Dual Infection of Hepatitis A Virus and Hepatitis E Virus- What Is Known?

Abstract

Viral hepatitis is an infection of human hepatocytes resulting in liver damage. Dual infection of two hepatotropic viruses affects disease outcomes. The hepatitis A virus (HAV) and hepatitis E virus (HEV) are two enterically transmitted viruses; they are single-stranded RNA viruses and have common modes of transmission. They are transmitted mainly by the fecal-oral route and ingestion of contaminated food, though the HAV has no animal reservoirs. The HAV and HEV cause acute self-limiting disease; however, the HEV, but not HAV, can progress to chronic and extrahepatic infections. The HAV/HEV dual infection was reported among acute hepatitis patients present in developing countries. The impact of the HAV/HEV on the prognosis for acute hepatitis is not completely understood. Studies showed that the HAV/HEV dual infection increased abnormalities in the liver leading to fulminant hepatic failure (FHF) with a higher mortality rate compared to infection with a single virus. On the other hand, other reports showed that the clinical symptoms of the HAV/HEV dual infection were comparable to symptoms associated with the HAV or HEV monoinfection. This review highlights the modes of transmission, the prevalence of the HAV/HEV dual infection in various countries and among several study subjects, the possible outcomes of this dual infection, potential model systems for studying this dual infection, and methods of prevention of this dual infection and its associated complications.

Keywords: HAV; HEV; dual infection; outcomes; prevention; treatment; viral hepatitis.

Figure 1

Possible routes of HAV/HEV dual infection. Humans are reservoirs for HAV and HEV, while pigs, wild boar, deer, and other animals are reservoirs for HEV only. (1) Waterborne dual infection has been confirmed for HAV/HEV via the fecal oral route. (2) Foodborne infection—ingestion of vegetables/fruits irrigated by contaminated water or seafood—has been confirmed for both viruses. (3) Blood transfusions, i.e., transmission via transfusion, have been confirmed for HEV (red) but are not a frequent source of HAV (blue). (4) Person-to person-contact such as MSM has been confirmed for HAV (red) but is not a frequent source of HEV (blue). (5) Vertical transmission, i.e., from mother to child, has been confirmed for HEV (red) but is not a frequent source for HAV (blue). For HEV/ HAV: Red means a confirmed source of infection; blue means not a frequent source, which is possible but not confirmed yet.