The first human case of virus B has been reported in Hong Kong, but how is it transmitted? And how deadly is it?

However, the virus can be deadly in other primates, including chimpanzees and capuchin monkeys, according to the Centers for Disease Control and Prevention (CDC).

Infection with humans is rare. Since the virus was discovered in 1932, approximately 50 human infections have been recorded, resulting in 21 deaths.

Past studies have shown that without timely treatment, the mortality rate for people who contract the viral infection can reach 70 to 80 percent.

Hong Kong's first person infected with type B virus fights for life after being attacked by monkeys

2. How does the B virus pass from macaque monkeys to humans?

The virus is present in the saliva, urine, and stool of infected macaques. Humans can also contract the virus if they are bitten or scratched by an infected monkey.

According to information from the CDC, infected macaque monkeys typically do not spread the B virus. Only people with weakened immune systems, people who are under stress, and people with blisters on their skin are more likely to shed the virus.

Laboratory workers, veterinarians, and others exposed to monkeys or their specimens are at increased risk of contracting viral infections. Infection can occur through scratches or cuts from contaminated cages or sharp surfaces, or through contact with the brain, spinal cord, or skull of an infected monkey.

Dr Ho Pak-leung, a clinical associate professor at the Department of Microbiology at the University of Hong Kong, said that if there is no skin break, the chances of infection are low.

“But if you have skin damage, such as a wound or eczema, and come in contact with saliva containing the virus, you can become infected,” Ho said on Thursday's radio show.

Flu-like symptoms such as fever, chills, muscle pain, fatigue, and headache may appear between 3 days and 1 month after infection. Infected people develop small blisters on wounds and body parts that came into contact with the monkey, and continue to experience symptoms such as shortness of breath and nausea.

The virus can spread to other parts of the body and cause inflammation of the brain and spinal cord, leading to muscle coordination problems, brain damage, and even death.

3. Is the infection treatable?

Despite relatively high mortality rates, antiviral drugs are available for preventive care and treatment of people exposed to or infected with B viruses. Experts debate at what point antiviral therapy should be discontinued, but some argue that lifelong suppressive antiviral therapy may be necessary.

4. What should I do if I get infected with the B virus?

Professor Ho said anyone attacked by a monkey should wash the wound with water and soap within five minutes. This is the time required for the virus to enter a person's cells, as past studies have shown.

He said the wound should be cleaned for 15 minutes to wash away the virus before it can enter cells. After that, it is necessary to immediately seek medical attention.

Hong Kongers ignore warnings and feed monkeys as humans risk their lives to fight the B virus

5. How can I prevent B virus infection?

There is no vaccine for B virus infection. People should avoid approaching, touching, or feeding macaques.

The Agriculture, Fisheries and Nature Conservation Bureau is asking people not to eat in front of the monkeys or make direct eye contact with them to avoid appearing provocative. You should also avoid carrying around plastic bags and hide them in your backpack.

Illegal feeding of wild animals, including monkeys, is subject to a fine of up to HK$10,000 upon conviction under the Wildlife Protection Ordinance.

When working with macaque monkeys, researchers must wear personal protective equipment such as lab coats, gloves, and face shields.

6. Where are the monkeys in Hong Kong? Are attacks common?

Officials estimate that there are about 1,800 wild monkeys in Hong Kong, distributed across 30 social units. These are mainly found in the country parks of Kamshan, Lion Rock and Shinmun.

Since 2009, the Ocean Park Conservation Foundation has run a monkey neutering program to control the monkey population in the long term.

In a 2017 response to MPs, the government said it had not received any reports of monkeys attacking people between 2014 and 2016.

During the same period, approximately 440 to 550 cases of monkeys causing a nuisance, such as searching for food in residential areas, were reported annually.

The department said Thursday that the city has recorded between 212 and 307 cases of monkey nuisance cases each year from 2021 to 2023, with 76 such reports in the first three months of this year. These cases also involved monkeys foraging for food in residential areas.