Xiao and his colleagues are especially wary about the threat of HIV/AIDS, and they try the best to protect themselves by using condoms even for a masturbation or oral sex, and avoiding kissing the clients.
Guo and his fellow volunteers visit and talk to male sex workers from time to time, distributing free condoms and lubricants.
"As far as we know, the proportion of MBs who are HIV-positive is much lower than that of the wider gay community," Zhu noted.
For those who are infected with the virus, however, receiving effective treatment can be difficult due to the fact that there are only a few HIV designated hospitals, and they have limited resources.
In addition to that, practices such as deliberately delaying treatment, administering the wrong drugs or overcharging are reported to BZICC.
"In 2011, three male sex workers died from AIDS, due to untimely treatments," Guo said.
Earlier in November, a local NGO advised a man diagnosed as HIV-positive, who suffered from lung cancer, to disguise his medical status after he was turned down for treatment at a hospital in Tianjin.
While the patient in this case was not a sex worker, the North China Region of the China Alliance of People Living with HIV/AIDS confirmed that discrimination in receiving treatment is common.
"We think patients have a 99 percent chance of being rejected by hospitals if they know the patients are HIV carriers," Li Hu, a manager of the alliance told Metro Beijing in a previous report.
Violent police tactics
Besides sexually transmitted diseases and widespread discrimination in medical treatment, another occupational hazard MBs face is violence.
Prostitution in China is illegal, and the attitude of Chinese police toward homosexuals or specifically MBs has long been controversial.
Beijing's periodic prostitution crackdowns in recent years have caused the biggest problems for MBs. Police stings are often set up to make arrests, with violent treatment often following in police station cells.
Dongdan Park in Dongcheng district and the Mudanyuan neighborhood in Haidian district are known as the popular gay "cruising" spots for hooking up in Beijing.
Nutritious lunch provided in Taipei's elementary school