The risk of getting AIDS can apparently be increased by heterosexual promiscuity or frequent contact with female prostitutes, according to research from Europe and Africa.

The results, reported in a letter to The New England Journal of Medicine, show that heterosexual men with AIDS had an average of 32 sexual partners a year, while healthy men had an average of three.

In addition, those with AIDS were more than twice as likely as healthy men to be regular clients of prostitutes.

Acquired immune deficiency syndrome is spreading rapidly in the United States, especially among homosexual men. As of last week, 12,256 cases were reported, with 6,171 deaths, according to the Centers for Disease Control in Atlanta. The number of cases is expected to double by next year.

The studies of 58 African men in Rwanda and Belgium are "very indicative" of heterosexual transmission of the disease, Dr. N. Clumeck of Brussels and several colleagues write.

They also report that, contrary to other findings, female prostitutes may transmit AIDS to men even when intravenous drugs are not involved. "Of 42 African women in whom AIDS . . . had been diagnosed," they report, "10 were professional prostitutes. In none of these women did we find a history of addiction to . . . drugs."