Dinâmica, sazonalidade e patologia da infestação por Psoroptes cuniculi (Delafond, 1859) em caprinos

Abstract

This thesis includes three chapter about the methods of diagnostic, pathology, population dinamics and seasonal fluctuation of the infestation by Psoroptes cuniculi in goats in the semiarid region of Paraíba. In the first chapter the technique of washing the auditory canal either with 50 or 100 mL of water was evaluated to determine the prevalence of the infection by P. cuniculi and to estimate the degree of infestation for population dynamics studies. The technique was efficient to estimate the prevalence of the infection by P. cuniculi, however the intensity of the infection and the population dynamics should be studied in slaughtered goats by opening the auditory canals to count the different stages of the parasite. In the second chapter the histologic lesions of psoroptic mange were studied in goats with different degrees of infestation. The lesions included varying degrees of parakeratotic hyperkeratosis, orthokeratotic hyperkeratosis, acanthosis, hypergranulosis, spongiosis, and dermatitis, with rare eosinophils. P. cuniculi was observed in the ear canal, occasionally in contact with the stratum corneum, but without causing traumatic lesions in the epithelium, which suggests that the lesions occur through a mechanical effect due to the presence of the mites together with the exudates, cerumen, and keratin residues. These findings suggest the infestation in asymptomatic goats that in asymptomatic goats and in those with mild infestation, psoroptic mange does not cause productive losses. However productive losses may occur in goats with severe clinical signs, which are rare in the Brazilian semiarid. The third chapter reports the prevalence and seasonal fluctuation of P. cuniculi mange in the semiarid region of Paraíba during the periods of June 1999 to May 2001 and from August 2011 to December 2012. The 541 goats (87.9%) parasitized by P. cuniculi were identified by collecting a total of 73954 mite, where only 4.4% (24 goats) showed clinical signs of otocaríase, ranging annually from 3.8% to 5 %. The clinical signs were clogged ear canals by large amount of ear canal, presence of lamellar crusts and purulent discharge. The monthly prevalence of the infestation varied between 66.66% and 100% without significant differences between months and between years. However the intensity of the infestation increases during the dry years.