Drug-resistant HIV primarily transmitted by untreated carriers
According to the Swiss HIV Cohort Study, approximately one in each 10 newly infected HIV carriers in Switzerland are resistant to at least one of the three classes of drugs used to treat AIDS. Contrary to prior assumptions, the resistant viruses are typically transmitted by individuals who have not received treatment.
In a study of 1,674 male carriers of HIV who had sex with other men, resistant viruses were detected in 140 patients. The study traced back the transmission chains of the viruses and found most transmission chains commenced in HIV carriers who were not yet undergoing treatment when the resistant viruses were transmitted.
"We were astonished to note that the resistant viruses are primarily brought into circulation by untreated people," Huldrych Gunthard, one of the study leaders, said. "Previously we had assumed that the resistant viruses came from patients for whom treatment had failed as resistances were produced while treatment was ongoing."
The researchers determined that combating resistant HIV strains was reliant on preventing transmission by people who are not undergoing treatment and combatting the resistant strains. They said the early detection of newly infected individuals is vital.
The team said that since many doctors are reluctant to discuss their patients' sexuality openly with them, many infections are not discovered until much later than they should be. Gunthard said there is much left to be done in the battle against AIDS.