Biomedical subjects
Claire-Lise Chaignat
Publications and source records attributed to Claire-Lise Chaignat.
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.
Feasibility of a mass vaccination campaign using a two-dose oral cholera vaccine in an urban cholera-endemic setting in Mozambique.
We conducted a study to assess the feasibility and the potential vaccine coverage of a mass vaccination campaign using a two-dose oral cholera vaccine in an urban endemic neighbourhood of Beira, Mozambique. The campaign was conducted from December 2003 to January 2004. Overall 98,152 doses were administered, and vaccine coverage of the target population was 58.6% and 53.6% for the first and second rounds, respectively. The direct cost of the campaign, which excludes the price of the vaccine, amounted to slightly over 90,000 dollars, resulting in the cost per fully vaccinated person of 2.09 dollars, which is relatively high. However, in endemic settings where outbreaks are likely to occur, integrating cholera vaccination into the routine activities of the public health system could reduce such costs.
A review of vaccine research and development: human enteric infections.
Worldwide, enteric infections rank third among all causes of disease burden, being responsible for some 1.7-2.5 million deaths per year, mostly in young children and infants in developing countries. The main infectious agents responsible for human enteric infections include several viruses (enteric adenoviruses, astroviruses, human caliciviruses (HuCV), rotaviruses (RV)) and several bacterial agents, such as Campylobacter jejuni, a variety of pathogenic Escherichia coli strains including enterotoxigenic E. coli (ETEC), several Shigella species, various Salmonella strains including S. typhi and S. paratyphi, the agents of typhoid fever, and Vibrio cholerae, the agent of cholera. While effective vaccines are available at present against typhoid fever and cholera, no vaccine is available against illnesses caused by HuCV, Campylobacter, ETEC or the Shigellae. Rotavirus vaccines have had more success, although RV disease prevention suffered a major setback in 1999 with the withdrawal of a live simian-human reassortant RV vaccine less than a year after its introduction. New live oral RV vaccines have now been developed and are or should presently be ready for licensure. This article reviews the state of the art in vaccine R&D against human viral and bacterial enteric infections of public health importance.
Effectiveness of mass oral cholera vaccination in Beira, Mozambique.
BACKGROUND: New-generation, orally administered cholera vaccines offer the promise of improved control of cholera in sub-Saharan Africa. However, the high prevalence of human immunodeficiency virus (HIV) infection in many cholera-affected African populations has raised doubts about the level of protection possible with vaccination. We evaluated a mass immunization program with recombinant cholera-toxin B subunit, killed whole-cell (rBS-WC) oral cholera vaccine in Beira, Mozambique, a city where the seroprevalence of HIV is 20 to 30 percent. METHODS: From December 2003 to January 2004, we undertook mass immunization of nonpregnant persons at least two years of age, using a two-dose regimen of rBS-WC vaccine in Esturro, Beira (population 21,818). We then assessed vaccine protection in a case-control study during an outbreak of El Tor Ogawa cholera in Beira between January and May 2004. To estimate the level of vaccine protection, antecedent rates of vaccination were compared between persons with culture-confirmed cholera severe enough to have prompted them to seek treatment and age- and sex-matched neighborhood controls without treated diarrhea. RESULTS: We assessed the effectiveness of the vaccine in 43 persons with cholera and 172 controls. Receipt of one or more doses of rBS-WC vaccine was associated with 78 percent protection (95 percent confidence interval, 39 to 92 percent; P=0.004). The vaccine was equally effective in children younger than five years of age and in older persons. A concurrently conducted case-control study designed to detect bias compared persons with treated, noncholeraic diarrhea and controls without diarrhea in the same population and found no protection associated with receipt of the rBS-WC vaccine. CONCLUSIONS: The rBS-WC vaccine was highly effective against clinically significant cholera in an urban sub-Saharan African population with a high prevalence of HIV infection.
Pandemic serovars (O3:K6 and O4:K68) of Vibrio parahaemolyticus associated with diarrhea in Mozambique: spread of the pandemic into the African continent.
Forty-two episodes of Vibrio parahaemolyticus infections were detected in Beira, Mozambique, from January to May 2004. The majority of the isolates (81%) belonged to the pandemic serovars (O3:K6 and O4:K68) of V. parahaemolyticus. The pandemic serovars were positive by group-specific PCR (GS-PCR) and a PCR specific for open reading frame ORF8 (ORF8-PCR), which are molecular markers of the pandemic clone, and were positive for tdh but negative for trh. The remaining 19% of the strains also possessed the tdh gene but were GS-PCR and ORF8-PCR negative and did not belong to the pandemic serovars. Patients with V. parahaemolyticus infection were older (mean age, 27 years) than patients infected by other diarrheal agents (mean age, 21 years). Ten percent of diarrhea patients from whom no V. parahaemolyticus was cultured were severely dehydrated, but none of the V. parahaemolyticus cases were severely dehydrated. This is the first report of the isolation of pandemic strains of V. parahaemolyticus in sub-Saharan Africa and clearly indicates that the pandemic of V. parahaemolyticus has spread into the African continent.
Can oral cholera vaccination play a role in controlling a cholera outbreak?
Control measures to limit the spread of a cholera outbreak in Pohnpei Island (Micronesia), included mass vaccination with the single-dose live-attenuated oral cholera vaccine CVD 103-HgR as a potential adjunct measure. The outbreak provided a unique opportunity to evaluate the practicality of use and effectiveness of this vaccine. Under field conditions encountered in Pohnpei, crude vaccine efficacy was estimated at 79.2% (95% CI: 71.9-84.6%) in the target population. Retrospective analysis suggests that mass vaccination with oral cholera vaccines can be a useful adjunct tool for controlling outbreaks, particularly if implemented early in association with other standard control measures.
Cholera in Mozambique, variant of Vibrio cholerae.
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