According to Chinese health officials, a man died in China after contracting the Monkey B virus, a rare infectious disease from primates. The victim, a 53-year-old veterinarian from Beijing, was the country’s first documented human case of the virus.

According to the Chinese Center for Disease Control and Prevention, the man worked in a nonhuman primate breeding research institute and dissected two dead monkeys in March. A month later, he experienced nausea, vomiting, and fever, and died on May 27. In April, his blood and saliva samples were sent to the center, where researchers discovered evidence of the Monkey B virus. Officials said two of his close contacts, a male doctor and a female nurse, tested negative for the virus.

The Monkey B virus, also known as the herpes B virus, is common in macaque monkeys but extremely rare — and often fatal — when it spreads to humans. According to Kentaro Iwata, an infectious-disease expert at Kobe University in Tokyo, it tends to attack the central nervous system and cause inflammation to the brain, resulting in a loss of consciousness. If left untreated, there is an 80% chance of death.

Since the first case of primate-to-human transmission in 1932, there have been fewer than 100 reported human infections of herpes B, many of which have occurred in North America, where scientists are more aware of the disease, according to Iwata. There are likely to be undetected cases of the virus, but experts still believe it is an extremely rare condition in humans.

Victims have typically been veterinarians, scientists, or researchers who work directly with primates and may have been exposed to their bodily fluids via scratches, bites, or dissections. Six weeks after a caged monkey flung a drop of liquid at her face, hitting her eye, a primate researcher in New York died. There has only been one documented case of an infected human spreading the virus to another person, according to the Centers for Disease Control and Prevention in the United States.

Both herpes B and the novel coronavirus are “the result of species jumps,” according to Nikolaus Osterrieder, dean of Hong Kong’s Jockey Club College of Veterinary Medicine and Life Sciences. “However, the important distinction is that in the case of herpes B, it is a dead end. “It is not jumping from one human to another,” he clarified. “On the other hand, SARS-CoV-2 acquired the ability to spread to a new host.”

Herpes B, according to Osterrieder, is very well-adapted to macaque monkeys and is unlikely to mutate in such a way that it begins to spread rapidly among humans. Nonetheless, both he and Iwata expressed their hope that more people become aware of the disease and take the necessary precautions, particularly when interacting with monkeys in non-research settings such as a zoo or in nature. Last year, Florida officials debated what to do about a rapidly expanding population of rhesus monkeys — an emerging tourist attraction — many of which carried the herpes B virus.

The discovery of the Monkey B virus in a human suggests that it may “pose a potential zoonotic threat to occupational workers,” according to Chinese health officials, who added that “it is necessary to strengthen surveillance in laboratory macaques and occupational workers.” On the Chinese social media platform Weibo, news of the veterinarian’s death had been viewed more than 110 million times by Monday.

“Aside from researchers, most people should avoid wild animals,” one post with thousands of likes said. “You may desire to be close to nature, but nature does not desire to be close to you.”

Dallas County health officials in Texas reported last week that a man had a rare case of monkeypox, which can also be transmitted when people are bitten or scratched by an animal.