What is B Virus? Hong Kong Records First Human Case of Rare and Potentially Fatal Virus After Monkey Attack

Symptoms of B virus in humans include fever, chills, muscle aches, fatigue, and headaches with blisters

Hong Kong has registered first ever human case of B virus, occurring when a 37-year-old man was attacked by a monkey. The health ministry disclosed this development earlier this month, with the Centre for Health Protection (CHP) currently probing the incident. Also known as herpes simiae virus, B virus infections in humans are uncommon, though cases have surfaced in various regions like the United States, Canada, mainland China, and Japan.


Primarily transmitted through monkey bites or scratches, human-to-human spread of the virus is exceedingly rare. The affected man reportedly sustained injuries from monkeys during a visit to Kam Shan Country Park at the end of February. Following subsequent symptoms of fever and decreased consciousness, he was admitted to Yan Chai Hospital on March 21. Tests on his cerebrospinal fluid confirmed the presence of B virus, and he is presently receiving critical care in the intensive care unit (ICU), as per CHP reports.

CHP spokespersons highlighted that macaque monkeys, commonly found in Hong Kong, naturally carry B virus in their saliva, urine, and stool. Initial infection can manifest flu-like symptoms, progressing to affect the central nervous system. Termed monkey B virus or herpesvirus simiae, the pathogen primarily affects macaques, akin to cold sores in humans.

While B virus infections are rare, the US Center for Disease Control and Prevention (CDC) warns of severe consequences, including brain damage or fatality if untreated. Human transmission usually occurs through monkey contact, with only one documented case of human-to-human spread, according to the CDC.

Symptoms of B virus in humans include fever, chills, muscle aches, fatigue, and headaches, potentially accompanied by blisters at the site of contact with the monkey. Prompt action is recommended upon exposure, including thorough washing and disinfection of the wound area for at least 15 minutes before seeking medical assistance.

Treatment involves antiviral medications to combat the virus's effects.

This article was first published on April 16, 2024