Evaluation of enrichment method for the detection of Vibrio cholerae O1 using a rapid dipstick test in Bangladesh.

BACKGROUND: To evaluate the specificity of the Crystal VC dipstick test for detecting cholera. METHODS: We compared direct testing using the Crystal VC dipstick test and testing after enrichment for 6 h in alkaline peptone water (APW) to bacterial culture as the gold standard. Samples positive by dipstick but negative by culture were also tested using PCR. RESULTS: Stool was collected from 125 patients. The overall specificities of the direct testing and testing after 6-h enrichment in APW compared to bacterial culture were 91.8% and 98.4% (P = 0.125), respectively, and the sensitivities were 65.6% and 75.0% (P = 0.07), respectively. CONCLUSION: The increase in the sensitivity of the Crystal VC kit with the use of the 6-h enrichment step in APW compared to direct testing was marginally significant. The Crystal VC dipstick had a much higher specificity than previously reported (91-98%). Therefore, this method might be a promising screening tool for cholera outbreak surveillance in resource-limited settings where elimination of false-positive results is critical.

Risk factors associated with typhoid fever in children aged 2-16 years in Karachi, Pakistan.

We analysed the data from the control group in a typhoid vaccine trial in Karachi to assess the differences in individual-, household- and cluster-level characteristics for developing typhoid fever. The annual incidence of typhoid in children aged 2-16 years in the control arm of the vaccine trial was 151/100 000 population. After adjustment, the risk of typhoid was lower with increasing age [risk ratio (RR) 0·89, 95% confidence interval (CI) 0·83-0·95], was higher with an increase in population density (RR 1·13, 95% CI 1·05-1·21) and was lower in the households using a safe drinking-water source (RR 0·63, 95% CI 0·41-0·99). Typhoid fever affects younger children living in areas of high population density and lack of access to safe water in Pakistan. A combination of environmental and biological interventions is required to prevent the continued epidemiological and economic impact of typhoid fever in high-risk areas of Pakistan.

Diarrheal illness in a cohort of children 0-2 years of age in rural Bangladesh: I. Incidence and risk factors.

AIM: To describe clinical characteristics and age- and season-specific incidences of diarrheal episodes, and to evaluate risk factors associated with the occurrence of diarrheal disease. METHODS: A total of 252 infants from rural Bangladesh were followed through household surveillance for 2 y from birth during the years 1993-1996. Demographic and household determinants were linked to the probability of illness using logistic regression models. RESULTS: The overall incidence of diarrhea was 4.25 episodes per child per year. Peak rates of overall, acute, and persistent diarrhea occurred in the 6-11-mo and 12-17-mo age groups. Diarrheal rates peaked during the spring and summer. Among host-related characteristics, having a sibling in the household and having had prior diarrhea were significant risk factors for diarrhea. Among environmental characteristics, spring season remained a highly statistically significant risk factor for diarrhea. CONCLUSION: Diarrheal disease continues to be a substantial burden in young children in rural Bangladesh. Most diarrheal episodes are of short duration, and should primarily be treated with oral rehydration therapy to prevent diarrhea-related mortality. Improved knowledge of oral rehydration therapy, feeding during episodes to prevent further malnutrition, prolonged breastfeeding, and the keeping of livestock in corralled areas of the home are advocated.

Safety and immunogenicity of an oral, inactivated enterotoxigenic Escherichia coli plus cholera toxin B subunit vaccine in Bangladeshi children 18-36 months of age.

A phase II safety and immunogenicity study of an oral-formalin inactivated enterotoxigenic Escherichia coli (ETEC) vaccine containing six colonization factors (CFA/I, CS1, CS2, CS3, CS4, CS5) and 1mg of recombinant cholera toxin B subunit (the CF-BS-ETEC vaccine) was carried out in an urban slum of Dhaka city in Bangladesh. The study was carried out in a double blinded, placebo controlled design in 158 children, 18-36 months of age. Children were given two doses of the CF-BS-ETEC vaccine or the placebo which consisted of E. coli K12. The vaccine was well tolerated. The immune response was studied in 60 children (30 each in the placebo and vaccine group). Significant vaccine specific IgA antibody-secreting cell (ASC) responses were seen 7 days after ingestion of the first and second dose of the vaccine. The responses to CFA/I (P