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Hepatitis E virus
Hepatitis E Virus (HEV) has a particle diameter of 32-34 nm, and is very labile. Based on its physicochemical properties it is presumed to be a calici-like virus.
The disease caused by HEV is called hepatitis E, or enterically transmitted non-A non-B hepatitis (ET-NANBH). Other names include faecal-oral non-A non-B hepatitis, and A-like non-A non-B hepatitis.
Hepatitis caused by HEV is clinically indistinguishable from hepatitis A disease. Symptoms include malaise, anorexia, abdominal pain, arthralgia, and fever. The infective dose is not known.
The incubation period for hepatitis E varies from 2 to 9 weeks. The disease usually is mild and resolves in 2 weeks. The fatality rate is 0.1-1% except in pregnant women. This group is reported to have a fatality rate approaching 20%.
Diagnosis of Hepatitis E is based on the epidemiological characteristics of the outbreak and by exclusion of hepatitis A and B viruses by serological tests. Confirmation requires identification of the 27-34 nm virus-like particles by immune electron microscopy in faeces of acutely ill patients.
HEV has not been isolated directly from foods. HEV is transmitted by the faecal-oral route. Waterborne and person-to-person spread, have been documented. The potential exists for foodborne transmission, especially through improper food handling by ill persons. Due to the difficulties to distinguish HEV from Hepatitis A, it cannot be excluded that food-borne cases have occurred.
The disease can be prevented by proper hygiene and thorough heating (over 80°C) of the foods.
The disease is most often seen in young to middle aged adults (15-40 years old). Pregnant women appear to be exceptionally susceptible to severe disease, and excessive mortality has been reported in this group.
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