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HIV surveillance data lack demographics
Without it, clinicians are missing part of picture
Researchers studied the nature of the HIV epidemic in Maryland to show in one microcosm of the U.S. epidemic that different populations of at-risk individuals have different sub-types of the virus and will need to be handled differently.
While the common HIV-1 subtype B is causing one epidemic in Maryland among men who have sex with men (MSM) and injection drug users (IDUs), a non-B subtype is causing an epidemic among new African immigrants in the state," says Jean K. Carr, PhD, MA, MSH, an associate professor at the Institute of Human Virology, University of Maryland School of Medicine in Baltimore, MD.
"In suburban Maryland, right outside Washington, DC, there is a large African immigrant population, and that's where we see those other subtypes," Carr says.
"The reason this is important is because when people are doing surveillance, they usually categorize people as African Americans, Hispanics, Caucasians, and others, but they don't make a distinction between African Americans who have arrived recently and those who have been here for generations," Carr explains. "But these two groups represent huge differences in the epidemic, and this paper is saying all states should make this distinction."
One issue is that patients who are infected with the non-B subtypes might have a course of disease that is different from expected. Or their viral load test might underestimate their viral load, leading to incorrect conclusions about their health status, Carr says.
"HIV clinicians should be open to the idea that in some African immigrant patients they are seeing a different subtype, and some of the assays they use might not be applicable to that subtype," she adds.
"We think of subtype B as a garden variety HIV, and most of the various assays like measuring viral load have been worked out on that subtype," Carr explains. "Most of the world is infected with subtypes that are not B, and it's only slowly being understood whether or not assays that worked on B will work on these."
There are new assays that will work better with non-B subtypes, including the Abbott m2000 assay, she adds.
Maryland's department of health and mental hygiene identified 47 unique non-B subtype strains and a non-B prevalence of 12.9%. The people infected with non-B strains were mostly non-Hispanic black and female.1
"The difference epidemiologically is that the subtype B epidemic is primarily male because a lot of injection drug use is driving it, and this has more males involved than females," Carr says. "The African immigrant epidemic is mostly female and almost exclusively transmitted by heterosexual sex."
The non-B patients lived mostly in the Maryland suburbs of Washington, DC, while most of the HIV-1 subtype B cases were in the Baltimore, MD, metropolitan area.1
"Overall, the non-B subtypes were a small prevalence in the state, but there was a concentration in the Washington, DC metropolitan area," Carr says. "In terms of the country, it's probably between 1% and 2% prevalence."
Ban lifted on HIV infected
President Barack Obama in January, 2010, lifted the 23-year-old ban that prohibited foreigners with HIV infection from entering or staying in the U.S.
In Maryland, many of the African immigrants were HIV-negative when they arrived in the United States, but their social networks are among people who are from the countries where non-B subtypes are prevalent, Carr notes.
"And they go back home periodically," she adds.
"Also, people infected with HIV would visit with a tourist visa, so even though there was a state department policy prohibiting people with HIV from entering the U.S., it didn't completely abrogate those different infections from getting in," Carr says.
Most of the non-B subtypes have a similar clinical disease pattern as the B subtype. But there is one exception, Carr says.
"One non-B subtype is definitely more pathogenic," she says. "That's subtype D, which is found in Uganda, and it's definitely associated with higher viral loads and faster disease progression."
The subtype D seems to be fading out in terms of its proportion of the population, probably because it's killing itself as well as its hosts, she adds.
"We saw only one subtype D case," Carr says. "The non-B subtypes we saw primarily were ones that would have come from Cameroon, Nigeria, and Ethiopia."
Researchers increasingly favor HIV surveillance data distinguishing between recent African immigrants and long-standing African Americans because the disease clusters and screening are different.
Clinicians dealing with patients from a population that more commonly has non-B subtypes would need to use different viral load and genotype tests. But they might not know to vary their screening tests without knowing that certain populations are more likely to be infected with non-B subtypes, Carr explains.
"Prevention efforts would be very different between those two populations," she adds. "The inner city African American population of Baltimore is primarily impacted by injection drug us, so you do needle exchange and harm reduction techniques."
For the recent African American population, it would be more important to look at safe prenatal visits to make sure women are screened, she says.