U.S. health experts are turning to sophisticated computer mapping technology and electronic medical records to identify pockets of Americans most at risk of HIV infection.

In one study, presented on Tuesday at 2011 National HIV Prevention Conference in Atlanta, researchers at the Cleveland Department of Public Health saw big improvements in rates of HIV testing when they added reminders to patients' electronic health records about the need for routine testing.

In another, officials in the Los Angeles County Department of Public Health used disease mapping technology to identify HIV-infected patients not getting adequate treatment -- increasing the risk of transmission.

Dr. Jonathan Mermin, director of the division of HIV/AIDS Prevention at the Centers for Disease and Prevention, which sponsored the conference, said the studies, and others like it, will help as the agency implements the National HIV/AIDS Strategy introduced by the White House last summer.

That plan aims to focus resources where HIV is most heavily concentrated -- among gay and bisexual men of all races, blacks and Hispanics.

Currently, about 1.2 million people in the United States are infected with HIV, the virus that causes AIDS, and about one out of five people who are infected do not know it.

And rates are much higher among high-risk individuals, according to data from a CDC study of 21 cities presented at the meeting by CDC's Dr. Alexandra Oster.

Oster's team found that HIV continues to severely impact three groups at high risk of infection -- men who have sex with men, injection drug users and poor heterosexuals.

The study, which included data on nearly 30,000 individuals, found 19 percent of men who have sex with men were infected with HIV, 9 percent of injection drug users were infected, and 2 percent of heterosexuals in low-socioeconomic groups were infected.

That compares with infection rates of just 0.47 percent in the overall U.S. population. Among those who were infected, nearly half did not know they were HIV positive.

ELECTRONIC REMINDERS

To help remind doctors of the need for testing, Dr. Ann Avery of the Cleveland Department of Public Health studied the impact of adding reminders to the electronic medical record system used at MetroHealth, a Cleveland-based hospital system that provides care to patients regardless of insurance status.

When they started the study, only 4 percent of patients aged 13 to 64 were screened for HIV from 2008 to 2009.

To increase routine HIV testing, last July MetroHealth added an HIV testing prompt to the electronic medical records system reminding doctors to screen all patients aged 13 to 64 if they had not been previously tested.

Within six months of the changes, HIV testing in the hospital's outpatient clinics rose dramatically, increasing by nearly two-thirds. The effort was especially effective at increasing testing among men, with first-time testing rising from 2.9 percent of those tested to 6.1 percent.

Separately, a team led by Dr. Jennifer Sayles, director of Office of AIDS Programs and Policy for Los Angeles County used disease mapping software to track HIV infection and treatment rates among the county's more than 10 million residents.

Sayles studied treatment coverage among more than 12,000 HIV-infected individuals whose care was paid for through the Ryan White HIV/AIDS Program, which provides HIV-related services to those who do cannot afford their care.

Overall, 90 percent of patients reported getting antiretroviral drugs to keep the virus under control.

But a cross-check of postal codes showed significant variation in treatment by neighborhood. Where patients lived also played a role in how well their infection was controlled.

In general, blacks, people under 24, recent substance abusers, recent prisoners and the poor were more likely to have poorly controlled disease.

Sayles said the study will be used to help target resources to those who need it most.

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