A troubling new report projects that, at a time when Americans are less likely to be diagnosed with HIV, half of black gay or bisexual men and a quarter of Latino gay or bisexual men will contract the disease. The study was published by the Centers for Disease Control (CDC) and presented at the Conference on Retroviruses and Opportunistic Infections in Boston this week.

To compile its first national look at how different communities, especially men who have sex with men (MSM), are affected by HIV and AIDS, the CDC looked at data including HIV diagnoses and death rates from HIV from 2009 through 2013. [2009 to 2013?] Using that information, the CDC predicted the likely trajectory of diagnoses in the coming years. Now, they found, 1 in 99 Americans is expected to become HIV positive. That's a drop from a previous report, which used data from 2004-2005 and concluded that 1 in 78 Americans are likely to receive the diagnosis.

In a statement, CDC National Center for HIV/AIDS, Viral Hepatitis, STD, and Tuberculosis Prevention director Jonathan Mermin said the information should be taken as a call to action, rather than a declaration of fact. “The prevention and care strategies we have at our disposal today provide a promising outlook for future reductions of HIV infections and disparities in the U.S.," he said, but warned that "hundreds of thousands of people will be diagnosed in their lifetime if we don’t scale up efforts now.”

Prevention is possible. When taken daily, drugs like Pre-exposure prophylaxis (PrEP) can reduce the likelihood that those most at risk for contracting HIV will get a positive diagnosis. Recently, the CDC said that a quarter of gay and bisexual men who are sexually active should be taking preventative medication. But that recommendation has proven difficult to execute. CBS News reported in December:

Recent studies show that despite having been approved by the Food and Drug Administration in 2012, 1 in 3 primary care doctors and nurses have never even heard of PrEP. "PrEP isn't reaching many people who could benefit from it, and many providers remain unaware of its promise," said CDC Director Dr. Tom Frieden said in a statement.

Overall, minorities are much more likely to become HIV positive than white Americans.

The CDC notes there's no evidence that black Americans have riskier sex than their white counterparts. The agency suspects, instead, that the discrepancy is linked to a higher prevalence of STDs in the black community. According to the CDC, high rates of STDs mean "an increased risk of infection with each sexual encounter." Poverty, stigma and poor access to healthcare exacerbate the situation.

There is also a geographic disparity:

Still, CDC officials remain hopeful that the numbers will change. Eugene McCray, who is the director of the CDC’s Division of HIV/AIDS Prevention, said that “If we work to ensure that every American has access to the prevention tools we know work, we can avoid the outcomes projected in this study.”

Danielle Wiener-Bronner is a news reporter.