Capivaras (Rodentia) e Carrapatos (Acari: Ixodidae): alterações ecológicas e a interação do hospedeiro e parasita em áreas urbanas

Abstract

The recent and human caused environmental changes interfered with the evolutionary interactions between parasites and hosts. These changes accidentally benefited those few animals species, more adapted to the altered environment. However, the biodiversity of parasites was affected, and some parasitic species were benefited as well. In the case of ticks, those species which, after the changes, found abundant hosts and suitable environment were benefited. In Brazil, capybara (Hydrochaeris hydrochaeris Linnaeus 1766) and the associated ticks Amblyomma cajennense Fabricius 1787 and Amblyomma dubitatum Neumann 1899, expanded in many urban areas where they threaten human well-being and domestic animals. These ticks cause pruritic skin lesions and blood feed on their hosts moreover, they are associated, in some places, with the transmission of Spotted fever, a highly lethal disease for man. This study aimed to analyze the factors that determine the establishment and expansion of capybaras and ticks in urban areas in the city of Uberlandia, Minas Gerais State, Brazil. For this purpose in 2008 monthly direct counting of capybaras per transect in four urban areas and an ecological reserve were held and abundance and density index were calculated. Ticks were collected from the environment in the summer of 2008 using CO2 traps and flannel dragging on the same transects. It was observed that populations of capybara, in groups with number of individuals higher then those found in natural areas, were established in such places that, in addition to food and water bodies, were protected day and night surveillance. The greater abundance of ticks of the species A. cajennense and A. dubitatum was found at the site with the greatest abundance of capybaras. The results therefore indicate that beyond the minimum requirements for the establishment of capybaras such as food and water, protection from men itself, even though accidentally, is a major factor in the establishment and proliferation of capybaras in urban areas. This increase in the number of such host always implies in high environmental infestation of ticks and increased risk of bites and of pathogen transmission. Therefore, capybaras in urban areas should be considered synanthropic and effective methods of population control must be developed.