What Is Hepatitis E Virus And How Do You Get It?
Hepatitis E is a liver disease (viral hepatitis) caused by a virus known as hepatitis E virus (HEV). Statistically, 20 million people each year infected with this virus globally. According to WHO, this viral infection caused 44,000 (3.3%) mortality cases reported in the year 2015. It has been estimated that two billion people, representing one-third of the world’s population, live in endemic areas for HEV and, therefore, are at risk of infection. The incidence rate is high in south-east Asian countries and the main mode of transmission is contaminated water or fecal-oral route.
Hepatitis E virus is a small RNA virus has four types based on its genotype. Of this four, genotype 1 and 2 is a human pathogen and 3 and 4 exist in wild animals rarely, causes infection in human. Genotype 1 has been isolated from tropical and several subtropical countries in Asia and Africa and genotype 2 has been isolated from Mexico, Nigeria, and Chad. The first incidence case was documented in the year 1955 during an outbreak in New Delhi, India. In 2011, a recombinant subunit vaccine to prevent hepatitis E virus infection was registered in China. This vaccine is licensed and sold in China, but not yet been approved in other countries.
How is HEV Transmitted?
HEV is transmitted primarily by the fecal-oral route and has been reported to occur as large waterborne epidemics and small outbreaks in developing areas. Viral RNA becomes detectable in stool and blood serum during the incubation period. But scientific publication report says that this virus at present cause infection in many high-income countries, which is difficult to predict the route of acquisition of infection. HEV strains have also been isolated from several animal species including wild and domestic swine, deer, chicken, rat, ferret, and rabbit. Hepatitis E is considered a zoonotic infection with pig and wild boar serving as the main reservoir for human infections. An investigation by the Animal Health and Veterinary Laboratories Agency found hepatitis E in 49% of pigs in Scotland. The global burden of HEV infection is thought to be due to sporadically transmitted hepatitis E cases rather than to cases due to hepatitis E epidemic.
Drinking of contaminated water is the large proportion of clinical cases with this disease. Poor sanitation is the risk factor, allowing the virus to contaminate the water bodies. The other possible way of infection also been identified, such as intake of unprocessed meat or meat products of infected animals; infected blood and vertical transmission i.e., pregnant mother to fetus. According to WHO, the consumption of unprocessed shellfish is the source of sporadic cases in endemic areas. Pregnant women show more susceptibility to this infection than other group of people. This infection can cause adverse effect resulting in preterm delivery, abortion, stillbirth, and intrauterine fetal and neonatal death. The Department for Environment, Food and Rural Affairs (UK) said that evidence indicated the hepatitis E in the UK was due to food-borne zoonoses, citing a study that found 10% of pork sausages on sale in the UK contained the virus.
The incubation period after contact to the hepatitis E virus ranges from 3 to 8 weeks, with a mean of 40 days. The outbreaks of epidemic hepatitis E most frequently occur during and after heavy rainfalls because of their disruption of water supplies. During the incubation of HEV in host, it leads to the cause of acute pancreatitis, weakness in a limb due to inflammation of nerves, anemia, renal dysfunction, cryoglobulinemic disease i.e. blood contains large amounts of cryoglobulins and low platelet count which confers a risk of life-threatening bleeding. Jaundice is the symptomatic phase coincides with elevated hepatic aminotransferase levels.
Prevention of HEV
The transmission of HEV to general population can be reduced by maintaining high standards in the supply of water among the public and proper disposal of human waste. On an individual level, the infection risk can be reduced by maintaining hygienic practices such as hand-washing with safe water, particularly before handling and having the food.
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