The Rhipicephalus (Boophilus) microplus tick is responsible for considerable economic losses in Brazil, causing leather damage, weight loss and reduced milk production in cattle and results in the transmission of pathogens. Currently, the main method for controlling this tick is using acaricides, but their indiscriminate use is one of the major causes of resistance dissemination. In this study, the adult immersion test (AIT) was used to evaluate resistance in ticks from 28 properties located in five different states (Mato Grosso do Sul, Mato Grosso, Ceará, São Paulo, e Minas Gerais) and the Distrito Federal (DF) of Brazil. The resistance was found in 47.64% of the repetitions demonstrating an efficacy of less than 90% in various locations throughout the country. The larvae packet test was used to evaluate samples from ten properties in four states (Mato Grosso do Sul, Mato Grosso, Minas Gerais and Espírito Santo). Spray products belonging to the main classes of acaricides, including combination formulations, were used in both types of test. New cases of resistance were found on properties within the states of Ceará, Espírito Santo and Mato Grosso, where such resistance was not previously reported.
The present study evaluated the behavior of Rhipicephalus microplus naturally infesting Brangus cattle raised with Nellore animals in the municipality of Água Clara, state of Mato Grosso do Sul, Central Brazil. For the field experiment composed of a group with 15 Brangus animals and 15 Nellore animals and a control group with 30 Brangus cattle, all at the post-weaning stage. The 2 groups were kept for 6 months in 2 adjacent paddocks, naturally infested with ticks, at a stocking rate of approximately 0.6 of an animal unit per hectare (AU/ha). Every 18 days, the animals were weighed, and ticks on both sides of each bovine were counted. Every 36 days, blood was collected for hematocrit measurement and molecular diagnosis of the 3 pathogens that cause tick fever. The Brangus animals had 6.8 times more ticks than the Nellore cattle. No significant difference was observed in the weight gain of the Brangus and Nellore animals, and no correlation between the number of ticks and weight was observed in either group. During the 6 months of the study, all animals presented normal hematocrit, were positive for Babesia bigemina and Anaplasma marginale, and were negative for Babesia bovis. Animals in Group 1 produced 27% fewer ticks than the animals in Group 2. The production rate of engorged female ticks in Nellore and Brangus cattle was 0.83% and 2.01%, respectively. Considering the infestation pattern required to produce 10 engorged females/day/animal, the Nellore and Brangus animals required 1,204 and 497 larvae/day, respectively. Our estimates showed that Brangus cattle need only 11.3% of the larvae in the pastures with Nellore cattle to maintain the infestation level observed in the present study. Brangus animals raised with Nellore cattle do not have a lower parasitic load and continue to suffer from tick infestation. Finally, Nellore cattle raised with Brangus cattle do not act as a cleaner because this grouping does not contribute to a reduced infestation in the Brangus animals. Resumo: Este trabalho teve o objetivo de avaliar o comportamento da infestação de carrapatos (Rhipicephalus microplus) em bovinos da raça Brangus associado com Nelore no Brasil central em rebanho infestado naturalmente na região do município de Água Clara, MS, Brasil. Para o experimento de campo um grupo de 15 animais em inicio de recria da raça Brangus e 15 animais da raça Nelore e outro grupo controle com 30 animais Brangus, foram mantidos em dois piquetes geminados com lotação de aproximadamente 0,6 unidade animal por hectare (Ua/ha). A cada 18 dias os carrapatos foram contados dos dois lados do corpo dos bovinos após a pesagem dos mesmos. A cada 36 dias foi colhido sangue para realizar o hematócrito e o diagnóstico molecular para os três agentes da Tristeza Parasitária Bovina (TPB). A raça Brangus produziu 6,8 vezes mais carrapatos do que o Nelore e o seu ganho de peso não apresentou diferença estatística quando comparada com a raça Nelore. Ao longo de seis meses os animais não apresentaram hematócrito abaixo do normal e todos os a...
The objective of the study was to investigate the efficacy of cypermethrin, chlorpyrifos and piperonyl butoxide based pour-on and spray acaricides for the control of Rhipicephalus microplus in a naturally infested cattle herd. Fifty eight male Brangus cattle in the rearing phase were divided into treated (28) and untreated (30) groups. The treated group was subdivided in treated with a pour-on acaricide (13) and treated with a spray acaricide (15). Every 18 days, tick counts, acaricide treatment, weighing and clinical observation were performed on the animals, totaling four evaluation time points. The adult immersion tests were used for in vitro analysis of the study population to different chemical bases was assessed for primary results. Tick counts were separately compared between groups at each time point using the Kruskal-Wallis and Wilcoxon tests. Significantly fewer number of ticks were observed on the treated group compared to control group and also on the sprayed subgroup compared to pour-on subgroup (p<0.05). Our results indicate that the chemical treatment evaluated directly affects the number of ticks parasitizing animals and that products employing a spray application method may be more effective in controlling cattle ticks.
Neospora caninum is an obligate intracellular protozoan with canids (Canis domesticus, Canis lupus dingo, Canis latrans, Canis lupus) as its definitive hosts. The objective of this study was to detect anti-N. caninum antibodies in pregnant women seen at referral center for prenatal screening in the state of state Mato Grosso do Sul, Brazil. A total of 188 serum samples from pregnant women provided by the Instituto de Pesquisa, Ensino e Diagnósticos da APAE de Campo Grande (IPED/ APAE) were subjected to IFA test and western blot analysis. The samples were divided into three groups: 23/99 samples from the seropositive group for toxoplasmosis were positive for anti-N. caninum IgG antibodies, and 9/99 positive for IgM; in the HIV group, 7/33 were positive for IgG; and in the HIV+toxoplasmosis group, 13/56 were positive for IgG and two positive for IgM. The seropositivity for IgG was assessed by western blot by testing 43 IFA test positive samples using rNcSRS2 (Nc-p43) as antigen. The serological results of the present study suggest that exposure of these pregnant women to the parasite N. caninum and presence of IgM antibodies are indicative of recent infection. Further studies are needed to establish the possibility of active infection.
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