After a decade of declining numbers, scientists across the globe have been looking for answers as to why HIV infection rates began to rise again around 2000. A new study from Tel Aviv University has yielded a disturbing explanation.

By cross-referencing several databases and performing a molecular analysis of the virus found in patients, Prof. Zehava Grossman of Tel Aviv University’s School of Public Health at the Sackler Faculty of Medicine and the Central Virology Laboratory of the Ministry of Health found that an astonishingly high number of newly-diagnosed men with male sexual partners were found to have contracted the virus from infected, medicated partners who are already aware of their HIV-positive status.

These findings, reported in the journal Clinical Infectious Diseases, indicate that the public health approach towards HIV counseling and education needs to be reconsidered, Prof. Grossman says.

The rising numbers are in total contrast to the 1990’s, when infection rates dropped due to increased awareness of the virus.
Researchers had begun to suspect that the rise in infection rates was due to a change in social behavior, but hard evidence was lacking.

To unravel the mystery, Prof. Grossman and her colleagues at the Central Virology Laboratory directed by Prof. Ella Mendelson and Israel’s leading AIDS clinicians turned to the virus itself. Working with senior epidemiologists of the Public Health Services of Israel’s Ministry of Health, they conducted a comprehensive analysis of laboratory, clinical, and epidemiological data, including information about patients’ diagnosis and treatment, sexually transmitted diseases contracted along with HIV, and the molecular characteristics of the virus in different patients.

Prof. Grossman and her colleagues found that an overwhelming number of new cases were infected with HIV strains that had already developed resistance to existing HIV drug therapies. Because the virus can only become resistant if previously exposed to medication, this result indicates that new patients are often infected by an HIV-positive partner already receiving the therapies. More often than in the past, HIV found in different patients could be traced back to a common source.

Prof. Grossman made it clear that the need to establish the values of safe sex within at-risk populations is as imperative as it has ever been.