Clinical Report: Tularemia in Children: An Overlooked Infection in Denmark

Background

Tularemia is a zoonotic infection caused by Francisella tularensis and transmitted through infected arthropod bites, direct contact with infected animals, inhalation, or ingestion of contaminated food or water. Denmark has traditionally been considered a low-incidence country, but increasing numbers of diagnosed cases and recent seroprevalence data suggest ongoing exposure and broader recognition.

Data Highlights

• Reported cases: Denmark recorded 109 laboratory-confirmed cases from 2013 through 2024 and 32 cases in 2025.

• Seroprevalence: A nationwide study detected antibodies against F. tularensis in 2.2% of Danish blood donors.

• Clinical presentation: Both children had fever, inguinal lymphadenitis, and an adjacent punched-out inoculation ulcer.

Key Findings

• Both children were initially treated for presumed bacterial infection with beta-lactam antibiotics but did not improve.

• F. tularensis is intrinsically resistant to beta-lactam antibiotics, so persistent symptoms should prompt diagnostic reconsideration.

• Serology and PCR have complementary diagnostic roles; antibodies may be undetectable early, whereas PCR of lymph node aspirates or biopsy specimens can provide earlier confirmation.

• The absence of a recalled tick bite or animal contact does not exclude tularemia.

• One child improved after treatment was changed from doxycycline to ciprofloxacin, whereas the other recovered after a prolonged course of doxycycline.

Clinical Implications

Clinicians should consider tularemia in children with persistent fever and regional lymphadenitis, particularly when an adjacent punched-out ulcer is present or beta-lactam therapy fails. Early recognition and appropriate antimicrobial treatment are important to reduce prolonged illness and suppurative complications.

Conclusion

The increasing number of diagnosed cases in Denmark and the likelihood of underdiagnosis support greater clinical awareness. Whether the increase reflects geographic expansion or improved recognition and testing remains uncertain.

Related Resources & Content

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