Hepatitis A, D, And E Virus Infection

Viral hepatitis is a significant global health burden.  This article focuses on hepatitis A virus (HAV), hepatitis E virus (HEV), and hepatitis D virus (HDV), with hepatitis B virus (HBV) and hepatitis C virus (HCV) discussed extensively in separate articles.

HAV and HEV are nonenveloped, single-stranded RNA viruses transmitted primarily through the fecal-oral route and typically causing acute, self-limited infections.  HDV is a defective, circular RNA virus requiring HBV for replication, and is transmitted mainly through parenteral routes.  It can lead to severe chronic liver disease when superinfecting individuals with chronic HBV infection.

HAV is a member of the Picornaviridae family, causing an estimated 100 million new hepatitis infections annually (many of which are likely unreported).  The virus is prevalent in areas with poor sanitation and limited access to clean water, with higher incidence rates in Africa, Asia, and Latin America.  Because the virus is shed in the stool, transmission occurs via the fecal-oral route and outbreaks are often linked to unsanitary food (eg, undercooked shellfish) and water supplies.  Settings where hygiene may be suboptimal (eg, daycare centers, homeless shelters) can also contribute to person-to-person spread via the fecal-oral route.  Additional risk groups include international travelers, men who have sex with men (MSM), military personnel deployed to endemic areas, and people who use recreational drugs.