Risky sexual behavior among members of a subset（子集，小团体） of the gay community is still adding to the spread of HIV. Research published in the open access journal BMC Infectious Diseases has found that young white homosexual men have an important contribution in the local spread of HIV. Despite increased education and awareness of HIV in the Western world, the number of new infections continues to rise each year. To try and understand this phenomenon, researchers from Ghent University in Belgium compared the genetic information of viruses isolated from more than 500 patients – male and female, gay and straight, Caucasian（白种人，高加索人） and non-Caucasian – who were newly diagnosed at an HIV screening clinic between 2001 and 2009. Their aim was to pinpoint factors contributing to the local spread of HIV in order to inform the development of regional prevention strategies.

"Using genetic profiling techniques we were able to group viruses into 'clusters' of highly related variants", lead researcher Dr. Chris Verhofstede explains. "Clusters of viruses are indicative for the local onward（向前的，前进的） transmission of this particular viral strain. We defined more and larger clusters amongst the HIV subtype B viruses compared to the non-B viruses. We also found that clustered viruses are more frequently isolated from young Caucasian men who have sex with men and who have a high prevalence of other sexually transmitted diseases". In other words, it appears that a significant number of new HIV infections in the region occur as a result of high-risk behavior between young white homosexual men.

This finding confirms the results of epidemiological（流行病学的） studies. Verhofstede and co-workers suggest further research to allow the design of more targeted prevention programs focused on this group.