EPIDEMIOLOGY AND CONTROL OF CHOLERA BY DR. AWATIF ALAM

IDENTIFICATION: IDENTIFICATION: - An acute bacterial disease (enteric), - An acute bacterial disease (enteric), - sudden onset of profuse watery stools, - sudden onset of profuse watery stools, - occasional vomiting, - occasional vomiting, - rapid dehydration, acidosis, - rapid dehydration, acidosis, - circulatory collapse. - circulatory collapse.

Prognosis: * Asymptomatic infection occur much more frequently than clinical illness, * Asymptomatic infection occur much more frequently than clinical illness, * In severe cases (untreated), death can happen (within few hours ), * In severe cases (untreated), death can happen (within few hours ), * C.F.R ≈ 50%, but with proper Rx, C.F.R. < 1%. * C.F.R ≈ 50%, but with proper Rx, C.F.R. < 1%.

DIAGNOSIS: DIAGNOSIS: - Confirmed by culturing Cholera vibrio of serotype 01 from feceas, or or - significant rise in titer of antitoxic antibodies, - significant rise in titer of antitoxic antibodies, or or - presence of agglutinating or virbiocidal antibodies. - presence of agglutinating or virbiocidal antibodies.

Infectious Agent: Group A – Vibrio cholerae Serogroup 01 (which includes) (which includes) - El-Tor - classical or true : - classical or true : INABA, Hikojima, or OGAWA INABA, Hikojima, or OGAWA True cholera vibrio is demonstrated by:- - presence of specific O antigen and - presence of specific O antigen and - no hemolysis of goat or sheep RBCs if added to suspension of these cells. - no hemolysis of goat or sheep RBCs if added to suspension of these cells.

Group B – non cholera Vibrios. Group B – non cholera Vibrios. (Non pathogenic to man) (Non pathogenic to man) - Most vibrio strains elaborate enterotoxin resulting in similar clinical picture - Most vibrio strains elaborate enterotoxin resulting in similar clinical picture - In any single epidemic one particular type tends to be dominant - In any single epidemic one particular type tends to be dominant (presently El Tor biotype is predominant except in Bangladesh, where the classical biotype has reappeared). (presently El Tor biotype is predominant except in Bangladesh, where the classical biotype has reappeared).

In 1992, a new serogroup – a genetic In 1992, a new serogroup – a genetic derevative of the EL TOR biotype – emerged in Bangladesh and caused an extensive epidemic. derevative of the EL TOR biotype – emerged in Bangladesh and caused an extensive epidemic. It has now spread over large parts of Asia It has now spread over large parts of Asia and is termed Vibrio Cholerae o139 and is termed Vibrio Cholerae o139 “ BENGAL”. “ BENGAL”.

Occurrence:- Occurrence:- - During 19th century pandemic cholera repeatedly spread from India to most of the world. - During Ist half of 20th century, the disease was confined largely to Asia - During Ist half of 20th century, the disease was confined largely to Asia (except for severe epidemic in Egypt in 1947). (except for severe epidemic in Egypt in 1947). - Since 1961, cholera spread from Indonesia - Since 1961, cholera spread from Indonesia to Western Europe, and AFRICA. to Western Europe, and AFRICA.

OCCURRENCE:- - During 1977 and 1978 outbreaks were reported from Japan*, - During 1977 and 1978 outbreaks were reported from Japan*, - In 1983; 13 African countries reported the disease, - In 1983; 13 African countries reported the disease, - The Western hemisphere was free from cholera between 1911 – The Western hemisphere was free from cholera between 1911 – 1973 (except for 2 lab. acquired cases) (except for 2 lab. acquired cases)

OCCURRENCE: In 1991 cholera appeared in South America, In 1991 cholera appeared in South America, ( it had been absent for > century ). ( it had been absent for > century ). Within a year it spread to 11 countries, and through the continent. Within a year it spread to 11 countries, and through the continent. In 1992 large outbreaks began in India & Bangladesh. In 1992 large outbreaks began in India & Bangladesh. “Such outbreaks was caused by a previously unrecognized serogroup” ( O139\Bengal ). “Such outbreaks was caused by a previously unrecognized serogroup” ( O139\Bengal ). It is a more virulent variant of EL TOR biotype. It is a more virulent variant of EL TOR biotype.

Cholera in Southern Sudan 28 Jan. – 3 March 2006 Vibrio cholera Inaba has Vibrio cholera Inaba has been lab. confirmed. been lab. confirmed cases and 127 deaths cases and 127 deaths C.F.R 2.25 % C.F.R 2.25 % For more details check: For more details check:

SIZE OF THE PROBLEM GLOBALLY: – cases were reported – cases were reported between between In 1999, global incidence was about In 1999, global incidence was about , and Africa alone accounted for about 81% of the global total number of cases , and Africa alone accounted for about 81% of the global total number of cases. In 2000, multiple outbreaks were reported in populations in various islands of Oceania. In 2000, multiple outbreaks were reported in populations in various islands of Oceania.

Reservoir:- Reservoir:- Man : Man : - A patient during incubation period (faeces) - A patient during incubation period (faeces) - A patient during illness - A patient during illness (faeces & vomitus) (faeces & vomitus) - A patient during convalescence (faeces) - A patient during convalescence (faeces) - Contact through faeces - Contact through faeces

Mode of Transmission:- A. Primary ingestion of water (contaminated with faeces or vomitus of patients, or to lesser extent to faeces of carriers). to lesser extent to faeces of carriers). OR OR B. Ingestion of food contaminated by dirty water, faeces, soiled hands or flies. B. Ingestion of food contaminated by dirty water, faeces, soiled hands or flies. C. Use of soiled articles (e.g. utensils, clothes and bedlinen) “to lesser extent.”

Poor sanitation transmits many diseases. Each year 1.3 million children die from diarrhoeal diseases alone. Ensuring safe methods of excreta disposal, access to latrines at home and in schools, and encouraging hand washing.

INCUBATION PERIOD: INCUBATION PERIOD: Few hours – 5 days. Few hours – 5 days. “ The international I.P. is 5- days “. “ The international I.P. is 5- days “. Period of Communicability: Period of Communicability: - For the duration of stool ve+ stage - For the duration of stool ve+ stage (usually few days after recovery) (usually few days after recovery) - Carrier state may persist for few months - Carrier state may persist for few months *NOTE: *NOTE: Effective antibiotic eg. (tetracycline) reduce the period of communicability.

Suscept. And Resistance:- Susceptibility is general and variable Susceptibility is general and variable Gastric achlorhydria increases the risk Gastric achlorhydria increases the risk People with low S.E.S groups are at higher risk. People with low S.E.S groups are at higher risk.

Unsanitary environment:

WHO cholera 6th report stated factors favouring endemicity in India (lower Bengal area): High density population, High density population, Increased humidity, Increased humidity, Abundance of uncontrolled H20 supply, Abundance of uncontrolled H20 supply, High salinity and organic water contents. High salinity and organic water contents. **-An attack gives temporary immunity (against a homologus serotype through a rise in agglutinating, vibriocidal and antitoxin antibodies which all lead to resistance).

METHODS OF CONTROL A-Preventive measures:- A-Preventive measures:- 1- Sanitary disposal of human faeces (maintenance of fly proof latrines). 1- Sanitary disposal of human faeces (maintenance of fly proof latrines). 2- Protect, purify and chlorinate public 2- Protect, purify and chlorinate public water supplies. water supplies. (avoid cross connectns. with sewer syst.). (avoid cross connectns. with sewer syst.). 3- Control flies by spraying with insectici. 3- Control flies by spraying with insectici.

4- Cleanliness in preparation of food, 4- Cleanliness in preparation of food, 5- Pasteurize or boil milk, 5- Pasteurize or boil milk, 6- Sanitary supervision of commercial milk production, storage and delivery. 6- Sanitary supervision of commercial milk production, storage and delivery.

Control of patients, contact and environment:- Control of patients, contact and environment:- Reporting to local health authority, Reporting to local health authority, Cleanliness in preparation of food, Cleanliness in preparation of food, Pasteurize or boil of milk and sanitary supervision of commercial milk productn. storage and delivery. Pasteurize or boil of milk and sanitary supervision of commercial milk productn. storage and delivery.

Isolation or hospitalization with enteric precautions esp. for severely ill pts. Isolation or hospitalization with enteric precautions esp. for severely ill pts. eg. (effective hand washing + fly control measures). eg. (effective hand washing + fly control measures). Disinfection of articles soiled with faeces or vomits of patients (by heat, carbolic acid or other effective disinfectant). Disinfection of articles soiled with faeces or vomits of patients (by heat, carbolic acid or other effective disinfectant).

Contacts:- Contacts:- - Surviellance for 5-days. - Surviellance for 5-days. - Chemoprophylaxis with tetracycline. - Chemoprophylaxis with tetracycline. - No immunization necessary. - No immunization necessary. - Investigate contacts with source of - Investigate contacts with source of infection. infection. - Specific Rx:- - Specific Rx:- * Prompt fluid replacement using adequate volumes of electrolytes solutions, to correct dehydration. * Prompt fluid replacement using adequate volumes of electrolytes solutions, to correct dehydration.

Epidemic Measures:- Epidemic Measures:- 1- Essential measures : - Hygienic disposal of human faeces. - Hygienic disposal of human faeces. - Adopting emergency measures to assure a safe water supply (boiling and chlorination). - Adopting emergency measures to assure a safe water supply (boiling and chlorination). - Good food hygiene. - Good food hygiene.

Effective Food Hygiene Measures: a- Cooking food thoroughly & eating it while a- Cooking food thoroughly & eating it while still hot; still hot; b- Preventing cooked food from being contaminated by contact with raw food (water & ice), or with contaminated surfaces or flies. 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. c- Avoiding raw fruits or vegetables unless they are first peeled. d- Hand washing after defecation, esp. before contact with food or drinking water. d- Hand washing after defecation, esp. before contact with food or drinking water.

2- Two available types of vaccines which provide high level of protection for several months against vibrio cholerae serotype o1. vibrio cholerae serotype o1. ( Of use for travellers to endemic countries, ( Of use for travellers to endemic countries, but not yet used for public health purposes ). but not yet used for public health purposes ). 3- Notification ( of WHO & adjacent countries) is required if any case is first diagnosed in a country. 3- Notification ( of WHO & adjacent countries) is required if any case is first diagnosed in a country.

4- Health education in personal hygiene. 5- Search for source of infection. 5- Search for source of infection. 6- Specific measures during pilgrimage 6- Specific measures during pilgrimage season. season.

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