Cholera

CHOLERA (AOO) Epidemiology & Control

Cholera

Cholera is a severe diarrheal disease caused by the bacterium Vibrio cholerae.

The toxin released by the bacteria causes increased secretion of water in the intestine, which can produce massive diarrhea.

Sudden profuse effortless watery diarrhoea followed by vomiting muscular cramps dehydration acidosis renal failure shock and death

History

Ancient disease 1817-1923- 6 pandemic VC-classical 1854 - Filippo Pacini 1855- John Snow 1883 – Robert Koch 1961- 7th - Indonesia- El Tor Vibrio 1992 – new strain 0139 emerged Public health importance-Economic losses

Filippo Pacini(1854)

John Snow(1854)

Heinrich Hermann Robert Koch(1883)

Four Phases of Incidence

I - < 1817 India

II -1817-1923 Pandemic Phase (6 pandemics)

SEA, India, China, M.east,USSR , Europe, Africa

III -1923-1960 India & the East

IV -1961 7th Pandemic

Problem

WORLD 4.6million deaths / year 15-40 % of all deaths <5 in tropics 5-10% of all diarrhea in non epidemic situation 98% -India, Pakistan, Bengladesh

INDIA

1.7 episodes of diarrhea/ child / year 1/3 of total pediatric admissions

Endemic in Bengal, Bihar, Orissa, Assam, TN

2012 August 2nd week

Kerala

outbreak in Wayanad district among tribal population

2012 Kozhikode- Medical college 23 cases,

waynad (16) kkd(5) mlp(2) & 1 death (wynd)

Epidemiological features

1. Both an epidemic & endemic disease

2. Causes pandemics

3. No stable endemicity

4. Seasonal fluctuations are common

5. Seasonal fluctuations differs between regions

Cholera Epidemic

Abrupt onset

Create acute public health problem

Affects adults as well as children

High potential to spread fast & cause death

Case fatality 30-40 %

Epidemic curve of cholera

Self limiting Sudden rise &

gradual fall Tail due to

contacts & carriers

Hidden among carriers-inter epidemic period

Epidemiology

Gram negative non spore forming curved rods ferment glucose sucrose and

mannitol

Disease Agent

V.Cholera 01

El Tor - ogawa, enaba, hikojima

V.Cholera 0139 (Bengal) El Tor - has greater epidemicity - In apparent & mild cases are more - More resistant to disinfectants - Chronic carriers are more - Fewer secondary cases- Survive

longer in the external environment

Classification Scheme

Toxigenic V. cholerae

O1Division into 2 biotypes

inaba ogawa hikojima

A & B (A little C) Antigens

A & C

O139

A, B, C

Each O1 biotype can have 3 serotypes

Classical El Tor

Designed using information presented in review by NS Crowcroft. 1994. Cholera: Current Epidemiology. The Communicable Disease Report. 4(13): R158-R163.

Division into ribotypes

Division into 2 epidemic serotypes

Agent factors……..

Destroyed by - Boiling , Cresol - Super chlorination

Exotoxin acts on cAMP-Pathogenesis H –flagellar & O somatic antigen

Viability of Cholera Vibrio outside the body:-- In tap water (contam. with feces) = 5

days- In stool: (in summer) = 2 days- In stool: (in winter) = 8 days- In corpes = 4 wks- In clothings = 2-6 days- In dates (peelings) = 3 days- In fish = 2-10

days- In milk (raw) = 3 days- In milk (boiled) = 10 days

Epidemiology

Reservoir Man - Cases & Carriers - Asymptomatic & mild casesSub clinical cases &carriers- community spread 1 :50-100

Infective dose - 10¹¹ organisms

Incubation period - Hours –5 days (1-2 days)

Communicability - 7-10 days

Carries in Cholera

Pre clinical / Incubatory Convalescent - 2-3 weeks Contact / healthy < 10 days Chronic >10 yrs

Bacteriological examination Estimation of Antibody titre

Host

Age Sex Epidemics- adult Non epidemic -children

Environmental factors

Climate & season Earthquake ,flood Fairs ,festivals & Pilgrimage Poverty , illiteracy, ignorance, poor

standards of living with lack of sanitation

All are susceptible

Faeco oral transmission- direct contact

water(fluid) Faeces fruits&veg & Fomite Food

Mouth Urine Flies Fingers

MOT

Modes of Transmission

Water (infectious dose = 109) Food (infectious dose = 103) Person-to-person

Clinical Manifestations

www.who.int/entity/water_sanitation_health/dwq/en/admicrob6.pdf

Typical cases

Stage of evacuation Stage of collapse Stage of recovery

Signs

Collection of samples

Stool , Water or food samples

Rectal swab Rubber catheterTransport media – Venkatraman –

ramakrishnan(VR) or alkaline peptone water

Microbiological & Molecular Methods of Detection Microbiological culture-based methods using fecal or water samples

Rapid Tests Dark-field microscopy Rapid immunoassays Molecular methods - PCR

& DNA probes

www.city.niigata.niigata.jp/ info/sikenjo/521s...

Control of CholeraEpidemic I. Verification of the diagnosis

II. Notification

Disease under international health Regulations

So notifiable to the WHO within 24 hours Continued till the area is declared free of

cholera (Twice the incubation period after last

case)

III. Appropriate clinical management

(a) Early case finding -by rapid & aggressive

search (b) Establish treatment centers (c) Rehydration Therapy - No Dehydration - HAF - Some Dehydration -

ORS -Severe Dehydration - IVF (d) Maintenance Therapy (e) Antibiotic Therapy

Antibiotic therapy

Children TM (5mg/kg) + SM (25mg/kg) bd X 3days

Adults Doxycycline ( 300mg single dose)

Pregnancy Furazolidone (100mg qid X 3days)

IV. Epidemiological investigationV. SANITATION MEASURES

Water control

Excreta disposal

Food Sanitation

Disinfection – concurrent & terminal -cresol

VI. Chemo prophylaxis

Given to close contacts

Mass chemo prophylaxis is not indicated

Tetracycline 500 mg bd X 3 days

Doxycycline 300 mg (6mg/kg)

Vaccination PARENTERAL VACCINE

Subcutaneous injection 2 doses 4-6 weeks apart Protective value 50% Duration of protection 3-6 months Contraindication - Hypersensitivity Dosage schedule

1-2 years 0.2ml 2-10 0.3ml >10 0.5ml

Oral Vaccines -2 types

KILLED WHOLE CELL VACCINE

V.cholera 01 +Recombinant β-sub unit of toxin 2 doses 10-14 days apart Protective value 50-60 % Duration of protection 3 years

LIVE ATTENUATED VACCINE

Genetically attenuated classical V.cholerae

CVD 103-HgR strain Single dose Protection 80 % Antibiotics & proguanil to be avoided

( 1week before &1week after vaccination)

Contra indication - Hypersensitivity

Health education

a- Cooking food thoroughly & eating it while still hot; b- Preventing cooked food from being

contaminated by contact with raw food (water & ice), or with contaminated surfaces or flies.

c- Avoiding raw fruits or vegetables unless they are first peeled.

d- Hand washing after defecation, esp. before contact with food or drinking water.

National ADD control programme

ORT programme-1986-87 CSSM programme RCH programme

ORT corner

ORT depots

Thank you