Syphilis, once considered almost eradicated in the United States, is on the increase among gay and bisexual men, a federal study has determined.
Syphilis cases reported in the United States have doubled since 2005, the report from the Centers for Disease Control and Prevention says.
In 2013, there were 16,663 cases reported, the most elevated rate seen in the country since syphilis was practically eliminated at the beginning of this century.
The majority of the reported cases, more than 90 percent, were in either bisexual or gay men, while the infection rate for the highly contagious sexually transmitted disease among women stayed mostly level since 2005.
The increase suggests strategies that have worked in lowering infection rates among heterosexuals have not been as successful in the gay and bisexual population, CDC officials said.
"We've got to re-evaluate and look at new approaches that we can use to drive these rates down," says Gail Bolan, head of the Division of STD Prevention at the CDC.
While rarely fatal, the disease can result in health problems involving the brain and nervous system, including stroke and blindness, she says.
The rise of syphilis in gay and bisexual men is "a major public-health concern, particularly because syphilis and the behaviors associated with acquiring it increase the likelihood of acquiring and transmitting HIV," the CDC said in its weekly Morbidity and Mortality report.
Secrecy surrounding gay and bisexual sex and a lack of medical follow-up are feeding the increase in cases, it said.
"Many barriers to contacting and treating sex partners exist, including delays in reporting cases to the health department, anonymous partners, physicians who rely on patients to notify their partners, and the observed tendency of men who have sex with men to notify a smaller proportion of their sex partners than do heterosexuals," the agency said.
The CDC is recommending bisexual and gay men who engage in sex with multiple partners should have themselves screened for syphilis every three to six months.
It has also recommended preventative practices including the increased screening, promoting the use of latex condoms, seeking to limit the number of sex partners while encouraging more monogamous relationships involving disease-free partners.