Ixodes dammini: Induced skin lesions in guinea pigs and rabbits compared to erythema chronicum migrans in patients with lyme arthritis

Erythematous skin lesions occurred in rabbits 2 days after being fed upon by larvae or nymphs of the tick, Ixodes dammini. Similar lesions occurred in guinea pigs 7 days after a primary infestation with either larvae or nymphs. Host resistance to secondary feeding by larvae was demonstrated in guinea pigs and rabbits. Host resistance to secondary feeding by nymphs was seen in guinea pigs, but not in rabbits. Guinea pigs developed resistance to nymphs after being previously fed upon twice by larvae. All skin lesions in resistant guinea pigs contained large accumulations of basophils (49–76% of cells) with smaller (20–33%), but significant, numbers of eosinophils. These responses were characteristic of strong cutaneous basophil hypersensitivity reactions. Primary and secondary lesions in rabbits fed upon by larvae contained mostly mononuclear cells (46–52%) and moderate numbers (16–30%) of basophils and eosinophils. Primary and secondary lesions in rabbits fed upon by nymphs had few (3–11%) basophils and eosinophils and were dominated by mononuclear cells (73–86%). Thus, acquired resistance in guinea pigs and rabbits was associated with cutaneous basophil and eosinophil responses and the lack of resistance of rabbits to nymphs was associated with erythematous lesions dominated by mononuclear cells. The mononuclear nature of rabbit lesions induced by nymphal feeding was similar to that seen in erythema chronicum migrans in Lyme arthritis patients who are thought to have been fed upon by I. dammini nymphs. This study confirms the cutaneous basophil hypersensitivity characteristics of lesions in guinea pigs resistant to ticks and demonstrates a relationship between the mononuclear cell response of rabbits to nymphal I. dammini and the cellular response seen in patients with erythema chronicum migrans and Lyme arthritis.