Background Culturing is generally considered to be the gold standard for detecting Vibrio cholerae in stool, though it is not always feasible in resource-limited settings. The Crystal VC dipstick test allows for rapid stool testing for the diagnosis of cholera in the field. However, previous studies have found low specificities (49%–79%) associated with direct testing of stool for cholera using this kit when compared to culturing. Methods In the present study conducted in Dhaka, Bangladesh in 2013, we compare direct testing using the Crystal VC dipstick test and testing after enrichment for 6-hours 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-hour 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 hour enrichment step in APW compared to direct testing was marginally significant. The Crystal VC dipstick was found to have a much higher specificity than previously reported (91–98%). Therefore this method provides a promising screening tool for cholera outbreak surveillance in resource limited settings where elimination of false positive results is critical.
BackgroundAlthough endemic cholera causes significant morbidity and mortality each year in Nepal, lack of information about the causal bacterium often hinders cholera intervention and prevention. In 2012, diarrheal outbreaks affected three districts of Nepal with confirmed cases of mortality. This study was designed to understand the drug response patterns, source, and transmission of Vibrio cholerae associated with 2012 cholera outbreaks in Nepal.MethodsV. cholerae (n = 28) isolated from 2012 diarrhea outbreaks {n = 22; Kathmandu (n = 12), Doti (n = 9), Bajhang (n = 1)}, and surface water (n = 6; Kathmandu) were tested for antimicrobial response. Virulence properties and DNA fingerprinting of the strains were determined by multi-locus genetic screening employing polymerase chain reaction, DNA sequencing, and pulsed-field gel electrophoresis (PFGE).ResultsAll V. cholerae strains isolated from patients and surface water were confirmed to be toxigenic, belonging to serogroup O1, Ogawa serotype, biotype El Tor, and possessed classical biotype cholera toxin (CTX). Double-mismatch amplification mutation assay (DMAMA)-PCR revealed the V. cholerae strains to possess the B-7 allele of ctx subunit B. DNA sequencing of tcpA revealed a point mutation at amino acid position 64 (N → S) while the ctxAB promoter revealed four copies of the tandem heptamer repeat sequence 5'-TTTTGAT-3'. V. cholerae possessed all the ORFs of the Vibrio seventh pandemic island (VSP)-I but lacked the ORFs 498–511 of VSP-II. All strains were multidrug resistant with resistance to trimethoprim-sulfamethoxazole (SXT), nalidixic acid (NA), and streptomycin (S); all carried the SXT genetic element. DNA sequencing and deduced amino acid sequence of gyrA and parC of the NAR strains (n = 4) revealed point mutations at amino acid positions 83 (S → I), and 85 (S → L), respectively. Similar PFGE (NotI) pattern revealed the Nepalese V. cholerae to be clonal, and related closely with V. cholerae associated with cholera in Bangladesh and Haiti.ConclusionsIn 2012, diarrhea outbreaks in three districts of Nepal were due to transmission of multidrug resistant V. cholerae El Tor possessing cholera toxin (ctx) B-7 allele, which is clonal and related closely with V. cholerae associated with cholera in Bangladesh and Haiti.
Recurrent cholera causes significant morbidity and mortality among the growing population of Dhaka, the capital city of Bangladesh. Previous studies have demonstrated that household contacts of cholera patients are at >100 times higher risk of cholera during the week after the presentation of the index patient. Our prospective study investigated the mode of transmission of Vibrio cholerae, the cause of cholera, in the households of cholera patients in Dhaka city. Out of the total 420 rectal swab samples analyzed from 84 household contacts and 330 water samples collected from 33 households, V. cholerae was isolated from 20%(17/84) of household contacts, 18%(6/33) of stored drinking water, and 27%(9/33) of source water samples. Phenotypic and molecular analyses results confirmed the V. cholerae isolates to be toxigenic and belonging to serogroup O1 biotype El Tor (ET) possessing cholera toxin of classical biotype (altered ET). Phylogenetic analysis by pulsed-field gel electrophoresis (PFGE) showed the V. cholerae isolates to be clonally linked, as >95% similarity was confirmed by sub-clustering patterns in the PFGE (NotI)-based dendrogram. Mapping results showed cholera patients to be widely distributed across 25 police stations. The data suggesting the transmission of infectious V. cholerae within the household contacts of cholera patients through drinking water underscores the need for safe water to prevent spread of cholera and related deaths in Dhaka city.
Background The Cholera-Hospital-Based-Intervention-for-7-days (CHoBI7) mobile health (mHealth) program was a cluster-randomized controlled trial of diarrhea patient households conducted in Dhaka, Bangladesh. Methods Patients were block-randomized to three arms: standard recommendation on oral rehydration solution use; health facility delivery of CHoBI7 plus mHealth (no home visits); and health facility delivery of CHoBI7 plus two home visits and mHealth. The primary outcome was reported diarrhea in the past two weeks collected monthly for 12 months. The secondary outcomes were stunting, underweight, and wasting at a 12 month follow-up. Analysis was intention-to-treat. The trial is registered at ClinicalTrials.gov (NCT04008134). Results Between December 4, 2016 and April 26, 2018, 2626 participants in 769 households were randomly allocated to three arms: 849 participants to standard message, 886 to mHealth with no home visits, and 891 to mHealth with two home visits. Children under five years had significantly lower 12-month diarrhea prevalence in both the mHealth with two home visits arm (Prevalence Ratio(PR): 0.73 (95% Confidence Interval(CI): 0.61, 0.87)) and the mHealth with no home visits arm (PR: 0.82 (95% CI: 0.69, 0.97)). Children under 2 years were significantly less likely to be stunted in both the mHealth with two home visits arm (33% vs. 45%, Odds Ratio(OR): 0.55, 95% CI: 0.31, 0.97) and the mHealth with no home visits arm (32% vs. 45%, OR: 0.54, 95% CI: 0.31, 0.96) compared to children in the standard message arm. Conclusion The CHoBI7 mHealth program lowered pediatric diarrhea and stunting among diarrhea patient households.
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