Area public health officials have been tracking clusters of drug-resistant Shigella infections, with 16 reported cases in the Portland metro area since September 2023.
Consider Shigella infection in the differential diagnosis for patients presenting with crampy and/or bloody diarrheal symptoms, especially among persons experiencing houselessness (PEH), persons with substance use disorders, and men who have sex with men (MSM).
Situation
Shigella is spread via the fecal-oral route through contaminated food or drink, water, fomites or direct contact including intimate contact. In our area, Shigella has historically primarily affected men who have sex with men (MSM) and international travelers. Other recent outbreaks of illness have occurred via food service and contaminated freshwater bodies.
Since 2015, Shigella has caused multiple outbreaks among persons experiencing houselessness (PEH) in the Portland area. This population remains at high risk of infectious diarrheal disease.
Shigella is a notifiable condition in Oregon, with cases to be reported to local public health departments within one working day.
Providers, clinics and hospitals can help respond to this outbreak:
- Test for Shigella with PCR, while ensuring reflex culture and drug sensitivities for positive samples. Clinical laboratories should promptly forward specimens testing positive for Shigella by PCR to the Oregon State Public Health Lab for further analysis.
- Avoid antibiotic use for uncomplicated illness, reserving treatment for those with severe illness necessitating hospital admission and/or HIV diagnosis with CD4 count < 200.
- Wait for antibiotic sensitivities before treatment when possible.
- Provide supportive care for patients as a first priority.
- Report positive Shigella cases to the local health department in the patient’s county of residence.
- Collect current contact information to facilitate public health contact investigation, especially for unstably housed individuals who are likely to have Shigella.
- Work with public health or homeless service providers to provide outpatient short-term housing and access to hygiene (e.g., hotel vouchers) for patients with unstable housing.
- Provide detailed health education to patients about reducing spread (including through modified sexual activity), identifying recurrent illness for prolonged infection, and personal hygiene to limit spread and prevent disease. See below for further information.
- Persons with Shigella infection should generally be excluded from daycare, school, food service and health care work. Public Health will determine when the individual can return to these settings.
Background
Shigella is a bacterial diarrheal illness that typically presents with:
- moderate to high fever
- crampy abdominal pain,
- occasionally nausea and vomiting
- diarrhea typically lasts 3-10 days and often includes blood, mucus or pus
Most Shigella infections are self-limiting, but illness can be severe in immunocompromised hosts. Humans are the only reservoirs and can shed bacteria in the stool for 1-4 weeks after symptom onset. Ingesting as few as 10 organisms can be enough to cause disease.
Clackamas, Multnomah and Washington Counties see more than 100 confirmed Shigella cases each year. However, reported cases likely represent only a small fraction of total shigella disease burden (~10%). Local disease patterns suggest that fecal-oral spread through intimate (sexual) activity may account for up to half of cases and more than two thirds of all cases without international travel. The rest are typically attributed to other types of person-to-person spread including outbreaks among populations with lack of hygiene, shelter, and sanitation, and among people who use illicit substances. Outbreaks among these vulnerable populations can be difficult to control.
Available susceptibilities for strains seen in the Portland metro area since 2017 show high proportions of resistance to first line antibiotics, including fluoroquinolones, macrolides, and third generation cephalosporins. Unfortunately, co-circulation of multiple drug resistant strains with varying resistance patterns at any given time make empiric treatment inadvisable, as ineffective treatment is associated with prolonged morbidity for patients and prolonged shedding enabling persistent transmission and public health risk
Gay, bisexual. and other men who have sex with men (MSM)
Of about 300 individuals found to have drug-resistant strains since 2018, the majority have been MSM; about 40% HIV positive, 60% HIV negative. Of those who were HIV negative, approximately two thirds were on preventive medication for HIV (PrEP). This suggests that there may be opportunities for disease prevention education at routine HIV and sexual health care visits.
Persons experiencing homelessness
Since 2015, at least 5 person-to-person outbreaks/clusters of drug resistant Shigella have spread into persons experiencing homelessness (PEH). Rapid diagnosis, supportive care, and short term housing/hotel vouchers have been shown to be highly effective at reducing spread within this vulnerable population and reducing patient illness (morbidity).
Patient education for all symptomatic patients
In general, the spread of Shigella is best interrupted by the following:
- Wash hands often, especially after using the bathroom or changing diapers.
- Do not share or prepare food for others.
- Avoid swimming or other recreational water activities for at least two weeks after recovery.
- Avoid sexual activity for at least two weeks after you no longer have diarrhea.
- Stay home from school or from healthcare, food service, or childcare jobs while sick or until your health department says it’s safe to return.
For those who work in or attend school or daycare, work in food handling, or work in healthcare settings there are restrictions for returning to work after Shigella infection that include a requirement for two consecutive negative stool tests at least 24 hours apart, and resolution of of gastrointestinal symptoms (diarrhea, vomiting).
Patient education for at-risk patients
Routine HIV or sexual health (including PrEP) visits are an opportunity to educate patients about Shigella as an infection that can be spread during sexual activity. Key points:
- Shigella is a germ that is spread by getting poop in your mouth. It typically causes fever, crampy stomach pain, tiredness and at least two days of diarrhea, which can be bloody.
- Make sure to wash hands well before eating or preparing food.
- Avoid sexual activity if you have diarrhea now or have had it in the last two weeks.
- Avoid sexual activity with partners who have diarrhea now or have had it in the last two weeks.
- These behaviors may lower the risk of passing Shigella during sex:
- Wash your penis, scrotum, anus, and hands with soap and water before and after sexual activity.
- Use condoms or dental dams during oral sex and oral-anal sex, and use latex gloves during contact between hands/fingers and anus.
- Wash any sex toys with soap and water before and after use.
Resources
- CDC Shigella information
- OHA Shigella information
- 24/7 Notification of positive Shigella cases:
- Clackamas County Public Health: 503-655-8411
- Multnomah County Health Department: 503-988-3406 (choose option 3 after hours for urgent needs)
- Washington County Public Health Division: 503-846-3594
- Oregon Health Authority: Communicable Diseases 971-673-1111
Thank you for your partnership,
Christina Baumann, MD, MPH, Health Officer, Washington County
Teresa Everson, MD, MPH, Interim Health Officer, Multnomah County
Paul Lewis, MD, MPH, On-call Health Officer, Multnomah County
Sarah Present, MD, MPH, Health Officer, Clackamas County