Oral Presentation 64th International Conference of the Wildlife Disease Association 2015

Elephant Endotheliotropic Herpesvirus: emerging infectious disease in SE Asia or newly described endemic? (#29)

Supaphen Sripiboon 1 , William Ditcham 1 , Bethany Jackson 1 , Lian Yeap 1 , Carly Holyoake 1 , Ian Robertson 2 , Pallop Tonkeaw 3 , Preeda Lertwacharasarakul 4 , Kristin Warren 1
  1. Conservation Medicine Program, College of Veterinary Medicine, Murdoch University, Perth, WA, Australia
  2. Veterinary Epidemiology, College of Veterinary Medicine, Murdoch University, Perth, WA, Australia
  3. Faculty of Veterinary Medicine, Chiang Mai University, Muang, Chiang Mai, Thailand
  4. Faculty of Veterinary Medicine, Kasetsart University, Kampangsean, Nakornprathom, Thailand

Elephant endotheliotropic virus (EEHV) was first recorded to cause haemorrhagic disease in captive young Asian elephants in 19993 . Since then EEHV, a highly contagious disease, has been responsible for almost 60% of all deaths in young captive Asian elephants in North America and Europe1 . Whilst the virus was considered a newly emerging disease in Asian elephants, causing fatal disease in juveniles, it was considered to be non-pathogenic in African elephants3. Despite disease associated with EEHV infection being reported widely in zoos in Western countries, only limited research has been undertaken in home-range countries of Asian elephants. This study mainly focused on EEHV infection in elephants from captive facilities in Thailand, using molecular examination of archived tissue samples collected from 17 young Thai elephants that died between 2006 and 20142 . Three blood samples from suspected clinical cases were also analysed. The results indicated 14/20 individuals were positive for EEHV type 1. Further sub-typing of these cases revealed 12 aligned with EEHV1A, with five different distinct strains, and two cases aligned with EEHV1B, with only one distinct strain. Positive cases ranged in age (1-9 years), sex and geographical location. The results revealed large difference in genetic variation with no epidemiological relatedness in each case, supporting the new theory that EEHV1A and EEHV1B are more likely to be ancient endemic pathogens in Asian elephant, rather then newly emerging virus4. This was further supported by the fact that the affected elephants in this study had never been in contact with African elephants. Therefore, it is recommended that active surveillance and routine monitoring for EEHV in Asian elephants in their home-range countries should be undertaken in order to better understand the epidemiology of this disease and manage risk factors associated with disease transmission. 

  1. Hayward, G. S. 2012. Conservation: clarifying the risk from herpesvirus to captive Asian elephants. The Veterinary Record, 170(8), 202–203.
  2. Latimer, E., Zong, J.C., Heaggans, S.Y., Richman, L.K., and Hayward, G.S. 2010. Detection and evaluation of novel herpesviruses in routine and pathological samples from Asian and African elephants: Identification of two new probosciviruses (EEHV5 and EEHV6) and two new gammaherpesviruses (EGHV3B and EGHV5). Vet Microbiol. 147: 28-41.
  3. Richman, L.K., Montali, R.J., Garber, R.L., Kennedy, M.A., Lehnhardt, J., Hildebrandt, T., Schmitt, D., Hardy, D., Alcendor, D.J., and Hayward, G.S. 1999. Novel endotheliotropic herpesviruses fatal for Asian and African elephants. Science. 288: 1171-1176.
  4. Zachariah, A., Zong, J.C., Long, S.Y., Latimer E.M., Heaggans, S.Y., Richman, L.K., and Hayward, G.S. 2013. Fatal herpesvirus hemorrhagic disease in wild and orphan Asian elephants in Southern India. J Wildl Dis. 49: 381-393.