In the latest issue of Archives of Sexual Behavior, economist Andrew Francis credits the end of syphilis with spurring the Sexual Revolution. Kate Shaw reviews his theory:

In the early 20th century, syphilis was a dangerous sexually transmitted disease without a particularly effective treatment. As of the mid-1940s, more than 600,000 Americans had recently contracted the disease, and the probability that a random sexual partner would have syphilis was more than 1 in 100. But in 1943, penicillin was found to be an effective treatment for syphilis. Infection and death rates from the disease fell sharply, reaching a low in 1957.

Francis noted that “historical syphilis trends very closely mimic the AIDS epidemic of the last few decades:

The rate of syphilis deaths in 1939 was nearly as high as the rate of AIDS deaths in 1995, and the two diseases accounted for roughly the same percentage of deaths in those years. Additionally, studies suggest that a similar increase in risky sexual behavior may have occurred after the development of an AIDS treatment plan, the “highly active antiretroviral therapy.”

The author’s conclusion: using economic principles to understand how the costs of syphilis, AIDS, and other sexually transmitted diseases affect behavior may improve decisions about health policy during future epidemics.