Oral sex and a decline in condom use is helping to spread a stronger, more dangerous form of gonorrhea that can be impossible to treat.
The warning was issued by the World Health Organization on Friday, when it said studies from 77 countries have confirmed the spread of increasingly antibiotic-resistant forms of the disease.
The STD, which can cause infertility, is contracted by about 78 million people every year – most of them in poorer, developing countries where antibiotics are older and cheaper.
But the WHO found three cases in Japan, France and Spain where the infection was completely untreatable with even the most up-to-date medication.
"Gonorrhea is a very smart bug, every time you introduce a new class of antibiotics to treat gonorrhea, the bug becomes resistant," Dr. Teodora Wi, of the WHO, said in a news release.
She added that these cases may “just be the tip of the iceberg” given that reporting systems for the bug are not as comprehensive in poorer nations.
Oral sex is among the ways the infection can spread, with Joe.co.uk reporting it can cause bacteria to end up in the throat and develop immunity alongside throat bacteria – leading to a potentially untreatable strain of the STD.
The WHO adds that as well as this and decreased condom use, increased urbanization and travel, poor infection detection rates and inadequate or failed treatment are also behind the rise.
Symptoms of gonorrhea can include pain or burning when peeing, unusual discharge and, in some women, bleeding between periods. If untreated, it can lead to infertility.
Gonorrhea in Minnesota
Earlier this year, Minnesota’s health department reported there had been an "alarming" rise in the number of sexually-transmitted diseases.
This included a 25 percent bump in new gonorrhea cases, as well as a 30 percent rise in new cases of syphilis.
Gonorrhea and chlamydia (which rose 7 percent) were particularly prevalent among 15-24 year olds.
There were 5,104 reported cases of gonorrhea in Minnesota in 2016, up from 4,097 in 2015. Four out of five cases came from the Twin Cities metro.