Oral Cholera Vaccine (Shanchol) is Effective to Prevent Cholera: A Message Learnt from a Post Vaccination Diarrhoea Surveillance Study

Abstract

A diarrhea surveillance study was conducted after a mass vaccination with a new Oral cholera vaccine Shanchol, in India. During the study period between 2011-2013, a total of 4050 vaccinated, non-vaccinated resident and traveler diarrhoea patients were examined for different etiologial agents. Among the pathogens, toxigenic E. coli (15.15%), V. cholera (3.38%) and rotavirus (29.12%) were found to be main organisms. The isolation frequencies of V. cholera in vaccinated diarrhea patients, in non-vaccinated diarrhea patients in vaccinated area, in non-vaccinated diarrhea patients in neighboring vaccinated area and in non-vaccinated traveler diarrhea patients from other states were 0.72% (4 of 550), 2.3% (12 of 517), 3.7% (109 of 2885) and 12.2% (12 of 98) respectively. The isolation of V. cholerae from vaccinated diarrhea patients is significantly less than the non-vaccinated traveler diarrhea patients which indicate that reduction of cholera among vaccinated people might be due to immunization with Shanchol. Development of herd immunity may be responsible for less isolation of V. cholerae among non-vaccinated residents in vaccinated area compared to non-vaccinated traveler diarrhea patients. It is suggested to vaccinate the vulnerable population using Shanchol to prevent cholera infection in Puri, in other parts of the country and globe.