Population density and water balance influence the global occurrence of hepatitis E epidemics

Abstract

In developing countries, the waterborne transmission of hepatitis E virus (HEV), caused by HEV genotypes 1 (HEV-1) and 2 (HEV-2), leads to the onset of large recurrent outbreaks. HEV infections are of particular concern among pregnant women, due to very high mortality rates (up to 70%). Unfortunately, good understanding of the factors that trigger the occurrence of HEV epidemics is currently lacking; therefore, anticipating the onset of an outbreak is yet not possible. In order to map the geographical regions at higher risk of HEV epidemics and the conditions most favorable for the transmission of the virus, we compiled a dataset of HEV waterborne outbreaks and used it to obtain models of geographical suitability for HEV across the planet. The main three variables that best predict the geographical distribution of HEV outbreaks at global scale are population density, annual potential evapotranspiration and precipitation seasonality. At a regional scale, the temporal occurrence of HEV outbreaks in the Ganges watershed is negatively correlated with the discharge of the river (r = −0.77). Combined, our findings suggest that ultimately, population density and water balance are main parameters influencing the occurrence of HEV-1 and HEV-2 outbreaks. This study expands the current understanding of the combination of factors shaping the biogeography and seasonality of waterborne viral pathogens such as HEV-1 and HEV-2, and contributes to developing novel concepts for the prediction and control of human waterborne viruses in the near future.

Hepatitis E virus outbreak associated with rainfall in the Central African Republic in 2008-2009

“…In our study (which was not a seroprevalence study), a higher incidence (34% versus 21% of the febrile jaundice cases) was found in Bangui compared to the rest of the country. This might be due to the higher population density in Bangui with water supplies that are shared by a lot of people [2]. However, the incidence in the rest of the country was far from negligible with detected strains that are closely related to strains isolated in Bangui.…”

“…Hepatitis E virus (HEV) infection represents a significant public health problem in many parts of the world, particularly in Africa where it can cause outbreaks of acute hepatitis in areas with a high population density, heavy seasonal rainfall and high evapotranspiration rates [1,2]. HEV has two epidemiological profiles in humans.…”

Role of Hepatitis E Virus Infection in North American Patients With Severe Acute Liver Injury

“…Acute HEV infection with genotype 1 or 2 is a frequent cause of acute hepatitis and jaundice in many parts of the world because of spread of the virus through fecal–oral transmission ( 1 , 2 , 24 ). By contrast, cases arising from HEV genotypes 3 and 4 infection are zoonotic and account for most autochthonous HEV infections in European countries where pigs and wild boar are the main reservoir.…”

Hepatitis E Virus Infection: Circulation, Molecular Epidemiology, and Impact on Global Health

“…Sporadic outbreaks have also occurred in recent years in Asian and African countries, but with a low number of reported cases [ 133 , 134 , 135 , 136 , 137 ]. Using modelling approaches, a recent study describes the ecologically most suitable hotspots for HEV viruses: the Ganges Valley in India and Pakistan [ 138 ]. Important factors contributing to water-related outbreaks of HEV are population density, socio-economic conditions, the level of sanitation, and access to drinking water [ 14 , 138 ].…”

“…Using modelling approaches, a recent study describes the ecologically most suitable hotspots for HEV viruses: the Ganges Valley in India and Pakistan [ 138 ]. Important factors contributing to water-related outbreaks of HEV are population density, socio-economic conditions, the level of sanitation, and access to drinking water [ 14 , 138 ]. There are also frequent outbreaks in refugee camps, military camps, and emergency shelters in conflict- and catastrophe-affected regions [ 127 , 139 , 140 , 141 , 142 ].…”