Acquired immune deficiency syndrome (AIDS) is caused by an RNA retrovirus (HIV-1) and is readily transmitted heterosexually. The viral receptor is a differentiation antigen on the surface of a class of immunologically active cells including T 'helper' lymphocytes, some macrophages and antigen presenting cells. HIV may be transmitted vertically and viral antigens have been demonstrated in the placenta. Infants of infected mothers have at least a 60% probability of acquiring HIV in utero. The normal latent period after infection is between 2 and 5 years, and it is estimated that for every case of AIDS, 50-100 people may be infected. Extrapolation of these estimates suggest 1,000,000 may already be infected and the established risk group for AIDS may not reflect the pattern of present infection. In Central and East Africa there now appears to be an epidemic of enormous proportions. Oocytes and spermatozoa are not attacked by the HIV virus but associated lymphocytes or monocytes may be infected. Screening for HIV for semen donation is mandatory and precautions for infection with HIV should follow procedures adopted for hepatitis B virus.

Acquired Immunodeficiency Syndrome/*EPIDEMIOLOGY/TRANSMISSION Africa Disease Outbreaks/*PREVENTION & CONTROL Female Fertilization in Vitro Great Britain Human HIV/*ISOLATION & PURIF Pregnancy Pregnancy Complications, Infectious/*EPIDEMIOLOGY Risk Semen/MICROBIOLOGY Time Factors United States JOURNAL ARTICLE

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