Charles Passos Rangel

Frequency of antibodies to Babesia bigemina, B. bovis, Anaplasma marginale, Trypanosoma vivax and Borrelia burdgorferi in cattle from the northeastern region of the state of Pará, Brazil

Babesiosis, anaplasmosis, and trypanosomosis are relevant diseases, potentially causing morbidity in cattle, leading to economic losses. Borreliosis is import as a potential zoonosis. The objective of this study was to determine, by indirect enzyme-linked immunosorbent assay (ELISA), the frequency of seropositive cattle to Babesia bigemina, B. bovis, Anaplasma marginale, Trypanosoma vivax and Borrelia burgdorferi in cattle from the Northeastern region of Pará, Brazil. Sera samples from 246 female adult cattle from municipalities of Castanhal and São Miguel do Guamá were used. Crude antigens ELISAs were used to detect antibodies to all agents, except to A. marginale, to which an indirect ELISA with recombinant major surface 1a protein (MSP1a) antigen was used. Overall frequencies of seropositive animals were: B. bigemina--99.2%; B. bovis--98.8%; A. marginale--68.3%; T. vivax--93.1% and B. burgdorferi--54.9%. The frequencies of seropositive cattle to B. bovis and B. bigemina suggest a high rate of transmission of these organisms by tick in the studied region, which can be classified as enzootically stable to these hemoprotozoans. The low frequency of seropositive cattle to A. marginale may be attributed to a lower sensitivity of the recombinant antigen ELISA utilized or a distinct rate of inoculation of this rickettsia by ticks, as compared with Babesia sp. transmission. The high frequency of seropositive cattle to T. vivax indicates that this hemoprotozoan is prevalent in herds from the Northeastern region of Pará. The rate of animal that showed homologues antibodies to B. burgdorferi indicates the presence of the tickborne spirochaetal agent in the cattle population in the studied region.

Avian Spirochetosis in Chickens Following Experimental Transmission of Borrelia anserina by Argas (Persicargas) miniatus

Abstract This study reports the experimental transmission of Borrelia anserina to domestic chickens by infected Argas (Persicargas) miniatus. Clinical alterations as well as prepatent and patent periods were evaluated. Twenty-seven 67-day-old birds were divided into three groups in a randomized experimental design. The first group was exposed to ticks infected with B. anserina, the second group was exposed to noninfected ticks, and the third group was not exposed to ticks. Blood smears from each bird of groups 1 and 2 were prepared daily and examined for 25 days postexposure (PE). Examination of the blood smears from birds in group 1 revealed large numbers of spirochetes from days 5 to 12 PE. In this group the prepatent and patent periods were 5–7 and 4–7 days, respectively. Birds from group 1 presented ruffled feathers, pale combs, drowsiness, inappetence, loss of weight, and greenish diarrhea after day 6 PE. The current study confirms the viability of experimental transmission of B. anserina to domestic chickens by A. (P.) miniatus.

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.

Primary embryonic cells of Rhipicephalus microplus and Amblyomma cajennense ticks as a substrate for the development of Borrelia burgdorferi (strain G39/40)

Borrelia burgdorferi, the agent of Lyme borreliosis, is a spirochetes transmitted by ticks to humans and animals. Its cultivation in vitro in tick cells allows studies of its biology and provides methodology for future research in Brazil, and for the isolation of Borrelia spp. We examined in vitro the characteristics of embryonic cells of Rhipicephalus microplus and Amblyomma cajennense in cell culture and investigated the suitability of embryonic cells as a substrate for cultivation of B. burgdorferi. Subcultures were prepared from primary cultures of embrionary cells of R. microplus and A. cajennense maintained in Leibovitzs (L-15) complete medium at 28 ºC and 31 ºC, respectively. When a monolayer had formed, the L-15 was replaced with Barbour-Stoener-Kelly medium for experiments to infect cell cultures with B. burgdorferi. After 72 hours of cultivation, the spirochetes were counted using an inverted phase contrast microscope and dark-field illumination (400×). Survival, multiplication and the adherence of B. burgdorferi for embryonic cells of R. microplus and A. cajennense were observed. B. burgdorferi cultured with embryonic cells of R. microplus grew on average to a density (final count) of 2.4 × 10(7) spirochetes/mL, whereas in cell-free culture, an average of 2.5 × 10(7) spirochetes/mL were counted. When cultivated with A. cajennense cells, the final count of spirochetes was on average 1.7 × 10(7) spirochetes/mL, while spirochetes cultured under cell-free conditions replicated on average of 2.2 × 10(7) spirochetes/mL. Similar results were observed in the final count of Spirochetes cultivated in cells of R. microplus and A. cajennense, when compared with cell-free control. These results demonstrated that cells of R. microplus and A. cajennense have the potential to be used as growth substrate for B. burgdorferi in the study of its interaction with host cells.

In vitro cultivation and cryopreservation of Babesia bigemina sporokinetes in hemocytes of Rhipicephalus microplus

Cultures of tick hemocytes represent alternative cell lines for the isolation and cultivation of a variety of hemoparasites. The present study reports the development and evaluation of methods for the in vitro culture and maintenance of sporokinetes of Babesia bigemina in association with hemocytes of the tick Rhipicephalus microplus. Hemolymph, from engorged females infected with B. bigemina sporokinetes, was incubated at 28 °C in L15 culture medium supplemented with 40% fetal bovine serum. Adherence of hemocytes to flask surfaces and the development of B. bigemina sporokinetes commenced on the first day of cultivation. The protozoa demonstrated clear motility and the capacity to adhere to hemocyte membranes for up to 25 days, at which time the hemocytes began to show signs of degeneration. Examination of Giemsa stained hemocyte cultures, revealed the presence of pyriformis forms, as well as mature and immature sporokinetes with dark red nuclei, centralized or near the apical extremities. Sporokinetes harvested from culture supernatants were cryopreserved in liquid nitrogen. Inoculation of parasite-free hemocyte cultures with defrosted sporokinetes, demonstrated the viability and interaction of the protozoa with the hemocytes over 21 days. Cultured hemocytes of R. microplus hold potential for development as a tool in the study of host parasite interactions and as a substrate for the in vitro maintenance of B. bigemina sporokinetes.

Ticks on buffaloes (Bubalus bubalis) in the state of Rio de Janeiro, Brazil

Some tick species have been described parasitizing buffaloes, but reports from Brazil are rare. This study aimed to ascertain the species of ticks that parasitize buffaloes in the state of Rio de Janeiro. Seventeen farm properties were visited between June 2008 and December 2009, and buffaloes were inspected in relation to infestation. The ticks were identified and a semi-structured questionnaire on parasitism and treatment against ticks was filled out through interviews with the owners. The species identified were Rhipicephalus (Boophilus) microplus, Dermacentornitens and Amblyommacajennense. It was noted that 82.3% (14/17) of the properties visited presented animals infested with ticks, although 76.5% (13/17) had been administering acaricide treatment. Buffaloes in the state of Rio de Janeiro are often parasitized by ticks, especially in the larval and nymph stages.

Risk factors relating to helminth infections in cows during the peripartum

The aim of this study was to investigate whether season, lactation number, breed standard and milk production were risk factors relating to occurrences of gastrointestinal nematodes in dairy cows during the peripartum period. Eighty-four cows were randomly selected through proportional stratified sampling. In order to analyze the fecal egg per gram (EPG) count, the data were subjected to the Spearman test, Kruskal-Wallis test at 5% significance and linear regression. At the time of calving, the cows showed high EPG counts in relation to all variables analyzed. Among the animals studied, we observed that purebred Holstein cows at their first lactation and with high milk production showed high EPG counts (600) and comprised the group most at risk within the herd studied. In this group, the animals showed moderate EPG during the prepartum period (300) and a significant increase (p < 0.01) in EPG count from the time of calving (900), i.e. an increase of the order of 300%. Selection of animals for milk production in tropical countries should be based not only on productive potential, but also on adaptive features.

Assessment of weight gain and biological parameters of Rhipicephalus sanguineus females fed artificially via capillary tubes

This study assesses the weight gain of partially engorged Rhipicephalus sanguineus females that were artificially fed via capillary tubes and the influence of capillary tube feeding on the biological parameters of the non-parasitic stage of the species. The ticks were sorted into four groups, each containing ten females of a homogeneous weight. The groups were each treated for different feeding times, 2, 6, 12 and 24 hours. The weight gain of the artificially fed females was measured, and the biological parameters of the non-parasitic stage of the tick were observed for each treatment group. The statistical non-parametrical Dunn and Kruskal-Wallis tests were used to compare the results. The mean weights (mg) were 0.2±2.4; 4.3±5.8; 7.4±5.8 and 12.0±11.2 for the 2, 6, 12 and 24 hours feeding groups, respectively. The weight of the fed groups increased as the capillary feeding time increased, and this relationship was highly significant (P 0.05) were observed in the parameters of the non-parasitic stage for the artificially fed groups. It can be concluded that artificial feeding via capillary tubes provides an efficient and easy method for the artificial intake of blood by R. sanguineus. Furthermore, it was noted that the ticks fed in vitro were able to establish a new generation. The experimental method shows great promise in studies that aim to investigate biological disease agents.