ENDEMIC CHOLERA IN DELHI, 1995 - ANALYSIS OF DATA FROM A SENTINEL CENTER

Data on cholera cases admitted to the Delhi Infectious Diseases Hospit aI (IDH) are presented to describe the pattern of occurrence of choler a in Delhi in 1995. Rectal swabs from 4082 cases of acute diarrhoea ad mitted to the IDH were examined for excretion of Vibrio cholerae. Of t hem, 2004 (49%) and 4 (0.1%) were positive for IC cholerae O1 biotype El Tor and V. cholerae O139 respectively. Most cholera cases occurred during May - September (summer and monsoon months). The period from Ja nuary to March (winter) was completely free from cholera. The urban ar eas were not affected uniformly Of the 80 PIN (Postal Index Number) co de areas, 10 contributed to 57% of the cases. The early cases were sca ttered in PIN code areas distant from one another. The hospitalisation rates for cholera were the highest in children aged less than five ye ars and declined significantly with increasing patients' age. Males ha d significantly higher rates than females aged up to 20 years, whereas the situation was reversed in the 20 to 39 year age group. Four per c ent of the affected families had multiple cases. An estimated 1% of th e household contacts of hospitalised cases of cholera were themselves hospitalised for cholera within 2 days of the first admission. Of the 260 V. cholerae O1 isolates tested, 4%, 7%, 8%, 89%, 91% and 95% were resistant to tetracycline, nalidixic acid, chloramphenicol, co-trimoxa zole, streptomycin, and furazolidone respectively. The study highlight s the usefulness of surveillance data to identify groups, urban areas and seasons with increased risk for cholera and to allow control measu res to be focussed on those in greatest need.