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Hepatitis E
[dagger]. These authors contributed equally to this work.
INTRODUCTION
Until the beginning of the 21st century, hepatitis E was considered a rare disease in industrialized countries limited to travellers and persons residing in endemic areas in developing countries [1]. Today HEV is considered endemic in many industrialized countries, also in Europe, posing a risk to the growing population of immunocompromised people [2].
HEV is synonymous with the species Orthohepevirus A in the genus Orthohepevirus and is the sole member of the family Hepeviridae. It is a single-stranded RNA virus with four known genotypes. Genotypes 1 (HEV-1) and 2 (HEV-2) are restricted to humans, and transmitted faecal-orally via contaminated drinking water in developing countries [2]. Genotypes 3 (HEV-3) and 4 (HEV-4) infect humans, swine and other mammals. Whereas HEV-4 is mainly detected in Southeast Asia, HEV-3 causes sporadic HEV infections worldwide. HEV infections are normally mild and self-limiting [3]; however, in developing countries the case fatality can reach 10-20% in pregnant women [2].
Although the transmission route for HEV-3 is not fully understood, studies have suggested that wild boars and domestic swine are the main reservoirs for human infection [3], either through direct contact or through the consumption of raw or undercooked meat from animals with active infection [4-6]. Additionally, HEV has been isolated from untreated wastewater, swine manure, swine slurry storage facilities, river water and shellfish [3].
HEV seroprevalence in swine ranges from 46% to 100% in swine herds and from 23% to 90% in individual swine [7-10]. Positive polymerase chain reaction (PCR) indicating active HEV infection have been detected in most investigated swine herds and range from 8% to 73% in swine across all age groups [11, 12].
In Norway, HEV has been isolated from sewage [13], but no published data on seroprevalence of HEV in humans or animals exists. The objectives of this study were to estimate the seroprevalence of HEV in humans and swine in Norway, and investigate the association between direct contact with swine and HEV seroprevalence in humans.
METHODS
Study population
Blood donors
A convenience sample of serum from blood donors was collected from 10 different hospitals, located in urban and rural, as well as coastal and inland areas of Norway. Two millilitres of serum from...