A highly drug-resistant strain of cholera is now spreading over long distances, researchers warned in a letter to the editor of The New England Journal of Medicine.

From September 2018 to March 2019, a cholera outbreak with more than 10,000 suspected cases caused by a highly drug-resistant AFR13 7PET strain occurred in Zimbabwe. This strain had been introduced into East Africa from South Asia during 2013–2014.

By 2022, the AFR13 7PET strain was identified in cholera cases in southern and eastern Lebanon.

AFR13 7PET has probably contributed to a major cholera outbreak in Kenya between October 2022 and October 2023, with 12,120 cases, and to outbreaks in Tanzania and Comoros, where the number of cholera cases has been increasing since early 2024, researchers said.

In 2023, the highly drug-resistant strain was isolated from three European travelers returning from Kenya at different times of the year. In March 2024, it was isolated in Mayotte, a French island off the coast of southeastern Africa, initially from patients coming from Tanzania or Comoros, and subsequently from patients infected locally.

From 2019 onward, isolates have been resistant to the antibiotics azithromycin, ciprofloxacin, and third-generation cephalosporins.

These data demonstrate the need to “strengthen global surveillance of the cholera agent, and especially to determine how it reacts to antibiotics in real time," study leader Francois-Xavier Weill, MD, PhD, of Institut Pasteur in Paris said in a statement.

"If the new strain that is currently circulating acquires additional resistance to tetracycline, this would compromise all possible oral antibiotic treatment."