Jenevaldo Barbosa da Silva

Molecular and serological prevalence of Anaplasma marginale in water buffaloes in northern Brazil.

Bovine anaplasmosis, caused by Anaplasma marginale, occurs in tropical and subtropical regions throughout the world and is a major constraint on cattle production in many countries. Approximately 60% of the buffalo herds in South America are located in northern Brazil. However, compared with the research on cattle, research on buffaloes has been neglected. Therefore, the present study was conducted to investigate the distribution of A. marginale in water buffaloes in northern Brazil. A total of 500 buffalo blood samples was randomly collected from 16 provinces and was analyzed using both nPCR assay and ELISA techniques. The percentage of animals that were seropositive for A. marginale according to ELISA was 49% (245/500). The main risk factors associated with seroprevalence were the region (p=0.021; OR=1.2) and the reproductive status (p=0.0001; OR=1.6). Anaplasma marginale DNA was detected in 5.4% (27/500) of the sampled buffaloes. Our data provide information about the incidence of A. marginale infection in water buffaloes and may guide future programs aimed at controlling the disease in the northern region of Brazil. Although these water buffaloes are exposed to A. marginale, a low rate of A. marginale PCR-positive animals was found, which could be explained by the habitat in which the sampled animals live because they exhibited a low rate of attached ticks on their skin.

Genetic diversity and molecular phylogeny of Anaplasma marginale studied longitudinally under natural transmission conditions in Rio de Janeiro, Brazil

Anaplasma marginale is the most prevalent tick-borne pathogen in cattle in tropical and subtropical regions of the world. Major Surface Protein 1a (MSP1a) has been found to be a stable genetic marker for identifying A. marginale isolates within geographical regions. It is conserved in cattle during infection and tick-borne transmission of the pathogen. The aim of the present longitudinal study was to determine occurrences of genetic diversity associated with high prevalence of A. marginale under natural transmission conditions. Twenty calves were evaluated every 3 months during the first year of life. Rickettsemia levels due to A. marginale, measured as the number of msp1αcopies/ml in the blood of positive calves, ranged from 2.06×10(3) to 4.36×10(12). The numbers of MSP1a tandem repeats among MSP1a tandem repeats were 3 and 6. The predominant msp1α microsatellite was E, and another MSP1a tandem repeat was found that presented genotype G. Nineteen different MSP1a tandem repeats of A. marginale were found circulating in animals. The MSP1a tandem repeats 4-63-27 (27.5%), 78-24(2)-25-31 (n=21.6%) and τ-10(2)-15 (n=17.6%) were the ones most commonly observed. Twenty-two MSP1a tandem repeats resulted in new sequences with amino acid changes, as shown in this study. Thirty sequences were found for the first time in Brazil. Glycine, glutamate, serine and alanine amino acids were found at position 20. During the study, 80% (16/20) of the animals were infected by more than one genotype. Three animals were born infected, with MSP1a tandem repeats 4-63-27, 78-24(2)-25-31 and τ-10(2)-15, thus indicating occurrence of transplacental transmission. In the phylogenetic analysis, 19 different MSP1a tandem repeats of A. marginale were found in the cattle, which suggested that many MSP1a tandem repeats and high variation in MSP1a were occurring.

Prevalence Survey of Selected Bovine Pathogens in Water Buffaloes in the North Region of Brazil

Although the largest buffalo herd in the occident is in the north region of Brazil, few studies have been conducted to assess the prevalence of selected parasitic diseases in buffalo herd. The present study was therefore conducted to investigate the epidemiological of Toxoplasma gondii, Neospora caninum, Anaplasma marginale, Babesia bigemina, and Babesia bovis in water buffaloes in the north region of Brazil. A total of 4796 buffalo blood samples were randomly collected from five provinces and simultaneously analyzed by the IFAT and ELISA. The serological prevalence of T. gondii and N. caninum was 41.3% and 55.5% in ELISA and 35.7% and 48.8% in IFAT, respectively. The overall prevalence of A. marginale, B. bovis, and B. bigemina was 63%, 25%, and 21% by ELISA and 50.0%, 22.5%, and 18.8% by IFAT, respectively. This study shows valuable information regarding the serological survey of selected bovine pathogens in water buffaloes in the north region of Brazil which will likely be very beneficial for the management and control programs of this disease.

Influence of the physiological state on infestation by Rhipicephalus microplus in dairy cows

The purpose of this study was to identify the influence of physiological state, season, breed, number of lactations, dairy productivity, and stocking rate on infestation by Rhipicephalus microplus in dairy cows. Two hundred cows were selected through proportional representative sampling at the Seropédica Experimental Station (Pesagro-Rio), Brazil. Fully or partially engorged R. microplus females measuring between 4.5 and 8.0mm were counted on the right side of each animal. The tick infestation prevalence data were analyzed in relation to the risk factors, using multiple logistic regression. Associations between prevalence and its possible influencing determinants were measured using odds ratios. The average tick count of cows during the peripartum and lactation periods was significantly higher (p<0.05; OR=4.82) than the count in dry cows. Taurine animals showed significantly higher infestation (p<0.05; OR=3.28) than pure zebuine animals. Among cross-bred animals, the infestation was higher (p<0.05) in F1 animals (1/2 taurine×1/2 zebuine) than in Girolando animals (5/8 zebuine×3/8 taurine). Primiparous cows (p<0.05) had significantly heavier infestations than multiparous cows. Dairy production showed a positive correlation with tick infestation (p<0.03; OR=2.94), such that the most productive animals were the most parasitized ones. Animals kept at high densities were significantly more heavily infested (p<0.05, OR=6.32) than animals kept at low density. First-lactation and high-productivity taurine animals were more vulnerable to R. microplus, thus comprising a high-risk group in dairy herds.

Low genetic diversity associated with low prevalence of Anaplasma marginale in water buffaloes in Marajó Island, Brazil.

The rickettsia Anaplasma marginale is the etiologic agent of bovine anaplasmosis, an important tick-borne disease affecting cattle in tropical and subtropical regions of the world. In endemic regions, the genetic diversity of this pathogen is usually related to the high prevalence of the disease in cattle. The major surface protein 1 alpha (MSP1a) has been used as a marker to characterize the genetic diversity and for geographical identification of A. marginale strains. The present study reports the characterization of A. marginale MSP1a diversity in water buffaloes. Blood samples were collected from 200 water buffaloes on Marajó Island, Brazil where the largest buffalo herd is located in the Western hemisphere. Fifteen buffaloes (7.5%) were positive for A. marginale msp1α by PCR. Four different strains of A. marginale with MSP1a tandem repeat structures (4-63-27), (162-63-27), (78-24-24-25-31) and (τ-10-10-15) were found, being (4-63-27) the most common. MSP1a tandem repeats composition in buffalos and phylogenetic analysis using msp1α gene showed that the A. marginale strains identified in buffaloes are closely related to A. marginale strains from cattle. The results demonstrated low genetic diversity of A. marginale associated with low bacterial prevalence in buffaloes and suggested that buffaloes may be reservoirs of this pathogen for cattle living in the same area. The results also suggested that mechanical transmission and not biological transmission by ticks might be playing the major role for pathogen circulation among water buffaloes in Marajó Island, Brazil.

Molecular characterization of Anaplasma marginale in ticks naturally feeding on buffaloes

Anaplasma marginale is the most prevalent pathogen transmitted by ticks in cattle in tropical and subtropical regions of the world. However, the tick species involved in the transmission of A. marginale in buffaloes in Brazil have not been identified. The objective of the present study was to determine the presence of A. marginale in ticks parasitizing water buffaloes. A total of 200 samples of Rhipicephalus microplus, Dermacentor nitens, Amblyomma cajennense, and Amblyomma maculatum were collected and tested by conventional and quantitative PCR for the presence of the msp1a and msp5 genes. In the present study, 35 ticks (17.5%) were positive for A. marginale DNA by qPCR analysis. The positive ticks belonged to four different species: R. microplus (22.2%), A. cajennense (13.8%), A. maculatum (16.0%), and D. nitens (10.0%). Individuals of the three developmental stages (larvae, nymphs, and adults) of R. microplus and A. cajennense were found to be positive for A. marginale, only nymphs and adults of A. maculatum were found to be positive, and finally, only adults of D. nitens were positive for A. marginale. Our results suggest that R. microplus, A. cajennense, A. maculatum, and D. nitens ticks may be involved in the transmission of A. marginale in buffaloes. However, while A. marginale PCR positive ticks were recorded, this does not indicate vector competence; only that the ticks may contain a blood meal from an infected host. Additionally, the results show that the strains of A. marginale from buffaloes and cattle are phylogenetically related.

Infection of water buffalo in Rio de Janeiro Brazil with Anaplasma marginale strains also reported in cattle

Anaplasma marginale is the most prevalent pathogen of cattle in tropical and subtropical regions of the world and causes the disease bovine anaplasmosis. The importance of water buffalo in the world economy is increasing. In addition, while water buffalo may serve as a reservoir host for A. marginale, the susceptibility of this host for A. marginale cattle strains in Brazil has not been reported. The major surface protein 1 alpha (msp1α) gene has been shown to be a stable genetic marker for identification of A. marginale strains. Herein, we analyzed blood samples from 200 water buffalo and identified the A. marginale strains in an endemic area of Rio de Janeiro, Brazil, where ticks were present and water buffalo and cattle co-mingled. Ticks that were feeding on the study buffalo were collected and identified. The prevalence of A. marginale in water buffalo in this study was low (10%). Sequence analysis of the msp1α gene demonstrated the presence of 8 different A. marginale strains. Two A. marginale strains in the water buffalo, (α-β-β-β-Γ) and (α-β-β-Γ), were similar to those reported in cattle from nearby regions. The results of this study suggested that water buffalo in this region are naturally infected with the same strains of A. marginale found in cattle.

A comparative study of production performance and animal health practices in organic and conventional dairy systems

Health and production management strategies influence environmental impacts of dairies. The objective of this paper was to measure risk factors on health and production parameters on six organic and conventional bovine, caprine, and ovine dairy herds in southeastern Brazil over six consecutive years (2006–2011). The organic operations had lower milk production per animal (P ≤ 0.05), lower calf mortality (P ≤ 0.05), less incidence of mastitis (P ≤ 0.05), fewer rates of spontaneous abortions (P ≤ 0.05), and reduced ectoparasite loads (P ≤ 0.05) compared to conventional herds and flocks. Organic herds, however, had greater prevalence of internal parasitism (P ≤ 0.05) than conventional herds. In all management systems, calves, kids, and lambs had greater oocyte counts than adults. However, calves in the organic group showed lower prevalence of coccidiosis. In addition, animals in the organic system exhibited lower parasitic resistance to anthelmintics. Herd genetic potential, nutritive value of forage, feed intake, and pasture parasite loads, however, may have influenced productive and health parameters. Thus, although conventional herds showed greater milk production and less disease prevalence, future research might quantify the potential implications of these unreported factors.

Risk factors for anaplasmosis in dairy cows during the peripartum

Anaplasma marginale is endemic in tropical and subtropical areas around the world. Some studies have suggested that cows during peripartum may present a transient immunosuppression state and development of clinical signs of anaplasmosis. The aim of this study was to investigate the relationship between some risk factors and the seroprevalence of A. marginale in dairy cows during peripartum in Rio de Janeiro, Brazil. The risk factors analyzed in association with the prevalence of antibodies against A. marginale in dairy cows were calving season, reproductive experience, breed standard, tick infestations, stocking density, and milk yield. The antibodies against A. marginale were tested in indirect enzyme-linked immunosorbent assays. A primary screening using a 2 × k contingency table of the exposed variables with the outcomes was performed. All variables for which p < 0.20 were included in a fixed effects log regression. The risk factors investigated to anaplasmosis were calving (OR 2.61, IC 1.08–7.63), breed standard (OR 3.83, IC 0.08–0.28), reproductive experience (OR 33.7, IC 2.14–5.16), milk yield (OR 3.9, IC 2.24–7.03), Rhipicephalus microplus infestations (OR 10.3, IC 0.05–0.17), and stocking density (OR 22.3, IC 0.05–0.17). Low titers of antibodies against A. marginale during peripartum had been characterized as a period previous to development of clinical anaplasmosis. Thus, studies on anaplasmosis should consider each farm as an epidemiological unit, where environmental and immunological factors may influence the endemic status of the pathogen.Anaplasma marginale is endemic in tropical and subtropical areas around the world. Some studies have suggested that cows during peripartum may present a transient immunosuppression state and development of clinical signs of anaplasmosis. The aim of this study was to investigate the relationship between some risk factors and the seroprevalence of A. marginale in dairy cows during peripartum in Rio de Janeiro, Brazil. The risk factors analyzed in association with the prevalence of antibodies against A. marginale in dairy cows were calving season, reproductive experience, breed standard, tick infestations, stocking density, and milk yield. The antibodies against A. marginale were tested in indirect enzyme-linked immunosorbent assays. A primary screening using a 2 × k contingency table of the exposed variables with the outcomes was performed. All variables for which p < 0.20 were included in a fixed effects log regression. The risk factors investigated to anaplasmosis were calving (OR 2.61, IC 1.08-7.63), breed standard (OR 3.83, IC 0.08-0.28), reproductive experience (OR 33.7, IC 2.14-5.16), milk yield (OR 3.9, IC 2.24-7.03), Rhipicephalus microplus infestations (OR 10.3, IC 0.05-0.17), and stocking density (OR 22.3, IC 0.05-0.17). Low titers of antibodies against A. marginale during peripartum had been characterized as a period previous to development of clinical anaplasmosis. Thus, studies on anaplasmosis should consider each farm as an epidemiological unit, where environmental and immunological factors may influence the endemic status of the pathogen.

Low genetic diversity of Anaplasma marginale in calves in an endemic area for bovine anaplasmosis in the state of São Paulo, Brazil.

Major surface protein 1a has been used as a marker for genetic stability in identifying geographical isolates of Anaplasma marginale. We conducted a longitudinal study to ascertain the genetic diversity of A. marginale in a dairy cattle herd with a history of clinical anaplasmosis. A total of 20 calves were evaluated every 3 months, from birth to 1 year of age. They were evaluated using blood smears, IFAT, ELISA, and qPCR. Additionally, samples positive for the msp1a gene using nPCR were sequenced. The detection of A. marginale ranged from 20 to 90% using blood smears, 20-80% using ELISA/IFAT, and 15-100% using qPCR. We found evidence that suggested transplacental transmission of A. marginale in 15% (3/20) of the calves based on qPCR and 20% (4/20) based on blood smears. Additionally, these four animals were A. marginale ELISA/IFAT-positive. The A. marginale strains found were α-β(3)-Γ (n=7), α-β(2) (n=1), and α-β(2)-190-Γ (n=1). The new MSP1a tandem repeat 190 was described. The results showed that the genetic diversity of A. marginale in a group of calves up to 1 year of age from Taiaçu (SP) was low, with only three different strains identified, showing the microsatellite genotype E. Eighty percent of the animals evaluated had clinical signs of bovine anaplasmosis and were treated using oxytetracycline and imidocarb dipropionate. Additionally, it was found that 30% (6/20) and 10% (2/20) of the animals required a second and third treatment, respectively, based on clinical signs. Four animals infected with the α-β(3)-Γ strain died, showing that this strain is also involved in the clinical anaplasmosis cases in Brazil.