Paederus Dermatitis: Two Outbreaks of an Entomologic Disease in Austere Expeditionary Care

Paederus dermatitis, also known as dermatitis linearis, is an acute cutaneous condition caused by contact with the potent vesicant toxin paederin, produced by endosymbiotic Pseudomonas-like bacteria within Paederus spp. beetles. Paederin is a protein synthesis inhibitor that halts cell division, leading to vesiculation and necrotic breakdown of the epidermis. The resultant damage facilitates secondary infection, especially in austere conditions. Between October 2022 and July 2023, several US special operations teams forward deployed to various countries in East Africa reported over 17 cases of painful, blistering skin eruptions consistent with Paederus dermatitis, 2 of which are summarized in this report. To confirm the best treatment approach, 1 team's medic reached back to a deployed infectious disease physician in the same Combatant Command as well as through the DoD ADVISOR line to a dermatologist in the United States. All cases were managed with irrigation, followed by a combination of topical steroid and antibacterial ointments, with resolution occurring after 3 to 7 days, whereas 38% of the cases in July 2023 developed secondary cellulitis by day 7, requiring oral antibiotic treatment. Strict preventative measures were implemented to limit exposure while carefully observing each case, as this was critical to optimize medical readiness of the team. Ultimately, we seek to highlight the identification of beetles specific to East Africa, seasonal prevalence, and the importance of preventative measures as they vary depending on specific beetle characteristics. Additionally, we reiterate classic presentation features that help avoid misdiagnosis for cases that occur outside of the typical epidemiologic criteria.