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Epidemiology of Vibrio cholerae O139 with special reference to intrafamilial transmission in Calcutta
P G Sengupta1, B K Sircar, S K Mandal
1National Institute of Cholera and Enteric Diseases, Calcutta, India.
Insights
Vibrio cholerae O139 was found in 14.6% of healthy contacts in infected families, highlighting asymptomatic transmission. This study reveals potential contamination routes like hands and water, crucial for controlling cholera outbreaks.
Area of Science:
- Microbiology
- Epidemiology
- Public Health
Background:
- Vibrio cholerae O139 outbreaks pose a significant public health threat.
- Understanding transmission dynamics within households is crucial for effective control.
Purpose of the Study:
- To determine the prevalence of Vibrio cholerae O139 infection in healthy contacts and potential environmental reservoirs within index case families.
- To compare infection rates between index case families and neighborhood families to assess intrafamilial transmission.
Main Methods:
- Bacteriological screening of fecal samples from 27 index case families and 14 neighborhood families over 4 days.
- Screening of handwashings, stored drinking water, open well water, flies, and pond water for V. cholerae O139.
Main Results:
- V. cholerae O139 was isolated from 14.6% of healthy contacts in index case families, compared to 0% in neighborhood families (P = 0.002).
- The organism was detected in handwashings (3.7%), stored drinking water (8.0%), open well water (28.6%), flies (3.8%), and pond water (25.0%) associated with index case families.
- Asymptomatic infections were prevalent, similar to eltor cholera.
Conclusions:
- Asymptomatic carriers play a significant role in V. cholerae O139 transmission within households.
- Contaminated hands and water sources act as potential vehicles for intrafamilial spread.
- Findings are vital for developing community-level intervention strategies against V. cholerae O139 transmission.
Abstract:
A total of 27 families of hospitalised patients (index case families) suffering from acute watery diarrhoea caused by Vibrio cholerae O139, and 14 neighbourhood families were bacteriologically screened for 4 consecutive days to determine the extent of V. cholerae O139 infection amongst healthy contacts and other suspected vehicles of transmission at the intrafamilial level. V. cholerae O139 was isolated from faeces of 14.6% of healthy contacts in index case families as compared to none in neighbourhood families (P = 0.002). The organism could be recovered from 3.7% of handwashings of contacts of index cases and also from stored drinking water (8.0%), open well water (28.6%), flies (3.8%) and pond water (25.0%) used by the index case families and none from neighbourhood families. The large number of asymptomatic infected persons indicate an epidemiological similarity to that of eltor cholera. The organisms may be carried on hands and may act as a potential source of infection to other inmates through contamination of stored drinking water, open wells etc. The results will be useful in formulating strategies for intervention of transmission of V. cholerae O139 at the community level.