A nasty intestinal bacteria that causes severe diarrhoea is spreading fast among homosexual men as a sexually transmitted infection, and developing into a drug-resistant superbug.
Shigella infections are common in the third world due to inadequate sanitation and contaminated food or water, but have also become endemic in gay communities in developed countries, including the United States, the United Kingdom, and Australia.
The STI variants are spread by direct or indirect contact between the mouth and the anus, and the bacteria is highly contagious – 100 times more so than foodborne Salmonella – and causes bloody and prolonged diarrhoea.
A University of Cambridge study found in July that variants of sexually transmitted Shigella were causing more disease and becoming increasingly antibiotic-resistant in “sections of the UK’s LGBTQ+ community”.
There was a “sharp rise in laboratory diagnoses during 2025”, and senior study author, Professor Kate Baker from Cambridge’s Department of Genetics, said Shigella needed to be treated as a “distinct public health threat”.
“Many men who have sex with men are unaware of the serious and increasing risk posed by sexually transmitted Shigella,” Dr Baker said.
“Sexual infection is now a sustained part of Shigella transmission in the UK. It is vital that this message reaches the communities most affected, so we can help to prevent the spread.”
The study found that over 70% of sexually transmissible strains were resistant to at least one antibiotic, compared with 40% among non-sexually transmitted strains and 49% among travel cases.
Researchers said sexually transmitted infection rates began to rise dramatically in 2010, and suspect it may be linked to the emergence of gay sex apps such as Grindr, and the popularity of mouth-to-anus sexual practices, chemsex parties and group sex in the gay community.
Drug-resistant Shigella infections are also on the rise in the US, and are mainly occurring among adult men, many of whom also have HIV.
A CDC report from April noted that extensively drug-resistant cases went from 0% between 2011-15 to 8.5% in 2023, and hospital workers at the University of California Los Angeles (UCLA) are now reporting one case a month, up from one all year in 2022.
“It’s almost like an explosion of this pathogen in the community,” UCLA molecular biologist Shangxin Yang told CIDRAP in April.
South Australia Health issued an alert the state’s homosexual male population in March about an outbreak of drug-resistant Shigella, and warned men to look out for symptoms.
“Since the beginning of 2026, six cases of the same strain of multidrug-resistant Shigella have been reported in South Australia among gay, bisexual and other men who have sex with men,” SA Health said.
“As compared to this time last year, the total number of cases of Shigella infection reported is similar. However, the number of cases with multidrug-resistant strains reported in 2026 is higher.”
The emergence of the Shigella superbug comes after researchers in Europe linked a possible new sexually transmitted infection spreading among homosexual men in France and Spain to a gay sauna in Lyon.
Header image: Left, stock image (Pexels). Right, Shigella (CDC).
