Experts are worried about an untreatable strain of STIs that may be spreading through prostitutes from south East Asia, after a British man contracted a form of gonorrhoea that is said to be resistant to antibiotics.

Reports have revealed that an unidentified British man have contracted a strain of gonorrhoea that is resistant to two key antibiotics during his travels to south east Asia earlier this year.

The man's current partner in the U.K. has reportedly so far escaped infection but health officials said that they are now tracing the man's previous sex partners to help prevent further spread of the disease.

According to the Daily Mail, Public Health England believes the case to be the first time that the disease has not responded to the antibiotics azithromycin and ceftriaxone.

Cases of antibiotic-resistant gonorrhoea, also known as "super gonorrhoea," have prompted the World Health Organization (WHO) to issue several warnings that the infection could become immune to antibiotics in a "matter of years." The organization has attributed the rise to unsafe oral sex and a drop in the use of the condom.

Professor Johnjoe McFadden, molecular geneticist at Surrey University, expressed his belief that the rising cases of drug-resistant STIs may be spreading through prostitutes in south east Asia.

"Anyone who has frequent sex is more likely to have gonorrhoea, and the more frequent the more likely they are to pick up a resistant strain," he told the Daily Mail.

"Obviously people who have sex most often in this part of the world are prostitutes."

Professor Matthew Baylis, from Liverpool University, said that it is unlikely that the man was "the absolute first person in [the] entire world" to contract the drug-resistant strain and suggested that there may be "some people in south east Asia, perhaps, with this strain of gonorrhoea."

He warned that if the strain is found in a population in south east Asia, it could take the world back "to a time before Alexander Fleming and antibiotics were discovered, where it was an untreatable STI."

The Daily Mail noted that more than 35,000 people in England are infected with gonorrhoea each year. Gonorrhoea is spread by by unprotected vaginal, oral, and anal sex and can infect the genitals, rectum and throat. If left untreated, the disease can lead to infertility.