A study in Health Economics has uncovered an unintended consequence of a major medical breakthrough: while the availability of HIV treatments in the late 1990s dramatically improved survival, they also contributed to a resurgence in syphilis, a sexually transmitted infection.

Treponema_pallidum_Bacteria_(Syphilis)

Source: NIAID

Colorized electron micrograph of Treponema pallidum, the bacteria that cause syphilis.

Through statistical analyses of information from the Centers for Disease Control, as well as pharmaceutical industry sales data, investigators found that US states with higher AIDS prevalence experienced significantly larger increases in syphilis after highly active antiretroviral therapy (HAART) became widely available—with these increases concentrated among men, while rates among women continued to decline—suggesting that changes in sexual behavior following the reduced perceived risk of HIV had broader public health effects.

Data indicated that in the absence of HAART, there would have been 81% fewer syphilis cases between 1996 and 2008.

“With syphilis now at a 60‐year high, these findings offer timely insight into how life‐saving innovations can reshape population behavior and highlight the need for complementary public‐health strategies,” said corresponding author David Beheshti, PhD, of the University of Texas at San Antonio.

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