Risk factors for hepatitis E virus infection and disease

Abstract

Hepatitis E, caused by hepatitis E virus, is a disease of global significance, causing 20 million infections each year. Genotypes 1 and 2 have vastly different epidemiological patterns from genotypes 3 and 4. In genotype 1 and 2 endemic areas, most infections and illness occur in persons 15–30 years of age, with pregnant women being the most likely to experience severe disease. In genotype 3 and 4 endemic areas, most infections and illness occur in those of age 40–60 years, with males representing a large portion of those with severe disease. However, the lack of an easily accessible serologic assay in many countries continues to be a barrier to the diagnosis and recognition of hepatitis E virus.

Keywords:

• asymptomatic infection
• epidemiology
• hepatitis E
• hepatitis E virus
• risk factors
• severe disease

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Hepatitis E virus (HEV) seroprevalence estimates generally are in the 15–25% range among populations living in both genotype 1 and 2 endemic areas and genotype 3 and 4 endemic areas, despite the large differences in the numbers of clinical cases associated with infection from these genotypes.

• In genotype 1 and 2 endemic areas, most infections and illness occur in persons 15–30 years of age, with men slightly more likely to experience infection and disease than non-pregnant women.

• Pregnant women in low-resource countries in Asia and Africa are the most likely to experience severe consequences of HEV infection. The reasons are unclear, but it may be due to underlying nutritional deficiencies, immunologic dysregulation, environmental factors or viral subtypes.

• The epidemiology of HEV in Egypt and North Africa differs from other that in genotype 1 areas, with more clinical disease seen in children. This difference may be caused by subtype, co-infections, early childhood exposures or host genetic factors.

• In genotype 3 and 4 endemic areas, most infections and illness occur in those of age 40–60 years, with males representing a large portion of those with severe disease.

• Chronic HEV infection can occur in immune-suppressed individuals, especially solid organ transplant recipients, which can result in fulminant viral hepatitis or rapid progression to cirrhosis and death.

• The risk of transmission of HEV by transfusion of blood products has been confirmed with HEV RNA prevalence of approximately 1:2000 among voluntary blood and plasma donors.

• An effective subunit HEV vaccine has been developed and found be >95% effective in preventing clinical hepatitis from genotype 4 HEV infection, but is licensed only in China.

Notes