Viral food born infections

Dr. Dalia El-ShafeiLecturer, Community Medicine

Department, Zagazig University

Food born infections

Viral• Poliomyelitis• Hepatitis A&E

• MCD

Bacterial• Typhoid &

paratyphoid• Brucellosis• Diarrheal diseases:• Food poisoning• Dysentery• Diarrhea diseases in

children• Cholera

Parasitic• Ascariasis• Entrobiasis• Amoebic dysentery• Heterophiasis• Fascioliasis• Hydatid cyst• Giardiasis• Toxoplasmosis

Mode of transmission:Fecal oral infection: a) Food-borne infection (ingestion infection). Contaminated food: vehicles are milk and any food that may be contaminated by handling, flies, water, or dust, and sewage-polluted water.b) Hand-to-mouth infection

Symptoms FHMA Nausea Abdominal pain Vomiting Diarrhea Gastroenteritis Fatigue

PreventionPrimary

Environment sanitation

Health promotionInternational

measures

SecondaryI. Measures for

case: Case f &

notification Isolation &

disinfection Treatment &

release2. Measures for

cont: Surveillance Supervision Segregation Isolation immunization

TertiaryPrevent complications & care of handicapped

1- General measures

A) General Sanitation of Environment:Safe water supply, Sanitary wastes disposal (refuse & sewage), Insect control (flies & cockroaches).Food sanitation includes control of food

handlersB)Health education :proper clean habits (including clean hands)

2- ControlI. Control of Cases:

Case-finding: needs efficient medical care (clinical & laboratory services

Notification to the LHO.Isolation: allowed at home when sanitary requirements are fulfilled, otherwise must be

at fever hospital.Disinfection: - concurrent: excreta (1% crude

phenol), articles and fomites.- terminal for objects, and cleaning of the room.Treatment: general and specific chemotherapy.

Rehabilitation Release

Viral food born DiseasesPolio Hepatitis

AHepatitis E

IP 7- 14 d 15- 50 d 21- 42 dMode of transmis

sion

- Faeco-oral- Food-borne- Oral-oral (droplet)

faeco-oralParenteral

y (viraemia)

Contaminated water or

food supplies

Reservoir - Cases- Carriers (contact,

incubatory, convalescent)

-cases-Incubatory C

Infectivity

From IP to convalescence

Last week of IP till Jaundice

Agent - Polio virus Picorna virus

Viral food born Diseases

Polio Hepatitis A Hepatitis E

C/P - Inapparent 90%- Minor (Abortive)

9%- Major (CNS) 1%

-Inapparent (influenza-like)-Classical: pre-icteric,

icteric, post-icteric- Fulminate: fatal

Diagnosis

-Lab: throat wash & stools exam- Serological:

rising Ab

- Lab: stools exam- Serological: IGM, liver

enz.

Specific prevent

ion

- Vaccine - Seroprophylaxis

- Vaccine

Classical C/PPre-

icteric

•FHMA, myalgia, arthralgia•GE, tender liver, dark urine

Icteric •Jaundice (sclera)

•Enlarged tender liver

Post-icteric

•Convalescence

Prevention Active

immunization Inactivated

vaccine1 ml IM(deltoid)2 doses, 4 weeks

apart

1 -At risk: CLD, travelers, lab.

2 -Children

Sero-prophylax

isHuman Ig

Before or few days after exp

1 -Contacts (within 2 wks)

2 -At risk: travelers (before or within 2 wks)

UVR

&UVR

NO CROSS IMMUNITY

Most frequentEpidemic

I WildEndemic

II Oct 1999Sporadic

III

• Reservoir• Cases: all clinical forms• Carriers: all types (incubatory. Convalescent,

healthy & contact who are temporary carrier .

In endemic area health carrier are most frequent due to polluted environment.

• Period of Infectivity• Contact & healthy carriers: about 2weeks.• Case: From IP to convalescence(temporary)

Polio

In apparent (90%)

No clinical manifestations

Acquired immunity & carrier state

Manifest (10%)

Abortive (minor illness) 9%

CNS (major illness) 1%

Non-paralytic (FHMA +

Meningism)

Paralytic (spinal, bulbar, bulbo-spinal)

Case-fatality:2-10%

Mout

h &t

hroa

t su

rger

y

Pregnancy &

corticoster

oids

Excessive muscle activity & fatigue

Active

immunizati

on

Diagnosis

• Throat washing or stools• Serological (neutralizing Ab): rising titer

Specific prevention• Passive immunization (Sero-

prophylaxis): non-practical

Normal human Ig (0.3 ml/kg BW)Exposed susceptible (pre exposure – rapidly

post exposure)

• Active immunization:Sabin & Salk

Sabin Polio vaccine• Oral, live attenuated trivalent vaccine made of the three types, of polioviruses.• 2, 4 and 6 months of age • 3 drops orally on the tongue.• Recently a zero dose is giving after birth as additional dose.• Booster Immunization: a booster dose is given at 9 months, 18-24 months, and school age.

Sabin Polio vaccine action• live attenuated viruses of the vaccine

invade and multiply in the intestinal cells, stimulating: humoral and local cellular immunity

• Humoral immunity: by neutralizing antibodies in serum. It protects the CNS Against invasion by the poliovirus.

• Cellular immunity: local tissue immunity in the intestinal mucosa so prevents establishment of infection in the intestine, and so prevent a carrier.

Sabin Polio vaccine advantages

1. Gives humoral and tissue immunity 2. attenuated viruses are excreted in

stools, to disseminate infection in the community

3. easily administrated 4. used in mass immunization.

5. inexpensive.6. Protective value up to 95%,

7. life long immunity.

• Cold chain: regenerated below 4 C

• Contraindications:1- Pregnancy 2- Corticosteroids 3-

Immune-deficiency

• Complications:Paralysis: very rarely (1/5 million)

Salk Polio vaccine

• Trivalent vaccine, inactivated (formalin).

• Used in non-endemic areas and together with Sabin vaccine in endemic area.

• 4 doses, 1.0 ml each, IM, starting at 4 months of age.

• 1st 3 doses 6-8 weeks apart, 4th dose 7 months later.

• Booster dose : at school age, and whenever an epidemic or outbreak threatens.

• Action: Salk vaccine gives humoral immunity. no cellular immunity

• Protective Value: prevents < 90 % of paralytic cases, and lowers severity of paralytic effect in the affected.

• Salk is given in Egypt as quadruple Salk DPT, IM, 2 doses at 4 &6 months

Control

Cases FNIDTR

Contacts

Enlistment

Case-finding (2wks)Booster v. or sero-

prophylaxis

Epidemics

Mass oral v.

Epid. studyAvoid

predisposing factors

MOH polio eradication•Sabin (1968):1ry

& booster•Salk

Immunization

•Motivation •Periodic

campaigns•Surveillance

(1990)

Satisfactory

coverage rate

Case studyAn adult male 30 years old is complaining

from fever, malaise, nausea, vomiting, abdominal pain and dark urine.

a) What are the other signs you have to look for in this case?

b) What is the most probable diagnosis?c) How can you confirm this diagnosis?d) What is the proper management of this

case? What is the expected prognosis?e) What are the measures you should do

for contacts?

The other signs• Jaundice .• Enlarged tender liver • palpable spleen.

The most probable diagnosis

•Hepatitis A

Confirm this diagnosis

•detecting virus in stools• serological tests for IGM in acute cases • elevated liver enzymes (not specific)

Proper management of this case

• Finding: • Notification: to local health

authorities.• Isolation: • Disinfection: • Treatment• Release

Measures for contacts•Enlistment • Immunization: Active and passive immunization within 2 weeks of exposure.•Examination: for early case finding•Surveillance: for 6 weeks

Bovine Spongiform Encephalopathy (BSE)

Mad Cow Disease (MCD)

Cretuzefeld Jacob

Disease (CJD)