GRIDS, or 'Gay Related Immune Deficiency Syndrome', was the name given to AIDS when it was first observed in the West in the early 1980s.

As the vast majority of cases were seen in homosexual and bisexual males, it was considered primarily a gay ailment ('gay cancer' and 'gay plague', although not considered polite, were used to refer to the epidemic). Early studies focused on the sexual and social behaviour of gay and bisexual men, and it was believed that the presence of some sort of infectious agent in semen, such as cytomegalovirus (a very common strain of herpes) or Epstein-Barr virus (the root cause of mono, also in the herpes family) transmitted through lesions in the anal mucosa caused the syndrome. Stimulants, such as butyl nitrate or amyl nitrate (aka 'poppers'or Rush) were also thought to interfere with ones' immune system and contribute to the disease.

On July 27, 1982 the American Centers for Disease Control and Prevention (CDC) officially renamed 'GRIDS' to 'AIDS' (Acquired Immune Deficiency Syndrome).

Sources:

Canadian Broadcasting Corporation (CBC) News: The Fight for Gay Rights World Timeline:
http://cbc.ca/news/indepth/background/gayrights.html
ESOnline Magazine, published by Terenure College:
http://www.iol.ie/~terenure/esonline5/msmaids.html
AIDS Legal Referral Panel (ALRP) Law Manual Web Site:
http://www.alrp.org