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 are considered the gold standard for diagnosing cholera. However, one recent study, conducted in Bangladesh, found that conventional cultures identified only 66% of patients who were found to have cholera by other measures. This suggests that cholera globally may be widely underestimated.
A team of experts from the International Vaccine Institute (IVI) in Korea, icddr,b, Bangladesh, and Johns Hopkins University, USA 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. 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.
During two years of follow-up, 791 first episodes of AWD were 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. 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. “Similar analyses of other OCV randomized controlled trials are recommended to corroborate these findings.”
Read the journal paper:
About International Vaccine Institute (IVI)
The International Vaccine Institute (IVI) is the world’s only international organization devoted exclusively to developing and introducing new and improved vaccines to protect the world’s poorest people, especially children in developing countries. Established in 1997, IVI operates as an independent international organization under a treaty signed by 35 countries and the World Health Organization. The Institute conducts research in more than 30 countries throughout Asia, Africa and Latin America on vaccines against enteric and diarrheal infections, Japanese encephalitis, MERS-CoV, and dengue fever, and develops new and improved vaccines at its headquarters in Seoul, Republic of Korea. For more information, please visit www.ivi.int
Felicia An, Head of Communications, IVI
+82 2 881 1309 | Felicia.An@ivi.int
Tae Kyung Byun, Senior Manager of Korean Communications, IVI
+82 2 881 1159 | firstname.lastname@example.org