Shigella bacteria causes shigellosis, a highly contagious bacterial infection that is responsible for an estimated 450,000 cases in the United States each year. Therefore, it is the third most common bacterial enteric (intestinal) disease. About 242,000 of those infections are estimated to be antimicrobial-resistant.

Reported incidence was about 5.7 cases per 100,000 people in 2019 (underreporting is common). The main species in the U.S. are Shigella sonnei and Shigella flexneri; S. dysenteriae and S. boydii are rarer domestically.

Key Recent Trend: Rise of Extensively Drug-Resistant (XDR) Strains

A major public-health concern is the sharp increase in extensively drug-resistant Shigella. XDR is defined as resistance to five commonly used antibiotics: ampicillin, azithromycin, ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole.

According to a CDC analysis of nearly 17,000 Shigella isolates with resistance data (2011–October 2023):

• XDR isolates rose from 0% (2011–2015) to 8.5% in 2023.
• 510 isolates (3%) overall were XDR; the large majority of these occurred in 2022–2023.
• Most XDR cases were in adult men (about 86%), with a median age of 41 years. Among those with known HIV status, nearly half had HIV.
• Most were acquired domestically (roughly 82% of those with travel data reported no recent international travel).
• About 38% of XDR patients with available data were hospitalized; no deaths were reported in the analyzed cases.

Historically, U.S. shigellosis mainly affected young children (e.g., in day-care settings) and travelers, often with drug-susceptible strains. The epidemiology of XDR strains has shifted toward adult men, frequently linked to sexual contact (especially among gay, bisexual, and other men who have sex with men), though other routes remain important. There are no FDA-approved oral antibiotics specifically for treating these XDR infections.

Transmission

Shigella spreads easily through the fecal-oral route (as few as 10–100 organisms can cause infection). Common pathways include:

• Contaminated food or water (Drinking Water Route - Check out the Waterborne Pathogen Panel)
• Person-to-person contact (including in day cares, households, or among people experiencing homelessness)
• Sexual contact involving fecal exposure

Symptoms

Symptoms typically begin 1–2 days after exposure and last about 5–7 days (sometimes longer). They commonly include:

• Diarrhea (often watery, bloody, or prolonged)
• Fever
• Abdominal pain/cramps
• Tenesmus (feeling of needing to pass stool even when bowels are empty)

Many people recover with fluids and rest. Higher-risk groups for more severe or prolonged illness include young children, older adults, and people with weakened immune systems. Rare complications can include dehydration requiring hospitalization, bloodstream infection, reactive arthritis, or hemolytic-uremic syndrome.

At-Risk Groups

Anyone can get shigellosis, but higher risk is seen among:

• Young children (especially in group settings)
• International travelers
• Gay, bisexual, and other men who have sex with men
• People with HIV or other conditions that weaken the immune system
• People experiencing homelessness

Treatment and Prevention

Most infections are self-limited. Supportive care (hydration, rest) is the mainstay. Antibiotics may be used for severe cases, immunocompromised patients, or to reduce transmission in certain settings, guided by local resistance data or isolate susceptibility results. Avoid antidiarrheal medications that slow gut motility, as they can prolong illness.

Prevention focuses on hygiene:

• Thorough handwashing with soap and water (especially after bathroom use, diaper changes, and before food prep or sexual activity)
• Safe food and water practices, particularly when traveling
• Avoiding swimming or preparing food while symptomatic
• For those with recent infection: abstain from sex for at least two weeks after diarrhea ends
• Prompt exclusion from high-risk settings (child care, food service, healthcare) until cleared

Ongoing surveillance, antimicrobial stewardship, and targeted prevention in higher-risk communities are emphasized by public-health authorities because of the ease of transmission and the limited treatment options for resistant strains. Local health departments sometimes report clusters or increases (for example, in certain urban areas), so regional data can vary.

For the most current clinical guidance, consult CDC resources or a healthcare provider, especially regarding antibiotic choices given evolving resistance.

Other Websites

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