Asian Elephant Herpesvirus Infection

What is it?

Asian elephant herpesvirus infection, also known as EEHV disease (Elephant Endotheliotropic Herpesvirus), is a severe viral infection that primarily affects young Asian elephants, particularly those born in captivity. The virus attacks the cells lining the inside of blood vessels, a layer called the endothelium. This damage causes internal bleeding and heart dysfunction, which can lead to death within just a few days.

This disease is considered one of the leading causes of death in Asian elephant calves, both in zoos and in breeding facilities across Asia. The rapid progression of the disease makes treatment extremely challenging if it is not detected at an early stage.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Causes and risk factors

The disease is caused by specific herpesviruses called EEHV (Elephant Endotheliotropic Herpesvirus), of which there are several types. These viruses particularly infect endothelial cells, which form the inner lining of blood vessels.

It is believed that many adult elephants carry this virus in a latent state—dormant and without showing any signs of disease. The virus can reactivate and be transmitted to young animals, in whom it causes the severe and often fatal form of the disease.

Young Asian elephant calves, particularly between weaning age and a few years old, appear most vulnerable to severe disease. Stress, particularly that linked to weaning or changes in social group, may promote virus reactivation in latent carriers.

Elephants living in captivity, in zoos or breeding centres, are especially affected because the disease has been most thoroughly documented there. However, cases have also been reported in wild elephants.

Transmission

The exact mode of transmission is not yet fully understood. The virus appears to spread through direct contact between elephants, particularly through secretions such as saliva and nasal discharge. Latently infected adults likely serve as a reservoir, transmitting the virus to young animals during normal social contact within the herd, even without visible signs in the carrier adult.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

Treatment

There is no specific antiviral treatment definitively validated against EEHV, although some antivirals have been used in emergency cases in reported instances. Management relies mainly on intensive supportive care: urgent fluid administration to maintain circulation, cardiovascular support, and sometimes blood transfusions performed in specialist centres with the necessary equipment.

This supportive treatment must be started as quickly as possible, ideally as soon as the virus is detected in the blood, before clinical symptoms even appear, to give the animal the best chance of survival.

Prevention

Possible complications

Main complications are generalised internal haemorrhage, heart failure, and sudden death. In animals that survive thanks to prompt intervention, long-term sequelae are not clearly documented to date, but ongoing veterinary monitoring is still recommended.

When to see a veterinarian

Prognosis

The prognosis is very guarded in cases where symptoms have developed, as mortality is high even with supportive treatment. Early detection through blood testing, before clinical signs appear, combined with immediate care, significantly improves the chances of survival. Treatment centers using close monitoring protocols report better survival rates than those intervening only after symptoms appear.

Frequently asked questions

References

WOAH — Organisation mondiale de la santé animale (ex-OIE)

AVMA — American Veterinary Medical Association

Content reviewed by the TunisieVet editorial team · Updated 30 August 2026