Widespread emergence of Vibrio cholerae 0139 in India.

The National Institute of Communicable Diseases (NICD) has been monitoring the incidence of laboratory confirmed cases of cholera in Delhi in collaboration with Infectious Diseases Hospital (IDH) since 1965. Cholera and cholera-like cases from all hospitals in Delhi are admitted in IDH and the rectal swabs of all such cases are processed for isolation of Vibrio cholerae at NICD laboratory. Since April 1993, there has been isolation of Vibrio cholerae serotype 0139, in increasing numbers (831 out of 2,830, 29.2%) The isolates have been characterized and enterotoxin studies carried out. As a referral laboratory NICD has also confirmed the causative role of Vibrio cholerae 0139 in diarrhea outbreaks from various parts of the country. The implications of establishment of this newer serotype of Vibrio cholerae, as a potential epidemic strain are discussed.

Epidemiological features of cholera outbreak in Delhi in 1988.

During 1988 a large scale outbreak of cholera occurred in Delhi giving rise to a total of 1708 bacteriologically proved El Tor cholera cases, the highest number recorded in a single year in Delhi, following its first detection in 1965. Civil lines and Shahdara zones were the worst affected areas recording 85.7 and 55.7 cases per 100,000 population respectively. The highest incidence rate was observed in the age group of 1-4 years (77 per 100,000). Males and females were equally affected. The data of moving average show the endemicity of cholera in Delhi with an increasing trend. The risk factors identified are lower socioeconomic status, poor personal hygiene, drinking water and food storage practices.

Cholera outbreak in Delhi--1988.

Delhi experienced an outbreak of cholera during July-August 1988 which affected residents from all walks of life. A total of 1824 laboratory confirmed cholera cases were detected in two months period at I.D. Hospital, Delhi alone. The number of cholera cases in July-August 1988 was 5-10 times that of the same period during the previous years in the Capital. The outbreak was caused by Vibrio cholerae Ogawa biotype ElTor. Majority of the laboratory confirmed cases (about 74 per cent) were seen in children under the age of 15 years. Though the cases were spread all over Delhi, almost three-fourths of total cases were reported from two specific zones (Shahdara and Civil Lines). Most of the isolates were sensitive to all antibiotics tested. The proportion of isolates resistant to furazolidone during this outbreak was substantially higher than in previous years suggesting that the outbreak may have been caused by the introduction of a new strain rather than proliferation of endemic strain. The salient features of the outbreak are discussed.

Cholera gastroenteritis amongst children in Delhi.

Cholera gastroenteritis amongst 3595 children under twelve years suffering from acute watery diarrhea was studied for a period of five years (1982-86). V. cholerae 01 could be isolated from 31.7% of total specimens studied. Distribution in different age groups out of total gastroenteritis cases was 7.5% in less than 2 years, 13.1% in 2-5 years and 11.1% in greater than 5-12 years. Out of total cholera cases (1141 isolate) 23.4% occurred in the age group less than 2 yrs., 41.4% in 2-5 yrs. and 35.1% in greater than 5-12 yrs. Infection occurred more often in males in all the age groups. Throughout the study, cholera was observed during summer monsoon season with Ogawa being predominant serotype.