Oregon Zoo’s Elephant Calf Battles Deadly Virus, Offers Hope for Recovery

One-year-old Tula-Tu is responding to treatment for EEHV-1B as rapid diagnosis, intensive veterinary care and decades of elephant research underpin efforts to save her life.

A one-year-old Asian elephant calf at the Oregon Zoo in Portland, United States, is showing encouraging signs of recovery after being diagnosed with elephant endotheliotropic herpesvirus (EEHV), a potentially fatal disease that poses a significant threat to young elephants. The calf, Tula-Tu, was reported to be in stable condition on October 30, with improving blood-test results offering grounds for cautious optimism, although her recovery remains uncertain.

The veterinary team first detected subtle changes in her behaviour and energy levels on October 24, 2026. Given the speed at which EEHV can progress, treatment began immediately, before laboratory testing confirmed the infection on October 25. The emergency response included antiviral medication and plasma transfusions, alongside intensive monitoring and repeated blood tests. The early intervention reflects the importance of identifying the disease before it develops into a severe, potentially fatal condition.

Recent tests have shown normal platelet levels and an improving white blood cell count. These findings suggest that Tula-Tu is responding favourably to treatment. However, EEHV can cause sudden deterioration, making continued observation and supportive care essential.

A fast-moving threat to young elephants

EEHV is a major infectious threat to Asian elephants, both in the wild and under human care. In some cases, infection leads to EEHV haemorrhagic disease, which can damage blood vessels, cause internal bleeding and affect vital organs. Severe cases may become fatal within days of the first noticeable symptoms.

Early warning signs can include lethargy, reduced energy, changes in behaviour and loss of appetite. These symptoms may initially appear mild, but rapid diagnosis and treatment can be critical to survival.

The Oregon Zoo’s response was supported by its ability to conduct blood monitoring on site. Veterinary staff identified an abnormal white blood cell count and began precautionary treatment while awaiting advanced molecular testing. The diagnosis was subsequently confirmed as EEHV-1B.

Although EEHV-1B has been associated with fewer reported fatal infections than EEHV-1A, both strains can cause severe illness in young elephants. The identification of the strain therefore helps inform the medical response but does not remove the risk.

Experimental vaccine raises scientific questions

Tula-Tu made headlines earlier in 2026 when she became the first elephant on the United States’ West Coast to receive an experimental messenger RNA (mRNA) vaccine designed to protect against EEHV. Developed through research led by Baylor College of Medicine, the vaccine targets the EEHV-1A strain.

The calf’s current infection, however, is caused by EEHV-1B. Scientists do not yet know whether the vaccine may provide any partial cross-protection against this different strain. Her current response to treatment cannot therefore be attributed to the earlier vaccination.

The development of the experimental vaccine represents an important step in efforts to prevent EEHV-related deaths. Nevertheless, the disease remains difficult to control because several viral strains circulate among elephants, and preventive protection is still an area of active research.

Tula-Tu’s case may contribute to a better understanding of the virus and vaccine responses. The zoo has indicated that blood samples collected during her treatment can support ongoing collaborative research into EEHV and the effectiveness of emerging preventive approaches.

Care continues alongside the family herd

Tula-Tu is receiving round-the-clock monitoring through video surveillance and direct observation by animal-care and veterinary staff. She is briefly separated from the herd during medical procedures but spends the remainder of her time with her mother, Rose-Tu, and other adult female elephants.

Maintaining these family connections is an important aspect of her care, allowing the calf to remain in familiar surroundings while receiving necessary treatment.

EEHV is widespread among Asian elephants, many of which carry the virus in a latent state without displaying symptoms. Its presence does not mean that every infected animal will develop severe disease. Young elephants are particularly vulnerable, however, and can experience serious illness when the virus becomes active.

The zoo has a painful history with the disease. In 2018, Tula-Tu’s older sister, Lily, died from EEHV shortly before her sixth birthday. The loss strengthened the urgency of improving early detection, diagnostic capacity and treatment protocols.

Oregon Zoo’s long history of elephant conservation

The current emergency highlights a broader legacy of elephant care and research at the Oregon Zoo, whose elephant programme spans more than six decades. The institution traces its origins to 1888 and has developed from a small municipal animal collection into a major zoological and conservation centre.

A landmark in its elephant history came in 1962, when an Asian elephant calf named Packy was born at the zoo. He was the first elephant born in the Western Hemisphere in 44 years, and his birth helped advance understanding of elephant reproduction, maternal behaviour and calf development. The zoo subsequently became an important centre for research into Asian elephant breeding, veterinary care and welfare.

Another major milestone was the opening of Elephant Lands in 2015. The approximately six-acre habitat was designed to encourage natural behaviours, physical activity, social interaction and greater choice for the elephants. Its varied terrain and feeding opportunities reflect an approach to animal care that goes beyond basic shelter to consider the complex behavioural and social needs of these intelligent animals.

The zoo’s conservation work also extends beyond its grounds. For nearly 25 years, it has contributed funding and elephant blood samples to collaborative research seeking effective EEHV treatments and vaccines. In 2023, its veterinary staff worked with wildlife officials in Malaysia to establish Sabah’s first haematology laboratory for monitoring EEHV in elephants. Training and technical support have also helped strengthen disease detection and response among wildlife-health practitioners in Southeast Asia.

The zoo supports wider Asian elephant conservation through partnerships focused on protecting habitats, developing wildlife corridors and reducing conflict between elephants and communities in Borneo. These efforts recognise that the survival of the endangered species depends not only on veterinary advances but also on protecting wild populations and the landscapes on which they depend.

Cautious optimism amid continued uncertainty

For now, Tula-Tu remains under intensive care, with veterinary staff tracking her blood parameters and watching for signs of deterioration. Visitors may still see her at the Oregon Zoo, although she may occasionally remain off exhibit during treatment.

Her improving condition offers hope, but the outcome remains uncertain. The case underscores the importance of early diagnosis, specialised veterinary facilities and sustained research into a disease that continues to threaten young Asian elephants.

The experience also illustrates how decades of accumulated knowledge can inform an urgent response to an individual animal’s illness. While no single intervention guarantees recovery, advances in monitoring, treatment protocols and vaccine research are strengthening efforts to protect elephants in human care and, ultimately, contribute to the conservation of their wild counterparts.