The rate of syphilis infections in the U.S. is increasing - but only among men.

According to the Medical Daily, the Centers for Disease and Control reports syphilis infections have increased by 11 percent solely among men in 2012. The infections primarily occurred in men who identified as gay or bisexual.

Bisexual or gay men reportedly have a higher risk of contracting STDs than straight men.

About 20 million new STD infections occur each year, with 50 percent occurring in people ages 15 to 24.

Syphilis is caused by the Treponema pallidum bacterium, and signs of an infection include firm, round, small, painless sores on the mouth or genitals, skin rash and mucous membrane lesions. However, this STD can be easily cured in its early stages.

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