Isolamento e diagnóstico molecular de Leptospira spp. a partir do trato geniturinário de pequenos ruminantes do Semiárido Brasileiro.

Abstract

Leptospirosis is a disease widely spread in Brazil, whose main impact is the impairment of the reproductive performance of herds. This thesis was composed of three chapters that aimed at the serological, molecular and bacteriological detection of Leptospira spp. in fluids and organs of the genitourinary tract of goats and sheep kept under semiarid conditions. In chapter I, 40 sheep were studied, five (12.5%) were positive with an antibody titer of 50 and 2 (5%) with a titer of 100 for the Pyrogenes, Ballum, Icterohaemorrhagiae and Australis serogroups. DNA was found in 30 (75%) animals, with 93 (38.7%) positive samples, 48/120 (40%) from the urinary tract and 45/120 (37.5%) from the genital, with no statistical difference. A bladder sample was sequenced and showed 99% similarity to L. interrogans. Of the 240 cultures, 59 (24.5%) showed leptospira growth. Of these, 23 (39%) were confirmed by PCR. The cutoff point of 50 was more sensitive than that of 100. The large proportion of DNA in organs, urine and cultures and the bacterial growth of the genital tract reinforce its importance as an extrarrenal site and highlight the possible role of sheep in venereal transmission, as well as the sensitivity of the cutoff point 50 suggested its adoption in serology. Chapter II detected Leptospira spp. in 40 male goats. Serological data showed three (7.5%) animals positive for the Pyrogenes serogroup, at the cutoff point 1:50. Regarding the molecular test, 18 (45%) animals were positive, being detected in 25/120 (20.8%) urinary tract samples and in 23/120 (19.1%) urinary tract, with no statistical difference. A vas deferens sample showed 99% similarity with L. interrogans. Altogether, 240 cultures were evaluated and 36 (15%) showed bacterial growth. Of these, 27 (75%) had DNA confirmation of Leptospira spp. Thus, leptospirosis is present in an environment of adverse conditions and its spread may be linked to venereal transmission. In chapter III, of the 40 goat females processed, two (5%) were positive in the serology for serogroup Pyrogenes, at the cutoff point 1:50. A total of 29 (72.5%) animals were PCR positive, in 51/160 (31.8%) samples from the genital tract and 34/120 (28.3%) from the urinary tract, with no statistical difference. Bacterial growth was observed in 35/280 (12.5%) cultures and 9/35 (25.7%) were PCR positive. Two uterus samples showed 99% similarity with L. interrogans after sequencing. Thus, goats kept under semiarid condition were positive for Leptospira, with positive samples from both the urinary and genital tracts, this being the alternative form of adaptation and maintenance of the agent.