BackgroundDespite recent progress in understanding the molecular basis of Vibrio cholerae pathogenesis, there is relatively little knowledge of the factors that determine the variability in human susceptibility to V. cholerae infection.Methods and FindingsWe performed an observational study of a cohort of household contacts of cholera patients in Bangladesh, and compared the baseline characteristics of household members who went on to develop culture-positive V. cholerae infection with individuals who did not develop infection. Although the vibriocidal antibody is the only previously described immunologic marker associated with protection from V. cholerae infection, we found that levels of serum IgA specific to three V. cholerae antigens—the B subunit of cholera toxin, lipopolysaccharide, and TcpA, the major component of the toxin–co-regulated pilus—also predicted protection in household contacts of patients infected with V. cholerae O1, the current predominant cause of cholera. Circulating IgA antibodies to TcpA were also associated with protection from V. cholerae O139 infection. In contrast, there was no association between serum IgG antibodies specific to these three antigens and protection from infection with either serogroup. We also found evidence that host genetic characteristics and serum retinol levels modify susceptibility to V. cholerae infection.ConclusionsOur observation that levels of serum IgA (but not serum IgG) directed at certain V. cholerae antigens are associated with protection from infection underscores the need to better understand anti–V. cholerae immunity at the mucosal surface. Furthermore, our data suggest that susceptibility to V. cholerae infection is determined by a combination of immunologic, nutritional, and genetic characteristics; additional factors that influence susceptibility to cholera remain unidentified.

Cholera, caused by Vibrio cholerae, is a noninvasive dehydrating enteric disease with a high mortality rate if untreated. Infection with V. cholerae elicits long-term protection against subsequent disease in countries where the disease is endemic. Although the mechanism of this protective immunity is unknown, it has been hypothesized that a protective mucosal response to V. cholerae

Background Multiple Vibrio cholerae infections within the same household are common. The objective of this study was to examine the incidence of V. cholerae infection and associated clinical symptoms in household contacts of patients with cholera, and to identify risk factors for development of severe dehydration in this cohort. Methods Household contacts of hospitalized patients with cholera were observed with frequent clinical assessments and collection of serum and rectal swab cultures for a period of 21 days after presentation of the index case. Results Half (460/944) of all contacts reported diarrhea during the study period, and symptoms most frequently began two days after presentation of the index case. Antibiotics were used by 43% (199/460) of the contacts with diarrhea. Rectal swab culture for V. cholerae was positive in 22% (202/944) of contacts and 73% (148) of infected contacts experienced diarrhea. Significant dehydration developed in 26 contacts; predictors of dehydration included vomiting, each additional day of diarrhea, and blood group O status. Conclusions In urban Bangladesh, the burden of diarrheal illness in household contacts of cholera patients is higher than previously estimated and prophylactic intervention is feasible because the majority of symptomatic cases of V. cholerae infection in contacts begin soon after presentation of the index case. Reconsideration of targeted chemoprophylaxis for household contacts of cholera patients may be warranted.

No abstract

We examined demographic, microbiologic, and clinical data from patients presenting during 1988, 1998, and 2004 flood-associated diarrheal epidemics at a diarrhea treatment hospital in Dhaka, Bangladesh. Compared with non-flood periods, individuals presenting during flood-associated epidemics were older, more severely dehydrated, and of lower socioeconomic status. During flood-associated epidemics, Vibrio cholerae was the most commonly identified cause of diarrhea, and the only diarrheal pathogen whose incidence proportionally increased in each epidemic compared with seasonally matched periods. Rotavirus was the second most frequently identified flood-associated pathogen, although the proportion of cases caused by rotavirus infection decreased during floods compared with matched periods. Other causes of diarrhea did not proportionally change, although more patients per day presented with enterotoxigenic Escherichia coli, Shigella, and Salmonella species-associated diarrhea during floods compared with matched periods. Our findings suggest that cholera is the predominant cause of flood-associated diarrheal epidemics in Dhaka, but that other organisms spread by the fecal-oral route also contribute.