Classical RS1 and environmental RS1 elements in Vibrio cholerae O1 El Tor strains harbouring a tandem repeat of CTX prophage: revisiting Mozambique in 2005.

Currently, Vibrio cholerae O1 serogroup biotype El Tor strains producing classical type cholera toxin (altered strains or El Tor variants) are prevalent in Asia and in Mozambique. Mozambican strains collected in 2004 contained a tandem repeat of CTX prophage on the small chromosome and each CTX prophage harboured the classical rstR and classical ctxB. We found that the majority of the strains collected in 2005 in Mozambique contained extra elements on the large chromosome in addition to the tandem repeat of CTX prophage on the small chromosome. New type RS1 elements RS1(cla) and RS1(env), and a CTX(env) with rstR(env) and the classical ctxB were identified on the large chromosome of the Mozambican isolates collected in 2005.

Is HIV infection associated with an increased risk for cholera? Findings from a case-control study in Mozambique.

OBJECTIVE: As residents of sub-Saharan Africa are at high risk for HIV and cholera, it is biologically plausible that immune suppression caused by HIV infection predisposes to cholera. Our aim was to assess the potential association between both diseases. METHODS: We conducted a case-control study in Beira, Mozambique, a high-risk area for HIV and cholera. Between 1 January 2005 and 30 June 2006, experienced counsellors invited 132 suspected cholera cases and 528 age- and sex-matched controls to an HIV counselling and testing centre. RESULTS: Forty (30%) of the invited cases and 127 (24%) of the invited controls came for HIV testing. No significant differences in demographic and socio-economic baseline characteristics were detected between participants and non-participants. Twenty five of 167 (15%) individuals who underwent testing were found HIV-positive. The probability of a positive HIV-test was highest in participants between 40 and 49 years; 6 of 14 (43%) tested HIV-positive. Nine of 40 (23%) cholera cases were found to be HIV-infected compared with 16 of 127 (13%) controls (adjusted odds ratio 2.6; 95% CI 0.9-7.5; P = 0.08). DISCUSSION: The findings suggest that in a cholera-endemic area, HIV infection is associated with an increased risk for cholera. More research in HIV endemic settings is needed to confirm the findings and to explore the effect of HIV-related immunosuppression on the transmission of cholera.

Genetic diversity of El Tor strains of Vibrio cholerae O1 with hybrid traits isolated from Bangladesh and Mozambique.

Vibrio cholerae O1 strains that are hybrids between the classical and El Tor biotypes were isolated during two consecutive years (2004-2005) from diarrheal patients in Mozambique. Similar variants isolated in Bangladesh and recently isolated El Tor strains were analyzed for genetic diversity. Pulsed-field gel electrophoresis (PFGE) analysis using the restriction enzyme NotI, resulted in 18-21 bands showed five closely related PFGE patterns that were distributed similarly in both years (2004-2005) among the 80 strains tested in Mozambique. Overall based on the PFGE patterns the hybrids indicated an El Tor lineage. The restriction patterns of whole-chromosomal DNA grouped the hybrid strains from Mozambique into a separate cluster from Bangladeshi clinical and environmental hybrid strains. A high molecular weight band of 398kb that contain rstR allele of the classical type was detected from all hybrid strains, which was absent in all conventional classical and El Tor strains. This band could be designated as a marker for the hybrid strains. This study suggests that hybrid strains from Mozambique are closely related to each other, different from Bangladeshi hybrid strains that are diverse in nature and all hybrid strains differed markedly from conventional classical and El Tor strains.

Field evaluation of a rapid immunochromatographic dipstick test for the diagnosis of cholera in a high-risk population.

BACKGROUND: Early detection of cholera outbreaks is crucial for the implementation of the most appropriate control strategies. METHODS: The performance of an immunochromatographic dipstick test (Institute Pasteur, Paris, France) specific for Vibrio cholerae O1 was evaluated in a prospective study in Beira, Mozambique, during the 2004 cholera season (January-May). Fecal specimens were collected from 391 patients with acute watery nonbloody diarrhea and tested by dipstick and conventional culture. RESULTS: The overall sensitivity and specificity of the rapid test compared to culture were 95% (95% confidence interval [CI]: 91%-99%) and 89% (95% CI: 86%-93%), respectively. After stratification by type of sample (rectal swab/bulk stool) and severity of diarrhea, the sensitivity ranged between 85% and 98% and specificity between 77% and 97%. CONCLUSION: This one-step dipstick test performed well in the diagnosis of V. cholerae O1 in a setting with seasonal outbreaks where rapid tests are most urgently needed.