While the majority of worldwide hepatitis E viral (HEV) infections that occur in people are from contaminated water or food sources, there has also been a steadily rising number of reported cases of transfusion-transmitted HEV (TT-HEV) in blood donation recipients. For most, HEV infection is acute, self-limiting and asymptomatic. However, patients that are immunocompromised, especially transplant patients, are at much higher risk for developing chronic infections, which can progress to cirrhosis and liver failure, along with overall increased mortality. Because of the rising trend of HEV serological prevalence among the global population, and the fact that TT-HEV infection can cause serious clinical consequences among those patients most at need for blood donation, the need for screening for TT-HEV has been gaining in prominence as an important public health concern for both developing and developed countries. In the review, we summarise evidence for and notable cases of TT-HEV infections, the various aspects of HEV screening protocols and recent trends in the implementation of TT-HEV broad-based blood screening programmes.

Hepatitis E virus genotype 1 (HEV G1) is an important cause of morbidity and mortality in Africa and Asia. HEV G1's natural history, including the incubation period, remains poorly understood, hindering surveillance efforts and effective control. Using individual-level data from 85 travel-related HEV G1 cases in England and Wales, we estimate the incubation period distribution using survival analysis methods, which allow for appropriate inference when only time ranges, rather than exact times are known for the exposure to HEV and symptom onset. We estimated a 29.8-day (95% confidence interval (CI) 24.1–36.0) median incubation period with 5% of people expected to develop symptoms within 14.3 days (95% CI 10.1–21.7) and 95% within 61.9 days (95% CI 47.4–74.4) of exposure. These estimates can help refine clinical case definitions and inform the design of disease burden and intervention studies.

In this study we assessed the seroprevalence of hepatitis E virus (HEV) infection in both the Italian population and immigrants from developing countries in Foggia (Apulia, Southern Italy). The seroprevalence of HEV was determined in 1217 subjects [412 (34%) immigrants and 805 Italian subjects (blood donors, general population, HIV-positive, haemodialysis patients)]. Serum samples were tested for anti-HEV and confirmed by Western blot assay; in positive patients HEV RNA and genotype were also determined. There were 8·8% of patients that were positive to anti-HEV, confirmed by Western blot. The prevalence in immigrants was 19·7%, and in Italians 3·9% (blood donors 1·3%, general population 2·7%, HIV-positive patients 2·0%, haemodialysis patients 9·6%). Anti-HEV IgM was found in 38/107 (35·5%) of the anti-HEV-positive serum samples (34 immigrants, four Italians). This study indicates a higher circulation of HEV in immigrants and Italian haemodialysis patients, whereas a low prevalence of HEV antibodies was seen in the remaining Italian population.

Hepatitis E virus (HEV) infection results in hepatitis E, an acute and self-limited disease. The virus is transmitted in a faecal–oral manner and is a major cause of viral hepatitis in much of the developing world, where it causes rampant sporadic infections and large epidemics. A curious feature of hepatitis E is the unusually high rates of mortality that are observed in pregnant women, in whom the disease is exacerbated by the development of fulminant liver disease. In the absence of viable in vitro propagation systems, several geographical isolates of HEV have been maintained in vivo in nonhuman primates and, subsequently, the viral genome has been cloned and sequenced. HEV has been classified provisionally into a separate family known as the HEV-like viruses, which has at least four recognised genotypes, but has only a single serotype. The viral genome is a positive-stranded (+)RNA of ~7.5 kb and encodes at least three proteins. Open reading frame 1 (ORF1) encodes the viral nonstructural polyprotein, which has domains that are homologous to some of the replication and processing enzymes found in other +RNA viruses. The HEV protein itself remains poorly characterised. The protein encoded by open reading frame 2 (ORF2) is the major HEV capsid protein, and the protein encoded by open reading frame 3 (ORF3) appears to be involved in virus–host interactions. Several questions related to the biology, epidemiology and pathogenesis of HEV remain unanswered; the progress of a few of these is reviewed here.