Communicable Diseases in humanitarian settings

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“communicable” diseases

Infectious diseases that can be transmitted from one individual to another either directly by contact or indirectly by fomites and vectors.

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Communicable diseases

Air-borne diseases

• Legionellosis

• Meningococcal disease

• Pneumococcal infections

• Tuberculosis

• Viral haemorrhagic fevers

Diseases preventable by vaccination

• Diphtheria

• Haemophilus influenza

• Measles

• Mumps

• Pertussis

• Poliomyelitis

• Rubella

Zoonoses and vector borne

• Brucellosis

• Echinococcosis

• Rabies

• Malaria

• Plague

Sexually transmitted diseases

• Chlamydia infections

• Gonococcal infections

• HIV-infection

• Syphilis

Viral hepatitis

• Hepatitis A

• Hepatitis B

• Hepatitis C

Food- and water-borne diseases Cholera Hepatitis Botulism Campylobacteriosis Cryptosporidiosis Giardiasis E.coli Leptospirosis Listeriosis Salmonellosis Shigellosis Toxoplasmosis Trichinosis Yersinosis

WHO 2004: Low income countries leading mortality causes

Lower respiratory infections

Diarrhoeal diseases

HIV/AIDS

Prematurity and low birth weight

Stroke and other

cerebrovascular diseases

Coronary heart disease

Chronic obstructive pulmonary

disease

Tuberculosis

Neonatal infections Malaria

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MDG 6

Combat HIV/AIDS, Malaria and Other Diseases

• targets

– 1. Halt and begin to reverse, by 2015, the spread of HIV/AIDS

– 2. Achieve, by 2010, universal access to treatment for HIV/AIDS for all those who need it

– 3. Halt and begin to reverse, by 2015, the incidence of malaria and other major diseases

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HIV and crises

• How do crises affect HIV?

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1. Communicable disease cycle

Healthy State

Risk factors

Exposure factors

Susceptibility to infection

Biological evidence of

infection

Clinical Illness

Progression of disease

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Death

Immunity

Communicable diseases

Population Vulnerability

Individual susceptibility

Risk exposure

Individual physical and material resources

Immunity to pathogens

Health care services

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Higher incidenceHigher mortality

Malnutrition

Absence / Disruption of health

care

Poor Living Conditions

Poor Hygiene Wat/San

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Crises

Communicable Diseases

Epidemics

Effects of outbreaks on health system

1. Population panic2. Overcrowding of Health Services

I. Overwork of Health StaffII. Health Staff at exposed riskIII. Risk to patients

3. Malfunction of Health Services4. Increased morbidity

I. Further spread of outbreaks

5. Increased mortality6. Economic and social consequences

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2. What can be done?

Healthy State

Risk factors

Exposure factors

Susceptibility to infection

Biological evidence of

infection

Clinical Illness

Progression of disease

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Death

Immunity

Prevention

Treatment

Containment

Surveillance

Rapid assessment Surveillance Survey

Often qualitative or semi-quantitative data

quantitative data quantitative data

wide variety of data limited data Can gather wide variety of data

data on convenience sample of people and facilities

Often tries to gather data on every case of illness

Usually gathers data on sample of population

data at a single point in time

data over ongoing, prospective time period

data at single point in time

gathers data for numerator of prevalence and incidence; Denominator must come from separate source

Gathers data for numerator of incidence and prevalence ; Denominator must come from separate source.

Gathers data for numerator and denominator, allowing calculation of prevalence or incidence rates

surveillance

• Systematic ongoing collection, collation, and analysis of data and the timely dissemination of information to those who need to know so that action can be taken.

» World Health Organization

• The ongoing systematic collection, analysis, and interpretation of health data, essential to the planning, implementation, and evaluation of public health practice, closely integrated with the timely dissemination of these data to those who need to know.

» US Centers for Disease Control and Prevention

Surveillance

• Passive Surveillance – uses available data or reporting from health care provider or regional health officer

• Active Surveillance – periodic field visits to health care facilities to identify new cases

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Prevention

• Public level– Vector control

– Water and sanitation systems

– Blood safety requirements

• Individual level– Hand washing

– Condoms

• Public / Individual level– Vaccination

• Routine or during outbreaks

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Control measures

• Prevention of exposure:– Isolation, vector control, containment

– Hygiene and education

• Prevention of infection:– Vaccination, clean water

• Prevention of disease:– prophylaxis

• Prevention of death:– Case identification and management

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Surveillance in emergencies

• Objectives– identify public health priorities; – monitor the severity of an emergency by collecting and

analyzing mortality and morbidity data;– detect outbreaks and monitor response;– monitor trends in incidence and case-fatality from major

diseases;– monitor the impact of specific health interventions – provide information for programme planning, implementation

and adaptation, and resource mobilization.

DATA ➜ INFORMATION ➜ ACTION

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Disease Early Warning System (DEWS) Pakistan

• Covered 92 districts and ~ 60% of the population.• centralized in Islamabad, with regional hubs and

surveillance officers active at district level.• Weekly reporting includes priority epidemic

diseases and those with high morbidity & flood related diseases.

• Data sources include up to 2600 basic health units and all large government hospitals,

• Data relayed using a variety of media, SMS, fax, and telephone.

• Widespread compliance, due in part to the regular visits of the surveillance officers to facilities.

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Disease Early Warning System (DEWS) Pakistan

• quantity of weekly data reported places very high work burden on the surveillance officers, many of whom cover wide geographical areas.

• A lot of data but…– 90% of outbreaks have been detected by formal

immediate alerts.– Only 10% were detected through data analysis.

• incompatibilities with other “vertical” surveillance systems

• Not transitioning to integration into routine government surveillance systems

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DEWS- Film

• http://www.youtube.com/watch?v=s2Q5oQx4dGw&feature=bf_prev&list=ULQRFpUxJxcoE&lf=mfu_in_order

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True or False

• The geographical distribution of reported cases is indicative of where the disease is the worst.

• The case fatality rate data from health facilities is indicative of how deadly a disease is

• In a complex emergency where systems are disrupted it is important for the emergency surveillance system to capture as much information as possible

• HIV, TB and Malaria get a lot of attention and money from global initiatives so it is not appropriate to spend humanitarian funds

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Key information for designing surveillance systems

• What is the population under surveillance

– displaced population, local population etc

• What data should be collected and why

• Who will provide the data

• What is the period of time of the data collection?

• How will the data be transferred (data flow)?

• Who will analyse the data and how often?

• How will reports be disseminated and how often?

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Questions to ask when selecting diseases /conditions

• Does the condition result in a high disease impact (morbidity, disability, mortality)?

• Does it have a significant epidemic potential (e.g. cholera, meningitis, measles)?

• Is it a specific target of a national, regional or international control programme? (e.g.malaria, TB)

• Will the information to be collected lead to significant and cost-effective public health action?

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Key diseases to consider

• bloody diarrhea,

• acute watery diarrhea,

• suspected cholera,

• lower respiratory tract infection,

• measles,

• meningitis.

• Other endemic /epidemic prone diseases (egmalaria or viral haemorrhagic fevers)

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Risk factors

• Diarrheal diseases

– Overcrowding

– Inadequate quantity and/or quality of water

– Poor personal hygiene

– Poor washing facilities

– Poor sanitation

– Insufficient soap

– Inadequate cooking facilities

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Risk factors

• Acute respiratory infections

– Inadequate shelter with poor ventilation

– Indoor cooking, poor health care services

– Malnutrition, overcrowding

– Age group under 1 year old

– Large numbers of elderly

– Cold weather

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Risk factors

• Meningococcal meningitis

– Meningitis belt (although the pattern is changing to include eastern, southern & central Africa)

– Dry season

– Dust storms

– Overcrowding

– High rates of acute respiratory infections

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Risk factors

• Malaria – Movement of people from endemic into malaria-free

zones or from areas of low endemicity to hyperendemic areas

– Interruption of vector control measures– Increased population density promoting mosquito

bites– Stagnant water– Inadequate health care services– Flooding– Changes in weather patterns

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Risk factors

• Measles

– Measles vaccination coverage rates below 80% in country of origin, overcrowding,

– population displacement

• Tuberculosis

– High HIV seroprevalence rates

– Overcrowding

– Malnutrition

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Key terms • Incidence

– the number of new cases of a specified disease reported over a given period.

– number of new cases per 1000 people

• Case-fatality rate (CFR)– the percentage of persons diagnosed as having a specified disease who

die as a result of that disease within a given period,– usually expressed as a percentage (cases per 100).

• Attack rate (outbreaks):– The cumulative incidence of cases (persons meeting case definition since

onset of outbreak) in a group observed over a period during an outbreak.

• Epidemic threshold:– level of disease above which an urgent response is required– specific to each disease depending on infectiousness, other determinants

of transmission and local endemicity levels.

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Epidemic threshold

• Diseases for which one suspected case represents a potential outbreak and requires immediate investigation:– cholera

– measles

– typhus

– plague

– yellow fever

– viral haemorrhagic fever

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Case classification

• Suspected case – Clinical signs and symptoms compatible with the disease in question

but no laboratory evidence of infection (negative, pending or not possible)

• Probable case – Compatible clinical signs and symptoms, and additional

epidemiological (e.g.contact with a confirmed case) or laboratory (e.g. screening test) evidence for the disease in question

• Confirmed case – Definite laboratory evidence of current or recent infection, whether or

not clinical signs or symptoms are or have been present– Even if clinical symptoms are not -subclinical infection is a major

source of transmission

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Case definitions

• developed for each health event /disease /syndrome.– Use MoH or WHO definitions

• For consistency of reporting

• Used for surveillance not treatment

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Case definition: ACUTE WATERY DIARRHEA

Three or more abnormally loose or fluid stools in the past 24 hours with or without dehydration.

• suspect case of cholera:– Person aged over 5 years with severe dehydration or death from

acute watery diarrhea with or without vomiting.– Person aged over 2 years with acute watery diarrhea in an area

where there is a cholera outbreak.

• To confirm case of cholera:– Isolation of Vibrio cholera O1 or O139 from diarrheal stool

sample.

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Case definition: MEASLES

Fever and maculopapular rash (i.e. non-vesicular) and cough, coryza (i.e. runny nose) or conjunctivitis (i.e. red eyes)orAny person in whom a clinical health worker suspects measles infection.

• To confirm case:– At least a fourfold increase in antibody titre or– isolation of measles virus or– presence of measles-specific IgM antibodies..

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Scenario: early detection & response

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Scenario: delayed detection & response

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Zimbabwe Cholera

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Weekly attack rates, by district.

as of 31/01/09 W4

Weekly attack rates, by district.

as of 14/03/09 W11

Global system

• CDC– International Emergency and Refugee Health Branch

• European CDC• WHO

– DCE (disease control in humanitarian emergencies)• Part of Global Alert and Response department• Produce “public health risk assessment” for crises

– GOARN (global alert and response network) http://video.who.int/streaming/eprfilms/GOARN_Working_Together_in_Outbreak_Response.wmv

– Event management system

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WHO SHOC (strategic health operations center)

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International Health Regulations

• Legally binding international treaty – 194 signatory countries– entered into force on 15 June 2007,

• Purpose: enable international community to prevent and respond to acute public health risks– potential to cross borders and threaten people

worldwide

• requires countries to report certain disease outbreaks and public health events to WHO.

• requires countries to strengthen their existing capacities for public health surveillance and response.

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Humanitarian Crises and IHR (2005)

Potential for serious public health impact:

“The population at risk is especially

vulnerable (refugees, low level of

immunization, children, elderly, low

immunity, undernourished, etc.)”

“Concomitant factors that may hinder or

delay the public health response (natural

catastrophes, armed conflicts,

unfavourable weather conditions, multiple

foci in the State Party).”

Humanitarian Crises and IHR (2005)

Risk of international spread:

“Event in an area of intense

international traffic with limited

capacity for sanitary control or

environmental detection or

decontamination.”