and Mus musculus are hosts for Y. pestis. The marmot is a

* Rat fall is dened as more than one dead rat in a house, or more thanone house with dead rats, where it has been asertained that the deathsamong the rats have not been due to poisoning.


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primary arrier of the plague baillus in many Asian ountries.

Marmots are the only reatures besides humans who an

pass pneumoni plague from one to another under normal(not laboratory) circumstances.

Maintenance of epizootic cycle

A rodent speies may be highly suseptible but if it is rare it

is not important in the spread of plague. In colder climates,

because the breeding of both rodents and eas occurs in

summer and spring, the outbreaks may take plae during

these seasons. In warmer climates the breeding occurs

throughout the year. The population density builds up quikly

and outbreaks an our any time. The turnover of rodent

population is very fast and the population pressure keeps

uctuating up and down and this prevents the build-up of

a stable, resistant generation. This also keeps the yersinia-

rodent-ea cycle going, yet some resistance is essential on

the part of the host for the maintenane of a plague foi. A

totally suseptible population would soon die out.

Many biotic and abiotic factors inuence the persistence

of the disease in the wild rodent population and epizooti

plagues. The natural foi of plague are known to be

ompletely independent of humans. A balane is maintained

between suseptible and resistant hosts. Voles and gerbils

are resistant hosts to plague. Voles and eld mice are

natural reservoirs and keep the enzooti yle ongoing. Time

and again this balane is seen in any plague foi. Among

susceptible rodents--at varying intervals, sometimes manyyears apart--there is an outburst of plague among animals

(known as an epizootic). Another rodent, often a smaller

animal, may live alongside and arry the infetion between

the outbreaks with little, if any, sign of disease. Even when

conditions become unfavourable for the rodent or the ea

(or both), the infection can persist; the rodent goes into

hibernation and at low body temperature beomes more

resistant. The adult ea can survive without food or host

for a year or more, and larvae an prolong the pupa stage

until a new host enters the burrow and vibrations from its


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body call the new ea forth. And even if the ea dies out, Y.

pestis an apparently survive in the soil of burrows, though

this seems to vary between areas.

2.4 Vetor

Many species of eas can act as vectors for Y. pestis, but the

rat ea is the most important vector for the plague bacterium.

Rat eas (domestic plague) and wild rodent eas (natural

foci) are important for plague transmission. The rat ea is

shown in Fig. 3. The eas are piercing, sucking, wingless

insects. Both the sexes can transmit the disease. Xenopsyllacheopis is the commonest vector of plague among rats. It

likes to live in rat burrows; the male cheopis may desert

the rat to live exclusively in its burrow. But the rat ea can

adapt at various other loations as in the ities, espeially if

it is a port; if rats are not available, the ea can bite human

beings. X. brasiliensis is an equally efcient vector but it

prefers to inhabit roofs rather than burrows and prefers a

rural rather than urban environment.

Fiure 3: Rat ea

To act as an efcient plague vector, the ea must be

able to:

ingest the plague organism with its blood meal;


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live long enough for the pathogen to multiply

sufciently;

transfer the pathogen to an animal or human host

in sufcient concentrations to cause an infection in

the local rodent hosts; and

be present in large enough numbers to maintain

infetion in the loal rodent hosts.

After the ea has taken the infected blood, the average

time between the feed and infectivity is about 21 days, with

a range of 531 days (extrinsic incubation period). A vector

must have failities for reeiving the pathogen, and it must

be able to maintain the pathogen in its body. It must live

long enough to allow the pathogen to multiply. All three of

these factors contribute to the extrinsic incubation period of

the disease. The ea then must be capable of passing the

pathogen to the next host in sufcient numbers to cause

infection, and the ea must be present in sufcient numbers

in any fous to keep the infetion going in the rodent hosts

of the area.

The feeding habits of the vetor are related to the foraging

habit of the host. One ea may feed on its host only in its

burrow, another when the host is moving around outside

burrows. The habits of the ea and host must coincide.

The breeding pattern of the ea and the host must also be

related. Fleas must be ative in peak numbers in the adult

biting stage when the rodent hosts are breeding freely. These

are physiological factors. In addition, purely physical factorsalso ome into the piture.

2.5 Rik fator

Geographial, meteorologial and limati fators, as well as

the degree of advancement civilization--the type of buildings,

amount of overrowding, forms of sewerage, ativity of

shipping and other forms of transport, and the degree of

sanitationalong with other factors have an indirect inuence


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on the qualitative and quantitative distribution of the rodents

and insets that at as potential reservoirs and arriers ofY.

pestis. Though buboni plague has ourred in every part ofthe globe, it is conned chiey to warmer latitudes. Extreme

heat and dryness of atmosphere are inimical to its spread;

thus in tropial ountries it ours during the older months

of the year, when the mean temperature is between 100c

and 300c and the air has high relative humidity.

A combination of conditions (e.g. environmental,

climatic, hygienic) and a certain relationship between the

host-reservoirea vectormicroorganism and humans arenecessary. Sociocultural factors; certain occupations and

lifestyles such as hunting, cat ownership, sleeping on oors,

et. and religious myths and beliefs arry an inreased risk

of exposure. Pneumonic plague may be highly communicable

under appropriate climatic conditions; overcrowding and cool

temperatures failitate transmission.

Ecological changes created by natural disasters such as

earthquakes, volcano, ooding, drought, or human activitiessuh as enroahment, deforestation and mining disturb the

equilibrium density of rodents and their eas. As a result,

human populations can be exposed to vectors of plague.

2.6 Moe of tranmiion an erio ofcommunicability

Plague an be transmitted indiretly or diretly.

Iniret tranmiion

Such transmission occurs:

Through the bite of a ea originating from plague-

infected rats;

from the bite of a ea originating from a rodent that

has died of plague;

through the biting of humans by wild rodent eas


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among people exposed to wild rodents in their natural

habitats; and

through onsumption of amel meat infeted with

Yersinia pestis.

diret tranmiion

This form of transmission occurs:

From a plague-infected rodent or others while

handling infected animals or carcasses. If the animal is

infeted, some of the bateria ould enter the human

body through breaks in the skin. Hunters skinninganimals are at risk for this type of transmission.

Through person-to-person transmission through

airborne droplets from patients with pneumoni

plague (secondary or primary).

Through diret ontat with droplets ontaminated

with sputum. Infection through direct contact with

objets ontaminated with sputum from pneumoni

plague patients an lead to the development ofbuboni plague.

Through ontat with an animal with pneumoni

plague whih ours when Y. pestis infets the lungs,

or when the infeted animal oughs near another

person or animal. If cats develop a pneumonic plague,

they an beome a soure of infetion for people

through aerosol transmission.

During a laboratory aident. Plague may beome anosoomial infetion and requires strit use of proper

biosafety measures.

Bubonic and septicaemic plague do not spread from

person to person.

Untreated pneumoni plague patients an transmit

disease when they ough starting from onset till full reovery

or death.


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Treated patients an still transmit the disease during

the rst 48 hours after beginning of appropriate antibiotic

treatment.

The inubation period for buboni plague varies from

two to six days. For pneumonic plague, it is between one

and four days.

Dynamics of transmission

The dynamics of plague transmission are extremely intricate.

This an be gauged from the simple fat that there are

3000 ea species, of which at least 31 are proven vectorsof plague, and there are around 220 rodent speies that

an arry plague.

A fous may remain apparently stati for years, during

which the bacterium is passed from rodent to ea and from

ea to rodent without any variation. This enzootic plague is

kept going by the balane between resistant and suseptible

hosts in the foi. After an interval of many years, if the

balane between the suseptible and resistant rodents getsupset, the disease spreads rapidly and widely and auses

many deaths among rodents. This is alled epizooti plague.

Humans are usually not at risk from epizooti plague, unless

they intrude as hunters, trappers or nomads into the infeted

area.

In pneumonic form, Y. pestis is present in human sputum

and infetion spreads rapidly by diret ontat from person

to person. But apart from that form, and the septicaemicform that ends in pneumoni form of plague, the ontinuane

of epidemi plague depends mainly upon lose assoiation

between humans, rats and eas. The epidemic wave in people

follows losely the wave of infetion and death in rats.


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2.7 Types of plague

Sylvatic plagueThe sylvati plague is maintained in relatively resistant

hosts alled permanent reservoir hosts. These transmit the

infetion to less resistant animal hosts resulting in epizootis.

When infection-is endemic in sylvatic rodents, it may remain

dormant a long time before irumstanes favour its epidemi

spread. During this time human beings in villages oasionally

ontrat the infetion through handling an infeted animal,

but the disease usually does not beome epidemi unless

infetion spreads to what is sometimes termed a liaisonrodent, meaning a speies of rat that omes in ontat with

people. An epidemi starting in this way runs a harateristi

course, which consists of three phases: a pre-epidemic phase,

an epidemi phase and adeline phase.

In the pre-epidemic phase, the few cases that occur

are separated by onsiderable intervals of time. This is

followed by the rapid ourrene of a large number of

ases. Finally, there is a deline, but not so long drawn out.

Infection does not occur by direct contact with the sick. The

epizooti spreads by ontiguity from plae to plae, so that

an inreasing number of small foi are established.

dometi laue

Domesti plague is intimately assoiated with humans and

rodents living among them, and ours when infetion is

picked up from permanent reservoir hosts by peri-domestic

rodents, whih in turn transmit it to the ommensal rodents

and thence to people. The rat fall (rodent epizootic) may

be an early warning signal of imminent outbreak of buboni

plague.

per altum infetion

Plague may also our per saltum, in whih a fous of plague

suddenly appears several miles from the primary fous. This

new fous ats as the entre from whih the infetion an


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spread to the surrounding loalities. While the ontiguous

mode of spread is dependent upon the gradual dissemination

of plague among the rats, per saltum infetion results fromthe transport of infected rats or rat eas by railways, ships

or other means. It is probably owing to importation of plague

from ities that villages are infeted.

Plague epidemi yle is depited in Fig. 4

Fiure 4: Plague epidemi yle

DOMESTIC CYCLE SYLVATIC CYCLE

Uninfected host

Infected host

Diseased host

Pneumonic plagueBubonic plague Septicaemic plague

RECOVERY DEATH

Wild rodent

Domestic/Peri-domestic

Droplet

infection

Handling infected

tissues

Bioterrorism

Flea

DIAGNOSIS CASE MANAGEMENT,

Wild rodent

Flea


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Yersinia pestis infetion in humans ours in one of three

main clinical forms: bubonic, septicaemic and pneumonic.

Bubonic plague is characterized by regional lymphadenopathy

resulting from cutaneous or mucous membrane exposure.

Primary septiaemi plague is an overwhelming plague

bacteraemia usually following cutaneous exposure. The

plague agent penetrates the human organism through skin

lesions or through the muous membranes of the mouth,

nose or eyes. Primary pneumoni plague results frominhalation of aerosolized droplets ontaining Y. pestis.

3.1 Buboni laue

After an incubation period of two to six days, patients

typically experience a sudden onset of illness characterized by

malaise, headahe and shaking hills, whih are aompanied

by fever and pain in the affeted lymph nodes, whih beome

swollen (buboes). Buboes may occur in any regional lymphnode sites such as inguinal, axillary, supraclavicular, cervical,

post-auricular, epitrochlear, popliteal or pharyngeal. They

are usually unilateral. The bubo may remain enlarged and

tender for weeks following an otherwise satisfatory linial

recovery. Buboes may also get suppurative. Necrotic material

from suh buboes may ontain viable Y. pestis. The typial

linial buboni plague ase is presented in Figs. 5 and 6.

clinial manifetation3


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Figure 5: A patient with bubonic plague (inguinal bubo)

Figure 6: A patient with bubonic plague (axillary bubo)

3.2 setiaemi laue

This is usually seondary to buboni plague. Primary

septicaemic plague is a progressive; overwhelming infection

with Y. pestis in the apparent absene of a primary

lymphadenopathy. Plague septiaemia, whether primary or

seondary to buboni plague, may lead to metastati infetion

of other organ systems. Bloodstream infection may result in a

wide spetrum of pathologial events inluding disseminated


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intravascular coagulopathy (DIC), multiple organ failure, and

adult respiratory distress syndrome (ARDS). Septicaemic

cases also can experience endotoxic shock in some instanceswithout loalized signs of infetion. compliations inlude

pneumonia, meningitis, endophthalmitis, hepati or spleni

absesses, or generalized lymphadenopathy.

3.3 pneumoni laue

Plague pneumonia ours in two distint and epidemiologially

signicant forms. Primary pneumonic plague is the most

fulminating and fatal form of plague. The inubation period

is usually one to four days. The onset of the disease is

typially manifested by the sudden onset of hills, fever,

headahe, body pains, weakness and hest disomfort.

Cough, sputum production, increasing chest pain, difculty

in breathing, hypoxia and haemoptysis become prominent

as the disease rapidly progresses. Death usually ensues if

specic antibiotic therapy is not begun within the rst 1824

hours of disease onset.

Seondary plague pneumonia results from haematogenous

spread ofY. pestis to the lungs and is the most ommon

pneumoni plague. This invasive infetion provokes an

inammatory response and results in bacterial multiplication

in pulmonary tissue. This proess then spills over into the

alveolar spaes and provides a mehanism for Y. pestis to

be expelled during coughing episodes (patients sputum may

be bloody). Spread ofY. pestis to others by the respiratorydroplet route an initiate an epidemi of primary pneumoni

plague.

The ommon linial signs and symptoms observed in

different types of human plague are shown in Table 2.


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Table 2: common symptoms/syndromes of human plague

clinialsymptoms

Types of human plague

Buboni setiaemi Primaryneumoni

Sudden onset + + +

Fever + + +

Bubo + +/

cough with bloodstained sputum

+

3.4 differential ianoi

Bubonic plague may be confused with streptococcal or

staphylococcal lymphadenitis, infectious mononucleosis, cat-

scratch fever, lymphatic lariasis, tick typhus, tularaemia,

syphilis and other auses of aute lymphadenopathy.

Septicaemic plague mimics any non-specific sepsis

syndrome, or a gram-negative sepsis. Pneumonic plague may

be confused with other causes of acute, severe community-

aquired pneumonia, suh as pneumooal, streptooal,haemophilus inuenzae, anthrax, tularaemia, Legionella

pneumophila, leptospiral, hantavirus pulmonary syndrome,

and inuenza virus pneumonia.


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Standard case denition4

WHO recommends the case denition on criteria based on

epidemiology, and laboratory ndings in accordance with new

diagnosti tehniques11. This case denition is a reference

for International Health Regulation notication and should

be used for epidemiologial investigation when it is possible

and appropriate.

The ourrene of a suspet ase in an area not known to

be endemic for plague is an event to be notied to WHO in

accordance with the revised International Health Regulations

(2005). This notication triggers a verication process

that includes the consultation of an expert committee. The

expert committee may conrm the occurrence of plague

based on the available evidene and additional laboratory

investigations may be reommended.

An international meeting on preventing and ontrolling

plague was held on 711 April 2006 in Antananarivo,

Madagascar, recommended the following case denition

criteria based on epidemiology and laboratory ndings.


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Table 3: Criteria for conrmation of plague

Type Features Laboratory results

Suspetedase

compatible linialpresentation;and onsistent

epidemiologial

features, suh

as exposure toinfeted animals

or humans and/

or evidene of

ea bites and/or residene in or

travel to a known

endemi fouswithin the previous

10 days.

Presumptive

ase

Meets the denitionfor suspet ase

plus:

At least 2 of the 4 following tests

must be positive:

Microscopy: material from bubo,blood or sputum contains Gram-negative oobailli, bipolar

after Wayson or Giemsa staining;

F1 antigen detection in buboaspirate, blood or sputum;

a single anti-F1 serology withoutevidene of previous Yersinia

pestis infection or vaccination;- PCR detection ofY. pestis inbubo aspirate, blood or sputum.

Conrmedase

Meets the denitionfor suspet ase

plus:

An isolate from a linial sample

identied as Y. pestis (colonialmorphology and two of the four

following tests must be positive:phage lysis of cultures at 2025 Cand 37 C; F1 antigen detection;PCR; Y. pestis biochemical prole;

or a fourfold difference in anti-F1antibody titre in paired serum

samples;

or (in endemic areas whenno other conrmatory testcan be performed) a positiverapid diagnosti test using

immunohromatography to detet

F1 antigen.

Note: Case denitions assume that all diagnostic tests have been

validated for diagnosis ofY. pestis in linial speimens.


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The laboratory plays a vital role in surveillane and diagnosis

of plague. Efcient utilization of laboratory services can be

ahieved only by providing the right speimens olleted

in the right quantity and sent in the right ontainer at the

right temperature to the right laboratory.

5.1 Laboratory and surveillance

Plague surveillane requires laboratory support for evideneof plague activity in rodents, carnivores, eas and human

beings. Fleas are proessed for isolation of plague bailli,

identication and calculation of ea index (average number

of eas per rat). Serological investigations are carried out

for detetion of antibodies in rodent, arnivore and human

sera. Rodents must be identied to as the importance in

public health can differ according to the species (for instance,

black rat and brown rat). Rodent organs are processed for

the isolation ofY. pestis.

5.2 colletion, torae an tranort ofamle

Laboratory examination of specimens from clinically and/

or epidemiologically suspected case(s) is important to

establish diagnosis of plague to support appropriate

preventive and ontrol measures. When plague is suspeted,

clinical specimens should be collected urgently and specic

Laboratory in surveillancean ianoi

5


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antimirobial treatment begun without waiting for the

laboratory report.

Fiure 7: Flow of speimens, task assignment and feedbak at

various levels of laboratories

colletion an tranort of eimen

Dead rodentsRodent arasses or tissues an be transported

on wet ice, dry ice, freezer packs or in special containers lled

with liquid nitrogen. If these are not available, samples (such

as liver or spleen) can be taken from carcasses and sent at

ambient temperatures in Cary-Blair transport media.

Trapping of rodentsMultiple ath live traps are preferable

to snap or dead fall traps because eas tend to leave a dead

hosts body as it cools. Live traps are useful for capturing hosts

for ea collection, and tissue and blood samples. Traps must be

set at specic sites where there are burrows, nests, runways or

other evidene of rodent ativity.

Rodent seraBlood for serology can be collected from rodents

by a variety of tehniques inluding ardia punture. Samples

Subdistrit Speimen olletion

Distrit hospital Diret mirosopy

Divisional/State laboratory(Designated laboratory)

culture, Fluoresent Ab test,ELISA/Rapid diagnostic test

National referenelaboratory

Conrmatory tests

Reort


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olleted an be transported diretly in sterile, sealed tubes

under cold conditions (cool box with icepacks).

VectorsIf hosts are captured live, they should be anaesthesized

and plaed in a white enamel pan and brushed vigorously from

the tail end forwards with a toothbrush or omb. This will

dislodge eas from the hosts. Fleas will fall to the bottom of the

pan and can be collected by ea-sucking tubes and placed in

vials. These may then be transported to the nearest laboratory

capable of identication and further processing.

Fleas an also be olleted from rodent burrows by burrow

swabbing.

Carnivore seraBlood from dogs can be obtained from large

veins in the forelegs or hind legs after properly restraining and

muzzling them. Samples olleted an be transported diretly

in sterile, sealed tubes under old onditions.

Human samplesHuman blood, sputum, bubo aspirates, and

serum an be olleted and transported to the referene lab.

Human eimen

Speimens should be obtained from appropriate sites forisolating the bateria. As far as possible, these should be

olleted before initiation of antimirobial therapy.

The preferred specimen for microscopic examination

and isolation from a bubonic case is aspirated uid from

the affected bubo, which is expected to contain numerous

organisms (see protocol at annex 1).

Blood specimens for culture ofY. pestis should be taken

whenever possible. Organisms may be seen in blood smears

if the patient is septicaemic. Bacteria may be intermittently

released from affected lymph nodes into the bloodstream;

therefore, a series of blood specimens taken 1030 minutes

apart may be produtive in the isolation ofY. pestis.

A bronhial/traheal washing or sputum should be olleted

from a suspeted pneumoni plague patient. Sputum/throat

smears taken from pneumoni plague patients may ontain

too many other organisms to be of diagnosti value when

only Wayson stain is used. These smears should be stained


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with the more specic direct uorescent-antibody (DFA) test

or subjeted to a validated enzyme immunoassay test.

In biopsies or in specimens taken post-mortem where

reovery of live organisms is ompromised, lymphoid tissues,

spleen, liver, lung and bone marrow samples may yield

evidene of plague infetion by DFA test.

A brief summary of speimens required is shown in

Table 4.

Table 4: Laboratory speimens required for Plague diagnosis

clinial preentation seimen

Bubonic

Pneumoni

Septiaemi

Post-mortem

Bubo uid/aspirate

Serum

Bronchial/tracheal washing

Sputum

Serum

Blood

Blood

Biopsy from lymph nodes, lungs,bone marrow, spleen, liver

preaution in hanlin eimen

As these speimens are known to or thought likely to ontain

infetious substanes, the following preautions should be

applied:

Follow strict aseptic technique (gowns, gloves,

masks)..

Wash hands before and after the olletion of

material.

Plae the speimen aseptially in an appropriate

sterile ontainer.

Tightly lose the ontainer.

Label and date the ontainer.


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pakain/ tranort of eimen

In accordance with currently accepted biosafety norms, Y.

pestis is listed under Biosafety II level. Therefore, the WHOGuidelines for the safe transport of infectious substances

and diagnostic specimens (WHO/EMC/97.3) for shipping

dangerous goods should apply when the speimens are

to be shipped via air transport either domestially or

internationally.

The requirements, in brief, are:

A watertight primary reeptale.

A watertight seondary reeptale.

An absorbent material, whih must be plaed between

the primary reeptale and the seondary pakaging.

The absorbent material must be adequate to absorb

the entire ontents of all primary reeptales.

The receptacle must be at least 100 mm in the

smallest overall external dimension.

Itemized list of contents must be enclosed.

Reeptales must withstand, without leakage, internal

pressure difference of not less than 95 kPa (0.09

bar, 13.8 lb/in2) and temperature range of 40 oc

to +55 oc.

The outside package must be marked with identication

of the infetious substane, volume of ontents, and

the name and telephone number of the sender.

Infectious agents, serum or culture vessels should be

labeled with an alcohol-resistant, permanent ink marker,

giving the ontents and date. The materials should be sealed

with a medical-grade leak-proof tape to prevent inadvertent

leakage, and then wrapped with several layers of absorbent

material. The absorbent-wrapped materials are placed in

a leak-proof bag, soaked with disinfectant (quaternary

ammonium or phenolic solutions) and sealed. The sealed bag

is then placed in the rst of the above mentioned containers.Depending on the speimen and the destination, the double

container is sent in a sealed box with or without coolant.


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Do not use wet ie for pakaging beause it melts and

leaks. Cool packs (plastic bags containing frozen foam/

refrigerant) are acceptable but must be placed in the boxin suh a way that, upon thawing, they do not permit

movement of materials within the box. Containers must be

espeially well sealed if they are being shipped under dry

ie onditions. Dry ie evaporates, and this must be taken

into onsideration when paking.

An important part of transportation is the proper

labeling of the ontainer and the inlusion of the paperwork

that identies the specimen(s), the clinical history or theepidemiological information, the senders identication and

address, the purpose for whih the speimen is sent and

the import/export licenses if necessary. The outside of the

container must be labeled with all the proper identication

and biohazard warnings. If transporting with dry ice, the

box must be identied with the correct label.

Loal urfae tranort

A network or a ourier servie should be used for transport

of specimens from a doctors ofce/surgery to a laboratory,

from a hospital to a diagnosti laboratory, or from one

laboratory to another.

The priniple of safe transport by this means is the same

for air or international transportthe material should not

have any possibility of leaking or esaping from the pakage

under normal onditions of transport.

The following practices should be observed:

specimen containers should be watertight and leak-

proof;

if the speimen ontainer is a tube, it must be tightly

apped and plaed in a rak to maintain it in an

upright position;

speimen ontainers and raks should be plaed in

robust, leak-proof plastic or metal transport boxes

with secure, tight-tting covers;


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For the performane of various tests, guidelines are

available in manuals from WHO, the centers for Disease

Control (CDC), Atlanta, or other nationally approveddouments. The interpretation of these tests should be in

conformity with the case denitions described earlier in this

doument.

Moleular tehnique

Moleular tehniques are powerful tools that an be used

to provide information about the etiologial agent that

annot be obtained by traditional diagnosti methods. When

standard mirobiologial methods fail to yield a viable isolate,

molecular-based tests may be the only means available to

conrm the presence ofY. pestis.

Moleular tehniques used by the diagnosti laboratory

are primarily for the purpose of grouping isolates to gain

more disriminatory power, ompared with the traditional

biologial typing methods. Reproduibility of moleular

diagnostic techniques is inuenced by biological and technical

variability; therefore, these techniques in the diagnostic

laboratory should be validated before appliation.

Polymerase chain reaction for the detection ofelete YeRinia eti ene

The PCR methodology has provided exquisite discriminatory

power in deteting low quantities of an infetious agent

nucleic acid in a specimen. Because of PCRs theoretical ability

to detet a single DNA opy, the use of PcR methodology

in a diagnosti laboratory has to be rigorously ontrolled to

prevent false-positive results.

Rai ianoti tet

Late diagnosis is one of the major auses of deaths among

human ases, as well as spread of the disease, sine it limits

the effetiveness of ontrol measures.


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The development of a rapid diagnostic test (RDT), based

on immunochromatographic detection of the F1 antigen,

which is specic to plague bacilli, is a major step forwardin ase management and surveillane of plague. The F1

dipstik assay on sputum and pus is an invaluable diagnosti

tool for pneumonic plague. F1 antigen could be detected in

sputum by ELISA and dipstick tests as early as the second

day after the onset of the symptoms and also up to 48 h

after treatment. This test is able to reliably conrm a suspect

case in 15 minutes, and is sufciently simple and robust

for use in the eld at peripheral level. The RDT contributes

to the redution in the delay in diagnosis, allowing for the

early treatment the only way for patient survival. Like

other dipstick assays, it is a semi-quantitative test involving

manual reading and a subjetive threshold. The test was

sensitive, reliable and easy to use. The test is useful for alert

and response to outbreaks. Its main advantages are a low

detection limit (15 ng/ml), results within 15 min, specicity

and sensitivity of ~100%, compatibility with samples from

both humans and rodents, insensitivity to ontaminants,prior treatment and low ost. The test must be performed

by specially trained health staff (see annexes 1 and 2 how

to use it).

RDT is ommerially available and an be purhased by

ountry or provided by WHO.

5.4 safe hanlin of infetiou material

in the laboratory

Handling ofY. pestis or material suspeted to harbour this

organism requires biosafety level II (BSL-II) environment

and preautions. However, when large volumes of ultures

are handled, BSL-III facilities are required. Only trained

personnel, working in a restrited area, should undertake

plague diagnosti work. The infetious material must be

handled only in biosafety cabinets (with vertical laminar airow

under negative pressure and vented to the outside).


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In accordance with national or institutional policy,

chemoprophylaxis or immunoprophylaxis, with regular

monitoring, should be provided to laboratory staff. Theymust wear gowns, gloves (with sleeves of gowns tucked

into gloves) and proper masks (if aerosol generation is

expected). Hand-washing before leaving the laboratory

should be mandatory.

A solution of 0.5% sodium hypochlorite should be used

to deontaminate the laboratory surfaes as well as for

managing the spills. In the latter case, sodium hypochlorite

should be sprayed into the spill, left for 10 minutes andfollowed by a 70% alcohol wash. Other germicidal solutions

ontaining phenol or quaternary ammonium ompounds

should be used in instanes where hypohlorite is onsidered

orrosive.

All ontaminated material must be plaed in highly visible

biohazard bags. These should be lled only to twothirds

apaity, sealed with sterility indiator autolave tape and

autoclaved at 115 oC for 15 minutes before disposal. Sharpsshould be disposed of in rigid puncture-proof containers

labeled with a biohazard sign and deontaminated with

autolaving.

The waste disposal must also onform to all other the

national/institutional guidelines.


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Long-term prevention and control of plague is primarily

based on the following activities:

Surveillane

Rodent ontrol

Vetor ontrol

case management

Chemoprophylaxis

Immunoprophylaxis

Infection control.

6.1 surveillane

Plague is primarily a disease of rodents; therefore, a natural

deline in human plague inidene would not justify the

onlusion that plague has disappeared from an area. With

the deline in human plague inidene in a partiular biotope

the infetion probably reedes to its original hostswild

rodents. Plague is not stati but shifts from plae to plae

through ontiguity of olony infetion among wild rodents,

whih eventually transfers the infetion to the ommensal

rodents on their path. Many bioti and abioti fators

inuence the persistence of the disease in wild populations

and the ourrene of epizooti plague. The natural foi of

plague are known to be maintained in wild rodents in a

prevention an ontrol6


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yli pattern. Sudden eologial hanges might reate a

spill-over of sylvatic plague into domestic environments.

Recent outbreaks have shown that plague may re-emergein areas after a long period of silene. Therefore, ontinuous

surveillane and vigilane should be maintained as a part of

epidemi preparedness and early warning systems.

Objetive:

To etet early warning signals of an outbreak.

To i n t i t u t e timely and appropriate ontrol

measures.To ae the impat of intervention measures.

To enure early ontainment of the outbreak.

To identify loal eologial fators or human ativities

that may result in increased plague exposure risks for

humans (e.g., through study of the rodent population

stress under whih migration takes plae, and the

shifting of rodent populations).

To etet trends in the epidemiology and epizootiology

of plague in a given region (e.g., by mapping out

the various species of eas vis--vis their sustaining

host).

Surveillance is not a one-time activity, it is a continuous

and ongoing systematic collection of data for action.

6.2 Organization of surveillance activities

The following organizational set-up is required for plague

surveillanein enzootic foci:

Identication of a nodal ofcer

One ofcer each at the province and district level should

be identied as the nodal ofcer for surveillance of plague.

He/she will be responsible for oordination and initiating

neessary ations based on analysis and interpretation

of surveillane data from all soures at the provine and


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distrit levels, respetively. He/she should preferably be the

surveillance ofcer of the province/district and should be

an experienced and senior ofcer trained in the principlesof epidemiology, surveillane, outbreak investigation and

management.

Fiel urveillane funtionarie

The following team members are required for effetive

plague surveillance:

Medical ofcers trained in epidemiology.

Entomologists.

Mirobiologist/Veterinarian.

Laboratory tehniians/assistants.

Field surveillance workers (rodent trappers).

Dening geographical area for surveillance

The geographical area for surveillance may be dened by

using one or more of the following criteria:

Known fous of plague.

Detection of plague ( Y. pestis) activity.

Report of suspected human case(s) of plague.

If limited resources do not permit active surveillance

in a wider area, villages losest to the known foi or from

where plague ativity has been deteted reently should be

taken up rst.

In the South-East Asia Region, natural foci of plague are

known to exist in India, Indonesia and Myanmar. These foci

require onstant surveillane as plague has the potential

to spread from wild rodents to peri-domestic and domestic

animals and humans. Surveillane needs to be further

initiated or intensied when there are ecological changes

such as earthquakes, ooding or heavy rainfall, and if the


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human habitation is in close proximity to the burrows of

wild rodents, beause the risk of transmission of infetion

to human beings inreases in these situations.

6.3 comonent of urveillane

A comprehensive surveillance system for plague

omrie:

Rodent surveillane.1.

Vetor2. (ea)surveillane.

Carnivore (dog) surveillance.3.

Human surveillane.4.

Roent urveillane

Rodent populations in the wild and peridomesti areas should

be ontinuously assessed for plague ativity.

The most ommon tehniques for monitoring plague in

rodent populations include:

collecting and examining dead rodents, including

post-mortem; and

trapping rodents for population data, serum, tissue

samples and ea collection.

When olleting biologial material, it is reommended

that standard universal preautions should be taken.

Rodent identication is important. The reservoir hostsinclude many species of rodents. R. norvegicus (Norway rat)

and R. rattus (Roof rat) are the commonest urban rodent

hosts. Tips for morphological identication of roof rat, Norway

rat and house mouse is presented in Fig. 9 and phenotypi

harateristis have been presented in Table 5 .


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Fiure 9: Roof rat, Norway rat and house mouse


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Table 5: Field haraters and measurements in

ommensal rodents

charater Norway rat(Brown rat)Rattus norvegi-us

Roof rat (Blackrat)Rattus rattus

House mouseMus musulus

Weiht 150600 gm 80300 gm 1021 gram

Hea anbody

Nose blunt,heavy, stockybody, 1825 cm

Nose pointed,slender body,1621 cm

Nose pointed,slender body,610 cm

Tail Shorter thanhead plus body,

uniformly darkoloured, na-ked, 1925 cm

Longer thanhead plus body,

uniformly darkoloured, na-ked, 1925 cm

Equal to or alittle longer than

head plus body,uniformly darkcoloured,naked, 711 cm

Ear Relativelysmall, close-set, appearhalf-buried infur, rarely over2023 mm

Large, promi-nent, thin andhairless, standwell out fromfur, 2528 mm

Prominent,large for size ofanimal, 15 mmor less

Fur Brownish-grey

on bak, grey-ish on belly

Brownish-grey

to blakish onbak, belly maybe white, greyor greyish-black

One subspeies

brownish-greyon bak , grey-ish on belly,another grey-ish on bak andgreyish-whiteon belly

Mammarylan

6 pairs 5 pairs 5 pairs

Habit Burrows, swims

and diveseasily, gnaws,live indoors,in sewers anddrains

Agile limber,

gnaws, oftenlives off theground in treesvines, etc.; livesindoors andoutdoors

climbs, some-

times burrows,gnaws; livesindoors andoutdoors

While olleting biologial material reommended

standard universal preautions should be taken.


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Safety measures to be adopted by rodent trappers,

an laue worker

Wear gloves and gum boots.

Use chemoprophylaxis if there is evidence of plague

ativity in a trapped rodent.

Convenient supply of snake anti-venom for rodent

athers.

Pre-exposure immunization against rabies for those

involved in arnivore surveillane.

Vetor urveillane

Vector (rat ea) surveillance should be regularly conducted

to determine the species, ea index and susceptibility to

insecticides. An increase in the density of eas increases

the potential of an outbreak. The ea index (absolute and

specic) or ea population density is calculated by dividing

the number of eas by the total number of rodents. Specic

ea index is important to know the potential for plague

transmission.

Specic ea index =No. of ea species collected

Total no. of rodents olleted

A specic ea index of one or above should be treated as

a high risk factor (critical ea index) and an early warning

signal of the risk of a potential outbreak. However, an inrease

in the average number of eas per host (absolute ea index)

may be of little concern when the particular ea species is

a poor vetor of plague. Poor vector species identied areNosopsylla nilgriensis, Nosopsylla spp., Ctenocephalides felis,

Ctenocephalides canis, Ctenocephalides orientalis, Styvalis

aporous and Styvalis ahale

carnivore urveillane

One of the most powerful tehniques for deteting evidene

of plague ativity is to ollet serum samples from arnivores

that onsume rodent prey or are likely to savenge fresh

rodent carcasses. Although some carnivore species (such


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as those belonging to the cat family) often die ofY. pestis

infetion, others apparently suffer little, if any, illness. Dogs

typially survive plague infetion and develop antibodies thatcan be detected for as long as six months.

Human urveillane

In areas known to be endemic for plague, all health

funtionaries and even the ommunity should be on the

alert for patients with symptoms suggestive of plague.

Case denitions must be disseminated to peripheral health

funtionaries as well as the ommunity in loal languages

to strengthen lay reporting (WHO case denitions for plague

are contained herein, Chapter 4). Even a single case of

suspected plague should be immediately notied to the higher

authorities. Following identication of a suspected case of

human plague, surveillane personnel should immediately

determine whether other cases exist or have occurred

reently in the viinity.

When sentinel animal sero surveillane indiates plague

ativity, or during rat falls, then human serosurveillane

may be undertaken.

6.4 Early warning signals

The surveillane system should be effetive to detet early

warning signals, whih are the preursors of a potential

outbreak.

Early warning signals surveillane mehanim of ete-tion

Rat fall Rodent surveillane. community andthe health personnel in the poten-tially at-risk areas must be aware ofthe urgeny of reporting rat falls.

Specic ea index more thanone

Flea surveillane

Seropositivity in rodent popula-tion

Detetion of plague ativity in ro-dents

Positive serology in anines carnivore surveillane

Suspeted ase of human plague clinial human surveillane


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Health failities must report immediately any ase of suspeted

plague that ts into the clinical case denition as mentioned

in chapter 4. A suspeted human ase of plague is a medialemergeny and should be treated as a potential outbreak,

warranting immediate investigation and follow-up action.

All the omponents of the surveillane systemolletion,

compilation, analysis and interpretation of data, follow-up

ation and feedbakmust be arried out in a systemati and

organized manner. This must be oordinated by the nodal

ofcer. Supervision and monitoring at all levels is mandatory

for ensuring effetive surveillane.

6.5 Roent urveillane an e-rattin ineaort

Seaports were major points of entry* of food materials, other

goods and people before the development of air transport.

Even today, major trading of food, goods and other materials

are arried out in seaports due to ost fators, and ships are

frequently infested with rodents. The ativities undertaken at

ports, suh as handling of foodstuffs, attrat many speies of

vermin. Similarly, ports are exposed to the risk of introduction

of vetors from any other part of their host ountry or any

other port in the world. Therefore, surveillane ativities in

ships and seaports should be arried out in the following

manner:

Surveillane ativities should inlude argo vessels,

passenger vessels, sailing vessels and fishing

vessels.

Surveillane ativities should inlude all areas in and

around the port areas, suh as port installations and

residential olonies.

*point of entry means a passage for international entry or exit oftravellers, baggage, argo, ontainers, onveyanes, goods and postalparels, as well as agenies and areas providing servies to them onentry or exit.


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Rats and mie an gain aess to ships diretly by

mooring ropes, hulls and gangways. They may be onealed

in cargo, ships stores and other materials taken onto theship. However, prevention through appropriate onstrution

and rat-proong will ensure almost complete control of

rodents aboard the ships. Some ships may require major

alterations, but most rat-proong measures can be readily

undertaken.

Inetion of hi an iuane of an exemtioncerticate

All vessels arriving from a foreign port must have a de-

ratting certicate issued in a designated approved port.

It is important that the de-ratting certicate is valid and

that the ship under inspection has been de-ratted within the

previous six months period.

If the de-ratting certicate was issued more than six

months previously, the ship must be inspeted at an approved

port and, if neessary, treated to ontrol the rodents, or

another exemption certicate issued. An exemption certicate

indiates that the inspeted ship is free from rodents.

Note: De-ratting certicate is issued after de-ratting which is

valid for six months. If it expires, then exemption certicate

is issued with or without de-ratting.

Rat elimination in an aroun ort area

There are ve basic steps when eliminating a rat population.For rodent control to be effective and efcient on a long-term

basis, all ve basic steps should be implemented:

Inspection

Sanitation

Exclusion

Population reduction (traps, baits, repellents)

Verication.


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Roent ontrol in hi

Deploy traps or poison bait stations near any possible(1)

spot a rat ould board.

Use multiple approahes.(2)

Deploy snap or wonder traps, sticky boards (glue

traps) and rodenticides.

Put traps where sign is found, in dark and

onealed spaes and near food or garbage.

Never throw a live rat overboard. They are good(3)

swimmers and may reah land.

Ways to prevent entry of rodents

into hi in eaort

When tying up in port, look for ways rats ould board the

vessel, and take steps to stop them.

Use rat guards on doklines lines where appropriate.

Seal entry points to the vessels interior, such as cable chases,

and put sreens or louvers over windows and vents.Inspect and shake out shing nets and lines before taking

them aboard. Rats partiularly like to nest and shelter in trawl

and seine nets and oils of line.

6.6 Health education and communityartiiation

People living in endemi areas should be provided with health

education regarding the signicance of rat falls, handling of

rat arasses, modes of transmission, symptomatology of

plague and the importane of immediate reporting to the

nearest health faility should a ase be suspeted. They

should also be informed about the ommon myths and

misoneptions about plague.

The ommunity should be eduated about prevention

and ontrol of plague. Health eduation an be undertaken


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by organizing talks and by involving media, publi relations

institutions, schools and community-based organizations and

nongovernmental organizations (NGOs).

6.7 Interetoral oorination

Various departments, suh as those responsible for traditional

mediine, soial welfare, loal development, revenue, forest,

veterinary/livestok/animal husbandry and agriulture,

should be involved in the surveillane ativities.

The existing intersectoral coordination mechanism foravian inuenza, zoonoses or emerging infectious diseases

may be used for decision-making and coordinating action

plans.

6.8 Roent ontrol

It is virtually impossible to completely control the wild rodent

population and equally impossible to control the eas that

feed on them. Prevention is based on ontrolling rodentpopulations in rural and urban settings as muh as possible.

Rodent control activities should be undertaken during inter-

epidemi periods only. Killing of rodents during epidemi

situations may result in large number of eas leaving the

dead rodents and biting human beings and transmitting the

infetion. Therefore, rodent ontrol measures should never

be undertaken during outbreaks.

The following methods are employed for rodent

control:

Environmental sanitation

Physial methods

chemial methods

Biological methods.


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Environmental anitation

Environmental control of domestic rats involves proper

garbage disposal, proper drainage systems, rat-proof foodstorage and the rat-proong of building structures.

In houe: The following preventive measures should be

taken:

Food should be stored in rat-proof containers such

as glass or earthenware jars or metal ans and bins

with lids.

Water storage ontainers should be overed andleaking taps repaired.

Food wastes must not be left where rats an get

at them. Tables and oors should be swept clean

of leftover food. Kithen refuse should be stored in

rat-proof containers with tight-tting lids.

The house should be searhed for holes in the walls

and oor. All openings more than 6 cm wide should

be sealed with rat-proof material (mortar, concrete,metal sheeting, wire mesh or other such material).

Speial attention should be paid to spaes under doors

and where pipes pass through walls, windows and

other openings, ventilation grills and gaps between

tops of walls and eaves. Aess to open windows

and eaves an be prevented by plaing metal guards

along overhead cables and external pipes.

If the exterior wall has a rough surface, a smooth

band of paint 10 cm. wide can be applied below

window height but preferably more than one metre

above ground level so as to prevent rats from limbing

up the walls.

Aroun houe: The following preventive measures should

be taken:

Premises, inluding yards and vaant plots, should

be kept lean and free of aumulations of junk and

debris.


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All plant growth likely to harbour rats or oneal their

ativities should be ut down.

Branches of trees growing close to the house should

be ut down to prevent easy aess to roofs.

In the community: The following preventive measures

should be taken:

Solid wastes should be olleted and disposed of

properly. Partiular attention should be given to piles

of industrial refuse, inluding damaged paking ases

and building materials, as they attrat rats.

complete sealing of drains and the sewage system or

other sanitation systems is also absolutely essential.

Rat-proof covers should be placed over access points.

Ends of ventilator shafts and disused drains should

be sealed off at the points of entry into the main

sewer. Other underground strutures, suh as drains

for surfae water and onduits for eletrial ables,

should also be rat-proofed as fully as possible.

Buildings where food is stored, such as warehouses,

should be made rat-proof.

Physical methods

Trap barrier system (TBS)

TBS is a type of physical control of eld rodents by putting

fences around crops. This system, described as eco-friendly,

is improved by fening around trap rops sown before

the main rop. The trap rop lures the rodents from the

surrounding areas and these rodents are trapped in large

numbers.

chemial metho

Chronic or multiple-dose poisons are slow to act, and several

meals may be required over a period of a few days before

they are effetive. The urrently and widely used poisons

in this group are the antioagulants. The best known is


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Warfarin, but others are also equally effetive. Table 5 shows

four ommonly used ompounds and their reommended

dosages for mice and rats. Many ready-to-use preparationsof antioagulants are available. The baits an be prepared

with loally available materials. The simplest preparation

is a dry medium-ground or crushed cereal to which the

onentrate is added. The addition of a vegetable oil may

make the bait more attrative for a time, until the oil turns

ranid. Sugar added to give a onentration of about 5 per

ent is also a useful additive.

Table 6: Multiple-dose rodenticides and their dosages againstommon rodents

comoun* Dosage in parts per million**

Houe moue Roof rat Norway rat

Warfarin 250500 250500 50250

Diphainone 125250 50100 50100

coumatetralyl 250500 250500 250

Pindone

Documents

Operational Guidelines on Plague[2]