The men and women participating in the study developed AIDS equally quickly after infection, indicating that women who use injection drugs develop the disease with as little as half the viral load of men. In addition, at viral loads that equal mens', the women had 1.6 times greater risk of progressing to AIDS than are men.
"These findings could be an important first step in understanding the course of HIV/AIDS in each gender," said Dr. Alan I. Leshner, Director of the National Institute on Drug Abuse (NIDA), National Institutes of Health, which funded the study. "Continued research needs to answer whether this HIV progression holds for a non drug-using population as well. Further, it can be concluded that if a given viral load measurement differs in clinical significance in drug-injecting women, treatment strategies using these measurements may have to be optimized separately from those of men."
Led by Dr. Homayoon Farzadegan, a team of researchers at Johns Hopkins School of Hygiene and Public Health studied specimens from 650 HIV-1-infected, injection drug users participating in a continuous study at a Baltimore clinic. HIV-1 load was assessed during an initial (baseline) visit, and again on followup visits 3 years later. The study was designed to analyze the relationship between gender using three different methods of measuring HIV-1 viral load. Results demonstrated significantly lower median viral load measurements in women by all three methods.
"These results were surprising," noted Dr. David Vlahov of the Hopkins research team. "We expected lower viral loads to be associated with slower progression of the disease, and this was not the case."
Explanation for the lower viral load counts in women in the study remains elusive, with researchers considering several alternatives: different HIV-1 dynamics in men and women, and/or gender-linked behavioral differences that might influence viral load, and hormonal differences.
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