Sept. 22 (HealthDay News) -- Older widowers who recently lost their wives are more likely to have a sexually transmitted disease than their counterparts who are still married, a new study has found.

The researchers behind the study add that drugs like Viagra could boost the risk, noting the widowers might be seduced by advertisements for sexual enhancement.

The risk that seniors have a sexually transmitted disease remains extremely low, at less than 1 percent, study co-author and Harvard researcher Kirsten Smith explained in a news release about the study.

"Nonetheless," Smith said, "older adults need to be aware that they are at risk of contracting a sexually transmitted infection if they take on a new sexual partner following a spouse's death."

The researchers examined data from more than 400,000 U.S. couples, who were aged 67 to 99 years in 1993.

Within six months to a year after their wives died, men were 16 percent more likely to be infected with a sexually transmitted disease. And for recently widowed men, the risk of having a sexually transmitted disease rose by 83 percent after 1998. That's the year that Viagra went on the market as a treatment for erectile dysfunction.

"For men ages 67 and older, the age group that we studied, the use of medications for erectile dysfunction may contribute to that risk by making sex possible," Smith said.

Gonorrhea was the most common STD in the men, the study authors noted.

The study appears in the Sept. 17 online edition and the November print issue of the American Journal of Public Health.

SOURCE: American Journal of Public Health, news release, Sept. 17, 2009