Elephant Endotheliotropic Herpesvirus Hemorrhagic Disease - The Impact on the European Captive Population of Asian Elephant (Elephas maximus)
Department of Reproduction Management, Leibniz Institute for Zoo and Wildlife research, Berlin, Germany
Elephant Endotheliotropic Herpesvirus (EEHV) is considered the major cause of calf mortality in the captive population of Elephas maximus. Presently, it is the most important infectious disease threatening not only captive as well as free-ranging Asian elephants.1 There are North American and European breeding facilities, which have lost several calves due to this hemorrhagic disease (HD) and others which are not or just minimally affected. The most typical presentation of this disease is an acute generalized haemorrhagic syndrome, due to vast endothelial destruction, causing sudden death.2 In symptomatic elephants, besides an important supportive therapy, famciclovir (first described in 19983), a human anti-herpetic drug, represents until today the most used antiviral treatment. In European breeding institutions, several thousands of euros were invested in antiviral drug treatment, but despite its high costs, it shows still a rather low efficacy, with survival rated ranging between 20 and 50 percent. To better understand and quantify the impact of EEHV-HD in the Elephas maximus European Endangered species Program (EEP) population, a case-controlled study was conducted, analysing a 30-year lifetime period, based on retrospective data reported by the European EEP Studbook, including 72 institutions holding 298 (84.214) Asian elephants. All captive-born individuals living in Europe were included in the study. EEHV- HD is responsible for the death of nearly one-third of all captive born Asian elephants in Europe. This is further aggravated in as much as 75% of the fatal cases occur between 1,4 and 3,2 years of age presenting, therefore, a serious risk to the conservation breeding efforts made by zoos. Currently, there are 41 calves at the refer risk age living in Europe, and as the world Asian elephant population continues to decline, finding and understanding the trigger elements on the onset of EEHV-HD becomes critical.
The authors would like to thank the European Association of Zoo and Aquaria’s Elephant Taxon Advisory Group, which supported and co-founded this study.
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2. Richman LK, Montali RJ, Cambre RC, Schmitt D, Hardy D, Hildebrandt T, et al. Clinical and pathological findings of a newly recognized disease of elephants caused by endotheliotropic herpesviruses. J Wildl Dis. 2000;36:1–12.
3. Schmitt DL, Hardy DG. Use of famciclovir for the treatment of herpesvirus in an Asian elephant. J Elephant Manager Assoc. 1998;9(2):103–104.