The World Health Organization (WHO) has warned that a dangerous strain of gonorrhea is being spread by oral sex and a decline in condom use.
Health experts said the sexually transmitted disease is becoming more resistant to antibiotics and might soon become impossible to treat.
"The bacteria that cause gonorrhea are particularly smart," WHO human reproduction specialist Teodora Wi said, according to CNN. "Every time we use a new class of antibiotics to treat the infection, the bacteria evolve to resist them."
About 78 million people are infected with gonorrhea every year. The Centers for Disease Control and Prevention (CDC) estimates that about 820,000 cases are in the United States.
Data from 77 countries suggests that gonorrhea's resistance to antibiotics is a global issue. In Japan, France and Spain, officials discovered three variants of the bacteria that were completely resistant to the best available drugs.
"These cases may just be the tip of the iceberg," Wi said, according to the BBC. She added that most gonorrhea infections occur in poor countries where medical research is lacking.
"It's important to understand that ever since antibiotics appeared on the scene, Neisseria gonorrhoeae has been fairly quick in developing resistance to all the classes of antibiotics that have been thrown at it," said Manica Balasegaram, director of the Global Antibiotic Research and Development Partnership.
Nevertheless, WHO stated that making new antibiotics is "not very attractive for commercial pharmaceutical companies."
In the U.S., gonorrhea is typically treated with two drugs: ceftriaxone and azithromycin. But experts say they are becoming less effective. In 2016, a group of infections in Hawaii showed new resistance to treatment.
"Since 2005, we have seen four isolated cases that showed resistance to both drugs," CDC spokesman Paul Fulton Jr. said. "But the Hawaii cases are the first cluster we have seen with reduced susceptibility to both drugs."
Gonorrhea is caused by the bacterium Neisseria gonorrhea and is transmitted through unprotected vaginal, anal or oral sex. Officials are worried most about the last one.
Antibiotic use can result in bacteria in the back of the throat. If gonorrhea is added to the mix via oral sex, a resistance to antibiotics can quickly develop.
"When you use antibiotics to treat infections like a normal sore throat, this mixes with the Neisseria species in your throat and this results in resistance," Wi explained. "In the US, resistance [to antibiotics] came from men having sex with men because of pharyngeal infection."
Meanwhile, the BBC reports that a decline in condom use is assisting the spread of the infection.
"The situation is fairly grim," Balasegaram said. "There are only three drug candidates in the entire drug [development] pipeline and no guarantee any will make it out."