A‘vaccine probe’ analysis
However, cholera outbreaks are still a serious problem in other parts of the world. At least 150,000 cases are reported to the World Health Organization each year. The disease is most common in places with poor sanitation, crowding, war, and famine. Common locations include parts of Africa, south Asia, and Latin America. If you are traveling to one of those areas, knowing the following cholera facts can help protect you and your family.
Vibrio cholerae, the bacterium that causes cholera, is usually found in food or water contaminated by feces from a person with the infection. Common sources include: municipal water supplies, ice made from municipal water, foods and drinks sold by street vendors, vegetables grown with water containing human wastes and raw or undercooked fish and seafood caught in waters polluted with sewage
So, recently, the sensitivity of fecal microbiological cultures for detecting cholera has come under question. Researchers reporting in PLOS Neglected Tropical Diseases investigated this claim using a ‘vaccine probe’ analysis of a completed cholera vaccine cluster randomized trial to support the sensitivity of conventional microbiological culture for cholera. An estimated 2.9 million cases and 95,000 deaths occur each year due to cholera; and microbiological cultures of stools; considered the gold standard for diagnosing cholera.
AWD were negative for Vibrio cholerae
However, one recent study, conducted in Bangladesh; found that conventional cultures identified only 66% of patients; found to have cholera by other measures. This suggests that cholera globally may be; widely underestimated. John D. Clemens and colleagues from both Korea and the US; re-analyzed the data of a phase III trial for a killed oral cholera vaccine (OCV); conducted in Bangladesh in 1985. In the trial, 50,779 people received at least two complete doses of either OCV or placebo.
So, the researchers reasoned that if the culture was not sensitive for cholera; the OCV should reduce cases of acute watery diarrhea (AWD) which were negative for Vibrio cholerae; the bacteria causing cholera. However, during two years of follow-up, 791 first episodes of AWD reported; and tested using microbiological culture; 365 of those were culture-positive for Vibrio cholerae.
Of the culture-negative cases, 215 occurred in the group that received the OCV and 211 in the group that received a placebo. So, there was no statistically significant difference in culture-negative AWD between those that received a vaccine and those that received a placebo.“We did not find any evidence of protection; implying that the culture diagnostics; used for cholera detection were reliable,” the researchers say in conclusion. “Similar analyses of other OCV randomized controlled trials; recommended to corroborate these findings.”