A bacterial infection known for causing dysentery is increasingly spreading through sexual contact, while some strains are becoming so resistant to antibiotics that experts warn they are approaching the limits of available treatment.

The bacterium, Shigella, infects nearly half a million people in the United States every year. Symptoms include diarrhea containing blood or mucus, stomach pain, cramps, fever, vomiting, and dehydration.

This is far more serious than an unpleasant rush to the bathroom. Shigella can become potentially deadly by draining bodily fluids and blood, leading to bacterial shock, septic shock, neurological complications, internal bleeding, and infection.

The disease can spread through the fecal-oral route when microscopic traces of infected feces enter another person’s mouth. Contaminated food, unsafe drinking water, and improperly washed hands are among the ways transmission can occur.

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It also takes remarkably little exposure to cause an infection. As few as 10 organisms can make someone sick, giving the bacterium ample opportunity to spread when sanitation or basic precautions break down.

Children under 5 are especially likely to become infected, often contracting the illness from other children at day care or school. Travelers visiting places with lower sanitation standards and people experiencing homelessness also face higher risks.

Yet researchers have identified gay and bisexual men, along with other men who have sex with men, as a population experiencing one of the fastest increases in Shigella infections. Experts describe the disease as endemic in these communities, meaning it is regularly and consistently present.

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A July study found that sexual transmission of the disease grew 15% faster between 2015 and 2020 than transmission connected to travel, food, or nursery outbreaks. That is not some marginal statistical curiosity when the infection can produce severe complications and lengthy hospital stays.

Emerging evidence suggests sexual contact may now be the primary transmission route in some cases. Researchers say, however, that measuring the extent of that spread is difficult when patients seeking medical care are not asked about sexual activity.

A lack of awareness may be fueling the problem. Many people apparently do not realize that Shigella, an infection often associated with contaminated food, dirty hands, or unsafe water, can also spread through sex.

“Many men who have sex with men are unaware of the serious and increasing risk posed by sexually transmitted Shigella,” said Cambridge geneticist Kate Baker, a lead author on the July study.

That blind spot carries consequences because Shigella strains transmitted through sex are proving serious. Research found that people who contracted the infection sexually were hospitalized for an average of four to five days.

The CDC reports that most drug-resistant Shigella cases have affected adult men. Scientists are particularly alarmed that multiple strains are developing resistance to medications commonly used against the infection.

“This isn’t just one form of sexually transmissible diarrhea,” Baker told Science Alert.

“This is multiple overlapping variants emerging that are all quickly becoming resistant to the drugs we use to treat them. It’s highly likely that if you contracted your Shigella through sex, you require different treatment to someone who contracted it through travel.”

That distinction creates another challenge for doctors trying to select an effective treatment. If the route of transmission is not discussed during medical care, physicians may lack information that research suggests could matter when deciding how to treat the patient.

Health Alert: Shigella infections are on the rise in the U.S., and some strains are becoming increasingly difficult to treat due to antibiotic resistance. The bacteria can spread through sexual contact and cause symptoms like diarrhea. ⚠️ @mimibrowntv breaks down what you need to know in Front Page News.

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The combination of easy transmission, low public awareness, severe symptoms, and rising antibiotic resistance presents a grim picture. With sexually transmitted cases increasing rapidly among gay and bisexual men, warnings about the risks are becoming harder to ignore.

Shigella is hardly a new disease, but drug-resistant variants are changing the stakes. A highly contagious bacterium that can cause bloody diarrhea, dehydration, internal complications, and hospitalization is now becoming increasingly difficult to treat, turning an already ugly infection into a potential superbug crisis.

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