Half of all new HIV transmissions occur when people are unlikely to know they carry the virus and in some cases, wouldn't test positive for it because they are so newly infected, a Canadian study says.
The study, to be published in the April edition of the Journal of Infectious Diseases, is one of the first in the world to quantify how many of the newly infected are responsible for spreading the disease to others.
And it raises troubling questions about how to deal with the problem: How can those at high risk be encouraged to come forward and undergo frequent, repeated tests when no one knows who they are? And should those at very high risk of contracting the disease be put on anti-retroviral therapy as a preventive measure?
"From the standpoint of public health, we have a major problem in Canada and North America," study author Mark Wainberg, director of the McGill University AIDS Centre at the Jewish General Hospital, said in a telephone interview yesterday.
". . . One of the things driving this entire epidemic is that people themselves are newly infected and are often the most infectious they will ever be throughout their lives and often not even know it."
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