Leptospirosis is strongly associated to estrus repetition on cattle

Molecular epidemiology of Leptospira spp. serogroup Sejroe associated with chronic bovine leptospirosis

Pathogenic bacteria Leptospira spp. are commonly associated with bovine leptospirosis, characterized chiefly by chronic and subclinical reproductive disorders. Strains from the Sejroe serogroup play a significant role in these chronic genital infections known as Bovine Genital Leptospirosis (BGL), which notably impact cattle health. This study aims to deepen our understanding of BGL by investigating the genetic diversity, geographical distribution, and specific anatomical sites of infection of the causative agents. Initially, uterine fragments and cervicovaginal mucus were collected from 47 cows and subjected to PCR targeting the lipL32 gene. Positive samples in lipL32-PCR (9 samples) underwent genotyping based on the secY gene. Subsequently, sequences were aligned with GenBank entries (108 sequences) and analyzed in silico. All nine sequences from this study were identified as L. interrogans with an identity >99 % to serogroup Sejroe reference strains (Norma and L53). In the broader analysis, the most prevalent species observed was L. borgpetersenii, followed by L. interrogans and L. santarosai. The haplotype network of L. interrogans revealed that haplogroups B and C exclusively included L. interrogans strains of genital origin, while haplogroup A encompassed strains from renal sources as well. These findings underscore the significance of the L. borgpetersenii genotype Hardjobovis and L. interrogans genotype Hardjoprajitno as the predominant circulating strains and highlight the existence of distinct haplogroups of pathogenic leptospires originating from genital sources. We advocate for the use of secY as an effective genetic marker for Leptospira spp. and stress the necessity for additional research prioritizing the genital tract. The outcomes of this study contribute to the development of improved control measures for chronic cattle diseases and provide valuable guidance for future investigations.

The presence of Leptospira spp. in the follicular fluid of naturally infected cows affects the overall efficiency of the in vitro embryo production technique

The relationship between Leptospira infection and reproductive failures, as well as the mechanisms that lead to it, has not yet been fully established. It has been hypothesized that the presence of Leptospira spp. in the follicular fluid (FF) could impair the oocyte developmental competence. Thus, the impact of the presence of Leptospira spp. in the FF on in vitro embryo production (IVEP) outcomes was assessed. Dairy cows (n=244) from different farms were subjected to ovum pick-up for cumulus-oocyte complexes (COCs) collection. After PCR analysis of the FF, cows were retrospectively allocated into either: positive (POS-FF) or negative (NEG-FF) group. Statistical modeling was conducted using the farm, PCR result, and laboratory in which the IVEP was performed as effects. Noteworthy, 26.6% of the animals were positive for Leptospira spp., and 70% of farms had at least one POS-FF cow in the herd. POS-FF cows had a lower number of COCs recovered (22.6 ± 1.2 vs 15.0 ± 2.8, P=0.036), rate of viable COCs (85.6 ± 0.9% vs 78.1 ± 2.8%, P=0.015), number of good-quality COCs (16.0 ± 0.9 vs 9.8 ± 2.1, P=0.026), cleaved embryos (11.9 ± 0.7 vs 7.5 ± 1.5, P=0.032), and blastocysts (7.3 ± 0.4 vs 2.3 ± 0.7, P=0.044) yielded per cow. In conclusion, the presence of Leptospira spp. in the FF of naturally infected cows impaired the amount of COCs recovered, decreasing the overall IVEP efficiency.

Leptospirosis as a cause of infertility in Uruguayan beef cattle

Leptospirosis, caused by pathogenic spirochetes of the genus Leptospira spp., is a globally significant zoonotic disease that affects humans and animals. In cattle, leptospirosis is associated not only with overt clinical manifestations but also with reproductive diseases, including infertility. This study assesses the potential correlation between leptospirosis and infertility in Uruguayan beef cattle. A case-control study involved 31 beef herds with no prior history of Leptospira vaccination. In each herd, veterinarians identified 10 non-pregnant (cases) and 25 pregnant cows (controls) using ultrasound, and blood and urine samples were collected from each cow. Serological diagnosis was performed using the Microscopic Agglutination Test (MAT), and quantitative PCR (qPCR) was used to assess Leptospira excretion. Additionally, antibodies against bovine viral diarrhea virus (BVDV) and infectious bovine rhinotracheitis (IBR) were tested. The results demonstrated an association between seropositivity to the Sejroe serogroup (cut-off 1:200) and infertility in cattle (OR=1.31; p-value=0.06). Furthermore, the level of Leptospira excretion (qPCR) in urine was associated with increased infertility risk, with cows excreting over 100 copies per mL of urine having the highest odds of infertility (OR=2.34; p-value<0.01). This study suggests a potential association between leptospirosis and infertility in Uruguayan beef cattle, emphasizing the importance of both serological and molecular diagnostics for assessing reproductive health in cattle herds. Future research should explore the impact of Leptospira serogroups on other reproductive disorders in cattle.

Seroprevalence and associated risk factors of leptospirosis in bovine dairy farms in Telangana state, India

The current cross-sectional study aimed to determine the seroprevalence of Leptospira infection in bovine dairy farms in the Telangana state of India, as well as the associated risk factors, in order to implement effective preventive measures for disease control. A total of 469 blood samples were collected from 67 herds/farms in different areas, covering 20 administrative districts in the state. These samples consisted of 253 from cattle and 216 from buffaloes. Questionnaires were used to collect data on host and epidemiological factors. The collected sera were tested using the gold standard serological test, the Microscopic Agglutination Test (MAT), which employed a panel of 18 reference serovars for Leptospira exposure. The statistical analysis of epidemiological data was carried out to identify the risk factors associated with Leptospira exposure. The overall observed seroprevalence at the animal and farm levels was 41.4% and 77.6%, respectively. The most prevalent anti-leptospiral antibodies were observed against the serogroups Icterohaemorrhagiae (32.4%), Pomona (22.2%), Javanica (19.1%), Australis (17.0%), Bataviae (15.5%), Autumnalis (12.9%), Hebdomadis (12.9%), and others, in the total reacting samples. At the animal level, the significant risk factors associated with exposure to Leptospira species were breed (p = 0.03) and health status (p = 0.03). Furthermore, the multivariate statistical analysis of farm factors revealed that farm size (p = 0.05), presence of dogs (p = 0.04) and rodents (p = 0.01) on the farm, use of fodder from wet soils (p = 0.04), and proximity to water bodies (p = 0.04) were significantly associated with exposure to Leptospira in the studied region. This study provides the first report from India highlighting the important risk factors at the herd/farm and animal level associated with Leptospira infections in cattle and buffaloes. The findings contribute to strengthening the one-health strategy by facilitating the design and planning of appropriate control measures to alleviate the burden of leptospirosis in bovines.

Unconventional Sites for Diagnosis of Leptospirosis in Bovine Anicteric Fetuses

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.

Genetic Analysis of LigA, LipL32, Loa22, and OmpL1 Antigens from Leptospira spp. Sejroe Serogroup: How Close We Are To a Vaccine Against Bovine Leptospirosis?

Bovine leptospirosis has as main causative agents Leptospira spp. from Sejroe serogroup. Vaccination is a crucial step to control this infection. The use of conserved proteins among Leptospira spp. is of great importance for a protective immune response. The aim of the present study is to genetically analyze antigens of Leptospira spp. from Sejroe serogroup strains isolated from cattle for a preliminary evaluation of vaccine candidates. Genes associated with antigenicity-LigA, LipL32, Loa22, and OmpL1-were analyzed through bioinformatic and immunoinformatic tools. Despite high diversity observed in strains, on an amino acid level, highly conserved regions were observed (> 90%), particularly in LipL32 gene. Moreover, highly conserved amino acid regions (> 30 aa) were observed in all genes, regardless of species, geographical origin or biological source of isolation. Superposed structures of protein fragments including all the predicted MHC-II and B-Cell epitopes were demonstrated. Results presented herein are preliminary, but a fundamental step towards the development of an efficient vaccine against bovine leptospirosis, a silent but enormously concerning disease.

Review: Bovine foetal mortality - risk factors, causes, immune responses and immuno-prophylaxis

This review of bovine foetal mortality (>42 d gestation) concluded that while the majority of risk factors associated with sporadic loss operate at animal-level, e.g. foetal plurality, those that operate at herd-level, e.g. some foetopathogenic infections, are more likely to result in abortion outbreaks. While the causes of foetal mortality have traditionally been classified as infectious and non-infectious, in fact, the latter category is a diagnosis of exclusion, generally without determination of the non-infectious cause. This review has also established that the traditional dichotomisation of infectious agents into primary and secondary pathogens is based on a flawed premise and these terms should be discontinued. The delicate balance of the maternal gestational immune system between not rejecting the allograft (conceptus) but rejecting (attacking) foetopathogens is stage-of-pregnancy-dependent thus the timing of infection determines the clinical outcome which may result in persistent infection or foetal mortality. Utilisation of our knowledge of the materno-foetal immune responses to foetopathogenic infection has resulted in the development of numerous mono- and polyvalent vaccines for metaphylactic or prophylactic control of bovine foetal mortality. While some of these have been shown to significantly contribute to reducing the risk of both infection and foetal mortality, others have insufficient, or conflicting evidence, on efficacy. However, recent developments in vaccinology, in particular the development of subunit vaccines and those that stimulate local genital tract immunity, show greater promise.

The Efficacy of Vaccination in the Prevention of Renal and Genital Leptospirosis in Experimentally Infected Sheep

(1) Background: Leptospirosis, mainly determined by strains belonging to serogroup Sejroe, has a direct impact on the reproductive efficiency of ruminants, such as sheep. In Brazil, Leptospira santarosai serovar Guaricura, known to be able to chronically colonize the uterine environment, is of special note. Although vaccination minimizes the effects of acute disease, whether or not it can protect from renal colonization remains controversial, and its effects on the genital tract are unknown. In this context, the present study aims to investigate the efficacy of vaccination in the prevention of experimental genital leptospirosis. (2) Methods: Eighteen sheep were divided into three groups: one vaccinated with a polyvalent commercial bacterin, one vaccinated with an autologous bacterin, and one unvaccinated. After 14 days, the sheep were experimentally challenged with 10⁸ leptospires (L. santarosai, serogroup Sejroe, serovar Guaricura, strain FV52) intraperitoneally. Serology and colonization of the urinary and genital tracts were carried out monthly by PCR for 210 days in all animals. (3) Results: Vaccination significantly elicited antibody titers with a predominance of agglutinins against serogroup Sejroe. Both urinary and genital infections were confirmed by PCR. Positivity in urine PCR was absent after D120, while genital infection persisted until the end of the study. Serological results and the finding that vaccination did not avoid renal colonization align with previous studies. Despite vaccination, Leptospira established chronic and asymptomatic colonization of the genital tract until D210, an outstanding finding that remains to be fully understood in its mechanisms. (4) Conclusions: This is the first study conducted to analyze the effects of vaccination in the prevention of genital leptospirosis.

Bovine leptospirosis: effects on reproduction and an approach to research in Colombia

Leptospirosis is the most widespread zoonosis worldwide, causing severe effects on beef and dairy cattle farming and other livestock. Colombia geographical location in the tropical zone, high biodiversity, and climatic conditions promote Leptospira growth and prevalence. This review article presents state-of-the-art knowledge about the effects of leptospirosis on bovine reproduction and a critical analysis of the research carried out in Colombia. The analysis of the information allows us to infer a sustained increase in prevalence over the last decade in the densest livestock production areas and a high serovar diversity of circulating pathogenic Leptospira. Given the zoonotic nature of leptospirosis, an inter-institutional effort is required to implement prevention, control, and monitoring programs under one-health concept.

Transient Presence of Live Leptospira interrogans in Murine Testes

Analysis of Leptospira dissemination and colonization of sex organs in rodents is of significant value as it queries the possibility of mammal-to-mammal venereal transmission. The aim of our study was to evaluate the presence and viability of Leptospira interrogans in testes of mice using models of infection that we previously developed. Using sublethal and lethal doses of bioluminescent strains of L. interrogans serovars Manilae and Copenhageni, we visualized the presence of leptospires in testes of C57BL/6 mice as early as 30 min and up to days 3-4 postinfection. This was confirmed by qPCR for the Copenhageni serovar after lethal infection of C3H/HeJ mice. In this model, no histopathological changes were noticed in testis. We further studied persistence of serovar Copenhageni in C3H/HeJ testes after lethal and sublethal infection, with different doses of leptospires. No viable leptospires were recovered from testes of lethally infected mice. However, we found live culturable Leptospira in testes of 19/19 (100%) sublethally infected mice at the acute phase but not at 15 days postinfection, which corresponds to the chronic phase of renal colonization. The data suggest that colonization of testes with live and potentially infectious leptospires is transient and limited to the spirochetemic phase of infection. Further studies are necessary to evaluate if presence of Leptospira in testes of mice leads to excretion in semen and to venereal transmission to female mice. IMPORTANCE Analysis of venereal transmission of Leptospira is important to determine if direct animal to animal transmission occurs, which could impact measures to prevent and treat leptospirosis. The goal of this study was to determine if live Leptospira colonize mouse testes. We found that colonization of mouse testes with live Leptospira was transient and limited to the acute spirochetemic phase of infection and that transient colonization of the testes was insufficient to cause histopathological changes.

Leptospirosis in rats and livestock in Bantul and Gunungkidul district, Yogyakarta, Indonesia

Background and Aim:

The animal reservoir of leptospirosis is comprised of both domestic and wild mammals, with rats known as the most important in the spread of the disease. The occurrence of this reservoir in residential areas increases the potential for leptospirosis transmission. This study aimed to investigate the type of reservoirs and estimate the prevalence of leptospirosis in rats and livestock animals in Bantul and Gunungkidul districts, Special Region of Yogyakarta Province, Indonesia.

Materials and Methods:

This research utilized a cross-sectional study design. Rat trapping and livestock (cattle, goat, and sheep) blood surveys were conducted at four locations in each district. Samples of rat renal and livestock blood serum were examined using the polymerase chain reaction technique to determine the presence of Leptospira bacteria. The data were analyzed descriptively by describing the species of rats trapped, the types of cattle, and the prevalence of Leptospira in the sample.

Results:

The rat species infected with Leptospira in Bantul district consisted of Rattus tanezumi 4.8% (3/63); Rattus norvegicus 12.5% (2/16); Bandicota indica 28.6% (2/7); and Bandicota bengalensis 50.0% (1/2). No rats were found to be positive for Leptospira in Gunungkidul district. The prevalence of Leptospira in cattle was 63.64% (7/11) in Bantul district and 50.00% (8/16) in Gunungkidul district. In goats and sheep, the prevalence of Leptospira was 22.22% (2/9) in Bantul district and 45.16% (14/31) in Gunungkidul district.

Conclusion:

The potential exists for transmission of leptospirosis from rats and cattle in Bantul and Gunungkidul Districts. It is necessary to increase leptospirosis awareness. Community education, especially for livestock farmers, needs to be improved to prevent the transmission of leptospirosis from livestock.

Growth dynamic of Leptospira spp. from Sejroe serogroup in different media formulae

The culturing of Leptospira strains from bovine clinical samples is challenging and has resulted in some gaps in securing an epidemiological understanding. Strains related to chronic reproductive leptospirosis in cattle belong to the Sejroe serogroup - not only Hardjoprajitno and Hardjobovis but also Guaricura genotypes. This study analyses the growth of Leptospira strains from serogroup Sejroe in different culture media, with the aim of suggesting better culturing approaches. To meet this objective, two culture media were applied: EMJH and T80/40/LH. In addition, three different cocktails of selective agents were chosen. The combinations of medium and selective additives resulted in 10 different tested formulae. The poor performance of Hardjobovis in EMJH indicated that its growth may represent a possible bias when culturing these strains from bovine samples. The most efficient medium for culturing Hardjobovis was T80/40/LH, while T80/40/LH medium + STAFF combination proved to be the best choice for growth, being recommended for obtaining a higher number of these strains from bovines.

Leptospirosis by Sejroe strains leads to embryonic death (ED) in herds with reproductive disorders

This study aims to evaluate the association between reproductive disorders and the main serogroups of Leptospira spp. in dairy herds. Blood samples from 216 cows from nine herds were collected for a Microscopic Agglutination Test (MAT), and a reproductive follow-up with ultrasonography was carried out monthly for at least 12 months. A total of 75 (16.5%) cows were reactive, while seroreactivity to a herd level ranged from 16.0% to 52.8%. Out of the nine herds, in five (55.0%) Sejroe was found to be the predominant serogroup and in four (45.0%) it was Icterohaemorrhagiae. The major reproductive problems identified were embryonic death (ED) and abortions. All herds presented ED and abortion was observed in three (33.3%). Herds with high seroreactivity (>20%) had more reproductive problems. Those with a predominance of Sejroe were associated with ED (P < 0.05), while those with Icterohaemorrhagiae were associated with abortion. The results show that different leptospiral strains lead to different reproductive problems, as well as showing that the main problem - ED - is caused by leptospirosis, particularly for those determined by strains of the serogroup Sejroe.

Bovine Genital Leptospirosis and reproductive disorders of live subfertile cows under field conditions

Bovine genital leptospirosis (BGL) is characterized by silent chronic reproductive disorders, most related to early embryonic death leading to estrus repetition, subfertility and abortions. However, most studies were conducted in slaughterhouses, which lacks reproductive and sanitary history of the studied animals. This study aimed to evaluate the occurrence of Leptospira sp. infection in live cows with history of low reproductive efficiency. Blood, urine, cervico-vaginal mucus and uterine fragment were collected from nine cows of the same herd presenting reproductive failure (abortions, estrus repetition and chronic infertility). Serology (MAT) and molecular analysis (PCR and nucleotide sequencing) were performed. Serology showed three (33.3%) seroreactive cows, two to Sejroe and one to Icterohaemorrhagiae serogroups. Six cows (66.7%) presented leptospiral DNA on genital samples, while all urine samples were negative. L. interrogans was identified in five samples, very closely related to strains from Sejroe (n = 3) and Icterohaemorrhagiae (n = 2) serogroups, while L. noguchii was identified in one sample. Results from this preliminary study demonstrates the presence of leptospires on uterus and reinforces the negative impact of leptospiral infection on reproductive tract, highlighting its association with reproductive failures on live animals.

An overview on the molecular diagnosis of animal leptospirosis

The most common presentation of animal leptospirosis is the subclinical and silent chronic form, that can lead to important reproductive disorders. The diagnosis of this chronic form remains a challenge. The aim of the present study is to gather and critically analyse the current information about molecular tools applied to animal leptospirosis diagnosis, particularly the silent chronic presentation of the infection. Regarding clinical specimens, samples from urinary tract were the most used (69/102, 67·7%), while few studies (12/102, 11·8%) investigated samples from reproductive tract. Concerning the molecular methods applied, the most used is still the conventional polymerase chain reaction (PCR) (46/102, 45%), followed by real-time PCR (38/102, 37·2%). The lipL32 gene is currently the most common target used for Leptospira detection, with 48% of studies applying this genetic marker. From all the studies, only few (21/102, 20·5%) performed gene sequencing. According to the majority of authors, current evidence suggests that lipL32-PCR is useful for an initial screening for Leptospira DNA detection in animal clinical samples. Posteriorly, if DNA sequencing could be performed on positive lipL32-PCR samples, we encourage the use of secY gene as a genetic marker. The molecular methods appear as the most important tools for the diagnosis of the chronic silent leptospirosis on domestic animals, reinforcing its evident impact not only on animal reproduction but also on a One Health context.

Evaluation of the diagnostic potential of recombinant leptospiral OMP A-like protein (Loa22) and transmembrane (OmpL37) protein in latex agglutination test for serodiagnosis of leptospirosis in animals

Leptospirosis is a re-emerging zoonotic disease of animals and humans caused by pathogenic Leptospira, which has major public health concerns. The study is aimed to express the recombinant outer membrane protein (OMP) A-like protein (rLoa22) and transmembrane (rOmpL37) protein of Leptospira interrogans serovar Hardjo in the Escherichia coli and their evaluation as a diagnostic antigen in the latex agglutination test (LAT) to detect anti-leptospiral antibodies in the sera of animals. The Loa22 and OmpL37 genes lacking signal peptide coding sequences were individually amplified (522 and 963 bp), by polymerase chain reaction, and directionally cloned into a pETite N-His Kan vector for expression. The expressed purified proteins were characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoblot, which confirmed leptospiral specific reactive protein with a molecular weight of ~19 and 36 kDa, respectively. The sensitized latex beads coated with these OM proteins separately were evaluated in LAT using cattle sera of microscopic agglutination test (MAT) confirmed positive (n = 53) and negative (n = 52) cases of leptospirosis. The rLoa22 LAT and rOmpL37 LAT revealed the relative diagnostic sensitivity of 94·34 and 96·23%, diagnostic specificity of 92·31 and 96·15% and accuracy of 93·33 and 96·19%, with the excellent agreement of Cohen's kappa value of 0·87 and 0·92, respectively. After extensive evaluation, this rapid recombinant protein-based field diagnostic test can be applied as a screening test for the detection of anti-leptospiral antibodies in the sera of animals in the field conditions.

Characterization of leptospiral DNA in the follicular fluid of non-pregnant cows

BACKGROUND

Bovine leptospirosis is mainly characterized by reproductive disorders. Contamination of the oocyte was previously demonstrated in vitro, resulting in some apparent damage. However, it is not clear whether it occurs under natural conditions. The present study aimed to characterize the presence of pathogenic Leptospira DNA in the ovarian follicles of non-pregnant cows.

METHODS

Follicular fluid samples were collected from 65 animals and subjected to lipL32 PCR and secY sequencing.

RESULTS

In total, seven of 65 (10.8%) were positive, indicating a possible early infection of the oocyte. Moreover, secY sequencing identified L. interrogans and L. santarosai, both very closely related to bovine strains from the Sejroe serogroup (Hardjoprjitno and Guaricura). We demonstrated that ovarian follicles can also be infected.

CONCLUSIONS

It was hypothesised that ovarian infection can contribute to embryonic death, causing reproductive failure and estrus repetition. In the present study, we show that the organism identified in the follicle is closely related to one that is known to be associated with reproductive disorders.

Expression of Recombinant Leptospiral Surface Lipoprotein-Lsa27 in E. coli and Its Evaluation for Serodiagnosis of Bovine Leptospirosis by Latex Agglutination Test

The expressed recombinant leptospiral surface adhesion lipoprotein (Lsa27) of pathogenic Leptospira in E. coli was evaluated for the detection of Leptospira antibodies in cattle sera by latex agglutination test (LAT). The Lsa27 lacking signal peptide coding gene sequences from L. interrogans serovar Pomona was amplified (~ 660 bp) by PCR and the amplicon was cloned into pETiteN-HisKan vector. The expressed recombinant Lsa27 histidine-tagged fusion protein (rLsa27) was Ni-NTA affinity purified under denaturation followed by renaturation methods. The purified rLsa27 was characterized by SDS-PAGE and immunoblot, which confirmed the leptospiral protein with a MW of ~ 25 kDa. Further, the prepared sensitized latex beads coated with rLsa27 were evaluated as a diagnostic antigen for detection of pathogenic Leptospira antibodies by using known microscopic agglutination test (MAT) positive (n = 74) and negative (n = 62) sera for Leptospira antibodies in LAT, which revealed the relative diagnostic sensitivity of 91.89% and specificity of 87.10% against the gold standard serological test, MAT. Furthermore, on evaluation of developed rLsa27 LAT using serum samples from cattle associated with the history of abortions and reproductive disorder (n = 309), the relative sensitivity of 96.15%, and specificity of 89.11% were observed. Therefore, this rapid field test using the rLsa27 is first of its kind and it could be used as a screening test for the detection of Leptospira antibodies or it can be complemented by other diagnostics for the diagnosis /surveillance of bovine leptospirosis.

Extra-renal bovine leptospirosis: Molecular characterization of the Leptospira interrogans Sejroe serogroup on the uterus of non-pregnant cows

Bovine genital leptospirosis is a chronic disease that causes reproductive disorders such as abortions, stillbirths, and estrus repetition, as well as economic losses. Despite clinical signs related to reproductive failure, the majority of studies have focused on the detection of Leptospira spp. in the urine, while few have considered the reproductive tract. Consequently, the aim of the present study was to investigate the uterus as an important extra-renal site of leptospiral infection in cows. A total of 42 non-pregnant cows were studied at a slaughterhouse. Blood samples and uterine fragments were collected for serology and molecular analysis, respectively. Concerning serologic results, 20.5 % presented as reactive, all of them against the Sejroe serogroup. Regarding lipL32 PCR, 26.2 % (11/42) of samples were positive for pathogenic Leptospira sp. Sequencing the secY gene short region enabled nine strains to be characterized, all of which were L. interrogans, with high identity (98.8 %-99.8 %) with serovar Hardjo. The use of molecular tools substantially improved the sensitivity of Leptospira sp. detection at species level and demonstrated that the uterus is an important site of bovine leptospiral infection. The findings of the present study reinforce our understanding that leptospiral uterine infection are associated to members of the Sejroe serogroup.

An historical view of the experimental leptospiral infection in ruminants

The first experimental infections with Leptospira in ruminants were conducted in the 1950s, primarily assessed the pathogenesis caused by serovar Pomona in cows. Throughout the decades, experimental infections have also demonstrated the clinical aspects of the infection by other strains, mainly Hardjo. Despite the important outcomes observed in experimental infections in ruminants, there is still a large discrepancy regarding the ideal dose, route, strain, model species or animal age that should be used to reproduce the acute and chronic leptospirosis in ruminants. In this context, the present study aimed to review the historical processes involved on the experimental leptospiral infection in ruminants. The inclusion criteria were papers that clearly described inoculation route, strain, dose, clinical signs and animal age. Overall, 37 experiments were noted. The most frequently reported clinical signs were fever, prostration, hematuria and death, with the majority of them occurring in young animals infected by incidental strains. Regarding reproductive problems, they occurred in the majority of the experiments and were also more related to incidental strains. In this context, abortions, retained placenta and weak fetuses were the most frequent symptoms. Noteworthy that although the mechanisms of the clinical acute disease either systemic or reproductive, is reasonably well understood, the physiopathology involved on reproductive problems due to the silent chronic infection is less discussed and remains to be elucidated. In this context, it is evident the need for studies focused on the genital infection and reproductive aspects of leptospiral infection in ruminants.

Leptospira sp. vertical transmission in ewes maintained in semiarid conditions

Leptospirosis is a globally distributed disease associated with reproductive failures in livestock; however, its pathogenesis has not been fully elucidated. Results from the present study indicate there is a presence of Leptospira sp. in organs and fluids of fetuses from ewes slaughtered in the semiarid region of Brazil. Twenty-nine fetuses from 23 ewes determined to be Leptospira sp.-positive using PCR were sampled (14 and 15 in dry and rainy seasons, respectively). Fetal samples of blood, central nervous system (CNS), lung, liver, spleen, stomach contents, peritoneal fluid, kidney, bladder, urine and reproductive system were collected. Diagnostic methods included the microscopic agglutination test (MAT), polymerase chain reaction (PCR) and bacterial isolation. Of the 29 fetuses, 24 (82.8 %) had at least one Leptospira sp.-positive organ or fluid, as determined using PCR, and of a total of 209 samples, 62 (29.7 %) contained leptospiral DNA. Of the 99 samples collected during the dry season, 42 (42.4 %) were positive, and of 110 samples collected during the rainy season, 20 (18.2 %) were positive (P = 0.0001). There was deoxyribonucleic acid (DNA) sequencing of three samples of kidney, CNS and liver, and in all of these, there was 99.3 % similarity with Leptospira interrogans. Leptospires were present in cultures of pooled samples from fetuses with deformities. Results indicate there is vertical (maternal-to-fetus) transmission which would represent an alternative transmission route for the spread of Leptospira sp. in ewes, suggesting molecular detection is essential in the investigation of leptospirosis in fetuses to identify animals that have been infected with this bacterium.

Genital bovine leptospirosis: A new look for an old disease

Bovine leptospirosis is often associated with host-adapted leptospires infections, such as strains belonging to the Sejroe serogroup. Although bovine leptospirosis by adapted strains may result in abortions, fetal death, premature births and the birth of weak and/or low-weight calves, this infection is more closely associated with subtler syndromes, such as subfertility and early embryonic death. In this way, this silent disease can go unnoticed and undiagnosed, compromising reproductive efficiency with a consequent decrease in the productivity of herds over long periods. For many years, genital tract infection has been considered a secondary effect of renal infection with the assumption being that leptospires are found in the genital tract due to bacteremia caused by renal colonization. In contrast to this hypothesis, there is some evidence in the literature that suggests that genital leptospirosis should be considered a specific syndrome dissociated from renal/systemic disease. Therefore, this paper aims to gather and critically analyze information about genital leptospirosis in cattle, considering the disease a distinct syndrome, herein denominated bovine genital leptospirosis (BGL), that requires a unique approach to diagnosis and treatment.

Biochemical parameters of blood in cows in latent course of leptospirosis

Changes in the biochemical parameters of blood in cows in the latent course of leptospirosis have been studied by the results of the reaction of microagglutination (RMA). The dynamics of biochemical blood parameters is manifested by hyperproteinemia, dysproteinemia, hemolytic anemia, hyperbilirubinemia, intra- and extrahepatic cholestasis, hyperfermentemia, mineral metabolism disorders, in particular hypocalcemia, hypophosphatemia, indicating the development of hepatopathy which should be classified as hepatocholangitis. It was determined that the pathological process is manifested in all animals for the titer of antibodies to one or another Leptospira serovar. Significant changes from the side of the hepatobiliary system in infested cows for the antibody titer kabura equaling 1:100, polonica 1:200, ballum 1:100, szvajzak 1:100–1:200, bratislava 1:800 and in animals for the titers kabura of 1:100–1:200; polonium 1:100; szvajzak 1:100–1:200; ballum 1:100; bratislava 1:100–1:200. At leptospirosis caused by bratislava and ballum serovars, a disorder of the functional state of the hepatobiliary system, characterized by an increase in the level of total protein, bilirubin, AST, GGTP and ALP activity was diagnosed as the urea, calcium and phosphorus levels in blood decreased. In the case of the latent course of the disease caused by kabura, polonica, szvajzak, ballumand bratislava serovars, a probably higher concentration of bilirubin, activity of aminotransferases (AST and ALAT), GGTP and ALP was determined in comparison to clinically healthy animals. In cows, in the presence of antibody titers kabura 1:100, polonica 1:200, ballum 1:100, szvajzak 1:100–1:200; bratislava 1:800, in 22.2% of cases, we recorded increase in the total protein against the background of dysproteinemia in 50.0–88.9% of animals, and increase in bilirubin in 78.6%, and increase in the activity of blood serum enzymes (AST, ALAT, GGTP, ALP), and also hypocalcemia and hypophosphatemia in 33.3–100.0%. The conducted studies indicate that in latent leptospirosis in cows, in addition to etiotropic therapy, one should include in the protocol the pharmacological correction preparations, which would contribute to the restoration of the functional state of the hepatobiliary system.

Epidemiology of Leptospira infection in livestock species in Saint Kitts

This pilot study describes the prevalence of Leptospira infection and exposure in livestock species, cattle, pig, sheep, and goats in Saint Kitts in the Caribbean region. Serum and kidney samples were collected from cattle, pigs, sheep, and goats at a local abattoir between September 2016 and March 2017. Cattle had the highest seroprevalence (79.8%) followed by pigs (64.8%), sheep (39.4%), and goats (24.8%). Highest seroprevalence was observed to serovars, Mankarso in cattle, Bratislava in pigs, Hardjo in sheep, and goats. Leptospira DNA was amplified from kidney samples of 18/99 cattle (18.2%), 11/106 pigs (10.4%), 4/106 sheep (3.8%), and 2/105 goats (1.9%). Our findings warrant further studies to assess leptospirosis associated economic burden to subsistence farmers and public health impact.