Epidemiological situation of hepatitis E in Africa

Hepatitis E virus (HEV) belongs to the Hepeviridae family, Orthohepevirinae subfamily, Paslahepevirus genus which includes eight genotypes. HEV genotype 1 (HEV-1) and genotype 2 (HEV-2) are specific to humans, while genotype 3 (HEV-3) and genotype 4 (HEV-4) circulate mainly in pigs, wild boars and deer, but have also a zoonotic potential. HEV genotype 5 (HEV-5) and 6 (HEV-6) viruses circulate in wild boars in Japan and genotype 7 (HEV-7) and 8 (HEV-8) viruses circulate in camelids. The worldwide distribution of HEV is influenced by ecological and socioeconomic factors. In developing countries in Africa, transmission of the virus through fecally contaminated water accounts for a high proportion of epidemics. Direct human-to-human transmission is less frequent, although cases of infection through blood transfusion have been reported in several countries. Thanks to the "One Health" approach, zoonotic transmissions of HEV from pig to human have been more recently observed. These zoonotic infections are mainly due to the handling or consumption of pork meat or contact with pig manure, contaminating the environment. They alert on professions or populations at-risk, such as livestock farmers or butchers. In addition, HEV infection is particularly severe in pregnant women, leading to fetal and maternal death due to acute liver failure. Finally, the development and application of serological or molecular detection tests in Africa indicates that HEV can be incriminated in symptoms without etiology or falsely attributed to other hepatic viruses or to the yellow fever virus. This review updates studies on the epidemiology of HEV in Africa, a crucial step to better understand the virus and develop surveillance strategies to prevent and better control epidemics.