Diphtheria

Corynebacterium ulcerans, a close relative of Corynebacterium diphtheriae, has become a problem as a causative agent of diphtheria-like diseases in humans. There are many reports of animal involvement as a route of infection, and outside of Japan, contact with livestock animals (cattle, sheep, etc.), ingestion of raw dairy products, and infection from infected pet animals (dogs and cats) have been reported. In Japan, there has been a death in 2018. Diphtheria toxin causes nerve paralysis and white pseudomembranes in the pharynx and other parts of the body. Antitoxins are effective.

See the illustration about the initial symptoms.

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Like C. diphtheriae, C. ulcerans produces diphtheria toxin and causes death, requiring early administration of diphtheria antitoxin along with macrolide antimicrobials.

Diphtheria toxin from Corynebacterium diphtheriae causes cell death in the diaphragm and myocardium. The mortality rate in developed countries is about 5-10%1). C. ulcerans produces diphtheria toxin as does C. diphtheriae, leading to death, so early treatment with macrolide therapy is recommended. In severe cases, diphtheria antivenom should be administered along with antimicrobial agents3),4).

1)Special Feature Diphtheria 2006-present. IASR 2006;27:331-2. [cited 2017 Feb 18] Available from: http://idsc.nih.go.jp/iasr/27/322-j/tpc322.html
2)Tiwari TS, Golaz A, Yu DT, et al. Investigations of 2 cases of diphtheria-like illness due to toxigenic Corynebacterium ulcerans. Clin Infect Dis 2008;46:395-401.
3)Centers for Disease Control and Prevention(CDC).Respiratory diphtheria caused by Corynebacterium ulcerans–Terre haute, Indiana, 1996. MMWR Morb Mortal Wkly Rep 1997;46:330-2.
4) Ministry of Health, Labour and Welfare. Q&A on Corynebacterium ulcerans.[cited 2017 Feb 18] Available from: http://www.mhlw.go.jp/bunya/kenkou/kekkaku-kansenshou18/corynebacterium_02.html