Hepatitis E is a hepatitis (acute disease, inflammation of liver) caused by a contagious virus called hepatitis E virus (acronym HEV).
Signs and symptoms
It is most common in adults between the ages of 15 and 40. Though children often contract this infection as well, they less frequently become symptomatic. Mortality rates are generally low, for Hepatitis E is a “self-limiting” disease, in that it usually goes away by itself and the patient recovers. However, during the duration of the
infection (usually several weeks), the disease severely impairs a person’s ability to work, care for family members, and obtain food. Hepatitis E occasionally develops into an acute severe liver disease, and is fatal in about 2% of all cases.
Clinically, it is comparable to
hepatitis A, but in pregnant women the disease is more often severe and is associated with a clinical syndrome called as 'fulminant hepatic failure'. Pregnant women, especially those in the third trimester, suffer an elevated
mortality rate from the disease.
Virology
The viral particles are about 33
nanometers in diameter, are non-enveloped and contain a single-strand
RNA, approximately 7300 basepair in length. It was previously classified family
Caliciviridae. However, its
genome more closely resembles the
rubella virus. It is now classified in a new virus family, named as
Hepeviridae.
Epidemiology
Patterns
Hepatitis E is prevalent in most
developing countries, and not uncommon in any country with a hot climate. It is widespread in Southeast Asia, northern and central Africa, India, and Central America. It is spread mainly through
fecal contamination of water supplies or food; person-to-person transmission is uncommon. Outbreaks of epidemic Hepatitis E most commonly occur after heavy rainfalls and
monsoons because of their disruption of water supplies. Major outbreaks have occurred in
New Delhi,
India (30,000 cases in
1956-
1957),
Myanmar (20,000 cases in
1976-
1977),
Kashmir,
India (52,000 cases in
1978),
Kanpur,
India (79,000 cases in
1991), and
China (100,000 cases between
1986 and
1988).
Recent outbreaks
In
2004, there were two major outbreaks, both of them in sub-
Saharan Africa. There was an outbreak in
Chad in which, as of September 27 there were 1,442 reported cases and 46 deaths. In
Sudan, which has been troubled with conflict recently (see,
Darfur conflict), they are also suffering from a severe Hepatitis E epidemic. As of September 28, there were 6,861 cases and 87 deaths, mainly in the West Darfur Region.
UNICEF,
Doctors Without Borders, the
Red Cross, and other international health organizations are currently working to increase the availability of soap, dig new wells, and
chlorinate water supplies and reserves. However, the existing resources are still not enough, and more personnel and funds are severely needed in the region to assure the
health and
welfare of the people. Increasingly, hepatitis E is being seen in developed nations with reports of cases in the UK, US and Japan. The disease is thought to be a zoonosis in that animals are thought to be the source. Both deer and pigs have been implicated.
Prevention
Currently, the only viable method of prevention is improving
sanitation, since no
vaccine exists for the disease. Proper treatment and disposal of human waste, higher standards for public water supplies, improved personal hygiene procedures and sanitary food preparation are all important measures in preventing the spread of this disease. Thus, prevention strategies of this disease are similar to those of many others that plague developing nations, and they require large-scale international financing of water supply and water treatment projects.
External links
Hepatitis | Viruses
E型肝炎