Man in critical condition after catching deadly 'B virus' from wild monkeys in Hong Kong

A man caught a rare but potentially lethal infection after being wounded by wild monkeys in a Hong Kong park and is currently in critical condition, health officials report.

The infection was caused by B virus, which is commonly found in the saliva, urine and stool of macaques, monkeys that live in various locations in the city, according to the Centre for Health Protection (CHP), an agency of the Department of Health in Hong Kong. The monkeys themselves usually are either asymptomatic or show only mild symptoms of infection, the Centers for Disease Control and Prevention (CDC) notes.

According to the infected man's family, he'd encountered the monkeys during a visit to Kam Shan Country Park — home to an area nicknamed "Monkey Hill" — in late February. His case is thought to be the first human infection with B virus in Hong Kong, the CHP noted.

B virus, also called monkey B virus or herpesvirus simiae, rarely infects people. From its discovery in 1932 to 2019, the virus sickened about 50 people, 21 of whom died of the infection, according to the CDC. Most of the affected people had been bitten or scratched by a monkey or were infected when the tissue or bodily fluids of a monkey had made contact with broken skin. There's only one known case of an infected person spreading B virus on to another person, the CDC notes.

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The first known human case of B virus in China was reported in 2021, in a veterinary surgeon in Beijing who'd dissected two dead monkeys and died of the infection about a month later.

In the current case in Hong Kong, the infected 37-year-old man was admitted to Yan Chai Hospital on March 21 "due to fever and decreased conscious level." As of Wednesday (April 3), he was being treated in the intensive care unit. A sample of the fluid that surrounds the brain and spinal cord tested positive for B virus.