IDENTIFICATION OF TWO LETHAL CASES OF ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS HEMORRHAGIC DISEASE IN SUMATRAN ELEPHANT CALVES IN INDONESIA

As many as a dozen cases of lethal acute hemorrhagic disease (HD) in young captive-born Sumatran sub-species Asian elephant (Elephas maximus sumatranus roman) calves raised naturally in camps in Sumatra have been observed in recent years. To address whether these deaths, like many others documented worldwide, might be associated with acute systemic infection by elephant endotheliotropic herpesvirus (EEHV), diagnostic polymerase chain reaction (PCR) tests followed by subtype deoxyribonucleic acid (DNA) sequencing analysis were carried out on pathologic tissue samples from two lethal HD cases that occurred within 6 days of one another in calves at the same camp. Viral DNA from five selected PCR loci was found to be present at high levels in both calves and proved to be the same EEHV1A virus species that has been described most commonly previously in numerous lethal or surviving symptomatic cases in North America, Europe, India, and Thailand. Furthermore, the two cases were identical at all five PCR loci tested (covering a total of 3,050 base pairs) and were therefore likely to have been infected from the same epidemiologic source herdmate. However, the strain involved (which was subtype-D2 in the vGPCR1 locus) differed from all previously characterized EEHV1A strains. In conclusion, these two calves are the first two confirmed HD cases in Sumatra alongside several other suspected HD cases in Sumatra that have succumbed to the same devastating EEHV1A-HD that has afflicted young Asian elephants worldwide over the past 25 yr. Because the progeny of some of the 1,500 remaining red-listed critically endangered Sumatra subspecies elephants are bred naturally in camps from wild parents it seems very likely that the EEHV1A herpesvirus identified here in these HD camp cases is also present in the free-ranging Sumatran elephant population, and this will have to be taken into account in future wildlife management policies and decisions.