AUGUSTA — An increase in syphilis rates this year has prompted an advisory by the Maine Center for Disease Control to health care providers across the state.

The advisory sent out today warns that there have been 19 infections since mid-July, bringing the annual total to 33. That’s roughly double the average in recent years.

Dr. Stephen Sears, Maine’s epidemiologist, says an increase in syphilis often corresponds with an increase in risky behavior, “and other diseases follow not far behind.”

The Maine CDC says the 19 recent cases involved men having sex with men. The advisory alerts health care providers to be on the lookout for symptoms, and to be prepared to discuss prevention of sexually transmitted diseases.