A severe gastrointestinal disease historically linked to contaminated food and water is increasingly spreading through sexual contact, and health officials warn that the bacteria are rapidly becoming resistant to standard medical treatments.
Shigellosis, an infection caused by the bacteria Shigella, triggers bloody diarrhea, dysentery, stomach cramps, vomiting and fever. While the illness has long circulated among young children in day care and travelers abroad, researchers have documented a steady rise in sexual transmission, especially among gay, bisexual and other men who have sex with men, ScienceAlert reported.
Surge in drug-resistant strains
In the United States, roughly 450,000 people contract shigellosis annually, leading to about 38 deaths, according to figures from Merck Manuals. Centers for Disease Control and Prevention data show that roughly 242,000 of those annual cases involve drug-resistant strains. Medical providers face increasing difficulty treating severe cases because the bacteria have developed defenses against frontline medications.
A CDC analysis evaluating nearly 17,000 Shigella isolates revealed that extensively drug-resistant strains rose from zero percent of tested samples in 2011 to 8.5 percent in 2023, according to ScienceAlert. The vast majority of these drug-resistant infections occurred in adult men who had not traveled overseas recently. Currently, there are no oral antibiotics approved by the Food and Drug Administration to treat these extensively resistant strains.
Clinicians on the front lines have noted the shift firsthand. At the University of California, Los Angeles, hospital staff now detect approximately one extensively drug-resistant Shigella case per month, compared to just one single case throughout all of 2022, molecular biologist Shangxin Yang told CIDRAP News. Yang described the increase as “almost like an explosion of this pathogen in the community.”
Hospitalizations and global impact
CDC records show that more than one-third of individuals diagnosed with extensively drug-resistant Shigella were hospitalized, and nearly half of those with a known HIV status were living with HIV, ScienceAlert reported. Epidemiologist Naeemah Logan of the CDC told CIDRAP News that the patterns reflect a broader international issue rather than an isolated domestic problem.
In the United Kingdom, researchers documented a parallel rise in sexually transmitted cases. A study published in The Lancet Infectious Diseases determined that sexually transmitted Shigella strains spread across geographic regions more than twice as fast as non-sexually transmitted variants, The News International reported. University of Cambridge geneticist Kate Baker, the study’s senior author, noted in a press release that sexually transmitted Shigella has shifted from being easily manageable with standard medications to “being close to untreatable over the course of the last decade or so.”
Scientists point to several factors fueling this resistance, including “bystander resistance,” where antibiotics prescribed for other sexually transmitted infections, such as gonorrhea, inadvertently select for resistant Shigella strains living in the gut.
Prevention and next steps
Most mild infections resolve on their own within three to seven days, and patients often recover with oral rehydration, according to the Mayo Clinic. However, severe infections can persist for months, and without effective oral medications, doctors must rely on limited intravenous options such as ceftriaxone.
Public health agencies advise people to adopt specific precautions to prevent transmission:
- Wash hands thoroughly with soap and water for at least 20 seconds before eating and after handling diapers or using the restroom.
- Avoid any sexual intimacy with anyone experiencing diarrhea or who has recovered from diarrhea within the previous two weeks, according to guidance from the California Department of Public Health.
- Use protective barriers during sexual contact and clean sex toys thoroughly.
Researchers reported in July that an experimental vaccine demonstrated strong protection in a two-week clinical trial of U.S. adults. However, with no authorized vaccine currently on the market, health authorities emphasize that early testing and candid conversations between patients and doctors remain critical to halting the spread.
