A strain of highly antibiotic-resistant gonorrhea first emerged in China in 2016, and cases of this tough-to-treat infection have tripled there in just five years, Chinese researchers report.

It’s a warning to the rest of the world, they said.

Strains resistant to the first-line treatment ceftriaxone (and many other antibiotics) “have spread internationally and collaborative cross-border efforts will be essential to monitoring and mitigating its further spread,” wrote a team led by Dr. Shao-Chun Chen, of the Chinese Academy of Medical Sciences in Nanjing.

A single intramuscular injection of ceftriaxone is the recommended first treatment for gonorrhea in both China and the United States.

But that could change. According to the latest data, by 2022 the prevalence in China of infections with Neisseria gonorrhea resistant to ceftriaxone “was 8.1% [of cases], approximately three times the 2017 rate of 2.9%,” the new study found.