Modeling the present and future distribution of waterborne Hepatitis E virus

Hepatitis E is among the major causes of acute viral hepatitis worldwide. Infections occurring in industrialized countries are caused by zoonotic genotypes 3 and 4, mostly due to the consumption of raw meat products such as pork liver, wild boar and deer meat. Conversely, in developing countries HEV infections are caused by HEV genotypes 1 and 2, due to the consumption of contaminated water. Transmission of waterborne HEV is recurrently leading to large outbreaks in East Africa and India, frequently striking refugee camps. In order to identify the climatic variables most favourable to the occurrence of waterborne HEV, we have built a global species distribution model (SDM) of waterborne HEV genotypes, using the maximum entropy method. The obtained model indicates that the most relevant bioclimatic variables are the precipitation seasonality, the mean temperature of the warmest quarter of the year and the precipitation during the driest quarter of the year. Other environmental variables relevant for the occurrence of HEV are human population density and soil wetness. Moreover, we have identified previously unknown geographical areas with high-risk of HEV outbreaks (mostly located in the Arabian Peninsula). Future models of potential HEV distribution have been obtained using predicted bioclimatic variables from downscaled global climate model data of CMIP5 (IPPC Fifth Assessment), and we have delimited geographical areas showing an increased risk of waterborne HEV occurrence by 2050. Overall, these results allow a better understanding of the geographical distribution of HEV and may be taken into account to optimize the management of refugee camps and the spatial distribution of water treatment facilities.