Three armed women forced him to accompany them to an isolated field near his bus stop.

The man was ordered to strip and was then raped by each of the women.

The traumatised victim told police one of the women had mocked him with the words: "Welcome to the world of AIDS."

The assault was the latest in a string of similar rapes in recent months.

"This seems to be something that's becoming very common, and it seems as if revenge is the motive," said East Rand police inspector Umgau Geelbooi Hadebe, who is leading the investigation into such assaults in the region of Johannesburg.

Women rapists have been reported in other provinces. Earlier this year, a man was raped in the town of Middleburg, 150km east of Johannesburg. Similar reports have come in from KwaZuluNatal and the Western Cape.

"It looks very much like there are women who are raping men because they were infected with AIDS," Inspector Hadebe said.

"The first attack took place about Christmas time, and the victim, an 18-year-old schoolboy, was also taunted that he was now infected with AIDS.

"This is very unusual, because we're used to dealing with men raping women."

But it is not so unusual, according to Delphine Senumaga, director of People Against Women Abuse.

"Men have been rape victims for quite some time," she said. "What has changed is that men are now responding to our rape awareness campaigns - they are coming forward to report the crime, whereas before they would have been shamed into silence."

Ms Senumaga said people who discovered they had been infected with HIV, either through their partner or by rape, might be driven to seek vengeance.

"When people find they are infected with the virus they react in different ways. Some want to hit back at those they feel are responsible," she said.

UN figures show 5.2 million of South Africa's 47 million people are infected with HIV.

The Australian

This report appears on NEWS.com.au.