Early HIV Testing May Reduce Transmission in High Risk Areas

An estimated 30 to 50% of new HIV infections originate from individuals who were recently infected, but a recent study found that primary infection screening programs that can detect HIV earlier could reduce transmission rates and slow down the epidemic.

In San Diego, an acute infection screening program was implemented using nucleic acid and serology testing to screen for HIV, which can detect the virus during the acute or primary stage of infections (7 to 10 days after exposure) compared with several weeks or months with other tests.

The cohort study, published in Clinical Infectious Diseases, analyzed HIV testing data from the San Diego County Department of Public Health and the San Diego Primary Infection Cohort between 1996 and 2012. Genetic analysis was also used to identify local chains of transmission.

In 2007, researchers established an acute infection screen program in Hillcrest, an area in San Diego with high incidence of HIV. The results of the study revealed that approximately 100 fewer new HIV cases were observed in the area in 2012 than would have been expected without the Early Test program.

“Our data suggests there was a decrease in incident diagnoses just based on testing for acute infection,” said study author Sanjay R. Mehta, MD. “We think that screening for acute infection targeted to geographically focused high-risk populations can reduce incident infections.”

At this time, screening programs that used similar methods to the Early Test program have been introduced in Seattle and San Francisco, but have yet to become widespread. Researchers noted that areas with a high prevalence of HIV would benefit the most from testing for primary infection.

The observational study was performed at a single site, meaning that although the findings suggest a cause and effect relationship between the Early Test program and a decreased incidence of HIV, it does not prove it. Still, the results could cause more HIV testing centers to begin offering primary infection screening.

“We used a combination of methods, including epidemiological data and phylogenetic data, to understand the changes in incident diagnoses in a population,” Mehta said. “This combination could be used in other studies to evaluate prevention programs or programs designed to reduce incidence of HIV.”