Risk factors associated with Leptospira sp. seroprevalence in goats in Northeast of Brazil.

Goat farming is of great importance for agriculture in Northeast of Brazil, which owns more than 90 % of the national herd, however, most studies on leptospirosis in goats in this region are local surveys with unplanned sampling. Thus, the objective of this study was to determine the factors associated with the seroprevalence of leptospirosis in goats in Northeast region of Brazil. Blood samples were collected from 4121 goats from 222 herds, belonging to the states of Ceará, Paraíba, Piauí , Rio Grande do Norte and Sergipe. Serological diagnosis was carried out using the microscopic agglutination test (MAT). In 82.9 % (95 % CI = 77.3-87.2 %) of the herds there was at least one animal seropositive for at least one of the serogroups of Leptospira sp., and 18.73 % (95 % CI = 17.5-19.9 %) of the animals were seropositive. Antibody titers ranged from 100 to 800 and the most frequent serogroups were Autumnalis (23.06 %) and Australis (20.98 %). According to the robust Poisson regression analysis, four factors were associated with seroprevalence: animal sex (female) (P = 0.040), educational level of the farmer (elementary school) (P < 0.001), contacting institution for technical support (P = 0.040) and presence of irrigation area (P = 0.002). There was a high frequency of Leptospira sp. in goats in the states of Northeast region of Brazil, and it's suggested the need for better technological and preventive assistance of herds.

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.

Spatial distribution of serologically reactive sheep to Leptospira spp. in the northeast region of Brazil

Considering the importance of leptospirosis in sheep farming and public health and the significance of identifying which serogroups circulate in sheep within each region, the objective of this study was to determine the seroprevalence and spatial distribution of the most frequent serogroups causing infection by Leptospira sp. in ovine herds in the Northeast region of Brazil. Blood samples were collected from 4197 sheep from 229 herds in 7 Northeastern States. Sera were analyzed via microscopic agglutination test (MAT). The frequency of seroreactive sheep for Leptospira sp. was 14.06%. The states of Alagoas, Ceará, Paraíba, Piauí, Rio Grande do Norte, and Sergipe, located in the Caatinga biome, had the highest frequencies of serologically reactive sheep, and Maranhão, in the Cerrado biome, had the lowest frequency. The most frequent serogroups were Autumnalis (19.49%), Australis (15.76%) and Serjoe (14.41%). In the states of Ceará, Paraíba, Rio Grande do Norte, and Sergipe, 100% of their municipalities had at least one seroreactive animal. The highest frequencies of seropositive animals were found in the municipalities of União (50%), Passagem (49.06%), Canindé (48.89%), Igaci (28.95%), Gararu (31.2%), Pirapemas (17.5%), and Angicos (16%) located in the states of Piauí, Paraíba, Ceará, Alagoas, Sergipe, Maranhão and Rio Grande do Norte, respectively. The animal-level prevalence (14.06%) obtained in the present study is significant, especially considering the rustic nature of the species and the adverse conditions of the region for the infectious agent. In semi-arid conditions, it has been suggested that perhaps sheep do not seroconvert detectable titers on MAT with a cut-off point of 1:100. It is important to highlight that the ovine population in the Northeast region of Brazil is composed of mixed animals, which have been considered more resistant to infection by Leptospira spp. Also, environmental factors hostile to the survival of the infectious agent in the studied region should be taken into consideration, since they may have influenced the seropositive animal-level prevalence. A noteworthy variation was observed in agglutinin titers, which ranged from 100 to 1,600, where 80.2% of the positive samples had titers ≤ 200. It is important to highlight that more elevated titers (≥ 400) were obtained in all seven states, which may suggest an acute infection caused by a non-adapted serovar, indicating that preventive and control measures focused on possible infection sources for sheep should be adopted. Although some states showed the same serogroups as the most frequent, a variety of serogroups was observed in municipalities, which may indicate different sources of infection, whether interspecies, intraspecies, or via alternative routes of transmission in semi-arid conditions, such as venereal. This indicates that even though sheep are more resistant to infection, they become exposed due to the environment or management conditions. As such, identification, isolation, and treatment of the affected animals are alternative measures recommended for prevention and control of leptospirosis in sheep in the semi-arid region. It is evident that despite the lack of rain observed in the last decade in the Northeast region of Brazil, which prevented the formation of favorable environments for the presence of Leptospira, the infectious agent remains among the sheep, as well as other production and wild animals in the region. Some factors may be contributing to this scenario, such as the fact that sheep farming in the region is = characterized mainly by subsistence systems, where veterinary assistance and adequate sanitary management are absent, thus increasing the possibility of contact with Leptospira. (AU)

Factors associated with the seroprevalence of caseous lymphadenitis in sheep from Northeastern Brazil.

Caseous lymphadenitis (CL) is one of the main infectious diseases in sheep, responsible for great economic losses, mainly in Northeast region of Brazil, which has the largest sheep flock in the country. Thus, the aim of this survey was to determine the factors associated with the seroprevalence of this disease in sheep from Northeastern Brazil using a planned sample of flocks and animals. Samples were collected from 2312 adult and young sheep of both sex from 196 farms, located in 51 municipalities in five Northeastern Brazilian states (Ceará, Paraíba, Piauí, Rio Grande do Norte, and Sergipe). Serological diagnosis was performed using the indirect ELISA technique. Factors associated with seropositivity were identified by variables extracted from epidemiological questionnaires administered to breeders, using univariable and multivariable analyses. Factors associated with prevalence were purebred sheep (Prevalence ratio - PR = 1.189; P = 0.017), ram acquisition from animal expositions (PR = 1.192; P = 0.020), offspring is separated from ewes (PR = 1.132; P = 0.048), water supplied to sheep from ponds (PR = 1.365; P = 0.002), and delayed disposal of infected animals (PR = 1.263; P = 0.027). Flock-level and animal-level prevalences were 93.88 % (95 % CI = 89.60-96.46%) and 37.46 % (95 % CI = 35.51-39.45%), respectively. In view of the high prevalence found here and based on the associated factors, the implementation of an efficient CL control programme in Northeastern Brazil is recommended.

Serological evidence of Leptospira sp. in humans from Fernando de Noronha Island, Brazil.

The prevalence of leptospirosis in humans is highly variable, being influenced by climatic factors, the presence of reservoirs, occupational exposure, recreational activity, and socioeconomic conditions. The objective of this study was to estimate the prevalence of Leptospira sp. and identify the predominant human serovars on the island of Fernando de Noronha, Brazil, based on a microscopic agglutination test. The prevalence of anti-Leptospira antibodies was 1.17% (4/341; I.C. 0.46%-2.98%), with the predominance of serovars Icterohaemorrhagiae, Javanica, Mini and Louisiana. This is the first study on the occurrence of antibodies against Leptospira sp. in humans in Fernando de Noronha and highlights the need to implement control and prevention strategies in this island environment.

Use of serological and molecular techniques for detection of Leptospira sp. carrier sheep under semiarid conditions and the importance of genital transmission route.

It is possible that there are peculiarities in the epidemiology of leptospirosis in regions with a semiarid climate, where the environment is often adverse, allowing the occurrence of alternative transmission routes. The objective of the work was to generate contributions to the diagnosis and epidemiology of Leptospira sp. infection in sheep reared in semiarid conditions, using serological, molecular and microbiological techniques for diagnosis in dry and rainy seasons. Samples of blood, vaginal fluid, urine, bladder, kidney, uterus, uterine tube, ovary and placenta were collected from 104 sheep (52 animals per season - dry and rainy) slaughtered 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 26 (25%) of the animals analyzed by MAT at 1:50 dilution (cut-off 50), while 69 (66.3%) animals had at least one organ/fluid with the presence of Leptospira sp. DNA. Overall, PCR was performed on 758 fragments of organs/fluids from the genital and urinary tracts, and 519 (68.5%) samples tested positive. PCR-positivity was statistically different in dry (46.2%) and rainy (11.5%) seasons for vaginal fluid. It was possible to perform the DNA sequencing in nine samples with 99% similarity to L. interrogans and recovery of viable strains in three samples of vaginal fluid. Regardless of the biological material used in PCR to detect carrier animals and the season, the highest MAT sensitivity values were obtained with cut-off 50 compared to 100. The results obtained indicate that, even in the adverse environmental conditions of the semiarid region, leptospires may survive and propagate by alternative routes of transmission, such as sexual, and the presence of PCR-positive genital tracts in ewes suggests that sexual transmission may play an important role in the epidemiology of the disease in sheep in Brazilian semiarid. In addition, it is suggested the use of titer 50 as cut-off point at serology in semiarid conditions.

Influence of breed on the clinical and hemato-biochemical parameters in sheep experimentally infected with Leptospira sp.

Early diagnosis of leptospirosis may aid in a favorable prognosis in infected animals, but there are few reports of clinical and hematochemical changes in the ovine species, nor whether the breed exerts any influence on the response to infection. Thus, the objective of the present study was to evaluate the clinical, biochemical and hematological alterations in Santa Inês and crossbred ewes challenged with Leptospira interrogans serogroup Pomona serovar Kennewicki. Twenty-four sheep were used in this experiment, 12 crossbred (group A) and 12 Santa Inês (group B). In each group, sheep were conjunctivally and intraperitoneally challenged. During 60 days post-infection the ewes were evaluated for the presentation of clinical signs and the blood was collected for hemogram and serum biochemistry. Concentration of urea and creatinine; serum aspartate aminotransferase activity (AST); gamma-glutamyltransferase (GGT); total protein and albumin; total bilirubin, direct and indirect were analyzed. The urine of these sheep was collected for urinalysis. Only two Santa Inês sheep showed blood in the urine. Clinical signs implicated in Leptospira sp. infection were not identified. Some sheep had anemia, especially crossbred. However, anemia may be attributed to the more effective cellular response that has been identified in crossbred animals. Only one animal presented leukocytosis with neutrophilia, while 11 presented atypical leukopenia, especially those of the Santa Inês breed. There was a decrease in total protein and albumin, as well as the increase in gammaglutamyltranspeptidase (GGT), especially in Santa Inês sheep. The level of aspartate aminotransferase (AST) remained within the normal range for the species. A significant increase (p < 0.05) in conjugated bilirubin levels in challenged animals was detected. Only one sheep intraperitoneally challenged presented a high level of urea in the blood, but the creatinine level remained within the normal range. The intraperitoneal route was responsible for more significant changes (p < 0.05) in the hemogram and biochemistry when compared to the conjunctival route. The results indicate that crossbred sheep have a more efficient cellular response than Santa Inês sheep, which may confer a greater resistance to infection. Clinical signs are not good parameters to follow the development of leptospirosis in crossbred and Santa Inês breed. Hematological and biochemical analyzes were useful in the detection of anemia and possible liver changes caused by leptospirosis. The intraperitoneal route was able to cause more conclusive alterations of the analyzed parameters, however, it is possible that the alterations caused by the conjunctival route reproduce in a more faithful way what happens in a natural situation of infection.