Contribuições para o diagnóstico e epidemiologia da leptospirose em ovinos criados em condições semiáridas.

Abstract

In regions with a semiarid climate, there are environmental factors that are adverse to the survival and spread of leptospires, so the role of peculiarities in transmission routes that are independent of the environment needs to be further investigated. Thus, it sought to generate contributions to the diagnosis and epidemiology of infection by Leptospira sp. in sheep reared in semiarid conditions. In Chapter I, a study was described of 104 adult female sheep sampled during the dry and rainy period, between the years 2018 and 2019. Samples of vaginal fluid, urine, bladder, kidney, uterus, uterine tube, ovary and placenta were collected in the slaughter line for subsequent molecular detection through the polymerase chain reaction (PCR). The samples with the best reactions were amplified and subjected to genetic sequencing. For bacteriological culture, only vaginal fluid and urine were used, while the blood was destined for serological investigation through the microscopic agglutination test (SAM). In total, anti- Leptospira sp. in 26 (25%) of the animals analyzed by SAM in the initial 1:50 dilution, while 69 (66.3%) animals had at least one organ/fluid with the presence of leptospiral DNA. Of the 758 samples of organs/fluids from the genital and urinary tracts, in 519 (68.5%) samples there was DNA. In the analysis of the statistical variables of each type of biological material between dry and rainy periods, only in the vaginal fluid had a significant difference between the proportions (p <0.001), in which the dry period overlapped. It was possible to perform the sequencing in nine samples with 99% similarity to L. interrogans and isolation in three samples of vaginal fluid. And in three cultures of vaginal fluid, positive results were obtained in PCR, indicating the recovery of viable strains. In Chapter II, a study was carried out to detect vertical transmission of Leptospira sp. in fetuses of sheep slaughtered in the Northeastern Semiarid. After slaughtering the progenitors, the fetuses were removed from the uterine environment and taken to the laboratory, where they were necropsied. Blood samples from the matrices and fetuses were collected to investigate the occurrence of anti-Leptospira sp. through SAM. For molecular analysis through PCR from the conceptuses, samples of the central nervous system (SNC), lung, liver, spleen, stomach contents, peritoneal fluid, kidney, bladder, urine and reproductive system were collected and from those who were at the beginning of formation , the samples consisted only of central nervous system and macerated chest (choroid ovoid). 23 progenitors were sampled and of these, seven showed antibodies from the title 50. Regarding the fetuses, 29 were collected, two (6.9%) of whom were seropositive in titration 10 for the serogroups Pyrogenes, Tarassovi and Autumnalis. In PCR, 24 (82.7%) had at least one positive organ. Of a total of 209 samples, 61 (29.2%) demonstrated the presence of leptospiric DNA. Leptospiric DNA sequencing was possible in three samples of kidney, CNS and liver fragments with 99.3% similar to L. interrogans. In macroscopic analysis, it was observed that three fetuses had multiple malformations.