Objective: To investigate the effects of disease progression and zidovudine antiretroviral therapy on semen parameters in human immunodeficiency virus type 1 (HIV-1) seropositive men.

Design: Cross-sectional analysis of semen parameters of 166 HIV-1 seropositive men in various stages of disease progression as defined by peripheral CD4+ cell count. Clinical symptoms and zidovudine therapy status were obtained from medical records and clinical interviews.

Patients: Human immunodeficiency virus type 1 seropositive men participating in clinical studies at the Fenway Community Health Center (Boston, MA), the University of San Francisco (San Francisco, CA), and Brown University (Providence, RI).

Main outcome measures: Ejaculate volume; sperm concentration, motility, forward progression, morphology, total sperm count; seminal immature germ cell; and white blood cell (WBC) concentrations.

Results: Human immunodeficiency virus type 1 seropositive men that were not on zidovudine therapy and were in early disease stage (> 200 CD4+ cells/mm3) had normal semen parameters as defined by World Health Organization criteria. In contrast untreated men in advanced disease stage (< or = 200 CD4+ cells/mm3) had significant reductions in sperm concentration and total sperm count and an increased percentage of abnormal sperm forms. Men receiving zidovudine antiretroviral therapy, regardless of disease stage, had normal semen parameters similar to those of untreated early disease stage patients. Seminal WBC concentrations were not affected significantly by disease progression but were reduced in patients receiving zidovudine.

Conclusion: Most HIV-1-infected men in this study had semen parameters consistent with fertility. Disease progression was associated with reduced semen quality, but this effect appeared to be abrogated by zidovudine therapy. Zidovudine was also associated with a significant reduction of WBC numbers in semen. As seminal WBC are principal HIV-1 host cells in ejaculates of HIV-1-infected men, this effect could explain recent laboratory and epidemiological evidence that zidovudine therapy is associated with a reduced prevalence of HIV-1 in semen and a lower rate of sexual transmission.