Increased Group A Streptococcus Infections Among Persons Experiencing Houselessness — Missoula, Montana, July 2024–September 2025
- Presentation Day/Time: Friday, April 24, 1:45 PM
- Presenter: Jeffry Mutuc, MD, MPH, National Center for Immunization and Respiratory Diseases, Division of Bacterial Diseases
The Issue
- In February of 2025, the Montana Department of Public Health and Human Services (MTDPHHS) identified multiple severe group A Streptococcus (GAS) cases among persons experiencing houselessness (PEH) in Missoula, Montana, with concern for a potential outbreak.
What We Did
- MTDPHHS, Missoula Public Health (MPH), and CDC conducted a joint investigation to assess GAS burden and factors associated with infection among PEH.
What We Found
- We identified 69 laboratory-confirmed GAS cases, 39 among PEH, including 15 invasive cases and one death. Cases among PEH predominantly occurred among those who were male (85%), White (62%), or American Indian (26%), and most presented with wounds and active infection (74%).
What This Means
- GAS infection incidence in Missoula was approximately 100 times higher among PEH than the housed population. Whole-genome sequencing suggested multiple unrelated transmission events rather than a single outbreak. The high prevalence of wounds among PEH underscores the need for improved wound prevention, access to care, and targeted health messaging in this population.
