Parasites and health status of free-ranging capybaras (Hydrochoerus hydrochaeris) in the Atlantic Forest and Caatinga biomes of Brazil.

Due to the degradation and loss of its natural habitat, the presence of capybaras in urban environments and crop areas has been frequently reported in various regions of Brazil. The objective of this study was to identify the parasitic fauna of free-living capybaras in two impacted biomes of the northeastern region (Atlantic Forest and Caatinga), as well as to evaluate the impact of parasitism on the health of these rodents. For this, ticks, fecal and blood samples (for hematology and serum biochemistry evaluation) were collected from 23 free-ranging capybaras from four areas of Atlantic Forest (areas 1, 2 and 3) and Caatinga (area 4) biomes. Of the 23 animals with parasites, 73.9% (17/23) were parasitized simultaneously by gastrointestinal parasites (GIP) (Strongylida, Strongyloides chapini, Capillaria sp., Trematoda and Eimeria sp.) and Amblyomma ticks (larvae of Amblyomma sp. - areas 1, 2, and 3; Amblyomma dubitatum - areas 1 and 2; A. sculptum - areas 3 and 4), while 26.1% (6/23) were parasitized exclusively by ticks. The trematode Hippocrepis hippocrepis was collected during the necropsy of one animal that died during the study. Most hematological and serum biochemical parameters were within the reference values for the species, except AST, albumin, urea, and Na, which presented higher values. Some parameters presented statistically significant differences associated with parasitism, with higher values for animals with co-infection (GIP and ticks) than animals parasitized by ticks only: leukocyte counts (p = 0.0332), neutrophils (p = 0.0498), monocytes (p = 0.0443), as well as creatinine (p = 0.0422) and lactate (p = 0.0307). This may mean that the GIP identified in this study can have a greater impact on the hematological and serum biochemical parameters. However, although parasitized and living in threatened biomes, the animals were healthy, demonstrating that they could be adapted to parasitism. Amblyomma sculptum was recorded for the first time in capybaras in the Caatinga biome in Pernambuco state. The presence of A. sculptum evidences the need for studies about the infection by Rickettsia on capybaras and their ticks, to provide data on the potential risk of occurrence of Brazilian Spotted Fever in Pernambuco state, within a One Health perspective.