Estudos da toxicidade de alguns carrapatos comumente encontrados no Brasil (Acarina: Ixodidae)

Abstract

The primary object of these experiments was to determine the degree of toxicity caused by immature and mature stages and to compare the nature of the auricular cutaneous lesions in rabbits caused by four different tick species commonly found in Brazil: Boophilus microplus Canestr., Haemaphysalis leporis-palustris Packard, Amblyomma cajennense Fabricius and Rhipicephalus sanguineus Latr. The experiments were conducted in Itaguaí, Rio de Janeiro using 57 white rabbits and ticks from Rio de Janeiro, Minas Gerais and Mato Grosso. The rabbits were infested and reinfested with the different developmental stages of the four tick species. The present investigations have revealed that each of the four tick species harboured a toxin which had an affinity for the epidermis as disclosed by the nature of the auricular cutaneous lesions of white rabbits. In the case 81 of B. microplus the toxicity of the continuously feeding developmental stages was initially mild but progressively increased to reach its peak during the adult phase. R. sanguineus larval infestations were not followed by an epidermal response but successive infestations with larvae or a primary exposure to adults followed by that of larvae showed that the hosts had acquired an immunity. A macroscopically visible toxic epidermal response due to larvae, nymphae and imagines of H. leporispalustris was not seen. Cutaneous lesions were nevertheless seen in rabbits that had a previous experience with n y m p h a e . All developmental stages of A. cajennense are far more toxic than those of the other three species under discussion. An epidermal response after one or several successive infestations was constantly observed.