Investigation of anti-Leptospira spp. antibodies and leptospiruria in cats attended to a veterinary teaching hospital in southern Brazil.

Leptospirosis is a bacterial zoonosis that affects both humans and animals worldwide. Currently, it is known that cats may be susceptible to infection. This study aims to investigate the presence of anti-Leptospira spp. antibodies and leptospiruria in cats, using Microscopic Agglutination Test (MAT) and Real-time Polymerase Chain Reaction (PCR) techniques, respectively. A total of 76 cats, undergoing comprehensive anamnesis, general physical examination, and complementary exams were included in the investigation. Among the 76 cats tested, 9.2% (7/76) exhibited the presence of anti-Leptospira spp. antibodies, while Leptospira spp. DNA was detected in at 1.3% (1/76) of the evaluated urine samples. No significant associations were observed between the serological and molecular diagnostic results and the assessed variables, including clinical data and laboratory results of cats testing positive. This study provides insight into the occurrence of Leptospira spp. infection and leptospiruria in cats treated at a veterinary teaching hospital in southern Brazil.

Toxoplasma gondii Survey in Waterfowl and Gulls from Eight USA States.

Sera from 391 waterbirds from eight USA states were tested for Toxoplasma gondii antibodies using the modified agglutination test. Fifteen different waterbird species (26.6%; n=104) were seropositive. Of the adults, 25.4% (n=52) showed a significantly higher T. gondii seroprevalence compared with juveniles (13.4%; n=17); however, sex was not a significant factor.

A novel Bayesian Latent Class Model (BLCM) evaluates multiple continuous and binary tests: A case study for Brucella abortus in dairy cattle.

Bovine brucellosis, primarily caused by Brucella abortus, severely affects both animal health and human well-being. Accurate diagnosis is crucial for designing informed control and prevention measures. Lacking a gold standard test makes it challenging to determine optimal cut-off values and evaluate the diagnostic performance of tests. In this study, we developed a novel Bayesian Latent Class Model that integrates both binary and continuous testing outcomes, incorporating additional fixed (parity) and random (farm) effects, to calibrate optimal cut-off values by maximizing Youden Index. We tested 651 serum samples collected from six dairy farms in two regions of Henan Province, China with four serological tests: Rose Bengal Test, Serum Agglutination Test, Fluorescence Polarization Assay, and Competitive Enzyme-Linked Immunosorbent Assay. Our analysis revealed that the optimal cut-off values for FPA and C-ELISA were 94.2 mP and 0.403 PI, respectively. Sensitivity estimates for the four tests ranged from 69.7% to 89.9%, while specificity estimates varied between 97.1% and 99.6%. The true prevalences in the two study regions in Henan province were 4.7% and 30.3%. Parity-specific odds ratios for positive serological status ranged from 1.2 to 2.2 for different parity groups compared to primiparous cows. This approach provides a robust framework for validating diagnostic tests for both continuous and discrete tests in the absence of a gold standard test. Our findings can enhance our ability to design targeted disease detection strategies and implement effective control measures for brucellosis in Chinese dairy farms.

Modelling variation in test sensitivity for monitoring leptospirosis in beef cattle.

When Bayesian latent class analysis is used for diagnostic test data in the absence of a gold standard test, it is common to assume that any unknown test sensitivities and specificities are constant across different populations. Indeed this assumption is often necessary for model identifiability. However there are a number of practical situations, depending on the type of test and the nature of the disease, where this assumption may not be true. We present a case study of using a microscopic agglutination test to diagnose leptospiroris infection in beef cattle, which strongly suggests that sensitivity in particular varies among herds. We develop and fit an alternative model in which sensitivity is related to within-herd prevalence, and discuss the statistical and epidemiological implications.

Occurrence of serological reactions for Leptospira spp. in donkeys and mules from Minas Gerais, Brazil.

Research concerning leptospirosis in donkeys and mules has been neglected around the world. Therefore, the aim of this study was to investigate the epidemiological situation of the prevalence of anti-Leptospira spp. antibodies in donkeys and mules from the state of Minas Gerais, Brazil. Blood serum samples were collected from 180 animals (109 donkeys and 71 mules) in two rural properties from the state of Minas Gerais, Brazil, and then submitted to a microscopic agglutination test (MAT). Urea and creatinine values were also quantified. Epidemiological variables such as age, breeding system, contact with other animal species, source of water and food, vaccination against leptospirosis, presence of reproductive alterations, and rodent control were also investigated. From 180 samples collected, 39 (21.67%) showed positive results in the MAT, at a dilution ≥ 1:100. Some animals were reactive for more than one serovar. The serovar Tarassovi was the most frequent (14.07%), followed by Hardjo (11.85%) and Wolffi (11.11%). There was a statistically significant difference between animals from 0 to 3 years of age reactive in the MAT in comparison to the other age groups. Most of the animals had urea and creatinine concentrations within the acceptable reference limit; however, there was a significant increase in creatinine levels in some of the test animals. The studied properties showed differences in some epidemiological aspects such as vaccination of the animals, presence of reproductive problems in the herd, and rodent control. Such aspects pointed as risk factors that may influence the frequency of positive serological results in property 1. The present study demonstrated that the prevalence of leptospirosis in donkeys and mules is high and several serovars are being maintained by these animals, representing a potential public health risk.

USE OF A POINT OF CARE TEST TO DETERMINE THE PREVALENCE OF ANTIBODIES TO TOXOPLASMA GONDII IN BLACK BEARS FROM NORTH CAROLINA AND PENNSYLVANIA.

Toxoplasma gondii is an important protozoan parasite of humans and animals throughout the world. Black bears are among the animals with the highest seroprevalence of T. gondii in the United States. A rapid point of care (POC) test is commercially available to detect antibodies to T. gondii in humans. We evaluated the utility of the POC test to detect anti-T. gondii antibodies in 100 wild black bears from North Carolina (n = 50) and Pennsylvania (n = 50). In a blind study, sera were tested by the POC test, and results were compared to the modified agglutination test (MAT). Overall, anti-T. gondii antibodies were detected in 76% (76/100) black bears by both MAT and POC tests. One false positive and one false negative result in the POC test were obtained in bears from Pennsylvania. The sensitivity and specificity of the POC test were both 99% when compared to the MAT. Results from our study indicate the POC test could be a useful screening tool for serological surveillance of T. gondii in black bears.

Identification of the most effective serovars to be included in the MAT antigen panel to optimize the serodiagnosis of Leptospira infection in Northern Italy.

The microscopic agglutination test (MAT) assay is adopted as a world-wide reference test for the serodiagnosis of leptospirosis in humans and animals. One of the main limitations of MAT is the lack of sensitivity and serodiagnostic antigens should be periodically updated with locally circulating serovars in order to optimise its performance. The aim of this study was to determine the need to implement the antigen panel currently adopted in Northern Italy for the diagnosis of Leptospira infection in dogs. For this purpose, a group of 288 dogs with and without clinical signs potentially consistent with Leptospira infection or found to have an increased C-reactive protein (CRP) serum concentration, sampled in 2013-2016 in Northern Italy, were tested by MAT comparing the results obtained with a nine antigens panel (Australis-Bratislava, Ballum-Ballum, Canicola-Canicola, Grippotyphosa-Grippotyphosa, Icterohaemorrhagiae-Copenhageni, Icterohaemorrhagiae-Icterohaemorrhagiae, Sejroe-Hardjo, Pomona-Pomona and Tarassovi-Tarassovi serovars) routinely adopted and a panel expanded to 27 antigens. In general, the antigen panel currently adopted in Northern Italy for the routine MAT assay resulted adequate for the diagnosis of Leptospira infection in dogs. The main exception concerns the Sejroe serogroup, with the Saxkoebing and Sejroe serovars that were more effective than Hardjo for diagnosis in dogs and whose inclusion in the antigen panel is recommended. Among other antigens evaluated in this study, Cynopteri serovar was detected with high frequency but its pathogenic role in dogs and as public health threat deserve further investigation.

Microscopic detection of Leptospira bacterial organisms in urine sediment from a young dog with leptospirosis and a review of the pathobiology and diagnosis of canine leptospirosis.

Samples collected from an 11-month-old Dachshund-mix dog with a history of acute azotemia, fever, and enlarged and irregular kidneys were received at the Colorado State Veterinary Diagnostic Laboratory (CSU VDL). The submitting veterinarians were concerned about lymphoma versus acute nephritis/pyelonephritis. The CSU clinical pathology laboratory received urine for urinalysis and kidney aspirates for cytologic evaluation. Urine had also been submitted for aerobic culture and Leptospirosis PCR, and serum was submitted for Lepto-5 microscopic agglutination testing (MAT). Upon examination of a wet mount of the urine sediment, technical staff noted "vibrating" clumps of granular-appearing material throughout the slide, which prompted the preparation of a stained sediment slide for pathologist review. Very small, faintly staining organisms were observed, and an attempt was made to picture-match these with published reports of Leptospira in dog urine, but none could be found. In addition, some references claimed that Leptospira organisms are not seen in urine with light microscopy. The suspicion that these organisms were Leptospira sp. was supported by the MAT results and later confirmed by PCR. The organisms subsequently exhibited strong positive immunolabeling for the Leptospira antigen. This case report provides a searchable record of Leptospira organisms visualized by routine light microscopy in dog urine during natural infection and a review of canine leptospirosis pathobiology and diagnosis.

Investigation of Brucella canis and Brucella abortus Seropositivity by In-House Rapid Slide Agglutination Test and In-House ELISA in Northern Cyprus.

The incidence of Brucella canis (B. canis) in humans is unknown in Northern Cyprus. In this study, we investigated the prevalence of B. canis and Brucella abortus (B. abortus) infection in human sera and evaluated the results obtained by agglutination-based techniques using standardized antigens made from B. canis comparatively. All of the subjects were negative in terms of Rose-Bengal plate test. Undiluted serum samples were initially screened by rapid slide agglutination test (RSAT), and those which were found positive were retested in the dilution of 1/25-1/200. Confirmation of the positive results was performed by using 2-mercaptoethanol standard agglutination test (SAT). The test antigen was prepared from the less mucoid M (-) variant of B. canis, and 1/1,048 titered dog antiserum was used as positive control. In 225 serum samples, 3.6% (8/225) was positive by B. canis M (-) RSAT, 4.4 % (10/225) was positive by B. canis M (-) indirect enzyme-linked immunosorbent assay (iELISA). 5.3% (12/225) was positive by B. abortus S99 RSAT and 9.8% (22/225) was positive by B. abortus S99 iELISA. Nine samples were positive by both B. abortus S99 RSAT and B. abortus S99 iELISA. Seven samples were positive by both B. canis M (-) RSAT and B. canis M (-) iELISA. One patient was positive by all methods. It is important to evaluate patient samples with RSAT and iELISA. Until the notification system gives better results to the Ministry of Health, in order to reach the real data for Northern Cyprus, multicenter prevalence determination studies should be done for future.

New insights on Leptospira sp. infection in ewes maintained in field semiarid conditions.

Leptospirosis is poorly studied in small ruminants raised in field semiarid conditions. In this study we compared serological, bacteriological and molecular diagnostic methods in ewes maintained in field Brazilian semiarid conditions. Blood, vaginal fluid and urine samples were collected from 60 Morada Nova ewes raised in a semi-intensive system in the Brazilian semiarid. Diagnostic tests performed were microscopic agglutination test (MAT), polymerase chain reaction (PCR) and bacterial isolation. Anti-Leptospira sp. antibodies were found in eight (13.33%) animals analyzed by MAT at reciprocal titer 25 (cut-off 25), while Leptospira sp. DNA was detected in urine or vaginal fluid of 56 animals (93.33%). There was growth of leptospires in 10 urine cultures and in 11 vaginal fluid cultures, however, two of urine (2/60-3.33%) and eight cultures of vaginal fluid (8/60-13.33%) were confirmed by PCR. Two samples of vaginal fluid (one of each animal) were submitted to sequencing demonstrating 99% similarity with L. santarosai and L. interrogans. The highest MAT sensitivities were obtained with reciprocal titer 25 (cut-off 25) compared to 50 and 100. The performance of different diagnostic techniques for leptospirosis in ewes raised in field semiarid conditions allowed a better evaluation of the herd, as well as made it possible to identify carrier animals. Genital route may be important for efficient transmission and without dependence on environmental factors in ewes from semiarid, as well as it's highlighted that titer 1:25 in serology was more efficient, indicating its use in ewes in field semiarid conditions.

Leptospira sp. infection in bats: A systematic review and meta-analysis.

Bats are the only flying mammalian animals and are distributed worldwide. Bats are well-known hosts of several zoonotic viruses and bacteria, including Leptospira sp. Here, we performed a systematic review and a meta-analysis of evidence of Leptospira sp. infection in bats by examining studies published between 1964 and 2021. We reported the frequencies of various species and serogroups on all continents, several species and feeding habits of bats, and different diagnostic tools. Together, 33 papers from all continents with seven to 2077 individuals from one to 31 species were included. Molecular detection was conducted in most studies, followed by MAT (Microscopic Agglutination Test) and isolation and identification. Molecular characterization of Leptospira sp. revealed L. borgpetersenii as the most frequent species. Moreover, 179 positive samples for MAT contained the most likely infecting serogroups described, particularly the Australis serogroup. The percentage of positive tests in isolation and identification ranged between 0% and 0.5%. The highest frequency of Leptospira infection among the continents was observed in Asia, whereas South America had the lowest percentage. Finally, Nycteridae and Rhinonycteridae were the most frequently infected bat families. Our study provides valuable information about the epidemiology of Leptospira sp. infection in bats.

Use of machine-learning algorithms to aid in the early detection of leptospirosis in dogs.

Leptospirosis is a life-threatening, zoonotic disease with various clinical presentations, including renal injury, hepatic injury, pancreatitis, and pulmonary hemorrhage. With prompt recognition of the disease and treatment, 90% of infected dogs have a positive outcome. Therefore, rapid, early diagnosis of leptospirosis is crucial. Testing for Leptospira-specific serum antibodies using the microscopic agglutination test (MAT) lacks sensitivity early in the disease process, and diagnosis can take >2 wk because of the need to demonstrate a rise in titer. We applied machine-learning algorithms to clinical variables from the first day of hospitalization to create machine-learning prediction models (MLMs). The models incorporated patient signalment, clinicopathologic data (CBC, serum chemistry profile, and urinalysis = blood work [BW] model), with or without a MAT titer obtained at patient intake (=BW + MAT model). The models were trained with data from 91 dogs with confirmed leptospirosis and 322 dogs without leptospirosis. Once trained, the models were tested with a cohort of dogs not included in the model training (9 leptospirosis-positive and 44 leptospirosis-negative dogs), and performance was assessed. Both models predicted leptospirosis in the test set with 100% sensitivity (95% CI: 70.1-100%). Specificity was 90.9% (95% CI: 78.8-96.4%) and 93.2% (95% CI: 81.8-97.7%) for the BW and BW + MAT models, respectively. Our MLMs outperformed traditional acute serologic screening and can provide accurate early screening for the probable diagnosis of leptospirosis in dogs.

Glanders and brucellosis in equids from the Amazon region, Brazil.

Glanders and brucellosis are zoonotic infectious diseases that affect equids in several countries worldwide. On Marajó Island (Amazon region of Brazil), Marajoara and Puruca horses, which are well adapted to the climatic and territorial adversities of the region, play a fundamental role in the local economy and in the sociocultural lives of the population. However, these animals have undergone a drastic reduction in number, markedly due to precarious veterinary care, unknown causes of morbidity and mortality, and disordered crossing with other breeds introduced to the island. Thus, this study aimed to investigate the occurrence of glanders and brucellosis in equids on a property located in the municipality of Soure, Marajó Island (Brazil). Serum samples were collected from 388 animals (357 horses and 31 mules), maintained in an extensive breeding system, in a property that was also extensively breeding buffaloes, goats, and sheep, with contact among species. The sera were tested for glanders using an indirect ELISA (ELISAi), and the results were confirmed by immunoblotting. The diagnosis of brucellosis was made using the Rose Bengal test (RBT) and confirmed through the Serum Agglutination test (SAT) and 2-mercaptoethanol test. In the case of glanders, 2.31% (9/388) of animals were positive in ELISAi test, of which eight had results confirmed by immunoblotting, representing 2.06% seropositivity in the entire herd. For brucellosis, serum samples from 6.7% (26/388) horses were reactive in the RBT, of which 4.12% (18/388) had a titer ≥50 and 2.06% (8/388) had a titer ≥100 in the SAT. This is the first study to report the occurrence of glanders and equine brucellosis in the municipality of Soure/Marajó Island. Monitoring the occurrence of such diseases is extremely important since they affect the herds economically and zootechnically, in addition to their high zoonotic potential. The number of animals sampled in this study, as well as the way they are raised and managed, is representative of the total equid population of the island. These results, combined with previous studies on buffaloes, indicate that these diseases are endemic in the Marajo Island.

Determination of an optimal ELISA cut-off for the diagnosis of Toxoplasma gondii infection in pigs using Bayesian latent class modelling of data from multiple diagnostic tests.

Toxoplasma gondii infection in pigs is commonly diagnosed using serological tests that detect IgG antibodies targeted against the parasite. Such tests include enzyme-linked immunosorbent assay (ELISA), modified agglutination test (MAT), and western blot (WB), which are commercially available as rapid test kits. In this study, we evaluated the manufacturer recommended cut-off of ELISA-PrioCHECK test kit and determined a new optimal cut-off for identifying T. gondii infections in pigs. Assessment of the commercial ELISA kit was done by including data from two additional serological tests, MAT, and WB, applied to seven pig population categories with varying prevalences. A total of 233 plasma samples that were previously used in other studies for investigating T. gondii seroprevalence in pigs in Denmark were randomly selected for inclusion, including 95 samples that had previously been analysed with all three tests and an additional 138 samples that were analysed using the three serological tests for this study. In the absence of a gold standard test, a latent class model was fit to the data to obtain estimates of sensitivity and specificity for each of the tests along with prevalence in each of the populations. A cut-off that maximized the sensitivity and specificity of the ELISA test was then selected. The optimal cut-off value for percent of positive control (PP) in ELISA-PrioCHECK was estimated to be 27.7 PP, which is higher than the cut-off value of 20 PP that is recommended by the manufacturer. At this cut-off, the estimated sensitivities of ELISA, MAT and WB were 99.2% (96.3-100.0%), 96.3% (88.0-100.0%), and 89.8% (80.0-98.0%), respectively. The estimated specificities of ELISA, MAT and WB were 95.2% (92.5-97.6%), 99.6% (97.5-100.0%), and 98.2% (95.9-100.0%), respectively. Our findings have broad relevance to the use of the ELISA-PrioCHECK test kit for detecting Toxoplasma gondii infection in pigs.

Urban landscape and infection risk in free-roaming cats.

Despite public concern on the role of free-roaming cats as reservoirs of zoonotic agents, little is known about the influence of urban and peri-urban landscapes on the exposure risk. We evaluated the seroprevalence of three zoonotic agents (Chlamydia felis, Coxiella burnetii and Toxoplasma gondii) in domestic cats (Felis catus). Two hundred and ninety-one free-roaming cats were trapped in Murcia municipality (Southeast Spain), and their sera were tested for specific antibodies against T. gondii using a modified agglutination test (MAT), and for C. felis, C. burnetii and feline immunodeficiency virus (FIV) antibodies with ELISA technique. Pathogen seroprevalence at 95% CI was calculated for each sex and age category (up to and over 12 months) and compared with a chi-squared test. The role of human population density and urban landscape characteristics on the risk of pathogen exposure in the cat population was explored using generalized linear models. Seropositivity against a single pathogen was found in 60% of the cats, while 19% was seropositive for two or three pathogens. Seroprevalence of C. felis was 8% (CI95% : 5-11), 37% (CI95% : 31-42) for C. burnetii and 42% (CI95% : 36-47) for T. gondii. In addition to these three pathogens, FIV seropositivity was low (1%, CI95% : -0.1 to 2) and adult cats were more likely to be seropositive to C. burnetii than young individuals (OR: 2.3, CI95% : 1.2-4.2). No sex or age class differences in seroprevalence were observed for the rest of the pathogens. Seropositivity was correlated with water surface areas for C. felis, and not with crop areas. Coxiella burnetii seropositivity was correlated with the percentage of urban areas (continuous with only buildings and discontinuous, that include buildings, parks, and pedestrian and urban green areas), human population size and peri-urban areas with shrubs, and not correlated with other agricultural landscapes (orchards and crop areas). However, the seroprevalence of T. gondii was only associated with agricultural landscapes such as orchards. The detection of hotspot areas of high pathogen exposure risk is the basis for municipal services to implement surveillance and risk factor control campaigns in specific-risk areas, including (a) efficient health management of urban cat colonies by geographical location, population census and health status monitoring of the components of each cat colony, (b) improvement of hygiene and sanitary conditions at the feeding points of the cat colony and (c) free-roaming cat trapping for health monitoring and, in the long term, to know the evolution of the health status of their populations.

Evaluation of diagnostic tests' sensitivity, specificity and predictive values in bovine carcasses showing brucellosis suggestive lesions, condemned by Brazilian Federal Meat Inspection Service in the Amazon Region of Brazil.

Cervical bursitis is a suggestive lesion of bovine brucellosis. Diagnostic sensitivity and specificity of two brucellosis serological tests, Rose Bengal (RB) and serum agglutination test with 2-mercaptoethanol (SAT/2-ME), and of isolation and identification (bacteriology) were evaluated through Bayesian latent class analysis (BLCA). A total of 165 paired serum and cervical bursitis samples detected at inspection by Brazilian federal meat inspection services were analyzed. The best model fit to the data occurred when accounting for the conditional dependence between serological tests. According to this model, RB and SAT/2-ME had almost the same sensitivity, 0.960 [0.903 - 0.992] and 0.963 [0.906 - 0.994] with 95 % Credible Interval (95 %CrI), respectively. Specificities were 0.9068 [0.562 - 0.997] and 0.875 [0.546 - 0.990] for RB and SAT/2-ME, respectively, also with 95 %CrI. Bacteriology had lower sensitivity than serological tests, 0.594 (95 %CrI: [0.525 - 0.794]) and the highest specificity of all evaluated tests, 0.992 (95 %CrI: [0.961-1.00]). Prevalence of infected animals was 0.829 (95 %CrI: [0.700-0.900]). BLCA showed that both RB and SAT/2-ME fitted to the purpose of initial screening the brucellosis suspect in carcasses with cervical bursitis in a reliable way. The results of RB or SAT/2-ME can guide the sanitary actions for brucellosis control and help the implementation of a risk-based surveillance system in the meat production chain. This strategy is especially true in remote areas with large beef cattle herds, raised extensively, where in vivo tests are rarely performed due to logistic and management constraints, as in the Northern region of Brazil.

Emerging leptospirosis in urban Sydney dogs: a case series (2017-2020).

Canine leptospirosis has not been reported in the Sydney dog population since 1976. However, between 2017 and 2020, leptospirosis was confirmed in 17 dogs, five of which were known to hunt rodents. Dogs infected between 2017 and 2019 lived within a 3 km radius in the Inner City of Sydney (n = 11). In 2020, cases emerged across a broader area of Sydney; Inner City (n = 1), Inner West (n = 3), Lower North Shore (n = 1) and Upper North Shore (n = 1). The disease was characterised by severe hepatorenal involvement resulting in an unusually high case fatality rate (88%). In conjunction with supportive clinical signs, diagnosis was confirmed by real-time PCR on whole blood (n = 1), kidney (n = 1), urine (n = 4), whole blood and urine (n = 9) or by seroconversion (n = 3). Antibody titres determined by Microscopic Agglutination Test (MAT) to Leptospira serovars were measured in 12 dogs: seven were positive for serovar Copenhageni, one was positive for serovar Hardjo, three were negative for all serovars, likely due to insufficient time for seroconversion before death and one had a low positive titre (1/50) for serovars Australis and Robinsoni. This sudden emergence of a highly fatal disease in pet dogs in Sydney has led to the introduction of Leptospira vaccination protocols for dogs living in inner Sydney using a monovalent vaccine containing serovar Copenhageni. The success of this vaccination program will require ongoing research to understand the emergence of leptospirosis in this region and the serovars involved.

First detection of antibodies against Leptospira among free-ranging neotropical non-human primates in the Peruvian Amazon lowland rainforest.

Leptospirosis is a bacterial zoonotic disease with multiple serogroups that infects wildlife and humans alike. Several studies have detected the presence of leptospiral antibodies in captive Neotropical primates, suggesting that they are asymptomatic carriers. However, the presence of antibodies in free-ranging primates and their potential role as reservoirs for this pathogen is not known. In this study, we used the Microscopic Agglutination Test (MAT) to screen two species of free-ranging tamarins for the presence of Leptospira antibodies using a panel of 21 serogroups. A total of 56 primates (26 Leontocebus weddelli and 30 Saguinus imperator) were screened at the Estación Biológica Río Los Amigos in Madre de Dios, Peru. MAT results with titres of ≥100 in single samples were considered seropositive. Prevalence ratios (PR) were estimated for age group, sex and host species identity. Overall, 51.8% (29/56) of animals were reactive for at least one Leptospira serogroup. Serogroups were distributed as follows: Iquitos (41.1%), Icterohaemorrhagiae (14.3%), Sejroe (3.6%), Autumnalis (1.8%) and Bataviae (1.8%). No significant differences (p > .05) were found for seropositivity frequencies among categories within assessed variables. These results suggest that free-ranging L. weddelli and S. imperator might serve as reservoirs for pathogenic Leptospira serogroups. Given increasing human-wildlife contact, future studies that test for active infection are required to determine potential transmission risks to humans.

High specificity of the Salmonella Pullorum/Gallinarum rapid plate agglutination test despite vaccinations against Salmonella Enteritidis and Salmonella Typhimurium.

In Europe, monitoring of breeding stock for Salmonella Pullorum (SP) or Salmonella Gallinarum (SG) infections is compulsory at the point of lay. Vaccinations against Salmonella Enteritidis (SE) and Salmonella Typhimurium (ST) are increasingly administered in Europe. These vaccines might induce cross-reactions in the rapid plate agglutination (RPA) SP/SG test due to shared O-antigens, possibly resulting in a lower test specificity. The extent to which the specificity of SP/SG serological tests is influenced by SE and/or ST vaccinations in the field has not been reported. In this paper, we report the diagnostic and flock specificity of the commercially available RPA SP/SG test using 1:2-1:16 serum dilutions on four panels of sera: SPF sera, field sera from flocks of varying age and SE/ST vaccination status, and reference sera from an international proficiency testing scheme. The results showed that the use of live SE/ST vaccines did not influence the specificity of the RPA SP/SG test. Inactivated vaccines showed a drop of the diagnostic specificity to 96.54% and a flock specificity of 34.1% when the 1:2 serum dilution was used. The 1:8 serum dilution showed a diagnostic specificity of 99.41% and a flock specificity of 86.4%. In conclusion, the use of SE/ST vaccines has either no effect or a modest effect on the specificity of the RPA SP/SG test used to monitor flocks. The main factors are the type of vaccine, and the serum dilution used for testing and a cut-off.

Seroprevalence and risk factors for Leptospira spp. in small ruminants of semi-arid zone in northeastern Colombia.

Leptospirosis in small ruminants is an economically important disease that causes important losses by pathologies of the reproductive tract. The present study aimed to estimate the seroprevalence and risk factors associated with Leptospira spp. in small ruminants under traditional husbandry systems. A cross-sectional epidemiological study was carried out in a sample of 1039 animals which included 793 sheep and 245 goats from 49 farms of 10 municipalities of northeastern areas of Colombia. The MAT test using a panel of 13 laboratory serovars was performed to diagnose the Leptospira spp. antibodies in the serum samples of animals. A structured questionnaire was filled in each farm to obtain information on putative risk factors, and its association with Leptospira spp. infection was detected by univariate and multivariate logistic regression. The general seroprevalence showed a rate of 13.9%, the 79.6% of farms showed at least one positive animal, the 14.2% and 0.4% of positive animals showed titers ≥ 1:100 and 1:200, respectively. The seroprevalence in sheep and goats showed a rate of 13.1% and 16.2%, respectively. The most common serovars in positive animals were Autumnalis (3.6%), Tarassovi (3.4%), Bratislava (2.9%), Mini (2.9%), Bataviae (1.4%), Canicola (0.3%), and Grippotyphosa (0.3%). The univariate and multivariate analysis showed as risk factors the absence of housing system (OR = 3.412 CI: 1.347-8.152), the absence of quarantine measures to new animals (OR = 1.371 CI: 0.943-1.978), and the protective factor identified was the use of Toggenburg breed (OR = 0.571 CI: 0.249-1.074). This exploratory study showed the Leptospira spp. positive small ruminants located in the northeastern areas of Colombia with titer associated with chronic and subclinical infection.