Abstract
Until recently, hepatitis E was thought to be largely confined to hyperendemic areas in Asia, Africa and Mexico. Over the
last 10 years it has become clear that this is not the case, as it is surprisingly common in developed countries. In these
settings, it is caused by HEV genotypes 3 and 4, and is a porcine zoonosis. It causes a range of human illness including
acute and chronic hepatitis, and a spectrum of neurological injury. HEV RNA has been found in donated blood from an
increasing number of countries, and in some locations with a very high incidence. The clinical phenotype and burden of
disease in humans is still emerging. In contrast to previous ‘received wisdom’, zoonotically transmitted HEV may be one
of the most successful zoonotic viral infections in human history. How did we, as a scientific community, get this so badly
wrong? This review considers this question from a largely clinical perspective, explores the places HEV has been ‘hiding’
and the emerging clinical phenotype in humans.
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