Global Alert and Response (GAR)

Hepatitis E


Surveillance and Control

- Endemicity
- Incidence/ Epidemiology
- Trends
- Immune prophylaxis
- Vaccines

Surveillance and control procedures should include:

  • provision of safe drinking water and proper disposal of sanitary waste
  • monitoring disease incidence
  • determination of source of infection and mode of transmission by epidemiologic investigation
  • detection of outbreaks
  • spread containment

Endemicity
Data on the endemicity of HEV infection have predominantly been collected in areas where outbreaks have been reported. As an exception, seroprevalence studies carried out in Egypt, where outbreaks of HEV have not been noted, showed rates of up to 60%, suggesting that most infections occurred early in life and were asymptomatic or mild.15

Outbreaks have been reported from Algeria, Bangladesh, Borneo, China, Egypt, Ethiopia, Greece, India, Indonesia, Iran, Côte d'Ivoire, Jordan, Libya, Mexico, Myanmar, Nepal, Nigeria, Pakistan, southern Russia, Somalia, eastern Sudan, and The Gambia.10, 18

Most outbreaks have occurred following monsoon rains, heavy flooding, contamination of well water, or massive uptake of untreated sewage into city water treatment plants.10, 28, 48

Incidence/Epidemiology
Outbreaks of hepatitis E are more common in parts of the world with hot climates and are rare in temperate climates.

Outbreaks are mainly associated with faecally contaminated drinking water; exceptions are food-borne epidemics (raw or uncooked shellfish).

HEV was first identified in India, and has since been recognized in the Middle and Far East, in northern and western Africa, the central Asian Republics of the former Soviet Union, in China and Hong Kong SAR.29

Epidemic and sporadic cases have been reported from southeast and central Asia, the Middle East, northern and western Africa and North America (Mexico).40, 41

30 000 cases were reported in New Delhi, India, (1955 - 1956) after the flooding of the river Yamuna and contamination of the city's drinking water.58
20 000 cases occurred in Mandalay, Myanmar, (1976-1977) with 18% case fatality rate in infected pregnant women.10
52 000 cases were reported in Kashmir, India, in 1978.27
100 000 cases were reported in China between 1986 and 1988.48
11 000 cases occurred in Somalia, and about 4 000 cases were reported in Mexico between 1988 and 1989.

Low incidence is reported in Italy and Spain (1995).29, 31

Click here for: Epidemiology map

Trends
Hepatitis outbreaks occurring in Europe prior to the 20th century, and believed to be hepatitis A, had the epidemiologic characteristics of hepatitis E.40, 41

HEV, more labile and shed in lower titres than HAV, may have disappeared from more industrialized countries in the recent past, just as HAV is currently diminishing in importance in these countries.41

Immune prophylaxis
There is no available immunoglobulin (IG) prophylaxis at present.

IG prepared from donors in non-HEV-endemic countries does not prevent infection.41, 48

The efficacy of IG prepared from donors in HEV-endemic areas is unclear, although convalescent human sera have given promising preliminary results for passive protection.10

Experimental immune prophylaxis against HEV based on recombinant antigens appears to confer short-term protection and may be useful for pregnant women in endemic areas and travellers coming into these regions.

Vaccines
At present, no commercially available vaccines exist for the prevention of hepatitis E. However, several studies for the development of an effective vaccine against hepatitis E are in progress.41, 55, 61, 62

A 55 kDa recombinant HEV-derived ORF2 protein has been used to vaccinate rhesus monkeys against different strains of hepatitis E. Although primates could still be infected, the vaccine protected them from the symptoms of disease.55, 62

The direct intramuscular injection of purified plasmid DNA containing the full-length ORF2 of HEV has induced a prolonged humoral immune response (>12 months) to the expressed structural protein ORF2 in 80% and 100% of two separate groups of challenged mice, respectively.19

Because swine HEV is immunologically cross-reactive with human HEV and their capsid genes are very conserved, swine HEV may prove useful as an attenuated vaccine for immunization against human hepatitis E through the "Jennerian" approach.33

 


Epidemiology map





Source: Centers of Disease Control and Prevention (CDC), Atlanta, USA:11
http://www.cdc.gov/ncidod/diseases/hepatitis/slideset/hep_e/slide_5.htm

Geographic distribution of hepatitis E.11, 41 (Note: The map of HEV infection generalizes available data and patterns may vary within countries.)

 

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