The bacteria also spreads during sexual contact that involves the anus, putting men who have sex with men at a higher risk of infection.

In the U.K., the spread of the disease through sex grew 15 percent faster annually from 2015-2020 compared to spread through other methods of transmission, according to a July study.

A few simple steps can prevent illness. Wash your hands with soap and water for at least 20 seconds before you eat, engage in sexual activity or change a diaper, according to the clinic. Avoiding sexual contact for at least two weeks with anyone who has diarrhea or who recently recovered from diarrhea is also advised.

It's a warning not to have sex with people with diarrhea. Also, there are various interesting things about the disease when sexually transmitted vs not, for instance a study linked by the article theorizes that being sexually transmitted is why the disease is becoming resistant to medication:

It has been speculated that the acquisition of azithromycin resistance for Shigella moving into sexual transmission networks was driven by bystander resistance.9,10,12 This phenomenon refers to the evolution of antimicrobial resistance in an off-target organism following treatment for a co-infection. In the case of shigellosis-affected MSM in the UK, this was assumed to be driven by the overlapping epidemic of gonorrhoea, for which there is an intensive screen and treat programme.9,12 Our results are consistent with this hypothesis.