By Aminu Magashi Garba
A News-release obtained by Health Reporters had revealed that better targeting at the district and neighborhood level could make anti-cholera efforts much more effective and dramatically reduce the burden of this disease, according to two new studies led by scientists at Johns Hopkins Bloomberg School of Public Health.
One of the teams of scientists developed a high-resolution map of cholera cases in most of Africa in a study published in The Lancet online on March 1. These maps show that while cholera is considered endemic in many African countries, most cases of the disease are concentrated in relatively few areas. Focusing anti-cholera efforts on these hotspots could reduce the region’s annual burden of the disease by 50 percent by targeting fewer than five percent of districts in sub-Saharan Africa, the scientists estimate.
According to the News-release, Cholera is widely underreported, with estimates of the actual global burden ranging up to 4 million cases and 143,000 deaths a year. There are 150,000 infections and thousands of deaths each year around the globe, according to the World Health Organization (WHO). Much of this burden lies in sub-Saharan Africa, where frequent cholera outbreaks are a major source of social and economic disruption. Resources to fight cholera, including oral cholera vaccines (OCVs) and funds to build water and sanitation infrastructure, are limited in comparison with the population potentially at risk—including roughly a billion people in sub-Saharan Africa.
“To eliminate cholera as a public health problem we need to target control measures efficiently to those at highest risk,” says Justin Lessler, an associate professor in the Bloomberg School’s Department of Epidemiology and co-lead author of the Lancet study.
It further revealed that using this approach, 38·4% of cholera cases could be prevented by covering 50·8 million people in five countries: Somalia, Nigeria, Democratic Republic of the Congo, Sierra Leone, and Ghana.
In another study “The PLoS Medicine study”, a team co-led by Andrew Azman, a research associate in the Bloomberg School’s Department of Epidemiology, used detailed data from a 2011 cholera epidemic in Chad to make a computational model that could simulate realistic epidemics. The team, working with colleagues from École Polytechnique Fédérale de Lausanne, based these simulations on “fine-grained” data that showed the locations of victims’ homes and timing of infection, allowing the researchers to see how it spread, from house to house, day by day.
The scientists modeled the use of Oral Cholera Vaccine (OCVs), antibiotics, and point-of-use water treatment (POUWT) against simulated outbreaks. They found that even assuming realistic logistical delays, the early application of these combined interventions to individuals living in close proximity to cholera victims should be highly effective.
The News-release highlighted that “Oral Cholera Vaccine (OCV) appeared to be by far the most effective of the interventions. In the simulations, it reduced the duration of outbreaks by an average of 68 percent and the number of cases by 81 percent when applied within its optimal range, an area of 100-meter radius centered on each cholera case household. Adding POUWT and antibiotics improved that outcome only slightly.” The modeling also showed that when applied in this case-area targeted manner, OCV can be more than 40 times more efficient at averting cholera cases than traditional mass-vaccination campaigns.
The study that appeared in the Lancet Online of 1st March 2018 was supported by the Bill & Melinda Gates Foundation.
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