Multnomah County health officials express growing concern as Shigella infections continue to rise across Oregon. Cases have steadily increased since 2012, with a significant jump occurring recently. January 2025 alone brought 40 new confirmed cases, adding to a worrying trend.
Data shows Multnomah County bears most of the burden, accounting for 61% of all cases in this outbreak. Infection patterns reveal how quickly Shigella spreads, with initial cases appearing in spring 2024 before rapidly moving into Portland Metro communities by summer.
Health department spokespersons call current infection rates “concerning” as transmission occurs between various population groups. Both housed and unhoused residents face risk, though preliminary reports suggest February numbers may show slight improvement over January’s spike.
Medical experts track 14 distinct subclusters within affected areas, indicating multiple transmission pathways rather than a single source like contaminated restaurant food. Such widespread community transmission makes containment efforts particularly challenging for county officials.
How Shigella Attacks Your Body
Shigella bacteria cause shigellosis, an intestinal illness that attacks the digestive system aggressively. Once ingested, these tiny microorganisms pass through the stomach and into the intestines, which multiply rapidly.
Shigellosis leads to inflammation as these bacteria invade cells lining your intestinal walls. Your body responds by sending immune cells to fight off infection, creating intense inflammatory responses in your gut. When infection progresses untreated, many patients develop dysentery—severe diarrhea containing blood and mucus. According to CDC ‘’Shigella spreads easily; swallowing just a small amount of Shigella germs can make you sick. Shigella germs are in poop, so anything that gets contaminated by poop can potentially spread the germs. Shigella can spread from one person to another or through contaminated water, food, surfaces, or objects.’’
Most people notice symptoms about 1-3 days after exposure. Stomach pain often strikes first, followed by fever reaching up to 103°F. Diarrhea typically begins mildly but can quickly become severe, containing blood or mucus. Some patients also experience painful bowel movements, nausea, or vomiting.
Medical professionals see cases across all demographics, affecting people regardless of housing status. However, spread occurs most readily in crowded living conditions or areas with limited sanitation access. A single infected person can unknowingly pass bacteria to many others through microscopic fecal particles on hands, surfaces, food, or water.
Tracking Infection Patterns
Nationwide surveillance identifies 197 total cases of Shigella associated with this particular bacterial strain. Genetic analysis confirms most infections share common characteristics, suggesting a related source spreading across multiple regions.
Scientists mapped 14 distinct transmission pathways within affected communities, indicating complex spread patterns rather than a typical foodborne outbreak. Each path represents separate chains of infection moving through different social groups and geographic areas.
Multnomah County bore heavy impact throughout 2024, documenting 158 confirmed cases as infection rates climbed steadily. Medical records show significant increases during summer months when initial cases in Portland Metro began spreading rapidly among various population groups.
Early analysis of February 2025 data suggests a potential downward trend compared to January. Health department officials report six confirmed cases plus three suspected infections awaiting laboratory confirmation for February. While preliminary figures appear promising, epidemiologists continue monitoring closely for signs of a sustained reduction in transmission rates.
Health departments emphasize that human-to-human transmission creates complicated containment challenges compared to outbreaks from single sources such as contaminated restaurants. Officials continue gathering data to identify effective intervention points across all affected communities.
How People Catch Shigella
Shigella bacteria spread primarily through a fecal-oral route, meaning microscopic particles of feces-containing bacteria find their way into another person’s mouth. County health officials report less than 20% of cases originate from international travel to countries with limited sanitation infrastructure.
Person-to-person transmission accounts for most infections in Oregon, creating widespread community circulation. Close physical contact provides ample opportunity for bacteria to spread, with fecal-oral transmission occurring during intimate contact, including sexual activity. Health department investigations indicate this transmission route may account for between 50% and 67% of all cases without international travel history.
Housing status plays a significant role in vulnerability, with approximately one-third to half of cases affecting people experiencing homelessness or housing instability. Limited access to sanitation facilities makes regular handwashing difficult, allowing bacteria to spread more easily among unhoused populations.
Social connections further drive transmission patterns across communities. Officials identified that bacteria spread among housed and unhoused social groups who use drugs together, demonstrating how bacteria move between different population segments through shared activities and spaces.
Unlike many foodborne illness outbreaks, Multnomah County officials confirm that Shigella spreads directly between people rather than from contaminated food sources like restaurants. Multiple transmission routes make containment particularly challenging, requiring targeted interventions for specific community groups.
Protecting Yourself and Others
Medical experts from the Mayo Clinic and CDC recommend several key prevention measures:
- Hand hygiene: Wash hands thoroughly with soap and warm water for at least 20 seconds after restroom visits, diaper changes, and before cooking and eating meals. Hand sanitizer offers backup protection when soap remains unavailable.
- Diaper care: Handle soiled diapers carefully and immediately dispose of them in covered, lined garbage bins. Bacteria from feces quickly transfer to surfaces during changes, creating infection risks.
- Surface disinfection: Clean diaper-changing areas with bleach-based or EPA-approved disinfectants after each use. Focus on high-touch surfaces in bathrooms and kitchens where microscopic fecal particles collect.
- Water safety: Avoid swallowing water while swimming in lakes, ponds, or untreated pools. Drink only from treated municipal sources or filtered systems during outdoor activities.
- Activity restrictions: Avoid food preparation, limit intimate contact, and stay away from public swimming areas for at least two weeks after symptoms stop. Food service, childcare, and healthcare workers must test negative before returning to work.
- Medical attention: Seek medical help for severe dehydration signs, persistent vomiting, bloody diarrhea, or symptoms lasting longer than one week.
Who Faces Greatest Danger
Most people infected with Shigella recover entirely within five to seven days without specific treatment. Mild cases often resolve at home with rest and increased fluid intake to prevent dehydration from diarrhea symptoms.
Young children under five years old face substantially higher risks for complications. Children develop more severe symptoms and may struggle to maintain proper hydration when experiencing frequent diarrhea. Parents should watch for signs of lethargy, decreased urination, or excessive thirst, indicating dangerous fluid loss.
Adults over 50 years old show increased vulnerability to severe Shigella infections. Aging immune systems may struggle to contain the bacterial spread, allowing disease to progress rapidly. Underlying health conditions common in older adults further complicate recovery and increase hospitalization risks.
Dehydration poses the most immediate danger during active infection. Severe diarrhea rapidly depletes body fluids and essential electrolytes, leading to dangerous imbalances that affect heart function and other vital processes. Medical providers emphasize aggressive hydration as the primary treatment for preventing complications.
Short-term housing support programs effectively reduce the spread among unhoused populations. County officials identify temporary housing as “the best intervention for reducing transmission” because it provides access to private bathrooms, regular handwashing facilities, and reduced crowding compared to congregate shelters or encampments.
People with compromised immune systems need particular caution during outbreaks. HIV-positive individuals, transplant recipients, and those undergoing cancer treatments face higher risks for severe, prolonged infection requiring medical intervention and potentially hospitalization.
County Takes Action
Multnomah County Health Department distributes educational materials throughout affected communities. Flyers, posters, and digital resources explain transmission routes, prevention methods, and symptoms requiring medical attention in straightforward language accessible to diverse populations.
Work restrictions prevent further spread in high-risk settings. Food service employees, healthcare workers, and childcare providers must remain away from work until laboratory tests confirm complete clearance of Shigella bacteria. County officials enforce these restrictions to protect vulnerable populations from exposure.
Support services address the needs of unhoused community members with active infection. Programs include access to temporary housing, hygiene facilities, and medical monitoring during recovery. Mobile outreach teams connect with encampments to identify cases early and facilitate treatment access.
Health department staff focus on multiple transmission pathways simultaneously. Rather than seeking a single intervention, officials implement targeted strategies for different affected groups, including men who have sex with men, people experiencing homelessness, and international travelers.
Coordination between public health agencies, healthcare providers, and community organizations strengthens response effectiveness. Regular data sharing allows for quick identification of new clusters, while collaborative planning ensures resources reach areas with the greatest need.
Medical providers receive specialized guidance for recognizing and treating shigellosis cases. County bulletins update clinicians on current outbreak patterns, testing recommendations, and appropriate treatment protocols to ensure consistent care across all healthcare settings.
Staying Informed During Outbreaks
Public awareness remains key to containing the spread of Shigella throughout Oregon. Health departments maintain updated website information, including current case counts and prevention recommendations. Medical professionals urge seeking prompt care for severe symptoms, including bloody diarrhea, high fever lasting more than 48 hours, or signs of dehydration. Early intervention prevents complications and reduces transmission risks.
Community members play vital roles in outbreak containment by following recommended hygiene practices and staying home while symptomatic. These individual actions collectively reduce transmission rates across all groups. Looking ahead, health department officials express optimism about declining February numbers but remain vigilant as warmer weather approaches when outdoor activities and community gatherings increase.
