Top 5 Takeaways

  1. No Monkeypox Transmission in Jail Setting: Despite a confirmed case of monkeypox in Cook County Jail (CCJ), no secondary cases were detected among residents with intermediate-risk exposures who received symptom monitoring or serologic testing.
  2. Surface Contamination Detected: Monkeypox virus DNA was found on a surface in the dormitory, but no viable virus was present, highlighting the importance of thorough cleaning in such settings.
  3. Challenges in Monitoring and PEP Acceptance: Only a subset of exposed residents received serologic testing and symptom monitoring, and postexposure prophylaxis (PEP) acceptance varied based on the method of offering.
  4. Limited Transmission Risk in Congregate Settings: This case study suggests monkeypox transmission might be limited in similar settings without higher-risk exposures, but vigilance and adherence to infection control practices are crucial.
  5. Importance of Private Counseling for PEP: Offering PEP counseling in private settings led to higher acceptance rates, emphasizing the need for confidentiality in health interventions.


This MMWR Article was created prior to the conventional renaming of Monkeypox to its more standard and appropriate name, Mpox. To avoid confusion, Monkeypox is retained when writing this article, but all future works should use Mpox.


Original Article Author and Citation

Corresponding Author

Liesl M. Hagan,

Suggested Citation

Hagan LM, Beeson A, Hughes S, et al. Monkeypox Case Investigation — Cook County Jail, Chicago, Illinois, July–August 2022. MMWR Morb Mortal Wkly Rep 2022;71:1271–1277. DOI:


The report details a monkeypox case investigation in Cook County Jail, Chicago, in July-August 2022, during the multinational monkeypox outbreak. This was the first case in a U.S. correctional setting. The study aimed to evaluate transmission risk within the jail. Fifty-seven residents were identified as having intermediate-risk exposure to the infected individual.


The investigation involved categorizing exposure risk, symptom monitoring, serologic testing, and surface contamination testing. The approach was comprehensive, considering various factors like living arrangements, mask usage, and personal interactions.


The findings highlight the complexities in assessing exposure risk and effectiveness of various preventive measures in a correctional setting. The lack of secondary cases suggests limited transmission in such environments, but the study also underscores the challenges of enforcing mask use and the importance of thorough cleaning.


The investigation reaffirms the limited transmission risk of monkeypox in congregate settings like jails, provided there are no higher-risk exposures. It emphasizes the importance of maintaining infection control practices, educating residents and staff, and offering PEP counseling in a confidential manner.



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