Epidemic is shifting to blacks, Hispanics
Most common transmission is MSM
The most recent data from the CDC estimate that about one-quarter of the more than 1 million people living with HIV/AIDS do not know they are infected.
The data also show rising diagnoses among men who have sex with men (MSM), particularly those who are African American and Hispanic.
Although the data from 2003 are based on information from only 30 states, not including New York and California, this estimate provides the clearest picture to date of the impact of the epidemic on the American population.
"What we do is use information on new HIV diagnoses and data on the stage of disease when a person was diagnosed," says Kate Glynn, DVM, MPVM, an epidemiologist with the division of HIV/AIDS prevention at the CDC.
CDC officials estimate between 1.04 million and 1.19 million Americans are infected with HIV, and 24% to 27% of them do not know they are infected, she notes. "Knowing what we do about AIDS diagnoses in a balance of areas, exposure category, we extrapolate a distribution in those subgroups," Glynn says. "So we have estimates for all groups for the entire U.S."
The surveillance data also shows the greatest impact of the epidemic is among African Americans and Hispanics, she points out.
Investigators determined that 47% of people living with HIV/AIDS are African American, 34% are white, and 17% are Hispanic, and 74% are male, Glynn says.
The most common transmission group remains MSM (45%), while heterosexual contact accounted for 27%, and injection drug use accounted for 22%, Glynn says.
Among MSM, HIV diagnosis rates, between 2000 and 2003, were 4.4 times higher among African American men and 2.1 times higher among Hispanic men than among white men.1
Epidemiologists ideally would determine the burden of the HIV epidemic on a particular population, but there are no estimates for the number of MSM or high-risk heterosexuals in the United States, Glynn says.
Investigators have looked at the burden of a particular transmission category among the general population.
The findings suggest the rate of HIV diagnoses associated with MSM sex increased in each ethnic group, while the rates of diagnoses among injection drug users had a slight decrease or were stable in all ethnic groups. The findings were similar for women, Glynn says.
"In every transmission category, the rates were the highest among African Americans and second highest among Hispanics," she reports. "So clearly in terms of implications for prevention, this should remain a high priority in every racial ethnic group among men, and prevention of transmission should remain a high priority among women, especially black women."
CDC investigators also have examined the pool of infected people to see if there is something that could indicate whether these findings would change in the future, Glynn reports.
"We compared those among the diagnosis cases as compared with those living with AIDS, and what we saw is the cases of new HIV diagnoses were more likely to be female, black, and associated with high-risk heterosexual contact," she says. "This suggests this is more likely to be where the future is heading to some extent, with more diverse populations continuing to be impacted."
Although the CDC does not believe new diagnoses are identical to new infections, it is known that new HIV diagnoses are more likely to represent new infections than are new cases of AIDS, Glynn says.
The challenge is to reach the highest risk groups with tailored prevention services, she notes.
Another trend is that new HIV diagnoses among injection drug users are a little lower than those among AIDS cases, Glynn adds.
"That’s consistent with surveillance data that suggest rates of new HIV diagnoses attributed to IDU are stable or decreasing," she says.
CDC officials also have found that patterns of HIV diagnoses among people, ages 13 to 24, confirm recent reports of a resurgence of HIV among young MSM.2
The number of diagnoses among adolescent and young adult men rose from 1,040 in 1999 to 1,471 in 2003, in 25 states.2
In the same age group, the new diagnoses among women have steadily declined from 1994 to 2003, Glynn says.
For young men, there initially was a 30% decline in new diagnoses between 1994 and 1998, and then there was a 41% increase between 1999 and 2003, she says. "The recent increases among males were driven primarily by a 47% increase among young adults, ages 20 to 24, who are MSM, and the majority were black, non-Hispanics. It’s important to remember that what are reported here are new HIV diagnoses, so it’s not possible to determine whether the trends are due to increased HIV testing or a true increase in new HIV infections."
Some researchers have concluded that treatment optimism and a decreased fear of infection are playing a role, so they’re calling for more intensive efforts at prevention directed toward young MSM to reverse the recent trends, she notes.
"I think it’s also important to continue treatment among females and young adults to sustain recent declines," Glynn adds.
"More persons are living with HIV than ever before, and what we know is treatment successes have brought new challenges," she says. "It’s clear that effective treatment is a godsend for HIV-positive individuals and allows them to live longer and healthier lives, but it also means there’s a growing population in need of services, and increased prevalence means an increased opportunity for HIV transmission."
There also is a challenge of helping high-risk and HIV-infected people maintain safe behaviors over a lifetime and not just during crisis times, Glynn adds.
References
- Selik RM, Glynn MK. Trends in the HIV/AIDS epidemic, presentation M1-B0814. Presented at the HIV Prevention Conference, sponsored by the Centers for Disease Control and Prevention. Atlanta; June 2005.
- Rangel MC, Gavin L, Lee LM. Patterns of new HIV/ AIDS among adolescents and young adults in 25 states, presentation M1-B0802. Presented at the HIV Prevention Conference, sponsored by the Centers for Disease Control and Prevention. Atlanta; June 2005.
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