States battling rise in cases of sexually transmitted stomach bug shigella… as the bacteria becomes more resistant to standard treatment

A sexually transmitted disease that causes explosive, bloody diarrhea is spreading across the US, with cases rising in more than half of states.

Provisional data from the Centers for Disease Control and Prevention (CDC) show 27 states and territories recorded more cases of shigellosis, a gut infection, in the week to October 3 compared to the same time last year. These states were mostly in the Northeast, Midwest and West.

Nationwide, a total of 14,291 cases have been recorded so far this year, just 300 fewer than at this point last year.

The uptick in many states comes amid growing alarm over the spread of a ‘superbug’ strain of the bacteria that causes more severe symptoms and is resistant to the typical antibiotics doctors use to treat it.

Shigellosis is caused by shigella bacteria and is mainly transmitted via food prepared by an infected person or by touching contaminated surfaces.

But it is now increasingly being passed on during sex, particularly anal sex, where partners come into contact with tiny amounts of fecal matter. 

Patients suffer from an intense bout of diarrhea, often accompanied by significant amounts of blood in the stool, as well as stomach cramps, fever and vomiting. It can also be fatal in rare cases where it causes dehydration or malnutrition.

Normally, infections clear on their own within five days, but in severe cases, where antibiotics are needed, doctors say the drugs are now becoming less effective. 

The latest data from the CDC showed that, by state, California has recorded the most shigellosis cases so far this year, registering 2,970 infections – although this was down 10 percent on the same time last year.

New York City reported the second-highest number, registering 1,276 infections – up five percent on last year. And Florida recorded the third-highest tally, 1,070 infections – up 14 percent on last year. 

By state, Wyoming recorded the biggest surge in infections compared to this time last year after its cases doubled, rising from seven to 14 cases.

It was followed by Vermont, where infections surged 90 percent, from nine to 17 cases, and New Mexico, where infections jumped 75 percent, from 119 to 207.

At the other end of the scale, South Dakota registered the sharpest decline in cases after infections dropped 90 percent, from 64 to five cases, followed by Montana, where cases dropped 83 percent, from 12 to two, and Alaska, where they dropped 64 percent, from 11 to four.

The 27 out of 52 states and territories that have registered an uptick in infections so far this year compared to the same time last year were: Arizona, Florida, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Nebraska, Nevada, New Hampshire, New Mexico, New York, New York City, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Virginia, West Virginia and Wyoming.

Shigellosis infections are normally diagnosed among children under five years old, who are at higher risk of a severe infection due to having less developed immune systems, the CDC says. 

But data now show that cases are increasingly being diagnosed among gay or bisexual men, those who travel internationally, and homeless people.

About 450,000 Americans are diagnosed with shigellosis every year, estimates suggest, while about 6,000 are hospitalized and 40 die from the disease.

In a report by CDC researchers released in April, scientists warned that the ‘superbug’ strain of the disease was spreading. 

Analysis of nearly 17,000 cases showed the proportion caused by the extensively drug-resistant (XDR) strain rose from zero percent during 2011 to 2015 to 8.5 percent in 2023, the latest year available.

More than a third of patients who were diagnosed with the drug-resistant strain were hospitalized. No deaths were reported.

The researchers warned the spread of this strain suggested that shigellosis was being transformed from a self-limiting disease into an emerging public health threat. 

Of the patients infected with the superbug strain, 86 percent were men and 47 percent were also infected with HIV.

Researchers did not collect data on sexual orientation, but they warned that previous studies had shown the disease was more common among gay and bisexual men.

‘It’s a very concerning pattern of XDR Shigella strains that are being seen among vulnerable populations,’ Dr Naeemah Logan, an epidemiologist who was behind the research, told CIDRAP.

‘This is by no means unique to the US, but really part of a broader global pattern.’