EPFL scientists map high-risk areas for hepatitis E

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A team of EPFL scientists has collected environmental and epidemiological data from around the world to develop a map showing the riskiest areas for Hepatitis E epidemics. Their work, published in Scientific Reports, paves the way for new ways of research and prevention.

EPFL scientists have created the first world map of regions with the highest prevalence of hepatitis E virus (HEV). They hope their map – freely available online – will help governments and NGOs to design more effective prevention campaigns based on reliable data, particularly when it comes to creating refugee camps. The scientists' research has just been published in Scientific Reports.

In Europe, China, Japan and North America, the main way people reach HEV is to eat poorly treated pork, and the resulting illness is generally not fatal. However, in Mexico, India, Africa and in most Asian countries, HEV is contracted by coming into contact with the water of a river or well contaminated with fecal material. According to the World Health Organization, there are about 20 million HEV infections worldwide every year and about 50,000 deaths from the disease. Epidemics of hepatitis E are particularly lethal for pregnant women and generally occur after heavy rains and floods or after long months of drought.

Machine learning

To build their map, EPFL scientists have collected data on all hepatitis E epidemics recorded worldwide since 1980 and on environmental statistics such as temperature, soil moisture and precipitation over the same period. They also took into consideration the geographic location, the density of the population and the rate of evapotranspiration, or how much the river water evaporates during a drought. Evapotranspiration is important because the more intestinal pathogens found in the contaminated water that remains – the water that is often used for cooking, washing or even religious ceremonies – occurs, the more highly concentrated it is.

Thanks to machine learning, scientists were able to analyze all the data and get concrete results. "Our study confirmed that the areas most at risk are those with a high population density, strong seasonal rainfall and high rates of evapotranspiration", says Anna Carratalà, scientist of the EPFL Laboratory of Environmental Chemistry and lead author of the study. His co-author, Stéphane Joost, works at the EPFL Laboratory of Geographic Information Systems. "One way to reduce this risk is to artificially increase the flow of the river during the hottest and driest periods of the year".

The need for more data

EPFL scientists have performed a monumental task in bringing together data from different online sources, however their map is only a step towards the development of prevention campaigns in high-risk areas. For example, their map shows that measures need to be taken urgently in the north of India. According to Carratalà, the next step would be to add information on annual HEV concentrations in the Ganges river to their data, along with the number of hepatitis E cases registered in local hospitals. This would allow them to better understand how environmental factors influence hepatitis E epidemics in that region.

Scientists collaborated with the National Institute of Epidemiology of India to collect data on the country. In a new project, they will see how human activity affects HEV concentrations and other contaminants – such as antibiotic-resistant genes – in the Rhone in Switzerland and compare it with concentrations in the Ganges.

On this map, researchers compared the location of refugee camps with hepatitis E outbreaks recorded to date. © LCE / LASIG EPFL 2019

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