A man is seeking treatment after a syringe left in the back of a taxi that pierced the skin on his leg was found to likely contain HIV antibodies.

According to Beijing News, 37-year-old Xu Tian (not his real name) got into a taxi in Haidian district in the capital on Tuesday night. Sitting on the backseat, he felt a sting on his leg when he lifted it.

He told Beijing News that he found a syringe in the magazine rack fixed to the back of the front seat, and also a needle cap, which, like the syringe barrel, contained some sticky fluid.

He took the syringe to Chaoyang District Center for Disease Control and Prevention on Wednesday. He later found the fluid contained HIV.

A doctor, surnamed Jiang, at the department of sexually transmitted diseases and AIDS detection at the center, confirmed to China Daily on Friday that a man came to the center with a syringe at about 3 pm on Wednesday, saying he was punctured by it.

"We had never seen such an incident before, so we did a quick test with the fluid," said Jiang.

Jiang said there was "very little light yellow fluid" left in the cap and the syringe barrel, and the center took a sample of the fluid in the needle cap, and found it was HIV antibody positive after a quick test.

"Because the quick test was just preliminary the result may have been false," he said.

Jiang said the center has submitted a sample to the Chinese Center for Disease Control and Prevention for further tests.

"He went to Beijing Ditan Hospital for a blood test on Wednesday morning. In the evening, we called the hospital for his medication," said Jiang, believing that Xu had taken the medication within 24 hours of finding the needle.

A publicity staff member at the hospital surnamed Chen confirmed that the hospital had prescribed him preventive medication.

The result of the blood test was negative, reported Beijing News.

A police station in Haidian district questioned Xu for about four hours on Friday.

Ji Zhongcheng, Xu’s friend who accompanied him, said Xu’s doctor asked him to take regular tests in the first month.

"The police told me they will investigate the case," said Xu, who has been taking preventive medication.

The taxi company had refused to take responsibility, Ji added. Xu said he will sue the taxi company. The taxi driver waiting outside the inquiry room declined to comment.

Experts are cautiously optimistic about Xu’s chance of avoiding being infected with HIV.

Even if there are HIV antibodies in the fluid, it does not mean that the virus is definitely still alive, given that it was very fragile outside the human body, said Jiang.

Li Chaolin, president of the Chinese Foundation for Prevention of STD and AIDS, said the probability Xu will be infected is low.

"HIV has a lower chance of survival outside the body. If it has been outside the body for a long time, the virus may be inactivated," he said. "However, it is worth being vigilant. It will take three months to determine if he has got it."

Li said people who have been potentially exposed to the virus can go to local centers for disease control and prevention and hospitals such as Beijing You’an Hospital, Beijing Ditan Hospital and the 302 Military Hospital of China for tests.

"People who have potentially been exposed to the virus should go to standard medical institutes within 24 hours," said Chen. "Don’t panic. Doctors will assess whether preventive medication is necessary."

Contact the writers at wangqingyun@chinadaily.com.cn and dengzhangyu@chinadaily.com.cn