Endotheliotropic herpesvirus of the elephants

The authors want to summarize the current knowledge about the EEHV (elephant endotheliotropic herpesvirus) using the latest scientific literature and the first known Hungarian case. This herpesvirus group belongs to the newly described Proboscivirus genus within the Betaherpesvirinae subfamily that infects wild and captive elephants as well. Currently there are 7 known types of the virus, the most frequent is the EEHV1A subtype, that also appeared in Hungary. Despite of its worldwide of distribution, it usually causes an asymptomatic infection, while mainly in young asian elephants it can cause a very serious disease. The clinical course of the disease is very rapid with severe endothelial cell damage in the blood vessels leading to hemorrhages in various organs. With histopathology we can see the characteristic nuclear inclusion bodies in the endothelial cells which, according to some authors are pathognomonic. It is presently unknown what kind of predisposing factors lead to the severe illness, the virus is otherwise frequently detected in healthy African and Asian elephants. The African elephants are usually less severely affected. There are still gaps in the knowledge about the transmission and the pathogenesis in the scientific literature. The isolation, and passage of the virus on cell cultures are not successful yet, thus there are no vaccines available. However a one year old study reports that they could successfully multiply the virus in vitro up to 4 passages. The rapid identification of the virus is vital, still two-thirds of the affected calves die despite of the treatment. The EEHV affects around 20 percent of Asian elephant calves born in captivity and is responsible for two-thirds of all their deaths, so further research about the topic is strongly justified.