Certain "exotic" viruses may cause clinical diseases with potential liver involvement. These contain viruses beyond regular hepatotropic viruses (hepatitis A, -B(D), -C, -E, cytomegalovirus, Epstein-Barr virus) that are present in (sub)tropical areas and can cause "exotic viral hepatitis." They mainly transmit via arthropods (Crimean Congo hemorrhagic fever, dengue, Rift Valley fever, yellow fever). Yet, some may transmit by the aerosolized excreta of rodents (Hantavirus, Lassa fever) or via direct contact or contact with bodily fluids (Ebola). 

Although some exotic viruses, such as Ebola, may cause high fatality rates, their clinical presentation can range from mild flu-like symptoms, in most cases, to being potentially fatal. A small subset of people may develop severe disease with hemorrhagic fever, possibly with (fulminant) hepatitis. Liver involvement is usually caused by direct tropism for hepatocytes and Kupffer cells, causing virus-mediated and/or immune-mediated necrosis. 

For all exotic hepatitis viruses, PCR remains the most sensitive diagnostic method. Determining IgM/IgG antibodies is a reasonable alternative; however, cross-reactivity can be a problem in the case of flaviviruses. Licensed vaccines are available for yellow fever and Ebola and are currently under development for dengue. Exotic viral hepatitis predominantly observes a supportive therapy. 

It is crucial to detect these viruses in time to introduce preventive measures to control possible outbreaks.

J Hepatol. 2022 Nov;77(5):1431-1443. doi: 10.1016/j.jhep.2022.06.031. Epub 2022 Jul 9. PMID: 35817222.