EPIDEMIOLOGY AND TRANSMISSION OF VIBRIO-CHOLERAE O1 AND VIBRIO-CHOLERAE O139 INFECTIONS IN DELHI IN 1993

In 1993, rectal swabs from clinically suspected cases of cholera admit ted to the Infectious Diseases Hospital (IDH), Delhi were examined for Vibrio cholerae O1 and O139, Epidemiological data of 396 cholera case s were collected before the patients' discharge from IDH, Of the 1528 laboratory-confirmed cholera cases, 46% and 54% were caused by serotyp e O1 and O139 respectively, Both serotypes appeared and disappeared si multaneously, and peaked during the same time of the year, However, th e two serotypes affected persons of different age groups; about 65% of the O1 cases occurred in children aged less than 10 years, whereas th is age group accounted for 40% of the cases due to V, cholerae O139, A lthough there were some focal outbreaks due to serotype O139, both ser otypes had almost similar geographical distributions, Important risk f actors for transmission of cholera were almost equally prevalent in th e majority of both types of cholera cases, Since the seasonality, geog raphical distribution, and risk factors for transmission were similar for both serotypes, the study indicates that the preventive and contro l measures are also likely to be similar, The study also shows that th e emergence of V, cholerae O139 in 1993 did not affect the incidence, seasonality, and epidemiology of endemic V, cholerae O1 El Tor strains in Delhi.