Vesicular Eruption Secondary to Bites by Larval Amblyomma americanum
Tick-borne illness is an increasingly concerning cause of human infectious disease. Not only do ticks transmit disease, but their bites also may cause impressive local reactions. This report highlights a case of a widespread vesicular eruption secondary to bites by larval Amblyomma americanum sustained by a 58-year-old woman. This case posed a diagnostic challenge because of the unusually large number and wide distribution of bites as well as the subsequent vesicular reaction that ensued. It is necessary for dermatologists in tick-endemic areas to keep tick bites in the differential when evaluating vesicular eruptions. In addition, it is important for dermatologists to be aware of the tick species in their area.
Practice Points
- The range of Amblyomma americanum has expanded north in recent years from its core range in the southeastern United States. Warming temperatures also have increased the duration of the ticks’ active season.
- Amblyomma americanum can lay several thousand eggs. A person happening upon a newly hatched nest of larval ticks could sustain a widespread vesicular eruption secondary to tick bites.
- It is important to keep larval tick infestation in the differential when evaluating a patient with a new widespread vesicular eruption to expedite prompt removal of the offending ticks and to begin clinical monitoring.
Prevention of Tick Bites—Tick bites are best prevented by avoiding tick-infested areas; when these areas are unavoidable, tick bites may be prevented by wearing long pants with the pant legs tucked into boots. In addition, applying topical DEET (N,N-diethyl-m-toluamide) repellent to exposed skin and treating clothing with permethrin can be helpful.17 When used alone, DEET provides greater than 90% protection for up to 2.7 hours against A americanum.18 Permethrin-treated clothing alone is 79% to 100% effective at killing A americanum ticks or disabling them for several hours.19
Conclusion
Tick-borne illness is an increasingly important cause of human infectious disease. In addition to their role as a disease vector, ticks can produce primary skin disorders. This case posed a diagnostic challenge because of the unusually large number and wide distribution of bites as well as the subsequent vesicular reaction that ensued. It is important to keep tick larvae or adult tick bites in the differential when evaluating a patient to expedite tick removal and begin clinical monitoring. Recognition of A americanum larvae as a potential cause of pruritic papules may be helpful in similar cases. In addition, it is important for dermatologists to be aware of the tick species in their area.
