Oregon Zoo elephant Tula-Tu Holds steady after EEHV diagnosis

Oregon Zoo elephant Tula-Tu Holds steady after EEHV diagnosis

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Tula-Tu Holds Steady as Oregon Zoo Battles Deadly Elephant Virus

The survival of a single baby Asian elephant in Portland now carries weight far beyond the zoo’s fence — it is a live test of decades of vaccine research, plasma transfusion protocols, and a conservation network that stretches from Oregon to the forests of Borneo. The Oregon Zoo reported that Tula-Tu, the calf born in 2025 who became an instant celebrity, is holding steady after a week and a half of emergency care for elephant endotheliotropic herpesvirus, or EEHV, Oregon Zoo.

The young elephant was diagnosed last week and has since received antiviral medications, fluids, and a series of plasma transfusions. Her mother, Rose-Tu, has stayed close, nursing and comforting her.

A Week and a Half of Emergency Care

Since her diagnosis, zoo care staff have treated Tula-Tu around the clock. Her condition remains guarded, but the trajectory has bent toward hope.

Asian Elephant Tula-Tu Plays Outside, Gets Vet Checkup

“Tula remains in guarded condition, but she is showing encouraging signs,” said Dr. Carlos Sanchez, the zoo’s director of animal health. “Her white-cell counts are nearly back to normal and her viral load is trending down. She appears more alert and her appetite has improved — these are all positive indicators. She’s a tough little elephant.”

The zoo continues sending blood samples for molecular testing at three facilities: the Oregon Veterinary Diagnostic Laboratory at Oregon State University, Baylor College of Medicine, and the Smithsonian’s National Elephant Herpesvirus Laboratory. This week Tula-Tu also ventured outdoors into a behind-the-scenes yard, spent time with her father, Samson, and her aunties Sung-Surin and Chendra inside Forest Hall, and played with her favorite toy — a large blue ball that once belonged to her mother.

The Virus That Can Kill a Calf in Days

EEHV is a latent virus present in nearly all Asian elephants, wild and in human care. Most elephants develop natural immunity over time, but calves become highly susceptible as maternal antibodies decline, typically between the ages of 1 and 8. Once the virus activates, it can be life-threatening within a few days. The same fate befell Lily, another of Rose-Tu’s calves, who succumbed to the disease in 2018 shortly before her sixth birthday.

Earlier this year, Tula-Tu was the first elephant on the West Coast to receive an mRNA vaccine targeting EEHV-1A, the most common strain. Her current infection, however, comes from a different but related strain, EEHV-1B. Although EEHV-1B accounts for fewer reported fatal infections, both variants can cause severe disease in young Asian elephants.

“We do not know whether the EEHV-1A vaccine is protective for the -1B variant,” Dr. Sanchez said. “It’s possible, but to what degree remains unknown.”

Why Tula-Tu’s Blood Travels to Three Labs

Sanchez, who chairs the North American EEHV Advisory Group Research Committee, said Tula-Tu’s samples will feed several ongoing studies, including one with OSU and Baylor to better understand vaccine response. The virus also affects wild elephants. Scientists have confirmed roughly 200 EEHV deaths in Asian elephant range countries, though the true toll is harder to track there because poaching, habitat loss, and human-elephant conflict dominate the threats.

Tula-Tu received a new ball from WNBA team the Portland Fire in honor of her first birthday, Feb. 1, 2026. (Oregon Zoo)
Photo: koin.com

“The work we’re doing now could play a significant role in protecting future elephant calves from the disease, including those in range countries,” Sanchez said. “It’s very difficult to study the virus in wild elephants, but zoos can monitor the elephants in their care closely and obtain samples of blood and other fluids.”

The Oregon Zoo, recognized worldwide for an elephant care program spanning more than 60 years, has spent nearly 25 years funding research and supplying blood samples as part of an international effort. In 2023 its veterinary staff worked with Malaysian wildlife officials to establish Sabah’s first hematology lab to track EEHV in wild and captive elephants, and the zoo maintains a $1 million endowment supporting Asian elephants, including AZA’s SAFE program across all 13 range countries. Beyond direct care, the zoo partners with local groups in Borneo on reforestation, protected corridors, and peaceful coexistence between elephants and communities.

Advancements in early detection, vaccines, and transfusion protocols have improved survival outcomes significantly since Lily’s death in 2018. Whether the mRNA vaccine that protected Tula-Tu against one strain also shields her — and future calves — against EEHV-1B is the question still open, and the answer will shape how the next generation of Asian elephants is protected.

More on Oregon Zoo

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Elephant Tula Tu being treated for dangerous disease

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