Changing profile of Vibrio cholerae O1, O139 in Delhi & its periphery (2003-2005).

BACKGROUND & OBJECTIVE Cholera caused by either Vibrio cholerae O1 or O139 is endemic in Delhi and its peripheral areas. The present study was carried out to understand the changing epidemiology of V. cholerae in terms of prevalence of serotypes, antibiogram pattern and phage types. METHODS A total of 9858 stool samples from the admitted diarrhoea patients were used for the isolation of V. cholerae O1 and O139. Subsets of isolates were tested against thirteen antimicrobials and phage typed. RESULTS Among 4251 (43.1%) confirmed cases, 41.6 per cent were V. cholerae O1 and rest (1.5 %) V. cholerae O139. Detection of V. cholerae O1 serotype Inaba was 87.7 per cent during 2005 and rest were serotype Ogawa. Majority of cases (93.1%) were from Delhi. Male:Female ratio remained 1.5:1.0. Children below 5 yr age group constituted 32.7 per cent cases. Shift in the age groups and seasonal incidence were recorded. All 226 strains of V. cholerae O1 and O139 were resistant to nalidixic acid; 96 per cent V. cholerae O1 isolates were multidrug resistant (FX NA SXT). Phage type 27 (98.7%) was the most prevalent and the new phage types were 4, 16 and 25 in this area. INTERPRETATION & CONCLUSION Enhanced surveillance helped in bringing down cases from 47.7 per cent in 2003 to 36.8 per cent in 2005. Additionally, the changing epidemiology of V. cholerae O1 and O139 infections and drug resistance need regular monitoring.