United States: Multnomah County is once again witnessing an alarming upsurge in winter-season Shigella infections, marking the second consecutive year of elevated cases. According to the latest data from the county’s health department, January recorded the highest number of cases in any single month since 2012.
Shigella, a virulent bacterium, induces severe gastrointestinal distress, characterized by acute diarrhea, febrile episodes, and profound lethargy—a condition historically classified as dysentery. This pathogen primarily propagates when microscopic traces of fecal matter from an infected individual inadvertently enter another person’s oral cavity, as per health authorities.
The previous significant surge in Multnomah County accounted for 72 confirmed cases between November 2023 and January 2024, excluding instances linked to international travel. However, the current cycle has escalated to 105 reported cases within the same timeframe, with January alone contributing 40 infections, according to kgw.com.
Since 2012, Shigella infections have demonstrated a steady incline across Multnomah County, further exacerbated by the advent of antibiotic-resistant strains in recent years. Transmission dynamics underscore the pivotal role of sanitation accessibility, with the unhoused population disproportionately bearing the brunt of outbreaks—last year’s surge was predominantly localized in Old Town.
Although the bacterium occasionally disseminates through singular contamination events, such as tainted food in dining establishments, its predominant transmission vector remains direct interpersonal contact. This can occur through intimate physical interactions or indirect exposure via contact with contaminated surfaces followed by oral transmission.
The clinical manifestations of Shigella infections span from mild afflictions to life-threatening complications. The most severe cases are typically attributed to Shigella dysenteriae, a strain seldom encountered outside regions with inadequate sanitation infrastructure. Conversely, the prevalent strains in Oregon—Shigella flexneri and Shigella sonnei—tend to provoke less severe illnesses, as per kgw.com.
Per the Centers for Disease Control and Prevention, symptomatic individuals generally experience resolution within 5 to 7 days without pharmacological intervention. However, antimicrobial treatment may be necessitated in severe presentations or among immunocompromised individuals.
Local transmission constitutes the overwhelming majority of infections, with over 80% of cases originating within Multnomah County rather than from international sources. Between 2017 and January 2025, an estimated 91 percent of infections stemmed from direct human-to-human transmission rather than single-source contamination events.
Epidemiological insights indicate that approximately 78 percent of recorded cases involved male patients, with a median age of 42. Notably, 46 percent of cases were identified among gay or bisexual men, 44 percent were linked to individuals experiencing homelessness, and nearly one-third involved individuals who use illicit substances. In response, the county health department prioritizes temporary housing accommodations for those testing positive, recognizing the crucial role of sanitation in mitigating further spread, according to reports by kgw.com.
To curtail transmission, infected individuals are strongly urged to observe stringent preventive measures. These include refraining from occupational and educational engagements, adhering to rigorous hand hygiene practices, abstaining from food preparation for others, avoiding communal drug paraphernalia, discontinuing sexual activities, and steering clear of recreational water settings. Such precautions should persist for at least two weeks post-resolution of diarrheal symptoms.
