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Bovine trypanosomosis has been spreading in Brazil. In the present study, we evaluated the spatial distribution, prevalence and risk factors of this disease in the state of Goiás, Brazil, and performed both molecular and phylogenetical analyses of Trypanosoma vivax. A total of 4049 blood samples were collected from cattle for a period of 2 years. The parasitological diagnosis was performed using the Woo method and a questionnaire was administered to the farmers to document risk factors associated with the disease in the herd. Positive samples were DNA sequenced and compared to GenBank codes. The prevalence of T. vivax was 8.84%, occurring on 24 ranches only in dairy cattle and mainly in the central and southern portions of the state. The acquisition of new animals infected with T. vivax and the administration of exogenous oxytocin to cows using the same syringe and needle were the main associated factors (P ≤ 0.05). After an outbreak, milk production decreased by 39.62%. The presence of biting flies (tabanids, Haematobia irritans and Stomoxys calcitrans) was not a risk factor (P > 0.05) for the occurrence of T. vivax. The epidemiological data demonstrate the importance of restricting the practice of auctions as well as eliminating the use of exogenous oxytocin in animals during milking. The samples tested by polymerase chain reaction were positive for T. vivax and were genetically homologous with T. vivax found in different states of Brazil and west Africa based on the 18S rRNA gene.

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We have recently shown that repellency of the tick Rhipicephalus sanguineus sensu lato by the tick resistant dog breed, the beagle, is mediated by volatile organic compounds (VOCs) 2-hexanone and benzaldehyde present in beagle odour. Ectoparasite location of animal hosts is affected by variation in these odour components and their ratios. The aim of this study was to quantify the release rate, and the ratio, of 2-hexanone and benzaldehyde from beagles. The odour of three beagles was collected, for four days, over one week (day 0, day 1, day 4 and day 7). The compounds were identified using coupled high-resolution gas chromatography-mass spectrometry (GC-MS), and authentic standards of compounds were used to generate external calibration curves for quantification. Both compounds were found in all dogs on all days. The amount of benzaldehyde was always higher than that of 2-hexanone and so their ratio varied from unity, on average (over time) being 3.128±0.365, 1.902±0.390, 1.670±0.671ngmL(-1) for beagle 1, 2 and 3, respectively. There was no significant (p<0.05, F-test) effect of time. The overall mean was 2.233±0.387ngmL(-1). These results further previous findings by documenting the presence of 2-hexanone and benzaldehyde in beagle odour samples covering a 7-day period. This knowledge enables development of repellents to protect dogs from R. sanguineus s. l. infestation.

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