Top 5 Takeaways

  1. Increased Incidence: A significant rise in nontoxigenic Corynebacterium diphtheriae cases in Washington, with numbers increasing tenfold from 2012–2017 to 2018–2023.
  2. High-Risk Populations: Most cases occurred among residents experiencing unstable housing and recent illicit substance use, with severe outcomes like endocarditis and bacteremia.
  3. Laboratory Techniques: Despite advancements in microbial identification like MALDI-TOF, the spike in cases likely isn’t due to changes in laboratory protocols.
  4. Vulnerable Populations: The infection disproportionately affects vulnerable groups, particularly those with unstable housing or a history of substance use, underscoring social determinants of health.
  5. Public Health Implications: This rising trend highlights the need for public health strategies focusing on quality wound care and treatment to manage and prevent nontoxigenic C. diphtheriae infections.

Original Article Author and Citation

Corresponding Author

Amy G. Xie, MD –

Suggested Citation

Xie AG, Yomogida K, Berry I, et al. Notes from the Field: Increase in Nontoxigenic Corynebacterium diphtheriae — Washington, 2018–2023. MMWR Morb Mortal Wkly Rep 2024;73:405–407. DOI:


The article details an alarming rise in nontoxigenic Corynebacterium diphtheriae infections in Washington over a five-year period, marked by a substantial increase in case numbers and severity of infections, notably in vulnerable populations.


The study involved reviewing medical records and laboratory data from cases of nontoxigenic C. diphtheriae in Washington, using descriptive statistics and interviews with laboratory personnel to analyze trends and laboratory practices.


The findings suggest a potential public health crisis, with increasing incidence of a disease that disproportionately impacts marginalized groups. This underscores the importance of addressing social determinants of health in infectious disease prevention and control strategies.


This increase in nontoxigenic C. diphtheriae cases calls for enhanced public health measures, particularly among high-risk populations, and stresses the importance of continued surveillance and research to manage and prevent outbreaks effectively.

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