Half of Montreal HIV Transmissions by People Who Don't Know They're Infected
March 23, 2007
At a recent AIDS forum held in Montreal, a presentation showed HIV transmission during early infection is one of the epidemic's prime drivers in the city. Half of new HIV transmissions occur at a time when the transmitting patient is so recently infected he or she has not yet produced the antibodies for which standard diagnostic tests search, the study suggests.
"People are most likely to transmit the AIDS virus when they are first infected than in the chronic stages of the illness," said Michel Roger, a co-researcher at the University of Montreal. The study, led by McGill AIDS Center Director Dr. Mark Wainberg, followed 2,500 Montreal HIV patients for eight years. It used genetic tests to determine length of time since infection and to track the virus' path.
Its findings indicate that each newly infected person transmitted HIV to eight other people on average, said Bluma Brenner, a McGill AIDS researcher at Jewish General Hospital. One trial participant was determined to have transmitted HIV to 17 other people.
During early infection, HIV multiplies quickly, and viral loads are higher. People newly infected may or may not feel ill. Some people experience flu-like symptoms and others do not. Because 30 percent of HIV-infected people do not know it, identifying them is difficult but crucially important, said Wainberg. Quick treatment with HIV drugs may reduce the spread of infection.
However, mass screening is expensive and may not detect people recently infected, symposium participants heard. It may take up to six months for the body to produce the antibodies that trigger a positive result on standard tests.
The full report, "High Rates of Forward Transmission Events after Acute/Early HIV-1 Infection," was published in the Journal of Infectious Diseases (2007;195:951-959).
This article was provided by CDC National Prevention Information Network. It is a part of the publication CDC HIV/Hepatitis/STD/TB Prevention News Update.