Relative importance of the enterically transmitted human hepatitis viruses type A and E as a cause of foreign travel associated hepatitis

From discovery to treatment: tracing the path of hepatitis E virus

The hepatitis E virus (HEV) is a major cause of acute viral hepatitis worldwide. HEV is classified into eight genotypes, labeled HEV-1 through HEV-8. Genotypes 1 and 2 exclusively infect humans, while genotypes 3, 4, and 7 can infect both humans and animals. In contrast, genotypes 5, 6, and 8 are restricted to infecting animals. While most individuals with a strong immune system experience a self-limiting infection, those who are immunosuppressed may develop chronic hepatitis. Pregnant women are particularly vulnerable to severe illness and mortality due to HEV infection. In addition to liver-related complications, HEV can also cause extrahepatic manifestations, including neurological disorders. The immune response is vital in determining the outcome of HEV infection. Deficiencies in T cells, NK cells, and antibody responses are linked to poor prognosis. Interestingly, HEV itself contains microRNAs that regulate its replication and modify the host's antiviral response. Diagnosis of HEV infection involves the detection of HEV RNA and anti-HEV IgM/IgG antibodies. Supportive care is the mainstay of treatment for acute infection, while chronic HEV infection may be cleared with the use of ribavirin and pegylated interferon. Prevention remains the best approach against HEV, focusing on sanitation infrastructure improvements and vaccination, with one vaccine already licensed in China. This comprehensive review provides insights into the spread, genotypes, prevalence, and clinical effects of HEV. Furthermore, it emphasizes the need for further research and attention to HEV, particularly in cases of acute hepatitis, especially among solid-organ transplant recipients.

[Physical exposure by travelling]

Approximately 40 million Germans travel abroad every year. Air travel is the most frequently used mean of transportation followed by the automobile. During airplane flights rheumatic patients are subjected to numerous physical, biological and climatic factors which can cause stress and adverse effects on general health. Therefore, preventive strategies are helpful to protect against health damage, provided that there is general fitness for air travel. The present article focuses on physical and biological stress as well as psychological aspects during air travel and reviews prophylactic measures.

Evidence of extrahepatic sites of replication of the hepatitis E virus in a swine model

Hepatitis E virus (HEV) is the major cause of enterically transmitted non-A, non-B hepatitis in many developing countries and is also endemic in many industrialized countries. Due to the lack of an effective cell culture system and a practical animal model, the mechanisms of HEV pathogenesis and replication are poorly understood. Our recent identification of swine HEV from pigs affords us an opportunity to systematically study HEV replication and pathogenesis in a swine model. In an early study, we experimentally infected specific-pathogen-free pigs with two strains of HEV: swine HEV and the US-2 strain of human HEV. Eighteen pigs (group 1) were inoculated intravenously with swine HEV, 19 pigs (group 2) were inoculated with the US-2 strain of human HEV, and 17 pigs (group 3) were used as uninoculated controls. The clinical and pathological findings have been previously reported. In this expanded study, we aim to identify the potential extrahepatic sites of HEV replication using the swine model. Two pigs from each group were necropsied at 3, 7, 14, 20, 27, and 55 days postinoculation (DPI). Thirteen different types of tissues and organs were collected from each necropsied animal. Reverse transcriptase PCR (RT-PCR) was used to detect the presence of positive-strand HEV RNA in each tissue collected during necropsy at different DPI. A negative-strand-specific RT-PCR was standardized and used to detect the replicative, negative strand of HEV RNA from tissues that tested positive for the positive-strand RNA. As expected, positive-strand HEV RNA was detected in almost every type of tissue at some time point during the viremic period between 3 and 27 DPI. Positive-strand HEV RNA was still detectable in some tissues in the absence of serum HEV RNA from both swine HEV- and human HEV-inoculated pigs. However, replicative, negative-strand HEV RNA was detected primarily in the small intestines, lymph nodes, colons, and livers. Our results indicate that HEV replicates in tissues other than the liver. The data from this study may have important implications for HEV pathogenesis, xenotransplantation, and the development of an in vitro cell culture system for HEV.