Cholera
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Transcript of 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