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Historical enquiry into diseases with morbidity or mortality predilections for particular demographic groups can permit clarification of their emergence, endemicity, and epidemicity. During community-wide outbreaks of hepatitis A in the pre-vaccine era, clinical attack rates were higher among juveniles rather than adults. In community-wide hepatitis E outbreaks, past and present, mortality rates have been most pronounced among pregnant women. Examination for these characteristic predilections in reports of jaundice outbreaks in the USA traces the emergence of hepatitis A and also of hepatitis E to the closing three decades of the 19th century. Thereafter, outbreaks of hepatitis A burgeoned, whereas those of hepatitis E abated. There were, in addition, community-wide outbreaks that bore features of neither hepatitis A nor E; they occurred before the 1870s. The American Civil War antedated that period. If hepatitis A had yet to establish endemicity, then it would not underlie the jaundice epidemic that was widespread during the war. Such an assessment may be revised, however, with the discovery of more extant outbreak reports.

Space-time clustering of people who fall acutely ill with jaundice, then slip into coma and death, is an alarming phenomenon, more markedly so when the victims are mostly or exclusively pregnant. Documentation of the peculiar, fatal predisposition of pregnant women during outbreaks of jaundice identifies hepatitis E and enables construction of its epidemic history. Between the last decade of the 18th century and the early decades of the 20th century, hepatitis E-like outbreaks were reported mainly from Western Europe and several of its colonies. During the latter half of the 20th century, reports of these epidemics, including those that became serologically confirmed as hepatitis E, emanated from, first, the eastern and southern Mediterranean littoral and, thereafter, Southern and Central Asia, Eastern Europe, and the rest of Africa. The dispersal has been accompanied by a trend towards more frequent and larger-scale occurrences. Epidemic and endemic hepatitis E still beset people inhabiting Asia and Africa, especially pregnant women and their fetuses and infants. Their relief necessitates not only accelerated access to potable water and sanitation but also vaccination against hepatitis E.

Hepatitis E, which is caused by hepatitis E virus (HEV), may now be considered a zoonosis as well as an anthroponosis. Pigs, boars and deer have been identified as reservoirs, and their flesh and entrails--as meat and offal--as vehicles of HEV transmission. Shellfish also act as vehicles. Dietary, gastronomic and culinary preferences influence how extensively HEV conveyed by these vehicles can be inactivated before their ingestion by the host. Another route of infection is paved by HEV that is enterically shed by humans and by live animals into the environment. Although anthroponotic transmission of HEV is primarily environmental, zoonotic transmission may proceed along both foodborne and environmental routes.

Although autochthonous hepatitis E has been reported in developed countries, its extent and nature in the United Kingdom are unclear. The aim of the present study was to report the natural history, lifestyle risk factors and molecular epidemiology of autochthonous hepatitis E infection in southwest England. Three hundred and thirty-three patients with unexplained hepatitis were tested for markers of hepatitis E virus (HEV) infection over a 7-year period. HEV RNA isolated from the cases was amplified and characterized. Of the 333 patients, 21 had autochthonous hepatitis E. Patients were middle-aged or elderly and males were more commonly affected. Clinical manifestations ranged from asymptomatic infection to severe hepatitis. Of the 21 patients, 20 recovered within 6 weeks. None of the cases had travelled to an area endemic for HEV. None of the patients were vegetarian and all ate pork. Of the 21 cases, 20 occurred in the spring, summer and autumn months. All polymerase-chain-reaction-confirmed cases carried HEV genotype 3, which bore close sequence homology to HEV circulating in UK pigs. In the United Kingdom, autochthonous hepatitis E may be more common than previously recognized. Although the mode of transmission remains to be determined, it may be a zoonosis with pigs as a reservoir. Hepatitis E should be considered a public health issue in the United Kingdom.

Indigenous hepatitis E is increasingly recognized in developed countries, where it may be a zoonosis. We describe the first case of transfusion-transmitted hepatitis E in the UK from a blood donor who had no history of recent travel abroad. Follow-up of the donor and recipients of the blood products was carried out using serological and molecular techniques. Acute hepatitis E was transmitted to one of two recipients. The infected patient would have received a larger volume of the donor's plasma. HEV subgenomic sequences carried by the donor and recipient were identical. This is the first case of post-transfusion hepatitis E in the UK. Secondary transmission of hepatitis E indigenous to a nonhyperendemic country may occur by blood transfusion. It is important that blood donors inform the transfusion service of all post-donation illnesses so that appropriate interventions can take place.

The first nucleotide sequences of hepatitis E virus (HEV) acquired in the United Kingdom are described. The sequences are novel and are related most closely to HEV isolated from Greece (Greece 2 strain), consistent with their having been derived from an indigenous European virus. HEV was assumed until recently to be rare in the United Kingdom and other industrialised countries and, consequently, hepatitis E may be under-diagnosed in industrialised countries., (Copyright 2001 Wiley-Liss, Inc.)