Lesão cutânea macro e microscópica causada pelo carrapato Amblyomma sculptum em animais selvagens e domésticos

Abstract

Ticks are hematophagous arthropods belonging to the Arachnida class and ectoparasites to all classes of terrestrial vertebrates, which can cause harmful effects on humans and animals. These effects are established by their direct contact and their role as vectors of various pathogens, including bacteria, viruses, protozoa and helminths. In Brazil, rickettsiosis, Brazilian Spotted Fever, stands out, transmitted to humans by the immature forms, larvae and nymphs, of the Amblyomma sculptum tick. Adults of this species of tick have capybaras, horses, tapirs, swine and giant anteaters as their primary hosts. The transmission of pathogens by ticks is facilitated by the long parasitic period of several days and the skin is the site of interaction between the host, the ectoparasite and the pathogenic microorganism. Tick saliva is composed of pharmacologically active molecules that control host reactions, allowing demonstrated hematophagy and contributing to the dissemination of inoculated pathogenic microorganisms. However, some hosts may develop resistance to the tick, preventing it from attaching or feeding and, in these cases, the transmission of pathogens is also impaired. The mechanisms of resistance to ticks are still poorly understood, but their description would be essential for their induction in susceptible hosts through vaccines. Tick resistance has already been associated with a basophilic skin infiltrate in the context of an occurrence of a basophilic hypersensitivity reaction, described only in experimental models. Therefore, this project proposes to compare the macroscopic and microscopic skin lesions at the point of attachment of Amblyomma sculptum ticks on the skin of naturally infested wild Brazilian fauna, in order to elucidate possible resistance mechanisms. For this purpose, samples were collected from individuals belonging to the necropsy routine of the pathology and wildlife sectors of the Veterinary Hospital of FAMEV-UFU, in addition to samples from horses from a previous study. Of a total of 56 samples, 17, covering six host species, were considered for analysis. In the macroscopic evaluation, most of the animals presented discrete alterations and no individual exhibited alopecia, erosion, pustule or ulcer. In contrast, the microscopic evaluation revealed important alterations in the tissue and the differential count verified a high number of inflammatory cells, such as mast cells and eosinophils. The infiltrate with eosinophils was accompanied by more intense infiltrates and those with mast cells by more reduced infiltrates.