Doctors should offer testing for syphilis to men who have sex with men, people living with HIV and others at an increased risk of the sexually transmitted disease, a U.S. government-backed panel recommended on Tuesday.

The recommendation from the U.S. Preventive Services Task Force (USPSTF) reaffirms its 2004 guidelines.

"It's a great opportunity for primary care clinicians to identify people who are at a higher risk to be counseled about prevention and treated if needed," said Ann Kurth, a member of the USPSTF and the dean of the Yale School of Nursing in Orange, Connecticut.

Syphilis can progress to inflammatory lesions throughout the body and ultimately heart and organ problems, the USPSTF writes in JAMA. At any point, the infection can spread to the central nervous system, causing complications such as blindness and dementia.

In 2014, the number of new U.S. syphilis infections reached nearly 20,000, compared to 5,979 cases in 2005, according to the Centers for Disease Control and Prevention (CDC).

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The USPSTF says most syphilis infections in the U.S. in 2014 were in men who have sex with men. People with HIV are also at high risk for the infection, as are certain minority groups, geographic areas and young men.

Kurth said there is a solid testing approach and very effective and relatively inexpensive treatment regimens for syphilis.

The USPSTF can't say how often screening should be done, however. Some studies suggest improved detection when men who have sex with men and people with HIV are screened every three months, compared to every year.

The test is a two-step process which requires two positive results. The CDC recommends penicillin G benzathine as treatment.

Treating syphilis with antibiotics can lead to "substantial health benefits" by curing the infection, preventing late-stage disease and stopping its transmission to other people, according to the USPSTF.

The panel says the harms of screening "are likely to be small, including false-positive results that lead to further testing, anxiety, and possible stigma. Harms of treatment, such as allergic reactions to penicillin, are also small."

In an editorial, two researchers say the resurgence of syphilis is disheartening, given the availability of tools to combat it.

Lack of funding, changing sexual behaviors and a focus on HIV infections may have contributed to the increase in syphilis infections, write Dr. Charles Hicks, of the University of California, San Diego and Dr. Meredith Clement, of Duke University in Durham, North Carolina.

"The good news is that fixing what has gone wrong does not require huge capital investment, breakthrough technological advances, or massive restructuring of our health care systems," they write. "Improvements are at hand and require mostly focus and commitment on the part of the health care community."