Queensland Health Guidelines for Public Health Units
|1.0||February 2012||Full revision of guidelines.|
The agent is hepatitis E virus (HEV), the sole member of the Hepeviridae family. At least four mammalian genotypes (1-4) and one avian genotype exist. The mammalian genotype 1 and 2 strains are restricted to humans and are mainly responsible for large waterborne epidemics in endemic regions; the mammalian genotype 3 and 4 strains are found both in human and animal reservoirs (swine, wild boar etc) and appear responsible for sporadic cases of HEV infection. Understanding is evolving.
Laboratory definitive evidence
Detection of hepatitis E virus by nucleic acid testing
Detection of hepatitis E virus in faeces by electron microscopy
Detection of IgM or IgG to hepatitis E virus. If the person has not travelled outside Australia in the preceding 3 months, the antibody result must be confirmed by specific immunoblot.
Community Outbreak Criterion
Any case without a history of recent travel to relevant countries.
To notify on confirmation of diagnosis by telephone or facsimile.
Attending Medical Practitioners/ Medical Superintendents (or Delegates)
Not clinically notifiable.
Report only confirmed cases.
A confirmed case requires laboratory definitive evidence.
- To obtain history of travel to relevant countries; and if negative, to investigate potential source/s of infection.
- To provide advice to prevent further transmission.
- To monitor the epidemiology of HEV in Queensland.
Hepatitis E virus (HEV) is a major cause of epidemic and sporadic hepatitis in many subtropical areas of Asia, Africa and Mexico. In developing country settings, it causes large water-borne epidemics and mortality rates due to fulminant hepatitis can be significant.
Traditionally, developed countries were considered non-endemic with most HEV infections being sporadic, imported (through patient travel) and self-limited. In these cases, as HEV is not efficiently transmitted person to person, the public health risk is considered relatively low. This is still the case in Australia. In recent years NNDSS reports about 40 cases throughout Australia per year. NNDSS data for Australia indicate cases have occurred across all age groups, but with an unexplained excess of cases reported in males with a male to female ratio of 2:1. There are currently about 5 cases per year notified in Queensland.
In recent years, cases of HEV infection have been described in high-income countries outside Australia especially in Europe and Japan, in individuals without history of travel to endemic regions, indicating that HEV might be acquired locally. It is considered that zoonotic transmission through the consumption of contaminated animal-based food products may be responsible as animals, especially swine, can be infected and remain totally asymptomatic. It is therefore an emerging zoonotic infectious disease of potential public health significance.
From seroprevalence studies in Europe and USA, it is likely that most HEV infections are asymptomatic or minimally symptomatic.
The clinical presentation of HEV infection in humans is indistinguishable from hepatitis A. Symptoms include anorexia, jaundice, abdominal pain and hepatomegaly accompanied by fever, nausea and vomiting. HEV infection is usually self-limited but chronic HEV infections have recently been described in individuals with underlying conditions such as chronic liver disease, liver transplant, HIV infection and haematological malignancies and fulminant disease has been reported in Japan and Europe in males with underlying chronic liver disease (cited in Lewis et al).
HEV infection during pregnancy has been associated with high mortality rates in some endemic areas, but in non-endemic areas it appears less of an issue.
In subtropical countries where genotypes 1 and 2 are endemic, humans are the reservoir.
In sporadic cases across the world due to genotypes 3 and 4, domestic and wild pigs are likely main animal reservoirs; HEV has also been detected in deer, dogs, cats, cows, sheep, goats and other animal species.
In subtropical countries where genotypes 1 and 2 are endemic, transmission is primarily by the faecal-oral route; faecally contaminated drinking water is the most commonly documented vehicle of transmission globally.
In sporadic cases across the world due to genotypes 3 and 4, direct (faecal-oral) and foodborne zoonotic transmission appears likely. Case reports suggest the following food items were risk factors for the acquisition of HEV infection: pork pies, liver pate, wild boar meat and offal, undercooked or raw pork, home made sausages.
Shellfish has also been implicated as a potential source of infection.
HEV does not transmit readily from person to person. There are very few reports of family clusters of cases or person to person outbreaks.
Cases linked to blood transfusion have been reported in England and France.
In developing countries, there is evidence of vertical and sexual transmission. In European studies, there are no reports of sexual transmission and limited reports of vertical transmission during pregnancy.
The range is 15 to 60 days, mean 40 days.
Remember that person to person transmission is inefficient.
HEV viraemia and viral excretion in stools appear 1-2 weeks before the onset of clinical symptoms. From a few days to 2 weeks after the onset of clinical symptoms, HEV RNA is cleared from the blood and two weeks later (i.e. 4 weeks after onset of symptoms) it is cleared from the stools. Viral shedding in stools may persist in people who are immunocompromised.
Unknown. Over 50% of HEV infections may be anicteric; the expression of icterus appears to increase with increasing age.
Uncertain whether infection confers lifelong immunity.
In consultation with the attending medical practitioner, determine the source of infection:
- travel to endemic country
If not, question regarding:
- contact with a person with hepatitis
- blood transfusion
- consumption of raw or partially cooked shellfish and meat products
- recreational water exposure
- other potential faecal-oral exposure (childcare, sexual, social)
Determine occupation of case (in particular food handler, health care worker or child care worker)
Exclude from work or school while infectious, ie. until two weeks after the onset of jaundice.
The case should be advised of the nature of the infection and its mode of transmission. Cases should be advised, for the duration of the infectious period:
- not to donate blood
- not to prepare or handle food to be consumed by other people
- not to share drug paraphernalia
- to limit contact with others, especially pregnant women and people with immune deficiencies and chronic liver disease
- to practice good hand washing and hygiene practices. Hands should be washed with soap and water for at least 15 seconds and dried thoroughly on a disposable or clean towel frequently, and before handling food and after going to the toilet.
Household contacts, or those for whom the case has prepared food or drink while infectious.
Travel companions or others exposed to the same risk as the case.
Search for missed cases and maintain surveillance of contacts in the case's household or persons exposed to the same risk.
The contacts should be advised of the nature of the infection and its mode of transmission. Encourage early presentation to a health service if symptoms develop, with testing for HEV. Provide advice about careful hygiene.
Other control measures
If infection not acquired overseas, investigate possible sources (water, food or contact with another case).
- Educate about hygienic practices, in particular hand washing before eating and preparing food, and after going to the toilet.
- Advise travellers to developing countries to avoid drinking water (and beverages with ice) of unknown purity and eating uncooked foods e.g. uncooked shellfish, uncooked vegetables and fruits that are not peeled or prepared by the traveller.
A vaccine is under development.
Prepare a summary report of the investigation for the Communicable Diseases Branch, Queensland Health, on request.
Heymann D. (Ed). 2008. Control of Communicable Diseases Manual, 19th edition. American Public Health Association: Washington.
Lewis HC, Wichmann O, Duizer E. Transmission routes and risk factors for autochthonous hepatitis E infection in Europe: a systematic review. Epidemiology and Infection 2010;138:145-166.
Pavio N, Mansuy J-M. Hepatitis E in high-income countries. Current Opinion in Infectious Diseases 2010;23:521-527.