Density and behavior of capybara (Hydrochoerus hydrochaeris) ticks (Acari: Ixodidae) Amblyomma sculptum and Amblyomma dubitatum with notes on Rickettsia bellii infection: Assessing human exposure risk.

In several urban and peri­urban areas of Brazil, populations of Amblyomma sculptum and Amblyomma dubitatum ticks are maintained by capybaras (Hydrochoerus hydrochaeris). In some of these areas, this host and these tick species are associated with Brazilian spotted fever (BSF), a lethal human disease caused by the bacterium Rickettsia rickettsii. In this work, we evaluated the risk of human exposure to these tick species using four collection techniques to discern host-seeking behavior. The study was carried out in 10 urban sites inhabited by capybaras in Uberlândia, a BSF-free municipality in southeastern Brazil. Ticks were collected in areas of 400 m2 at each site and at three seasons. Within the same municipality, the distance and speed of A. sculptum nymphs moving towards the CO2 traps were evaluated. In a sample of ticks Rickettsia DNA was investigated. During the study period, 52,953 ticks were collected. Among these, 83.4 % were A. sculptum (1,523 adults, 10,545 nymphs and 32,104 larvae) and 16.6 % were A. dubitatum (464 adults, 2,153 nymphs and 6,164 larvae). An average annual questing tick density of 4.4/m² was observed, with the highest density recorded at one site in autumn (31.8/m²) and the lowest in summer at another site (0.03/m²). The visual search yielded the highest proportion of A. sculptum larvae, constituting 47 % of the total and 63.6 % of all A. sculptum larvae. In contrast, CO2 traps collected a greater proportion of nymphs and adults of A. sculptum ticks. In the case of A. dubitatum, the CO2 trap was the most efficient technique with 57.7 % of captures of this species, especially of nymphs (94.5 % of captures) and adults (97.8 % of captures). Ticks' ambush height on vegetation (9 to 77 cm), observed by visual search 30 times, yielded a total of 20,771 ticks. Of these, 28 (93 %) were A. sculptum ticks, with only two (7 %) identified as A. dubitatum ticks. Among A. sculptum ticks, the nymph was the most attracted stage to humans and larva in the case of A. dubitatum. Amblyomma sculptum adults and nymphs were significantly more attracted to humans than those of A. dubitatum, but A. dubitatum larvae were significantly more attracted than the same stage of A. sculptum. The maximum distance and speed of horizontal displacement for A. sculptum nymphs were five meters and 2.0 m/h, respectively. The only species of Rickettsia detected in ticks, exclusively in A. dubitatum, was R. bellii. Importantly, it was observed that the higher the proportion of A. sculptum in the community of ticks, the lower the rate of infection of A. dubitatum by R. bellii. In conclusion, host-seeking behavior differed between the two tick species, as well as between stages of the same species. A greater restriction of A. dubitatum ticks to the soil was observed, while larvae and nymphs of A. sculptum dispersed higher in the vegetation. The behavior presented by A. sculptum provides greater opportunities for contact with the hosts, while A. dubitatum depends more on an active search for a host, the hunter behavior. Taken together, these observations show that a human being crossing an area infested with A. sculptum and A. dubitatum ticks will have almost exclusive contact with A. sculptum larvae and/or nymphs. Humans in a stationary position (sitting, lying or immobile) are exposed to both tick species, but they are more attractive to adults and mainly nymphs of A. sculptum compared to the corresponding stages of the tick A. dubitatum. The negative effect of A. sculptum on A. dubitatum infection by R. bellii deserves further studies.

Free-living capybaras (Hydrochoerus hydrochaeris) in an urban area in Brazil: biochemical and hematological parameters

Capybaras have found favorable conditions for survival and reproduction in green urban environments. In recent years, the population of these large rodents has been increasingly abundant in several brazilian cities such as Uberlândia, a municipality of the southeastern region with a Cerrado biome. Capybaras are important in the Brazilian Spotted Fever epidemiological chain, by amplifying infection rates of the vector population. However, knowledge of this host's physiology is scarce. Thus, the aim of this work was to describe hematological and biochemical parameters of free-living capybaras groups in urbanized areas in the city of Uberlândia, Minas Gerais State, Brazil. Capybaras were captured in 4 different locations of Uberlândia city, Minas Gerais state, including 1 Condominium (P1), 1 Private Market Garden (P2), 1 Private Club (P3) and 1 Municipal Park (P4). The animals were baited into an octagonal iron corral and chemically contained with anesthetic darts. After sedated, blood was collected from the femoral vein in tubes with and without EDTA. Biochemical evaluation, hematological analysis with differential leukocyte counts and search for Dirofilaria sp. were done. The blood count and biochemistry values obtained from animals of different ages, sex and sectors (P1, P2, P3 and P4) were submitted to the Shapiro-Wilk normality test, considering 95% significance. Values that had a normal distribution were subjected to ANOVA tests followed by Student's t-test. Values that did not follow normality were submitted to the Kruskal-Wallis test, to obtain a P-value, with a significance level of 95%. A total of 19 capybaras were captured: 4 in P1, 6 in P2, 4 in P3 and 5 in P4. From the 19 animals, 13 were females (68.42%) and 6 were males (31.57%), 12 adults (63.15%) and 7 juveniles (36.84%). Apart from occasional skin scars and moderate to intense Ambyomma spp. tick infestations, all captured animals were healthy on a broad examination. From 5 animals captured in P4, despite the use of anticoagulant, blood from 4 animals clotted fast. No microfilariae were found in the thick drop test in any of the 19 animals sampled, and in 2 adult female capybaras captured in P1, Kurloff cells were observed. Hematological and biochemical values presented no major differences when comparing sex and age. Nevertheless, differences in liver and kidney profile were observed between the capybara groups, including ALT, alkaline phosphorus, BUN and creatinine. Blood from 4 animals clotted fast, despite the use of EDTA tubes. Blood clotting of samples with anticoagulant in this work could be associated with some physiological features inherent to capybaras. Many attempts were required to obtain enough blood from each individual due to the rapid hemostasis, what come in accordance with reports in literature. Kurloff cells were observed in 2 adult female capybaras captured in P1, which can be found in peripheral blood of female rodents during follicular phase of estrous cycle. Hematological and biochemical values differences in liver enzymes such as ALT and alkaline phosphorus, and kidney profile enzymes including BUN and creatinine could be associated to capture stress or dietetic variation between groups. Despite statistical relevant, the values were still in accordance with other works, although comparisons should be done with caution since various environments exert a diverse array of stimulus upon the animals such as parasitic, infective, stress, nutritional, social and undoubtedly blood parameters mirror them. In conclusion, this work contributes to the standardization of free-living capybaras' physiological parameters in urban areas.(AU)

Evaluation of response to anti-leptospira bacterin vaccination in pregnant ewes and the passive transfer of antibodies to their offspring / Avaliação da resposta à vacinação com bacterina anti-leptospira em ovelhas gestantes e a transferência passiva de anticorpos a suas crias

Leptospirosis in sheep is often underestimated, and leads to great economic losses for the sheep farming industry. The aim of this study was to evaluate the humoral immune response in pregnant ewes, after the injection of a commercial polyvalent vaccine for leptospirosis, and to observe the transmission of anti-Leptospira antibodies through the colostrum to the offspring. For this, 24 pregnant ewes were vaccinated for leptospirosis. Blood samples were collected prior to vaccination and then 7, 14, 21, 28, 35, 42 and 49 days after vaccination. In order to evaluate passive immunity transfer, blood samples of 32 lambs were collected during the first 48 hours after birth, and another collection was performed 10 to 21 days after birth. The lambs were placed into 2 groups: Group A (n=16): singleton lambs; and group B (n=16): twins. The sera samples were submitted to the Microscopic Agglutination Test (MAT), in which 21 Leptospira serovars were tested. The results were analyzed in a descriptive form. The number of sheep reactive to MAT gradually increased until 21 days after vaccination, and decreased right after. Of all the serovars contained in the vaccine, the largest proportion of animals were seroconverted to Hardjoprajtino serovar, Serjoe serogroup. Anti-Leptospira antibodies transferred through colostrum to lambs were detected by MAT in the serum collected 24-48 hours after birth. It was observed that 65.6% (21 out of 32) of the lambs were reactive. In the subsequent collections that occurred from 10 to 21 days after birth, a decrease in the number of animals reactive to the MAT was detected. There was no significant statistical difference for the passive transfer of antibodies between single or twin lambs.

A leptospirose é uma doença frequentemente subestimada em rebanhos ovinos e leva a grandes prejuízos à ovinocultura. O objetivo deste estudo foi avaliar a resposta imune humoral em ovelhas gestantes, após imunização com uma vacina polivalente comercial contra leptospirose, bem como verificar a transmissão dos anticorpos adquiridos às crias, pelo colostro. Para isto, 24 ovelhas gestantes foram vacinadas. Amostras de sangue foram coletadas pré-imunização, bem como 7, 14, 21, 28, 35, 42 e 49 dias após. Para avaliar a transferência passiva de anticorpos, os 32 cordeiros que nasceram dessas ovelhas foram amostrados nas primeiras 48 horas após o nascimento, bem como com 10 e 21 dias de vida. Os cordeiros foram divididos em dois grupos: partos simples (Grupo A; n=16) e partos gemelares (Grupo B, n= 16). O soro sanguíneo foi submetido à prova de Soroaglutinação Microscópica (MAT), na qual 21 sorovares de Leptospira foram testados. O número de ovelhas reativas à MAT aumentou gradualmente até os 21 dias após imunização, com posterior decréscimo. De todos os sorovares presentes na vacina, a maior parte dos animais soroconverteu para o sorovar Hardjoprajtino, do sorogrupo Serjoe. Anticorpos anti-Leptospira passaram pelo colostro e puderam ser detectados no soro dos cordeiros entre 24 e 48 horas após o nascimento. Foi observado que 65,5% (21 de 32) cordeiros foram reativos. Em coletas subsequentes, realizadas 10 e 21 dias após o nascimento, houve um decréscimo no número de animais reativos à MAT. Não houve diferença significativa na transferência de anticorpos entre cordeiros de partos simples e gemelares.