Sabah study expands the EEHV picture in Bornean elephants

A new Animals study on EEHV in wild and captive Bornean elephants in Sabah, Malaysia, helps fill a major surveillance gap for one of Asia’s most vulnerable elephant populations. The paper examines the prevalence and subtype distribution of elephant endotheliotropic herpesvirus in Elephas maximus borneensis, an endangered subspecies for which published epidemiology has been notably limited. (pmc.ncbi.nlm.nih.gov)

That gap has mattered for years. EEHV is a well-established cause of acute, often fatal hemorrhagic disease in young Asian elephants, with classic reports describing sudden onset, edema, oral lesions, cyanosis, and death within days. In Sabah, concern intensified after the first published Malaysian EEHV deaths, reported in 2021, identified EEHV1A in three wild-born Bornean elephant calves that died quickly after onset of clinical signs. The authors of that case report explicitly noted the need to determine prevalence, shedding patterns, and disease duration in the local population. (pubmed.ncbi.nlm.nih.gov)

The new study appears to answer part of that call by looking beyond fatal cases and sampling elephants during conservation management activities, which is important in a species where routine access is limited. Broader EEHV literature suggests why that matters: surveillance based only on sick calves likely misses a substantial amount of infection activity. Studies in Thailand found EEHV in multiple age groups, including subclinical animals, and work in China detected EEHV1B and EEHV4 in both wild and captive elephants, with authors warning that measured prevalence likely underestimates true infection because both viremia and shedding can be intermittent. (pubmed.ncbi.nlm.nih.gov)

The Sabah findings also sit within a wider conservation reality. Bornean elephants are a small, fragmented population, generally estimated at fewer than 2,000 animals concentrated largely in northeastern Sabah, and they face pressure from habitat fragmentation, conflict, and other anthropogenic threats. That means an infectious disease signal carries outsized weight, especially when the pathogen is already associated with high juvenile mortality elsewhere in Asian elephants. (pmc.ncbi.nlm.nih.gov)

Expert commentary tied directly to this paper was limited in public sources, but the surrounding field has been consistent on one point: EEHV surveillance has to be proactive. Review and case literature describe EEHV as nearly ubiquitous in adult elephants, while emphasizing that severe disease is concentrated in younger animals and that rapid intervention can be the difference between survival and death. More recent clinical reports, including work in Europe and Thailand, have underscored the value of regular monitoring for viremia and virus excretion, particularly in managed populations. (mdpi.com)

Why it matters: For veterinarians, wildlife health teams, and zoo clinicians, the practical takeaway is that opportunistic sampling during translocations, rescues, collaring, or routine management may be one of the best available tools for EEHV intelligence in free-ranging elephants. A negative result shouldn’t be overread, given intermittent shedding, but repeated PCR-based surveillance can still help identify circulating subtypes, map risk, and refine triage protocols for calves. For facilities caring for Asian elephants, the study is another reminder that disease planning has to include both apparently healthy carriers and the possibility of sudden deterioration in juveniles. (mdpi.com)

What to watch: The next step is whether Sabah’s wildlife and conservation network builds this into a longitudinal program, pairing prevalence snapshots with repeated sampling, clinical follow-up, and subtype-specific tracking. If that happens, the region could move from documenting EEHV presence to building an actionable early-warning system for one of the most consequential infectious threats facing young Asian elephants. (asesg.org)