Despite repeated tests showing negative results, a group of people live in fear, suspecting that they have been infected with HIV.

Experts believe they are suffering from a psychological phobia of AIDS, but they say they are patients of "HIV-negative AIDS".

Among them is 30-year-old Xiang Jun, who prefers not to use his real name, from Xiangtan, a city in central China's Hunan Province.

Since kissing a woman at a karaoke house in August 2010, he has noticed some changes in his body.

"My lymph nodes and muscles swell. At night, I sweat feverishly. I feel dizzy sometimes and can sleep for a whole day. When feeling ill, I want to kill myself," he says.

He has visited hospitals for two HIV tests, and both have come back negative for infection.

Still, Xiang has noticed that, after coming into contact with him, some of his relatives and colleagues have developed symptoms similar to his.

He suspects that his disease could be a new, more contagious form of AIDS.

On the Internet, many people have complained of experiencing symptoms similar to that of Xiang Jun. Some have also complained of other maladies, including joint aches, canker sores, and diarrhea, which resemble symptoms of HIV infection.

Some of them have managed to contact Zeng Guang, chief scientist of epidemiology with the Chinese Center for Disease Control and Prevention (CDC).

From 2009 to 2010, the CDC tested 59 volunteers from the group of "HIV-negative AIDS" patients, and found no evidence that any had been infected with HIV, says Deng Haihua, spokesman for the Ministry of Health.

The results did not suggest that they were infected by any new or unknown viruses, either, Deng says.

Still, some patients doubt these conclusions.

Xiang Jun has a friend Lin Fei, also using a fake name, who suspects that his entire family has exhibited these symptoms.

"My mother, my wife and my daughter all have fatigue and night sweats. Is it simply because of a 'psychological phobia?'" asks the 49-year-old man.

"My daughter is only six and my son is eight. If our symptoms are due to a psychological phobia, they are too young to know what AIDS really is," according to "Mr. Fear" from Shenzhen, a city in Guangdong Province.