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Leptospirosis is an infectious disease that affects domestic animals, wild animals, and humans. It represents a public health problem and has an important economic impact on livestock. This study aims to investigate the importance of genital and transplacental infection in the epidemiology of leptospirosis in cows maintained in Caatinga biome conditions, Northeastern Brazil, as well as reporting organs colonized by Leptospira spp. in embryos and fetuses. Blood, urinary tract (urine, bladder, and kidney), and reproductive tract (vaginal fluid, uterus, uterine tube, ovary, and placenta) samples were collected from 15 slaughtered pregnant cows. Two embryos and 13 fetuses were sampled. Central nervous system and choroid ovoid samples were collected from embryos. Blood, central nervous system, lung, peritoneal liquid, abomasal content, liver, spleen, urine, bladder, kidney, and reproductive system samples were collected from fetuses. Diagnostic methods included the microscopic agglutination test (MAT) using a collection of 24 serovars belonging to 17 different pathogenic serogroups of five species as antigens, as well as polymerase chain reaction (PCR). Anti-Leptospira spp. antibodies were found in 9 cows (60%), while 13 cows (86.67%) had at least one organ or urine with leptospiral DNA. No fetus was seroreactive. Among the embryos and fetuses, 13 (86.67%) presented leptospiral DNA, proving a high frequency of transplacental infection (100%). For cows, the most frequent biological materials regarding Leptospira spp. DNA detection were placenta (13 out of 15 samples; 86.7%), uterus (10 out of 15 samples; 66.7%), and vaginal fluid (5 out of 15 samples; 33.3%), while, for fetuses/embryos, the most frequent PCR-positive samples were choroid ovoid (1/2; 50%), spleen (6/13; 46.2%), kidney (5/13; 38.5%), and central nervous system (5/15; 33.3%). Sequenced samples based on the LipL32 gene presented 99% similarity with L. borgpetersenii. The results indicate that transplacental infection is an efficient way of spreading Leptospira spp. in cows maintained in Caatinga biome conditions. Therefore, prevention and control strategies must include actions that interrupt transmission through this alternative route. Full article

Background: Bovine leptospirosis is an important reproductive disease and abortion is a major sign, leading to economic impacts. Due to its multifactorial etiology, the proper diagnosis of the cause of the abortion is crucial. Necropsy of the fetuses followed by molecular analysis is recommended for diagnosis, and the investigation mainly occurs in the kidneys and liver. This study aimed to analyze unconventional sites for the presence of leptospiral DNA in bovine anicteric aborted fetuses. Methods: Five fetuses of the same herd were received for necropsy and diagnosis. Conventional lipL32-PCR was performed in the fetuses’ kidneys, livers, lungs, hearts, spleens, subcapsular kidney content, abomasal fluid, and in the cavity’s hemorrhagic contents. To complete the investigation, the sera of 30 cows of the herd were collected to perform the serologic screening by Microscopic Agglutination Test. In addition, six subfertile non-pregnant cows from the same herd were selected due to their low reproductive performance, and genital samples (uterine fragment and cervicovaginal mucus) and urine were collected for lipL32-PCR. PCR-positive samples were submitted to a nested PCR of the secY gene and intended for sequencing. Results: The herd presented seroreactive animals (11/30, 36.6%), all against the Sejroe serogroup, with titers between 200 and 1600. In necropsy, four fetuses showed hemorrhagic and anicteric lesions, while one fetus had no macroscopic lesions. Regarding molecular analysis, all the fetuses were positive in lipL32-PCR and the positive sites were the heart, lungs, subcapsular kidney content, thymus, kidneys, liver, and abomasal fluid. Only one fetus presented positive results in the kidney and liver, while three fetuses were positive in the abomasal fluid. Five of six cows were positive for lipL32-PCR, all being positive only in genital samples. Of the fetuses and the cows, seven sequences were obtained and all were identified as Leptospira interrogans serogroup Sejroe serovar Hardjoprajitno. Conclusions: In order to improve the diagnosis of leptospirosis in cows, it is recommended to perform a comprehensive analysis of the samples, beyond the kidneys and liver. Thus, we highly encourage testing multiple organs by PCR to investigate abortions suspected of bovine leptospirosis, particularly in anicteric fetuses. Full article

Ruminants ingest large quantities of clay minerals along with inorganic soil constituents in roughages. The layered structure of clay minerals, however, may adsorb cations and may, thus, interfere with the ruminants’ supply of essential trace metals, such as Zn, Mn, Cu, and Fe. As quantitative knowledge about interactions between clay ingestion and essential trace metal metabolism are largely lacking, this in vitro study focussed on the effect of clay on the solubility of dietary Zn and other bivalent trace metals in the digestive tract of ruminants. Therefore, buffered rumen fluid was used for the simulation of ruminal conditions (RC), acidified rumen fluid (pH 2) was used for abomasal conditions (AC), and duodenal chyme was used for duodenal conditions (DC). These media were added with gradient levels of zinc and incubated at 39 °C for 24 h in the absence or presence of clay minerals. Soluble Zn, Cu, Mn, and Fe were derived by centrifugation (10,000× g) of incubated media, and the supernatants were analysed. Clay depressed the solubility of added Zn in ruminal (65.3% vs. 16.5%), abomasal (97.7% vs. 33.7%), and duodenal conditions (41.3% vs. 21.1%), the results of which were statistically significant (p < 0.001). Moreover, clay reduced dissolved Cu (µg/mL) (RC: 0.13 vs. 0.10; AC: 0.16 vs. 0.13; DC: 0.10 vs. 0.08) and Mn (µg/mL) (RC: 3.00 vs. 1.80; AC: 5.53 vs. 4.80; DC: 3.18 vs. 1.77) (p < 0.05 in all cases). The presence of clay minerals increased the concentrations of solubilised Fe (µg/mL) in abomasal (1.80 vs. 2.86, p < 0.05) and duodenal conditions (1.76 vs. 2.67; p < 0.05). In total, the present in vitro study demonstrates the potential of clay minerals ingested with ruminant feeds for depressing the solubility of dietary Zn, as well as the depression of dietary Cu and Mn along the passage of the digesta from the rumen until the duodenum. Additionally, clay minerals may release Fe into the digesta. Full article

The aim of this study was to develop a 16S-23S ribosomal deoxyribonucleic acid internal transcribed spacer (ITS) quantitative polymerase chain reaction (qPCR) assay for the early diagnosis and rapid screening of brucellosis. Blood, milk, and tissue samples were spiked with B. abortus biovar 1 (B01988-18 strain) to determine the analytical sensitivity and specificity of the assay. The 95% limit of detection of the ITS qPCR assay was highest in tissue, followed by blood, then milk, i.e., 0.48, 4.43, and 15.18 bacteria/PCR reaction, respectively. The diagnostic performance of the assay was compared to the Brucella cell surface protein (BCSP) 31 qPCR assay and bacterial culture. Out of 56 aborted foetal tissue samples from bovine, ovine, and caprine, 33% (19/56) were positive for Brucella spp. The sensitivity and specificity of the ITS qPCR assay was 87% and 95% respectively, compared to 92% and 89% for the BCSP31 qPCR assay and 47% and 55% for bacterial culture, respectively. The assay was efficient, sensitive, and specific, making it a valuable tool in the early detection of the Brucella pathogen. Full article