HIV becoming more virulent

Damage to patients’ immune systems is happening sooner now than it did at the beginning of the HIV epidemic, suggesting that the virus has become more virulent, researchers report.

Conventional wisdom says several years will pass between HIV infection and the need for antiretroviral therapy. However, clinicians have observed that patients are entering HIV care with lower initial CD4 cell counts than in previous years, and now often require antiretroviral therapy soon after entering care, raising the question of whether HIV has become more virulent.

US researchers studied data from more than 2 000 HIV-positive active-duty military personnel, retirees, and dependents between 1985 and 2007 who had tested HIV-negative within the previous four years.

When they looked at patients’ first CD4 count after HIV diagnosis, they found that it decreased from an average of 632 cells per square millimetre in 1985-1990 to 514 in 2002-2007.

Additionally, 25% of patients diagnosed with HIV in recent years already had fewer than 350 CD4 cells per square millimetre, the threshold for when antiretroviral therapy should begin according to US guidelines, compared to only 12 percent of patients in the late 1980s.

Trend stabilising
The authors note that the trend seems to have stabilised, perhaps due to the widespread introduction of highly active combination antiretroviral therapy.

This is the first study from the United States which shows that the immune cells among recently diagnosed HIV patients has dramatically fallen during the HIV epidemic, the authors said in an official statement. These findings are similar to those found in a study from Europe, which suggests that these trends may be widespread.

“Unfortunately, it may no longer be true that there is a time period of several years between diagnosis and the need for treatment – instead this time-span is shortening” said study author Dr Nancy Crum-Cianflone, of the San Diego Naval Medical Centre. “Early diagnosis is important for several reasons including that patients can enter into medical care and begin treatment before the immune system becomes weak and opportunistic infections develop.”

The study is published in the May 1, 2009 issue of Clinical Infectious Diseases. – (EurekAlert, April 2009)