Hepatitis is a general term describing inflammation of the liver. It is a disease which can be transmitted by a whole group of different viruses such as the hepatitis A, B, C, D, or E viruses.Jaundice is a characteristic feature of hepatitis although the correct diagnosis can only be made from a blood test.
Hepatitis E was not recognised as a separate human disease until 1980. It is caused by infection by the hepatitis E virus, a single chain RNA virus.
While human beings are considered to be the natural host for human hepatitis E virus (HEV), anti-HEV antibodies or antibodies against closely related viruses have been found in primates and in several other species of animals, suggesting that it may be a zoonosis (i.e. a disease which can be transmitted from animals to human beings).
Transmission of HEV
Hepatitis E is a water-born disease and contaminated water or foods have been implicated in major outbreaks. Drinking tap water which has been contaminated with faeces has caused epidemics and eating raw seafood has been responsible for sporadic cases in endemic areas. The virus may spread from animals because several non-human primates and pigs, cows, sheep, goats and rodents are susceptible to infection. The risk factors for HEV infection are related to the poor sanitary conditions in a large part of the world.
Transmission between human beings is not thought to be common. There is nothing to suggest that it can be transmitted sexually or by transfusion.
Epidemics of hepatitis E have been reported in Central Asia and South-East Asia, North and West Africa and in Mexico, particularly when drinking water is frequently contaminated with faeces. However, sporadic cases of hepatitis E have also been reported elsewhere and serological studies have suggested that strains of hepatitis E are found throughout the world causing asymptomatic or weakly pathogenic infection.
Generally, hepatitis E is a self-limiting viral infection which resolves spontaneously. It is unusual for the virus to be excreted in faeces for long periods of time and no chronic infection is seen.
Overall, the mortality rate is between 0.5 and 4.0%. A sudden onset of the severe form of hepatitis is occasionally seen causing death of hepatocytes with liver atrophy which may be fatal. This form of the disease is known by the term fulminant hepatitis. It usually affects pregnant women and has a mortality rate of 20% during the third trimester of pregnancy.
The incubation period after exposure to HEV is 3 to 8 weeks. However, it is not known how long an infected person may transmit the disease for.
The typical signs and symptoms of hepatitis are: jaundice (a yellowish colour of the skin and sclera, dark urine, and pale stools), anorexia (loss of appetite), hepatomegaly (hypertrophy of the liver, which is painful to the touch), abdominal pain and tenderness on palpation, nausea, vomiting and fever. Cases of varying severity, from benign illness to life-threatening disease are seen.
Symptomatic HEV infection particularly affects young adults between 15 and 40 years old. infection is common in children and is usually asymptomatic or very mild without jaundice. It then goes undiagnosed.