Two Sporadic Cases of Erysipelothrix rhusiopathiae Infection, Minnesota 2024

Area of Science:

• Microbiology
• Infectious Diseases
• Public Health Epidemiology

Background:

• Erysipelothrix rhusiopathiae causes infections in humans, often linked to occupational exposures.
• Two human cases were identified in the Minneapolis-St. Paul metropolitan area in July 2024, prompting an investigation.
• The Minnesota Department of Health (MDH) initiated a study due to concerns of a potential outbreak.

Purpose of the Study:

• To investigate the source and potential outbreak of Erysipelothrix rhusiopathiae infections.
• To determine the epidemiological linkage and genetic relatedness of the two identified cases.
• To identify potential exposure routes and risk factors associated with these infections.

Main Methods:

• Epidemiological interviews were conducted with case-patients' families.
• Next-generation sequencing was performed on bacterial isolates at the MDH Public Health Laboratory.
• Electronic health records (EHRs) were queried to identify additional cases.

Main Results:

• Both case-patients were adults from the Hmong community with underlying health conditions.
• Potential exposures included raw or undercooked meat, possibly from a live animal market.
• Bacterial isolates showed significant genetic divergence (23,328 single nucleotide polymorphisms), and no additional cases were found in EHRs.

Conclusions:

• The two cases were deemed unlikely to be part of an outbreak due to lack of epidemiological linkage and genetic relatedness.
• Potential infection sources included undercooked meat consumption or environmental contact with contaminated raw meat.
• Further studies on rare Erysipelothrix rhusiopathiae cases are recommended to build evidence for future outbreak investigations.