Karen Weintraub

Special for USA TODAY

Stigma and discrimination have always played a major role in the global AIDS epidemic, but they are getting renewed attention this year at the ongoing International AIDS Conference in Melbourne, Australia.

A study released Monday at the conference shows that vulnerable communities in Nigeria fared far worse after legislation was passed criminalizing gay male sex. And in a panel scheduled for Wednesday , researchers were expected to discuss way to help advocates, doctors and patients combat stigma.

The past year has seen both unprecedented advances in gay rights - with expanded marriage equality in the U.S. – and even more significant setbacks, with discriminatory laws passed in Nigeria and Uganda and Russia's president Vladimir Putin speaking out against gay rights, said Richard Parker, a professor of sociomedical sciences at the Mailman School of Public Health at Columbia University in New York.

"The fact that in 2014, this kind of legislation is being passed in countries around the world is mind-boggling," he said, adding that such state-legislated prejudice "creates a climate of fear that drives people underground into the shadows, away from services."

The new study from Nigeria shows that patients who lack treatment are more likely to transmit HIV, the virus that causes AIDS, making it harder to control the epidemic, which has already infected 35 million worldwide.

"From Nigeria, we get a very clear answer that (the new laws) are aiding and abetting the virus and making it much more difficult if not impossible to provide basic services to people in need," said Chris Beyrer, incoming president of the International AIDS Society, which runs the conference.

Researchers were already studying Nigerian men who have sex with men when the anti-gay law was passed. After some investigating and soul-searching, the group decided to keep the study going, to measure the law's impact, said Stefan Baral, an associate professor and director of the Key Populations Program at the Johns Hopkins Bloomberg School of Public Health in Baltimore.

Results confirmed the researchers' fears. "We're seeing extremely high numbers of new infections and extremely high prevalence" of HIV, particularly among young men, since the law passed, Baral said. "There's an extremely clear link between that fear of seeking care among people who are at risk or living with HIV and their own health outcomes."

Donor money spent addressing AIDS will not go nearly as far in countries where there is tremendous stigma, he said.

Baral helped organize a panel today to look at ways to better define and measure stigma, which also affects sex workers, intravenous drug users, and former prisoners.

"Even though everybody pays lip service to the importance of stigma, there's been very limited investment in trying to understand how stigma manifests, how to measure it, how to intervene," he said. "I think because the science is in an early stage, there hasn't been a major investment in programs other than people getting together and discussing it."

The panel also featured success stories of "amazing people" providing services, such as condoms, and links to treatment, despite difficult circumstances, Baral said. "Change is possible, even in context of very stigmatizing environments."