The Centers for Disease Control and Prevention has issued a warning about a drug-resistant strain of shigella, a bacteria that commonly causes a gastrointestinal illness called shigellosis, as the agency is calling this new strain a public health threat.

According to a new report released by the CDC, drug-resistant shigella infections have increased 8.5% in the United States from 2011 to 2023, showing a rapid rise in cases. The first drug-resistant strain was identified in 2016. Shigella is estimated to cause 450,000 infections in the United States each year, and antimicrobial resistant infections result in an estimated $93 million in direct medical costs, according to the CDC.

Symptoms of shigellosis include diarrhea that can be bloody or prolonged and persist for more than 3 days, high fever, stomach pain, and feeling the need to pass a stool even when the bowels are empty, according to doctors. The bacteria is transmitted primarily through the fecal-oral route, where bacteria from the stool of an infected person is accidentally ingested or contacted.

Shigella spreads easily and can be transmitted in contaminated food or water or through sexual activity, experts say.

“Shigella can be spread much like E. coli through contaminated food or water, the difference is this strain is more highly associated with sexual activity,” said Dr. Scott Roberts, infectious disease specialist with Yale New Haven Health.

“For that reason, if you do have a partner that tests positive, you should abstain from sexual activity for several weeks. We don’t think of E. coli as spreading the way shigella does,” Roberts said.

XDR shigella, the new drug resistant strain of the bacteria, is resistant to all commonly recommended antibiotics, leaving doctors with limited treatment options and no approved oral antibiotics.

Instead, Roberts said that infected patients who do need antibiotics, are kept hospitalized and given intravenous antibiotics over the course of several days.

“Preventing shigella infection is hard because how do you know your salad is infected or not?” Roberts said. “The best things we could do is wash hands with soap and water, avoid people who are acutely sick, and boil and cook all foods thoroughly. But I also don’t want to sound too alarmist because the majority of cases, including for XDR shigella, improve with time and do not need antibiotics.”

Shigellosis typically has a very good prognosis, with most infected individuals recovering completely within 5 to 7 days without antibiotics, he said.

Young children under 5-years-old, the elderly, and immunocompromised individuals are more at risk. Those infected with Shigella are urged to drink plenty of liquids as dehydration is common. The prognosis for the drug resistant strain XDR shigella is roughly the same as the non-resistant bacteria, Roberts said. Shigellosis is rarely fatal and most deaths occur in people with preexisting conditions or those with compromised immune systems.

“The vast majority of people infected with shigella don’t need antibiotics,” Roberts said. “Those that do need to be admitted, that’s where it gets tricky. Because with this new strain, there is no oral antibiotic we can give now. So this strain has taken away that option from us. We would require in-person hospitalization for intravenous antibiotics. We do have intravenous antibiotics that can treat this new strain. But this requires several days in the hospital.”

Steps to take to help limit possible shigella exposure include:

Wash your hands with soap and water at key times.
Take care when changing diapers.
Avoid swallowing water while swimming.
When traveling internationally, follow safe food and water habits and clean your hands often.
If you or your partner has been diagnosed with shigellosis, do not have sex for at least two weeks after the diarrhea ends.

Stephen Underwood can be reached at sunderwood@courant.com