Prevalence of Elephant Endotheliotropic Herpesvirus (EEHV) in Wild and Captive Bornean Elephants (Elephas maximus borneensis) Sampled During Conservation Management Activities in Sabah, Malaysia.

Elephant Endotheliotropic Herpesvirus (EEHV) is a leading cause of fatal hemorrhagic disease in juvenile Asian elephants and represents a significant concern for elephant conservation. However, information on the epidemiology of EEHV in Bornean elephants (Elephas maximus borneensis) remains limited. This study investigated the prevalence and subtype distribution of EEHV in wild and captive Bornean elephants in Sabah, Malaysia, using samples collected during conservation management activities including rescue operations, translocation, GPS collaring, necropsies and routine veterinary examinations between 2009 and 2026. A total of 240 samples, comprising 100 whole-blood and 140 tissue samples from 110 elephants, were analyzed by conventional polymerase chain reaction (cPCR) targeting EEHV1 and EEHV4. EEHV DNA was detected in 6.4% (7/110) of elephants. Most positive cases were identified post-mortem, indicating a possible association of EEHV infection with mortality. EEHV1 was the only subtype detected, and sequence analysis showed close similarity to previously reported EEHV1A cases from Sabah. No EEHV4 was detected. Although no significant associations were observed between EEHV detection and population type, age group, sex, or sampling location, the detection of EEHV in both wild and captive elephants indicates that the virus is circulating in this endangered population. These findings provide baseline epidemiological data and support the need for continued surveillance and strengthened diagnostic capacity to inform EEHV management and conservation strategies in Sabah.