M. Sirajul Islam

Reduction of cholera in Bangladeshi villages by simple filtration

Based on results of ecological studies demonstrating that Vibrio cholerae, the etiological agent of epidemic cholera, is commensal to zooplankton, notably copepods, a simple filtration procedure was developed whereby zooplankton, most phytoplankton, and particulates >20 μm were removed from water before use. Effective deployment of this filtration procedure, from September 1999 through July 2002 in 65 villages of rural Bangladesh, of which the total population for the entire study comprised ≈133,000 individuals, yielded a 48% reduction in cholera (P < 0.005) compared with the control.

A 4-Year Study of the Epidemiology of Vibrio cholerae in Four Rural Areas of Bangladesh

How Vibrio cholerae spreads around the world and what determines its seasonal peaks in endemic areas are not known. These features of cholera have been hypothesized to be primarily the result of environmental factors associated with aquatic habitats that can now be identified. Since 1997, fortnightly surveillance in 4 widely separated geographic locations in Bangladesh has been performed to identify patients with cholera and to collect environmental data. A total of 5670 patients (53% <5 years of age) have been studied; 14.3% had cholera (10.4% due to V. cholerae O1 El Tor, 3.8% due to O139). Both serogroups were found in all locations; outbreaks were seasonal and often occurred simultaneously. Water-use patterns showed that bathing and washing clothes in tube-well water was significantly protective in two of the sites. These data will be correlated with environmental factors, to develop a model for prediction of cholera outbreaks.

Faecal contamination of drinking water sources of Dhaka city during the 2004 flood in Bangladesh and use of disinfectants for water treatment

Aims:  To describe the extent of faecal pollution and point of use water treatment strategy during and after the 2004 flood in Dhaka.

Genomic profiles of clinical and environmental isolates of Vibrio cholerae O1 in cholera-endemic areas of Bangladesh.

Diversity, relatedness, and ecological interactions of toxigenic Vibrio cholerae O1 populations in two distinctive habitats, the human intestine and the aquatic environment, were analyzed. Twenty environmental isolates and 42 clinical isolates were selected for study by matching serotype, geographic location of isolation in Bangladesh, and season of isolation. Genetic profiling was done by enterobacterial repetitive intergenic consensus sequence–PCR, optimized for profiling by using the fully sequenced V. cholerae El Tor N16961 genome. Five significant clonal clusters of haplotypes were found from 57 electrophoretic types. Isolates from different areas or habitats intermingled in two of the five significant clusters. Frequencies of haplotypes differed significantly only between the environmental populations (exact test; P < 0.05). Analysis of molecular variance yielded a population genetic structure reflecting the differentiating effects of geographic area, habitat, and sampling time. Although a parameter confounding the latter differences explained 9% of the total molecular variance in the entire population (P < 0.01), the net effect of habitat and time could not be separated because of the small number of environmental isolates included in the study. Five subpopulations from a single area were determined, and from these we were able to estimate a relative differentiating effect of habitat, which was small compared with the effect of temporal change. In conclusion, the resulting population structure supports the hypothesis that spatial and temporal fluctuations in the composition of toxigenic V. cholerae populations in the aquatic environment can cause shifts in the dynamics of the disease.

A community-randomised controlled trial promoting waterless hand sanitizer and handwashing with soap, Dhaka, Bangladesh.

Objectives  To pilot two intensive hand hygiene promotion interventions, one using soap and one using a waterless hand sanitizer, in low‐income housing compounds in Dhaka, Bangladesh and assess subsequent changes in handwashing behaviour and hand microbiology.

Classification of hybrid and altered Vibrio cholerae strains by CTX prophage and RS1 element structure

Analysis of the CTX prophage and RS1 element in hybrid and altered Vibrio cholera O1 strains showed two classifiable groups. Group I strains contain a tandem repeat of classical CTX prophage on the small chromosome. Strains in this group either contain no element(s) or an additional CTX prophage or RS1 element(s) on the large chromosome. Group II strains harbor RS1 and CTX prophage, which has an E1 Tor type rstR and classical ctxB on the large chromosome.

Microbiological Contamination of Drinking Water Associated with Subsequent Child Diarrhea

We used a prospective, longitudinal cohort enrolled as part of a program evaluation to assess the relationship between drinking water microbiological quality and child diarrhea. We included 50 villages across rural Bangladesh. Within each village field-workers enrolled a systematic random sample of 10 households with a child under the age of 3 years. Community monitors visited households monthly and recorded whether children under the age of 5 years had diarrhea in the preceding 2 days. Every 3 months, a research assistant visited the household and requested a water sample from the source or container used to provide drinking water to the child. Laboratory technicians measured the concentration of Escherichia coli in the water samples using membrane filtration. Of drinking water samples, 59% (2,273/3,833) were contaminated with E. coli. Of 12,192 monthly follow-up visits over 2 years, mothers reported that their child had diarrhea in the preceding 2 days in 1,156 (9.5%) visits. In a multivariable general linear model, the log10 of E. coli contamination of the preceding drinking water sample was associated with an increased prevalence of child diarrhea (prevalence ratio = 1.14, 95% CI = 1.05, 1.23). These data provide further evidence of the health benefits of improved microbiological quality of drinking water.

Susceptibility to Fluoroquinolones of Vibrio cholerae O1 Isolated From Diarrheal Patients in Zimbabwe

Financial Disclosures: Dr Lyketsos reported having received grant support from the National Institute of Mental Health, the National Institute on Aging, the Associated Jewish Federation of Baltimore, the Weinberg Foundation, Forest, GlaxoSmithKline, Eisai, Pfizer, AstraZeneca, Lilly, Ortho-McNeil, Bristol-Myers, and Novartis; having served as a consultant or advisor for AstraZeneca, GlaxoSmithKline, Eisai, Novartis, Forest, Supernus, Adlyfe, Takeda, Wyeth, Lundbeck, Merz, and Lilly; and having received honoraria or travel support from Pfizer, Forest, GlaxoSmithKline, and Health Monitor. No other disclosures were reported.

Microbiological Evaluation of the Efficacy of Soapy Water to Clean Hands: A Randomized, Non-Inferiority Field Trial

We conducted a randomized, non-inferiority field trial in urban Dhaka, Bangladesh among mothers to compare microbial efficacy of soapy water (30 g powdered detergent in 1.5 L water) with bar soap and water alone. Fieldworkers collected hand rinse samples before and after the following washing regimens: scrubbing with soapy water for 15 and 30 seconds; scrubbing with bar soap for 15 and 30 seconds; and scrubbing with water alone for 15 seconds. Soapy water and bar soap removed thermotolerant coliforms similarly after washing for 15 seconds (mean log10 reduction = 0.7 colony-forming units [CFU], P < 0.001 for soapy water; mean log10 reduction = 0.6 CFU, P = 0.001 for bar soap). Increasing scrubbing time to 30 seconds did not improve removal (P > 0.05). Scrubbing hands with water alone also reduced thermotolerant coliforms (mean log10 reduction = 0.3 CFU, P = 0.046) but was less efficacious than scrubbing hands with soapy water. Soapy water is an inexpensive and microbiologically effective cleansing agent to improve handwashing among households with vulnerable children.

Cholera Epidemic Associated with Consumption of Unsafe Drinking Water and Street-Vended Water—Eastern Freetown, Sierra Leone, 2012

During 2012, Sierra Leone experienced a cholera epidemic with 22,815 reported cases and 296 deaths. We conducted a matched case-control study to assess risk factors, enrolling 49 cases and 98 controls. Stool specimens were analyzed by culture, polymerase chain reaction (PCR), and pulsed-field gel electrophoresis (PFGE). Conditional logistic regression found that consuming unsafe water (matched odds ratio [mOR]: 3.4; 95% confidence interval [CI]: 1.1, 11.0), street-vended water (mOR: 9.4; 95% CI: 2.0, 43.7), and crab (mOR: 3.3; 95% CI: 1.03, 10.6) were significant risk factors for cholera infection. Of 30 stool specimens, 13 (43%) showed PCR evidence of toxigenic Vibrio cholerae O1. Six specimens yielded isolates of V. cholerae O1, El Tor; PFGE identified a pattern previously observed in seven countries. We recommended ensuring the quality of improved water sources, promoting household chlorination, and educating street vendors on water handling practices.