Diego Figueiredo da Costa

Flock-level risk factors associated with leptospirosis in dairy goats in a semiarid region of Northeastern Brazil.

A cross-sectional study based on a planned sampling was carried out to determine flock-level risk factors associated to Leptospira spp. infection in dairy goat flocks in a semiarid region of Northeastern Brazil. Serum samples from 975 adult dairy goats from 110 flocks were examined for Leptospira spp. antibodies by MAT using 24 serovars. A structured questionnaire focusing on risk factors for leptospirosis was completed for each flock. Of the 110 flocks 48 (43.6%; 95% CI: 34.2-53.4%) presented at least one seropositive animal, and most frequent serovar was Autumnalis (10.9%). Ninety-eight (8.7%; 95% CI: 5.7-12.9%; design effect=4.23) of the 975 goats tested seropositive at MAT, and serovar Autumnalis was also the most frequent (1.74%). Presence of rodents (OR=2.78; P=0.015) was identified as a risk factor. There was also association between history of infertility (OR=14.74; P=0.015) and prevalence of positive flocks. We suggest that a program of rodent control should be included in the flock management practices aiming to reduce transmission of the agent and then to reduce prevalence of positive flocks and occurrence of reproductive disorders such as impaired fertility.

Caracterização epidemiológica e fatores de risco associados à leptospirose em ovinos deslanados do semiárido brasileiro

The aim of this investigation was to determine the herd-level and animal-level prevalence of leptospirosis in sheep from the semiarid of Paraiba State, Northeast Brazil, as well as to identify risk factors. Blood samples were collected from 1,275 sheep from 117 flocks in 19 counties in the Sertao mesoregion, Paraiba. For the serological diagnosis of leptospirosis the microscopic agglutination test (MAT) using 24 Leptospira spp. serovars as antigens was carried out. Of the 117 flocks studied 33 (28.20%) presented at least one seropositive sheep, and of the 1,275 animals 69 (5.41%) were seropositive with titers ranging from 100 to 3,200. Reactant serovars were Autumnalis (49.30%), Andamana (27.53%), Sentot (17.39%), Whitcomb (4.34%) and Australis (1.44%). Herd size > 48 sheep (odds ratio =2.26; 95% CI =1.33-5.07; p=0.021) and participation in animal exhibits (odds ratio =9.05; 95% CI =0.96-85.71; p=0.055) were identified as risk factors. The need was suggested for studies on the isolation of the agent, characterization of its pathogenicity and its economic impact on sheep flocks of the region, and sanitary control in sheep agglomerations was recommended.

Caracterização epidemiológica e fatores de risco associados à infecção por Brucella ovis em ovinos deslanados do semiárido paraibano

The aim of this investigation was to determine the seroprevalence of Brucella ovis in sheep flocks and individual sheep in the Sertao mesorregion, Paraiba state, Northeastern Brazil, as well as to identify risk factors. Blood samples were collected from 1,134 sheep from 103 flocks in 17 counties. For the serological diagnosis of B. ovis infection the agar gel immunodiffusion test (AGID) was carried out. A flock was considered positive when there was at least one seropositive animal. Of the 103 flocks used, 21 (20.39%) presented at least one seropositive sheep, and of the 1,134 sheep examined 59 (5.20%) seropositive animals were diagnosed. Cleaning of facilities (odds ratio = 7.13; 95% CI=1.56-32.47; p=0.011) and purchase of animals (odds ratio = 6.06; 95% CI=1.39-26.48; p=0.017) were identified as risk factors. Based on the risk factor analysis, it is recommended the diagnosis of B. ovis infection prior to purchase of sheep and the periodic cleaning of the facilities on the farm.

Efficacy of leptospiral commercial vaccines on the protection against an autochtonous strain recovered in Brazil

In swine and bovines, leptospirosis prevention and control is carried out via vaccination of susceptible animals using bacterins. However, the efficiency of leptospirosis vaccines has been questioned. This work aimed to investigate the potency of five leptospirosis vaccines sold commercially in Brazil, challenging the animals with one autochthonous strain of Leptospira, Canicola serovar, denoted LO4, isolated from swine. The standard protocol was followed, and renal carriers of Leptospira were identified among the surviving animals by culture and PCR. Of the five vaccines tested, only two proved effective. None of the surviving animals was positive by culture; however, one animal was positive by PCR. Three of the five vaccines sold commercially in Brazil for the immunization of swine or bovines failed the test of the efficacy to protect the vaccinated animals following challenge with an autochthonous Leptospira strain, Canicola serovar. The two vaccines provided protection against the renal carrier state in the surviving animals. The criteria used to produce leptospirosis bacterins sold commercially in Brazil must be reviewed. The industry should support researches on leptospiral vaccinology to improve the quality of the present vaccines and discover new immunogenic strains, because it is known that vaccination is one of the most important tools to increase the reproduction rates in livestock.

Caracterização epidemiológica e fatores de risco associados à infecção por Chlamydophila abortus em ovinos deslanados do semiárido brasileiro

The aim of this investigation was to determine the flock-level and animal-level prevalences of Chlamydophila abortus in sheep from the semiarid region of Northeastern Brazil, as well as to identify risk factors. Blood samples were collected from 476 sheep of 72 flocks in 14 counties in the Sertao mesoregion, state of Paraiba. For the serological diagnosis of Chlamydophila abortus infection the complement fixation test (FC) was carried out. A flock was positive when presented at least one seropositive animal. From the 72 flocks, 38 (52.8%) presented at least one seropositive sheep, and 94 (19.7%) of the 476 animals were seropositive. Participation in animal expositions (odds ratio= 4.31; 95% CI= 1.80-10.35; p=0.011) was identified as risk factor. It is suggested that C. abortus infection is spread in sheep of the region, and based on the risk factor analysis sanitary control in animal expositions is recommended.

Strategies of the control of an outbreak of leptospiral infection in dairy cattle in Northeastern Brazil

The aim of the present study was to describe the strategies of the control of an outbreak of leptospiral infection in dairy cattle in Maranhão State, Northeastern Brazil. In the period from January to July 2015, 18 (17%) out of 106 cows presented abortion, six (5.7%) stillbirth, and 12 (11.3%) repeated estrus, totaling 24 animals with reproductive problems. The diagnosis of leptospirosis was based on serology (microscopic agglutination test—MAT), bacteriological culture, and polymerase chain reaction (PCR). Antibiotic therapy, vaccination protocols, and changes in management practices were suggested as control measures. Of all animals on the farm (n = 280), 136 (48.6%) were seropositive for at least one serovar of Leptospira sp. No pure leptospiral culture was obtained. Eight of the animals with reproductive problems yielded positive PCR results (vaginal fluid of seven animals and urine and vaginal fluid of one animal). Genetic sequencing of a vaginal fluid/urine PCR-positive sample revealed Leptospira borgpetersenii. One year after the adoption of control measures, no reproductive problems were observed. Thus, leptospirosis probably caused the reproductive failures in the herd, and the control and prevention measures implemented were efficient in controlling the disease.

High frequency of genital carriers of Leptospira sp. in sheep slaughtered in the semi-arid region of northeastern Brazil

Although some studies in sheep have indicated leptospire colonization of the genital tract, further studies are needed to clarify the role of genital carriers in this species. Thus, this study aimed to evaluate the colonization of pathogenic leptospires in the genital and urinary tract of slaughtered sheep. Fifty-seven adult, female woolless sheep destined for slaughter were used. Renal (n = 57), bladder (n = 57), ovary (n = 34), uterine tube (n = 44), and uterus (n = 33) samples were collected for molecular detection of Leptospira sp. DNA, and blood samples (n = 57) for serological testing. The molecular testing was performed using polymerase chain reaction (PCR), and the serological testing was performed using microscopic serum agglutination test (MAT). Samples with amplifying DNA were subjected to genetic sequencing. In total, leptospiral DNA was found in the tissues of 44 (77.2%) sheep, whereas only nine animals were positive on both PCR and MAT; there was slight agreement between PCR and MAT techniques (k = 0.0268; p = 0.684). In 61 (54.9%) genital tract and in five (4.4%) urinary tract samples, the leptospiral DNA was detected, with significant difference (p < 0.001). The genes of one sample from the uterine tube and another from the bladder were sequenced and demonstrated 99% similarity to Leptospira interrogans. Anti-Leptospira antibodies were detected in 11 (19.3%) of the tested animals. The results reinforce the importance of the genital tract as an extra-renal site of colonization, suggesting the possibility of venereal transmission in sheep.

Susceptibility among breeds of sheep experimentally infected with Leptospira interrogans Pomona serogroup

Leptospirosis is a disease that negatively affects the productive and reproductive indices of ruminants. Sheep are considered highly resistant to infection, although susceptibility may vary among breeds. Thus, the aim of the present study was to analyze the susceptibility between sheep breeds to the experimental infection by leptospires of the Pomona serogroup. Pomona serogroup, Kennewicki serovar strain (1 × 107 bacteria) was inoculated via the conjunctival route in 12 sheep divided into two groups, one comprising Santa Inês ewes and the other comprising crossbred sheep. In each group, five ewes were challenged with the bacterial strain and one was used as control. All sheep were monitored for 60 days, during which blood samples were collected for serological diagnosis and urine and vaginal fluid samples for molecular and microbiological analyses. Finally, as ewes were submitted to euthanasia and necropsy, some tissues of interest were collected for microbiological, molecular, and histopathological diagnoses. The groups were compared regarding the number of positive reactions according to diagnostic tests. All sheep in each group presented antibodies to Leptospira in all serological analyses, except animals of the control group. However the Santa Inês sheep presented higher concentration and duration of the titers, and their positive reactions were detected earlier than those in crossbred sheep. The antibody titers in group A (median 200, geometric mean 317.48) were significantly different from the group B (median 800, geometric mean 918.96) at D60 post-infection (P = 0,032). The Santa Inês sheep presented a higher number of positive reactions than did the crossbred sheep in the molecular diagnostic tests. According to the molecular diagnosis, the Santa Inês sheep presented more reactions (urine and vaginal fluid) compared to crossbred ewes, but there was no predominance in the detection of leptospiral DNA when comparing urine and vaginal fluid results, nor even between the number of positive kidneys and uterus. The Santa Inês sheep presented a higher number of positive bacteriological cultures. No sheep in either group presented alterations in anatomopathological and histopathological findings. Pure-bred sheep may be more susceptible than crossbred sheep to infection by Leptospira sp. Our findings emphasize the importance of the genital tract as a site of extraurinary infection and indicate the possibility of venereal transmission in the species.

Molecular and serological investigation of infectious diseases in captive and free-range crab-eating fox (Cerdocyon thous – Linnaeus, 1776) from northeastern Brazil

The aim of this study was to detect DNA and antibodies anti-Leishmania spp., Neospora caninum and Toxoplasma gondii in captive and free-range crab-eating fox (Cerdocyon thous) from northeastern Brazil. Twenty-five crab-eating foxes from different states of northeastern Brazil were sampled by this study. Blood samples were collected by cephalic or jugular vein punctures. The whole blood was submitted to PCR, and the sera samples to the serological analysis as follows: MAT for T. gondii, NAT for N. caninum, and ELISA for L. chagasi. The frequence of antibodies anti-T. gondii was 50% and 29.41% for free-range and captive wild canids, respectively. The frequence of antibodies anti-N. caninum observed by this study was 62.50% and 23.52% for free-range and captive wild canids, respectively. The frequence of antibodies anti-L. chagasi was 4.0% for captive wild canids. Co-infections cases were identified as follows: one captive wild canid seropositive for T. gondii and L. chagasi and two free-range animals seropositive for T. gondii and N. caninum. All PCR assays performed were negative for the pathogens analyzed. This study describes the presence of antibodies anti-T. gondii, N. caninum e L. chagasi in wild canids from northeastern Brazil and highlights the necessity of further studies on infectious diseases in free-range and captive wild canids.

Epidemiological Evaluation of Reproductive Infectious Agents in Sheep in the Brazilian Semiarid

The aim of this work was to identify sheep herds with history of reproductive failures (abortions and perinatal mortality) associated to presence of Chamydophila abortus, Brucella ovis and Leptospira spp . infections in the semiarid region of Northeastern Brazil. Blood samples were collected from 476 animals from 72 herds in 14 counties of the Sertao mesoregion, state of Paraiba. For the serological diagnosis of C. abortus , B. ovis and Leptospira spp. infections, complement fixation test (CFT), agar gel immunodiffusion test (AGID) and microscopic agglutination test (MAT) were used, respectively. Herd-level prevalence (herds with at least one seropositive animal) of C. abortus was 52.8%, followed by B. ovis (33.3%) and Leptospira spp. (27.7%); concerning seropositivity in animals there was also a higher frequency of C. abortus (19.7%), followed by B. ovis (12.1%) and Leptospira spp. (7.6%) (p < 0.05). Herds with history of abortion (31.9%; 23/72) and perinatal mortality (54.2%; 39/72) had at least one sheep seropositive to one of the infectious agentes. For abortions, herd-level prevalence of C. abortus was 60.8%, followed by B. ovis (43.4%) and Leptospira spp. (30.4%). For perinatal mortality, herd-level prevalence was 64.1% for C. abortus , 38.4% for B. ovis and 33.3% for Leptospira spp. It is suggested that these agents may be important causes of reproductive failures in the semiarid region, and, thus, it is recommended that herd owners should be informed on reasonable sanitary measures related to animal health, and advised to perform diagnosis in cases of abortion and perinatal mortality.