Elephant herpes virus
EEHV - Elephant endotheliotropic herpes virus
Cutaneous papillomatosis
African elephants:
These viruses can cause either benign localized skin nodules with pinkish color on the trunk and head or vulval lymphoid patches around genital openings, and have also been found in pulmonary nodules in otherwise healthy african elephants. The growths or lesions usually regress after several weeks and thought to represent occasional reactivation from hidden "latent" infections.
Asian elephants:
EEHV causes fatal haemorrhagic disease, attacking endothelial cells (blood vessels, heart and similar organs) among asian elephants and has become a dangerous problem lately. This disease is 90% fatal and preferentially targets juvenile captive Zoo elephants. The first case was identified in 1995 at the Washington Zoo and reported in Science in 1999 (the earliest confirmed case is from 1983.)
Up to Nov 2008, there have been 31 known cases in North America and 18 in Europe, including six animals that survived when treatment with an anti-herpesvirus drug (designed for use in humans) was administered very quickly after diagnosis. Although most cases have involved captive-born Asian elephants between the ages of 4 months and 18 years, several cases have involved older wild-born Asian adults as well as occasionally newborns, and three were in African elephants.
Of 78 Asian elephants born in the United States and Canada between 1978 and 2007 that lived up to two months of age, at least 19 have since died of this disease (and five more would have if not treated successfully).,
The virus seems to spread from immune, othervise healthy african elephants to asian elephants, especially older calves who may not have developed anti-bodies. However, there also appear to be a small proportion of wild-born captive adult “carrier” Asian elephants who have anti-bodies and therefore presumably survived mild infections when young.
It is possible to screen the DNA blood samples of suspected cases for EEHV within 12 hours and this test has been used to confirm acute EEHV disease cases and to trigger successful famcyclovir treatment of symptomatic animals. Afflicted young elephants usually die very fast, in several cases within 24 hours after the first signs, but there are six confirmed examples of cures in which EEHV1 infected calves with positive PCR DNA blood tests survived after fast early treatment with famciclovir (500 mg/70 kg body-weight, 3-4 weeks). The blood test has never been positive in healthy animals, but unfortunately even this expensive drug treatment was not effective in many other cases.
Mixture of african and asian elephants should be avoided where possible in the future, and precautions should also include avoiding exposures of juvenile captive Asian elephants (who are likely to be seronegative) to new long term close contacts with wild born Asian elephants (who may be seropositive carriers).
Recent genetic analysis of 18 cases in North America since 1995 has revealed that the disease is sporadic, with not one of these viruses being sufficiently closely related to any of the others to have been directly epidemiologically connected. They must instead have each been transmitted from one of 18 different unknown source animals and not from any of the other known cases. In fact, Molecular Virologists have now detected five or six different species of this particular type of herpesvirus (called Probosciviruses) in elephants, four of which EEHV1A, EEHV1B, EEHV2, EEHV3 and EEHV4 have all caused fatal disease. Current evidence has confirmed that EEHV2 and EEHV3 are native to African elephants where they cause the pulmonary nodules. EEHV5 is likely native to and benign in Asian elephants and might potentially provide protection against the others. EEHV1A has been found in skin nodules of African elephants in the US, but it is not yet clear whether the natural hosts are African or Asian elephants. These different EEHV species have evolved separately within elephant ancestors over the past 10 to 40 million years, which is from even before the Asian and African elephants and woolly mammoths diverged from a common ancestor about 7 million years ago. As in most mammals, several species of yet another very different type of herpesvirus called gammaherpesviruses or EGHVs are also often found in secretions from captive Asian and African elephants, but these do not cause any serious disease.
Among the several different Probosciviruses species, by far the most common causes of lethal disease in captive Asian elephants have been an assortment of different EEHV1 strains. Rather alarmingly, there are now confirmed reports of at least a half dozen cases recently attributed to EEHV1 also in elephant calves within several Asian countries. Additional research is urgently required to evaluate this situation within wild-range countries.
Note that latent herpesvirus infections are very common in nature, but they only rarely cross host species barriers. In fact, most human adults unknowingly harbor latent infections by between four and seven of the eight different species of human herpesviruses, although (except in immunosuppressed AIDS and organ transplant patients) these only rarely cause more serious disease than chicken pox, roseolla, mononucleosis, cold sores and shingles.
Herpes virus and captive breeding of elephants
Lately (2007) there has been criticism from animal welfare groups regarding captive breeding of elephants, accusing Zoos or other elephant breeding facilities of spreading the deadly Elephant Endotheliotropic Herpesvirus (EEHV).
I don't believe that running away from a problem by stopping the captive breeding program is the way to solve elephant herpesvirus....it is going to become a huge issue in the wild too in the future as the fragmented populations and controlled /captive breeding conditions in range countries in Asia become to resemble more and more the conditions in captivity here. It is better to figure out what is going on here now and learn how to control it and to continue to strengthen/enrich the gene pool in captivity as much as possible.
Herpes virus and artificial insemination
There is presently no evidence that it is transmitted by artificial insemination. In fact the several progeny of Onyx that have had it include at least three very different species of elephant herpesviruses. Furthermore, the virus that killed Haji the first born by AI is a novel EEHV1A/EEHV1B chimera that again is a very different virus from all other cases we have seen.
There are Research Groups in both the USA and Europe that offer DNA and serology tests for the viruses (eg The Elephant Herpesvirus Laboratory run by Dr Laura Richman and Erin Latimer at the National Zoological Park in Washington DC). Information about the tests, samples and documentation is given on the website at Consent Form for Elephant Endothelial Herpes Virus (EEHV) Testing, Request Form for EEHV Testing, Elephant History Form for EEHV Testing and Endotheliotropic Herpesvirus (EEHV) Elephant Care International Fact Sheet by Susan Mikota DVM
Sources, among others; Gary S. Hayward, Ph D. Johns Hopkins School of Medicine
38 Deceased elephants due to Herpes Virus.
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