Tick-borne tularaemia as a differential diagnosis in ulcerative skin infection and regional lymphadenopathy in children: a case report.

BACKGROUND: Tularaemia is a rare but re-emergent zoonosis in Germany, which reached a new peak in incidence in 2024. The infection rate of ticks in Germany with Francisella tularensis is only about 8% and the transmission of a clinically apparent infection by blood-sucking arthropods such as ticks, mosquitoes or horseflies accounts for about 30% of the infection routes in humans. Arthropod-borne tularaemia mainly presents as the glandular or ulceroglandular form. Delayed diagnosis and initiation of treatment with associated increased risk of complications are common. Those complications may include necrotizing abscess formation in up to 65% of cases. To our knowledge, only two cases of tularaemia following tick bites in children in Germany have been published to date. Both report cases of glandular tularaemia. The present case is therefore the first report of a clinically compatible, serology-supported presumptive case of ulceroglandular tularaemia following a tick bite in a child in Germany. It underscores the increasing relevance of tularaemia as a differential diagnosis in ulcerative skin lesions with regional lymphadenopathy.

CASE PRESENTATION: In the present clinical case, a 3-year-old white German boy presented with ulcerative skin infection, regional lymphadenopathy and fever following a tick bite. Calculated treatment with intravenous ampicill in and clindamycin as well as topical antiseptics initially did not result in lasting clinical improvement. In the course of typical clinical symptoms and indirect pathogen detection by serology, ulceroglandular tularaemia was assumed and appropriate oral treatment with ciprofloxacin was initiated, under which the symptoms resolved fast and completely.

CONCLUSION: The combination of increasing incidence rates, often delayed diagnosis, and therefore high complication rates underscores the clinical relevance of this case, which highlights the growing importance of tularaemia as a differential diagnosis in ulcerative skin lesions with regional lymphadenopathy.