High frequency of leptospiral vaginal carriers among slaughtered cows

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.

Seroprevalence of Coxiella burnetii, Leptospira interrogans serovar hardjo, and Brucella species and associated reproductive disorders in cattle in southwest Ethiopia

In Ethiopia, Coxiella burnetii, Leptospira Hardjo, and Brucella spp are recognized as the primary factors contributing to cattle reproductive issues. A cross-sectional study was conducted in southwest Ethiopia from October 2020 to October 2021 to assess the risk of reproductive disorders associated with L. Hardjo, Coxiella burnetii, and Brucella spp. Moreover, the study aimed to identify the factors associated with reproductive disorders. Using an indirect ELISA, antibodies against these pathogens were observed in serum samples collected from 461 cattle. We employed multivariable random effect logistic regression analysis to identify potential risk factors associated with reproductive disorders in cattle. The study areas showed a prevalence of 25.16 % (95 % CI: 21.20-29.12) for cattle reproductive disorders. The presence of Leptospira Hardjo (OR = 2.9, 95 % CI: 1.17-4.02) and Coxiella burnetii (OR = 3.0, 1.49-5.94) antibodies was associated to the occurrence of cattle reproductive disorders. Seropositivity to pathogens B. abortus, C. burnetii, and L. Hardjo, along with co-infection of all three, showed association with cattle abortion. The presence of L. Hardjo seropositivity and co-infection with C. burnetii were related to dystocia in cattle. Cattle with retained fetal membranes were associated with co-infection seropositivity to these pathogens. Additionally, B. abortus seropositivity was linked to cases of repeated breeding in cattle. Age, breeding practices, and dog access to cattle showed associations with reproductive disorders, with odds ratios of 2.3 (95 % CI: 2.03-4.69), 2.9 (95 % CI: 1.83-4.82), and 6.5 (95 % CI: 1.04-2.53) respectively. This research indicates that Brucella abortus, Coxiella burnetii, and Leptospira Hardjo, which are responsible for severe zoonotic diseases, have a substantial negative impact on cattle production by causing reproductive disorders. To address the transmission of these diseases, it is essential to implement effective mitigation strategies and enhance public awareness. Additional investigation is necessary to identify and understand the factors contributing to cattle reproductive disorders in the specified area.

A systematic review on leptospirosis in cattle: A European perspective

Leptospirosis is a zoonotic disease which is globally distributed and represents a classic One Health issue that demands a comprehensive understanding of the hosts, transmission paths, and risk factors of transmission. Bovine leptospirosis often results in economic losses through its severe impact on reproduction performance while it threatens human health at human-cattle-environment interfaces. However, a clear analysis of the disease characteristics in European cattle is currently lacking. The objective of this review was to summarise the current knowledge on the epidemiology of bovine leptospirosis in Europe. We conducted a systematic literature review, screening four electronic databases, and filtered articles published between 2001 and 2021, in English, German, and French. Sixty-two articles were ultimately included in the review. The seroprevalence of leptospirosis in cattle was remarkably variable among studies, probably reflecting local variations but also heterogeneity in the study designs, laboratory methods, and sample sizes. Risk factors positively associated with the disease were diverse, related to local, environmental, and climatic parameters as well as farming practices. The most reported circulating Leptospira serogroups in European cattle were Sejroe (58.5%), Australis (41.5%), Grippotyphosa (41.5%), Icterohaemorrhagiae (37.7%), and Pomona (26.4%), which have also been associated with human infections worldwide. Abortion (58.6%) and fertility disorders (24.1%) were the most frequently reported signs of leptospirosis in European cattle and were generally associated with chronic infections. This work highlights several research gaps, including a lack of harmonisation in diagnostic methods, a lack of large-scale studies, and a lack of molecular investigations. Given that predictions regarding the climatic suitability for leptospirosis in Europe suggest an increase of leptospirosis risk it is important to raise awareness among stakeholders and motivate an integrated One Health approach to the prevention and control of this zoonotic disease in cattle and humans.

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.

Neglected zoonotic bacteria causes and associated risk factors of cattle abortion in different agro-ecological zones of southwest Ethiopia

Three zoonotic bacteria, Coxiella burnetii, Leptospira spp, and Brucella spp, cause cattle abortion and significant losses in the livestock sector. However, these infections were neglected diseases in Ethiopia. Between October 2020 and October 2021, a cross-sectional study was carried out in southwest Ethiopia to determine the prevalence of abortion and identify the major zoonotic bacterial causes and risk factors that contribute to abortion. Using an indirect ELISA, antibodies to Brucella abortus, Leptospira Hardjo, and Coxiella burnetii were detected in serum samples taken from 461 cattle. Potential risk factors for cattle abortion were found using a multivariable random effect logistic regression analysis. The prevalence of cattle abortion was found to be 22.56 % (95 % CI: 18.74-26.38) in the study areas. Leptospira Hardjo (OR=1.8, 95% CI: 1.04-3.00), Coxiella burnetii (OR=2.7, 95 % CI: 1.26-5.62), and Brucella abortus (OR=9.8, 95 % CI: 1.27-17.15) were all associated with the occurrence of abortion in cattle, as were their co-infections (OR=8.1, 95 % CI: 1.28-39.33). Other risk factors for cattle abortion included breed (OR=16.7, 95 % CI: 2.20-26.77), herd size (OR=2.5, 95 % CI: 1.16-4.68), breeding method (OR=2.3, 95 % CI: 1.33-3.90), and contact with dogs (OR=2.2, 95 % CI: 1.34-3.53). According to the findings of this study, Brucella abortus, Coxiella burnetii, and Leptospira Hardjo are serious zoonoses that cause significant production loss in cattle due to abortion. To prevent transmission of these zoonotic diseases, it is crucial to implement effective control measures and increase public awareness. The causes of cattle abortion in the study areas should also be isolated and characterized.

Bovine Leptospirosis in Caatinga Biome, Brazil: New Insights into Diagnosis and Epidemiology

Bovine leptospirosis causes economic losses and raises public health concerns. It is possible that there are peculiarities in the epidemiology of leptospirosis in regions with a semiarid climate, such as the Caatinga biome in Brazil, where the climate is hot and dry, and the etiological agent require alternative routes of transmission. This study aimed to close knowledge gaps to the diagnosis and epidemiology of Leptospira spp. infection in cows from the Caatinga biome, Brazil. Samples of the blood, urinary tract (urine, bladder and kidney) and reproductive tract (vaginal fluid, uterus, uterine tube, ovary and placenta) were collected from 42 slaughtered cows. Diagnostic tests included were the microscopic agglutination test (MAT), polymerase chain reaction (PCR) and bacterial isolation. Anti-Leptospira spp. antibodies were found in 27 (64.3%) of the animals analyzed using MAT at a 1:50 dilution (cut-off 50), while 31 (73.8%) animals had at least one organ/fluid where the presence of Leptospira spp. DNA was identified, and 29 animals (69%) were positive at bacteriological culture. The highest sensitivity values for MAT were obtained at the cut-off point of 50. In conclusion, even under hot and dry climate conditions, it is possible that Leptospira spp. can spread through alternative routes such as venereal transmission; moreover, a cut-off of 50 is recommended for the serological diagnosis of cattle from the Caatinga biome.

Serological and Molecular evidence of pathogenic Leptospira species in cattle from slaughterhouses in Veracruz State, Mexico

Cattle raising is the most important livestock activity in Mexico, highlighting the fact that the Country is eight place worldwide in the production of bovine meat. However, cattle can be affected by leptospirosis (a bacterial disease caused by 17 species of spirochetes of the genus Leptospira), which cause reproductive problems that translate into great economic losses. Additionally, these zoonotic agents can cause a rapidly evolving febrile condition in humans, which can be solved after the first week of symptoms or could progress to develop a severe late-phase manifestations. Despite the great impact of these agents on the economy and Public Health, epidemiological surveillance against the infectious disease that cause is not present in municipal slaughterhouses (MS). Therefore, the aim of this study was to identify, using serological and molecular methods, the circulating Leptospira species in three MS in Veracruz State. The frequency of anti-Leptospira antibodies was 67.5%. Additionally, five sequences were recovered that were 99% similar to L. interrogans. This work represents the first national effort for the evaluation of MS as sentinel units, that allow establishing the diversity of species of the genus Leptospira that circulate in cattle and establishing intervention measures for workers risk mitigation, who come into contact with the fluids and organs of infected animals.

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.

A global one health perspective on leptospirosis in humans and animals

Leptospirosis is a quintessential one health disease of humans and animals caused by pathogenic spirochetes of the genus Leptospira. Intra- and interspecies transmission is dependent on 1) reservoir host animals in which organisms replicate and are shed in urine over long periods of time, 2) the persistence of spirochetes in the environment, and 3) subsequent human-animal-environmental interactions. The combination of increased flooding events due to climate change, changes in human-animal-environmental interactions as a result of the pandemic that favor a rise in the incidence of leptospirosis, and under-recognition of leptospirosis because of nonspecific clinical signs and severe signs that resemble COVID-19 represents a "perfect storm" for resurgence of leptospirosis in people and domestic animals. Although often considered a disease that occurs in warm, humid climates with high annual rainfall, pathogenic Leptospira spp have recently been associated with disease in animals and humans that reside in semiarid regions like the southwestern US and have impacted humans that have a wide spectrum of socioeconomic backgrounds. Therefore, it is critical that physicians, veterinarians, and public health experts maintain a high index of suspicion for the disease regardless of geographic and socioeconomic circumstances and work together to understand outbreaks and implement appropriate control measures. Over the last decade, major strides have been made in our understanding of the disease because of improvements in diagnostic tests, molecular epidemiologic tools, educational efforts on preventive measures, and vaccines. These novel approaches are highlighted in the companion Currents in One Health by Sykes et al, AJVR, September 2022.

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.

Bovine endometrial cells do not mount an inflammatory response to Leptospira

Leptospirosis causes abortion, premature birth, and stillbirth in cattle, but the mechanisms remain unclear. Infected cattle shed Leptospira intermittently and present a range of clinical symptoms, making diagnosis difficult. The primary route of Leptospira transmission in any animal is the colonization of the renal tubule and excretion by urine; however, Leptospira can also colonize the female reproductive tract of cows and can be transmitted by semen. Vaccination against Leptospira in the US is routine in cattle, but immunity is not guaranteed. The cell wall of Leptospira contains toll-like receptor agonists including peptidoglycan and lipopolysaccharide. The capacity of Leptospira to initiate an innate inflammatory response from uterine endometrial cells is unknown but may be a cause of reproductive failure. Using cell culture, we tested the capacity of bovine endometrial epithelial cells or human monocytes to elicit an inflammatory response to Leptospira borgpetersenii serovar Hardjo strain TC273. Cells were exposed to either heat-killed Leptospira, Leptospira outer membrane, Escherichia coli lipopolysaccharide, Pam3CSK4 or medium alone for 2 to 24 h. Exposure of bovine endometrial epithelial cells or human monocytes to heat-killed Leptospira or Leptospira outer membrane did not induce the expression of IL1A, IL1B, IL6, or CXCL8, while exposure to E. coli lipopolysaccharide or Pam3CSK4 increased the expression of IL1A, IL1B, IL6, and CXCL8 compared to control cells. This data suggest that Leptospira does not trigger a classical inflammatory response in endometrial cells. Understanding the interaction between Leptospira and the female reproductive tract is important in determining the mechanisms of Leptospirosis associated with reproductive failure.

Lay summary

Cows infected with the Leptospira have abortion and stillbirth. It is not known how Leptospira causes pregnancy failure in the cow. We tested if Leptospira causes inflammation in cells of the uterus which triggers pregnancy failure. We collected cells from the uterus of healthy cows at the abattoir and placed them into culture with Leptospira and measured the expression of genes associated with inflammation. To our surprise, cells of the uterus did not respond to Leptospira; however, the same cells did respond to other disease-causing bacteria found in the uterus. This suggests that cells of the uterus can recognize bacteria and produce an inflammatory reaction but not in response to Leptospira. This finding suggests the immune system of the uterus cannot detect Leptospira which may go on to cause reproductive failure in cows. Understanding how Leptospira interact with cells of the uterus will help reduce pregnancy failure of cows with leptospirosis.

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.

Cross-sectional survey for sheep leptospirosis in the northeast region of Brazil

Sheep farming has shown expressive growth, even in the Northeast region of Brazil, with rainfall below expectations in the last decade. This growth has been observed not only in the number of herds, but also in the number of properties involved in sheep farming. Although expressive, the production of small ruminants still presents low levels of performance, mainly due to the occurrence of diseases, which constitute an obstacle to this activity. The aim of this study was to determine the factors associated with the seroprevalence of leptospirosis in sheep in Northeastern Brazil. Blood samples were collected from 3438 sheep in 190 herds from 48 municipalities, belonging to the states of Ceará, Paraíba, Piauí, Rio Grande do Norte and Sergipe. Serological diagnosis was performed using the microscopic agglutination test (MAT). In 76.3 % (95 % CI = 69.79-81.81) of the herds there was at least one animal seropositive for at least one of the Leptospira spp. serogroups and 14.94 % (95 %CI = 13.8-16.18) of the animals were seropositive. The state of Paraíba had the highest herd (95.7 %) and animal (26.6 %) prevalences, followed by Ceará (93.9 % and 23.7 %, respectively). The most frequent serogroups were Autumnalis (18.68 %), Australis (17.9 %) and Pyrogenes (15.18 %). There was no association between the studied variables and the herd-level prevalence of leptospirosis. High herd and animal-level seroprevalences was found for sheep leptospirosis in the semiarid region of Northeastern Brazil, and there is a need to implement control and prevention measures, such as quarantine, serology, vaccination and adequate treatment, in addition to the introduction of proven healthy animals, mainly in the states of Paraíba and Ceará, aiming to reduce the prevalence of disease.

Leptospira spp. in Naturally Infected Dairy Cow from a Brazilian Border Region

Leptospirosis is an important infectious disease, which can generate large economic losses, especially in the dairy herd. The pathogen that causes this disease may have its entry in Brazilian herds facilitated by the existence of a large extension of land borders. Therefore, the objective of this work was to investigate the presence of DNA and antibodies against Leptospira spp. in samples of vaginal mucus and serum from naturally infected bovine females from small rural dairy farms in a border region. Blood and vaginal mucus samples were collected from 70 Holstein cows, from small rural dairy farms between October 2017 and June 2018. The inclusion criteria for dairy cattle of any breed were aged over 2 years, not vaccinated against leptospirosis, and presenting a history of any reproductive problem such as abortion, stillbirth, repetition of heat, absence of heat, and lack of conception. Blood was collected by puncturing the coccygeal vein; for the collection of vaginal mucus, it was necessary to use a tampon with an applicator. For the detection of anti-Leptospira spp. antibodies, the sera were submitted to microscopic agglutination test (MAT) and, for DNA detection, the vaginal mucus was submitted to the PCR technique. Among the 70 cows, 42.86% had reagents in MAT and the most likely serovar was Wolffi (43.47%). In 74.28% of the vaginal mucus samples, it was possible to amplify the Leptospira spp. DNA. The results of this work show the presence of Leptospira spp. antibodies and DNA in samples of serum and vaginal mucus from naturally infected bovine females from small rural dairy farms in a border region (Brazil × Paraguay). These results demonstrate the importance of considering bovine females as potential vaginal carriers of Leptospira spp. Thus, it highlights the importance of further studies to better understanding of this issue, in addition to carrying out molecular and serological tests, to monitor the infection and further characterize epidemiological studies of leptospirosis in herds from regions that face this international frontier challenge.

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.

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.

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.

Laboratory Diagnosis of Bovine Abortions Caused by Non-Maintenance Pathogenic Leptospira spp.: Necropsy, Serology and Molecular Study Out of a Belgian Experience

Bovine leptospirosis is a bacterial zoonotic disease caused by pathogenic Leptospira spp. The pathology and epidemiology of this infection are influenced by the numerous existing serovars and their adaptation to specific hosts. Infections by host-maintained serovars such as Hardjo are well documented, unlike those from the incidental ones. In July 2014, an emerging phenomenon of an increased incidence of icteric abortions associated with leptospiral infection occurred in southern Belgium. First-line serological analyses targeting cattle-adapted serovars failed at initial diagnosis. This study provides a comprehensive description of laboratory findings—at the level of necropsy, serology and molecular diagnosis—regarding icteric and non-icteric abortions (n = 116) recorded during this time (years 2014–2015) and associated with incidental infection by serovars such as Grippotyphosa, Australis and Icterohaemorrhagiae. Based on these tests, a diagnostic pathway is proposed for these types of infection in cattle to establish an affordable but accurate diagnosis in the future. These investigations add insights into the understanding of the pathogenesis of bovine leptospirosis associated with serovars classically described as non-maintenance.

Identification of Pathogenic Leptospira Species in the Urogenital Tract of Water Buffaloes (Bubalus bubalis) From the Amazon River Delta Region, Brazil

In the current context of deforestation and fire in the Amazon, buffaloes could be a cost-effective and sustainable alternative for cattle production in the region, as they can convert low-quality foods and be raised in floodplain areas. However, little is known about the reproductive diseases that affect these animals; thus, the purpose of this study was to perform the molecular characterization of Leptospira spp. in the urogenital tract of water buffaloes (Bubalus bubalis) raised in the Amazon River Delta region in Brazil. Samples were collected from 114 kidneys, 204 ovaries, and 160 uterine swabs of slaughtered buffaloes in the Macapá microregion of Amapá State (Brazil) and were subjected to PCR to detect bacterial DNA. Positive amplicons were sequenced to identify Leptospira species. Among the total samples, 11/473 were PCR positive (2.3%), including 10 kidney samples and one uterine swab sample. DNA sequencing identified two pathogenic species from the kidney samples: L. interrogans, accounting for 60.0% (6/10) of these samples, and L. borgpetersenii, accounting for 20.0% (2/10), while 20.0% (2/10) were identified only at the genus level. The bacterium in the uterine swab sample was identified as L. interrogans with genetic proximity to strains belonging to the serovar Hardjo. This is the first report of leptospires species identified in buffaloes from the Amazon River Delta region and revealed that these animals may be carriers of different pathogenic Leptospira species, similar to bovines, including showing genital colonization.

Short communication: Uterine leptospiral infection is strongly associated to strains of serogroup Sejroe on experimentally infected hamsters

Leptospira infection is influenced by the host species and the bacterial strain involved. Important differences on their tissue distribution are referred, also depending on the host and the studied strain. Considering tissue distribution of leptospires the majority of the studies focus on a single strain, or strains from the same serogroup with different inoculation doses. Nevertheless, none had associated different serogroups with their tissue distribution. Thus, the present study aims to investigate the hypothesis that tissue distribution of Leptospira spp. on experimentally infected hamsters may vary according to the strain serogroup. Females of Golden Syrian hamsters were used for the experimental infection with Leptospira isolates (n = 13) belonging to serogroups Icterohaemorrhagiae (n = 8) and Sejroe (n = 5). PCRs were conducted in renal, hepatic and uterine tissue. Seven out of the thirteen studied hamsters presented acute clinical signs and were euthanized before the 21° day p.i. (strains VF237, VF52, U81, UFF-SG001, UFF-G19, UFF-B15, L1-130), while the others presented a subclinical infection. Regarding to the PCR results it was possible to observe that, all but one strain (UFF-SG001), which was detected on all the studied tissues, presented some differences on their tissue distribution. All strains could be detected on at least one tissue and a significant association was observed for the occurrence of the strains of serogroup Sejroe in uterus (p = 0.044). The results of the present study indicate that strains of serogroup Sejroe are strongly associated to uterine infection on experimentally infected hamsters.

Zoonotic Pathogen Seroprevalence in Cattle in a Wildlife-Livestock Interface, Kenya

A cross-sectional study was conducted to determine the seroprevalence of Brucella spp. and Leptospira spp. and risk factors of exposure in cattle in three zones with varying land use types and wildlife-livestock interactions. Five villages were selected purposively; two in areas with intensive livestock-wildlife interactions (zone 1), another two in areas with moderate livestock-wildlife interactions (zone 2) and one in areas where wildlife-livestock interactions are rarer (zone 3). Sera samples were collected from 1170 cattle belonging to 390 herds in all the zones and tested for antibodies against Brucella abortus and Leptospira interrogans serovar hardjo using ELISA kits. Data on putative risk factors for seropositivity of these pathogens in cattle were collected using a questionnaire. The overall apparent animal-level seroprevalence of brucellosis and leptospirosis was, respectively, 36.9% (95% CI 34.1-39.8) and 23.5% (95% CI 21.1-26.0). Brucella spp. seroprevalence was higher in zone 1 than in zones 2 and 3 (χ2 = 25.1, df = 2, P < 0.001). Zones 1 and 2 had significantly higher Leptospira spp. seroprevalence than zone 3 (χ2 = 7.0, df = 2, P = 0.029). Results of multivariable analyses identified animal sex (female) and zones (high interface area) as significant predictors (P < 0.05) of animal-level seropositivity of Brucella spp. For Leptospira spp., important predictors of animal-level seropositivity were animal sex (female), zones (moderate interface area) and herds utilizing a communal grazing reserve. The seroprevalences of Brucella spp. and Leptospira spp. in cattle were higher in areas with moderate to high wildlife-livestock interactions than those with rare interactions.

Serological and molecular characterization of Leptospira kirschneri serogroup Grippotyphosa isolated from bovine in Brazil

Leptospirosis is a zoonotic disease caused by a bacterium of the genus Leptospira that affects domestic animals, including cattle. Despite of this importance in livestock, little is known about the epidemiology of leptospirosis in cattle in Brazil and other tropical countries. In this context, the objective of this study was to perform the culture of urine and kidney (n = 372 animals) of slaughtered bovines of Minas Gerais state (Brazil), in order to obtain pure cultures of Leptospira strains and carry out its characterization by serological (microscopic agglutination test) and molecular techniques (rrs, secY sequencing and variable-number tandem-repeat genotyping). One strain, named UFU 02, was obtained from a male bovine without apparent alterations in ante-mortem examination. The strain was characterized belonging to species Leptospira kirschneri and serogroup Grippotyphosa. The serogroup Grippotyphosa is most often described in wild species, suggesting a link between domestic and wild cycles/environments. Considering the importance of the country in livestock breeding, the knowledge about leptospiral strains could help to control the disease in the herds.

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.

Infectivity and virulence of leptospiral strains of serogroup Sejroe other than Hardjo on experimentally infected hamsters

To assess the virulence of leptospires from the serogroup Sejroe (from ruminants), hamsters were tested against 12 strains. Three Guaricura strains induced severe lethal disease, in contrast to the Hardjo strains. Although with the preliminary outcomes, this finding may be useful for the control of bovine leptospirosis in the Americas, where Guaricura is prevalent.

Genomic characterization and comparative analysis of Leptospira kirschneri serogroup Grippotyphosa UC5/2011, a strain isolated after mare abortion: Implications for genital animal leptospirosis

The genome of a Brazilian strain of Leptospira kirschneri serogroup Grippotyphosa isolated from a mare post-abortion was sequenced and analyzed. High symmetrical identity and few structural differences were found when compared with a European strain of the same serogroup, L. kirschneri serovar Valbuzzi strain 200702274. Genes associated with virulence and antimicrobial resistance were found. Knowledge of the virulence evolution of Leptospira remains limited, especially in diseases of the reproductive sphere. We highlight the importance of virulence studies in the sphere of genital leptospirosis.

Reduced susceptibility in leptospiral strains of bovine origin might impair antibiotic therapy

Leptospirosis is a worldwide zoonotic disease determined by pathogenic spirochetes of the genus Leptospira. The control of bovine leptospirosis involves several measures including antibiotic treatment of carriers. Despite its importance, few studies regarding antimicrobial susceptibility of strains from bovine origin have been conducted. The aim of this study was to determine the in vitro susceptibility of Leptospira strains obtained from cattle in Rio de Janeiro, Brazil, against the main antibiotics used in bovine veterinary practice. A total of 23 Leptospira spp. strains were investigated for minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) using broth macrodilution. At the species level, there were not differences in MIC susceptibility except for tetracycline (P < 0.05). Nevertheless, at the serogroup level, differences in MIC were observed among Sejroe strains, mainly for ceftiofur, doxycycline and in MBC for streptomycin (P < 0.05). One strain presented MBC values above maximum plasmatic concentration described for streptomycin and was classified as presenting reduced susceptibility. Efficacy of antimicrobial therapy on bovine leptospirosis could be compromised due to occurrence of infection by Leptospira strains presenting reduced susceptibility.

Occurrence of uterine carriers for Leptospira interrogans on slaughtered cows

Reproductive tract is an important site of infection for chronic leptospirosis and cooperate in pathogenesis of reproductive failure, leading to economic losses. Since serology techniques cannot detect chronic carriers, the molecular analysis of clinical samples is an alternative to detect these animals on livestock. The aim of the present study was to perform a retrospective study in order to detect leptospiral uterine carriers in slaughtered cows. Tissue samples were collected from 50 post-pubertal, nonpregnant cows. These samples were fixed in 10% buffered formalin, paraffin-embedded and stored. PCR targeting lipL32 gene and molecular characterization by secY sequence was performed. Leptospiral DNA was identified in 18% (9/50) examined blocks. Two sequences were characterized as L. interrogans. These findings suggest that the presence of infectious leptospires in uterus is associated with the physiopathogenesis of the reproductive failure.

Potentially Pathogenic Leptospira Species Isolated from a Waterfall in Thailand

We collected water and soil samples from a waterfall in Thailand to investigate the presence of potentially pathogenic Leptospira. Isolation of Leptospira from all the 17 environmental samples was successful. Based on 16S rRNA gene sequence analysis, a diverse group of Leptospira species was recovered from waterfall samples including 2 pathogenic species (Leptospira alstonii [5/17, 29%] and Leptospira kmetyi [1/17, 6%]); 1 intermediate species (Leptospira wolffii [9/17, 53%]); and 2 non-pathogenic species (Leptospira meyeri [1/17, 6%] and Leptospira idonii [1/17, 6%]). The high prevalence of pathogenic and intermediate Leptospira indicates that a waterfall may serve as a natural reservoir of possible pathogens of leptospirosis.

Plurality of Leptospira strains on slaughtered animals suggest a broader concept of adaptability of leptospires to cattle

Leptospirosis in bovines is in majority determined by the host-adapted serovars, mainly Hardjo (types Hardjoprajitno and Hardjobovis), that belong to the serogroup Sejroe. Members of other serogroups as Pomona and Tarassovi have been eventually reported, mainly when outbreaks occurs. Nevertheless, the real role of other strains (non-Hardjo) on determining disease or being transmitted by cattle free of apparent clinical signs of acute infection remains to be elucidated. In that context, the aim of the present study was to investigate the hypothesis that strains of serovars/serogroups other than Hardjo may also be maintained and shed by cattle free of clinical signs. Samples of urine and/or vaginal fluid were collected from 697 bovines from a slaughterhouse located close to Rio de Janeiro, Brazil. Culturing yielded 19 isolates what represents the largest number ever obtained in Brazil on similar studies. These strains were serogrouped and genetically characterized. Fifteen of those were described in other papers and four are first described on the present study. Isolates belong to three different species (Leptospira santarosai, L. alstonii and L. interrogans) and five serogroups (Sarmin, Tarassovi, Shermani, Grippotyphosa and Sejroe). The majority (84.2%) of the isolates belongs to the species L. santarosai, the most prevalent species on cattle in the studied region. Non-Hardjo (non-Sejroe) strains represent 57.9% of the isolates, what indicates an unexpected high diversity of serogroups obtained from these cattle. This suggest that non-Hardjo (non-Sejroe) strains may also be maintained and shed by cattle and that finding must be considered in the epidemiology and control of the disease.