The geographic distribution of Argas (Persicargas) miniatus and Argas (Persicargas) persicus (Acari: Argasidae) in America, with morphological and molecular diagnoses from Brazil, Chile and Cuba.

High similarity of morphological traits has historically overshadowed the identities and distributions of poultry-associated soft ticks Argas (Persicargas) miniatus and Argas (Persicargas) persicus in America. In order to model the occurrence of both parasites in the continent, in the current study we performed morphological and molecular analyses to identify ticks collected in hen houses from Brazil and northern Chile. Combining these results with literature data, and the examination of Argas allotments deposited in the tick collections "Coleção Nacional de Carrapatos Danilo Gonçalves Saraiva" (Brazil), the "Coleção Acarológica do Instituto Butantan São Paulo" (Brazil), and the "Colección Zoológica de la Academia de Ciencia de Cuba" (Cuba), we present a critical list with the localities where A. (P.) miniatus and A. (P.) persicus have been reported in the American continent. Our results confirmed the presence of A. (P.) miniatus in Brazil and Cuba, and A. (P.) persicus in Chile, which in particular, constitutes the first molecularly confirmed report of the later species for South America. Although A. (P.) miniatus and A. (P.) persicus have been documented in 21 American countries, the identity of some reports must still be considered as uncertain until detailed morphological and/or molecular studies are performed. When contrasted to a Köppen-Geiger climate classification, A. (P.) miniatus predominantly occurs in equatorial and A. (P.) persicus in arid climates. However, until undetermined reports of both species are correctly identified, any conclusion on their geo-climatological occurrence throughout the American continent would be rather speculative.

Isolation of Rickettsia rickettsii from the tick Amblyomma sculptum from a Brazilian spotted fever-endemic area in the Pampulha Lake region, southeastern Brazil.

Brazilian spotted fever (BSF) is a tick-borne disease caused by the bacterium Rickettsia rickettsii, the deadliest spotted fever of the world, transmitted in southeastern Brazil mainly by the tick Amblyomma sculptum, a member of the Amblyomma cajennense species complex. In the present study, over 5000 adults of A. sculptum ticks were collected by dry ice traps in the Municipal Ecological Park, alongside the Pampulha Lake region, a BSF-endemic area of Belo Horizonte city, state of Minas Gerais, southeastern Brazil. Ticks were taken alive to the laboratory, where a sample of 2100 specimens was processed for isolation of R. rickettsii. For this purpose, ticks were macerated and intraperitoneally inoculated into guinea pigs. Only one out of 21 inoculated guinea pigs presented high fever within 21days post inoculation with tick homogenates. This febrile animal was euthanized and its internal organs were macerated and inoculated into additional guinea pigs (guinea pig passage). A spleen sample from a febrile guinea pig was used to inoculate Vero cells, resulting in a successful isolation and in vitro establishment of rickettsiae. Rickettsia-infected Vero cells were used for molecular characterization of the rickettsial isolate through PCR and DNA sequencing of fragments of three rickettsial genes (gltA, ompA, and ompB), which were all 100% identical to corresponding sequences of R. rickettsii from GenBank. The present R. rickettsii isolate was designated as strain Pampulha. A minimal infection rate of 0.05% R. rickettsii-infected ticks was estimated for A. sculptum population of the Pampulha Lake region. Our results, coupled with epidemiological evidences, suggest that R. rickettsii strain Pampulha, isolated from A. sculptum ticks in the present study, is the strain responsible for human clinical cases of BSF in the Pampulha Lake region of Belo Horizonte city.

New records and human parasitism by Ornithodoros mimon (Acari: Argasidae) in Brazil.

The bat tick Ornithodoros mimon Kohls, Clifford & Jones is currently known by only few reports in Bolivia, Uruguay, Argentina, and the state of São Paulo in southeastern Brazil. Here, we expand the distribution of O. mimon in Brazil to the states of Minas Gerais (southeastern region), Goiás (central-western), Pernambuco, and Rio Grande do Norte (northeastern). Ticks were collected on human dwellings, where there had been repeated complains of tick bites on persons during the night. Tick bites were generally followed by intense inflammatory reactions that lasted for several weeks at the bite site. Bats and opossums were reported to inhabit the attic of the infested houses. In addition, a free-ranging opossum (Didelphis albiventris Lund) trapped in Rio Grande do Norte was found infested by argasid larvae. Based on morphological and/or molecular analysis, all ticks were identified as O. mimon. From one of the sites (Tiradentes, state of Minas Gerais), 20 field-collected nymphs were tested by a battery of polymerase chain reaction protocols targeting tick-borne microorganisms of the genera Babesia, Hepatozoon, Rickettsia, Borrelia, Anaplasma, Ehrlichia, and Coxiella; no tick specimen was found infected by any of these microorganism genera. The current study expands northwards the distribution of O. mimon, which has been shown to be very harmful to humans because of the intense inflammatory response that usually occurs after tick bites.

Does Rhipicephalus microplus tick infestation increase the risk for myiasis caused by Cochliomyia hominivorax in cattle?

The larval phase of Cochliomyia hominivorax (screwworm) is an obligate parasite of vertebrate animals, particularly mammals, and widespread in South America, where it remains one of the most important parasitic diseases of domestic animals. The skin of cattle highly infested by ticks, with cutaneous lesions, exudation of tissue fluid and blood scent seems to produce the ideal environment for fly attraction. However, an association between these parasites was never investigated. The aim of this work was to verify if there is an association between Rhipicephalus microplus tick load and the occurrence of C. hominivorax myiasis in cattle, and to quantify the risk. Sixty bovine (Bos taurus taurus, Angus breed) under field conditions were observed for 24 weeks, during which weekly tick counts and examination for the presence of myiasis were performed. There was a significant association between a high tick burden (24-week mean above 50 ticks per animal) and myiasis occurrence (P=0.0102). The calculated relative risk (RR) for C. hominivorax myiasis occurrence in cattle with high tick burden was 3.85 (CI95%=1.23-12.13); indicating that cattle highly parasitized by R. microplus have about four times more risk of myiasis than those with a low parasite load. As far as we aware, this is the first statistically based evidence of the relationship between R. microplus parasitic load and occurrence of myiasis by C. hominivorax. This result could be useful for the design of integrated control strategies for these parasites and to provide more information for the understanding of cattle tick parasitism in cattle production.

Clinical aspects and dynamics of auricular parasitosis in Gir cattle / Aspectos clínicos e dinâmica de parasitoses auriculares em bovinos da raça Gir

We evaluated the dynamics of ear infestations caused by Rhabditis spp. and Raillietia spp., which were correlated with animal age, intensity of clinical signs and climate factors. Sixty-four Gir cattle were distributed into three groups: GA - 23 calves with 4 to 6 months of age; GB - 18 calves with 7 to 12 months of age; and GC - 23 heifers with 13 to 33 months of age. Five samplings, defined as S1, S2, S3, S4 and S5 were performed every three months from August 2008 to August 2009. The ear secretion was collected using the auricular washing method for the right ear and a swab for the left ear. A clinical assessment of the animals was performed, and they were classified according to the presence and severity of otitis. The highest relative frequency of rhabditosis was 52.2% in GC at the last sampling. In the first sampling, 42.2% of the animals were infested by Raillietia spp. The older cattle were more susceptible to infestations by both parasites. No correlation of Rhabditis spp. and Raillietia spp. parasitism with climate factors was found. The results showed that both parasites could infest Gir cattle, and in most cases, there was no co-infestation. Only older animals parasitized by the nematode showed clinical signs of the disease.

Avaliou-se a dinâmica da infestação auricular causada por Rhabditis spp. e por Raillietia spp., relacionando-a com a idade dos animais, com a intensidade dos sinais clínicos e com os fatores climáticos. Utilizaram-se 64 bovinos Gir, distribuídos em três grupos: GA - 23 bezerros de quatro a seis meses de idade, GB - 18 bezerros de sete a 12 meses e GC - 23 novilhas de 13 a 33 meses. Foram feitas cinco coletas a cada três meses. A secreção auricular foi coletada utilizando o método de lavagem auricular na orelha direita e um swab na orelha esquerda. Fez-se avaliação clínica dos animais classificando-os de acordo com a presença e gravidade da otite. A maior frequência relativa da rhabditiose encontrada foi de 52,2%, no GC na ultima coleta. Na primeira coleta, 42,2% dos animais estavam infestados pela Raillietia spp. Os bovinos mais velhos foram mais suscetíveis às infestações de ambos os parasitos. Não foi encontrada correlação entre o parasitismo por Rhabditis spp. e por Raillietia spp. e os fatores climáticos. Concluiu-se que ambos os parasitas podem infestar bovinos da raça Gir e na maioria dos casos, não ocorreram infestações simultâneas. Apenas os animais mais velhos, parasitados pelo nematóide, apresentaram sinais clínicos da doença.

Caracterização do controle de Haematobia irritans e Rhipicephalus (Boophilus) microplus no Triângulo Mineiro e Alto Paranaíba, Minas Gerais / Characterization of Haematobia irritans and Rhipicephalus (Boophilus) microplus control in Triângulo Mineiro and Alto Paranaíba, Minas Gerais

O controle eficaz de Haematobia irritans (mosca-dos-chifres) e Rhipicephalus (Boophilus) microplus (carrapato-do-boi) é um fator crucial à maior rentabilidade da pecuária brasileira, porém ainda constitui-se um desafio. Um maior conhecimento das práticas adotadas no combate destes parasitos faz-se necessário para que se possam estruturar estratégias de controle mais próximas da realidade do produtor rural e mais fáceis de serem executadas. Este estudo caracterizou, através de entrevistas, as práticas adotadas no controle desses ectoparasitos em 23 propriedades da mesorregião do Triângulo Mineiro e Alto Paranaíba, Minas Gerais. A maioria dos entrevistados reconheceu a importância desses parasitos para a atividade pecuária, entretanto, diversos problemas relativos ao controle parasitário foram observados. O controle da mosca-dos-chifres e do carrapato-do-boi era uma prática rotineira em, respectivamente, 17,4% e 95,7% das propriedades, geralmente realizado em função de elevado grau de infestação dos animais. Mais de seis aplicações de ectoparasiticidas eram realizadas por ano em todas as propriedades que empregavam tratamentos para o controle da mosca e em 76,5% daquelas que combatiam o carrapato. Os produtos eram aplicados principalmente com bombas costais manuais (63,6%) e sem a contenção dos animais em 45,5% das propriedades. A diluição dos produtos segundo recomendações dos fabricantes era realizada por 45,4% dos entrevistados, porém, 63,6% aplicavam um volume de solução por animal menor do que o tecnicamente recomendado. Utilizava-se principalmente a associação de piretróides e organofosforados para o controle de ambos os parasitos. Apesar de utilizar rotineiramente ectoparasiticidas, o uso de equipamento de proteção individual (EPI) não era comum entre os entrevistados. A maioria dos entrevistados conhecia algumas características epidemiológicas dos parasitos, entretanto, o controle parasitário adotado na maior parte das propriedades tende a comprometer não apenas a eficácia dos tratamentos, mas a suscetibilidade dos parasitos e a sustentabilidade do controle.

The effective control of Haematobia irritans (horn fly) and Rhipicephalus (Boophilus) microplus (cattle tick) is crucial for increasing the productivity of livestock industry in Brazil, but still remains a challenge. A greater knowledge about parasite control in the field is necessary to establish control strategies closer to farmer's reality and easier to be performed. This study characterized the practices adopted for controlling such ectoparasites on 23 cattle ranches from the Triângulo Mineiro and Alto Paranaíba region in the state of Minas Gerais, through interviews. Most interviewees recognized the importance of these parasites to livestock, however, many problems related to parasite control were observed. Control of horn flies and cattle tick was a routine in 17.4% and 95.7% of the ranches, respectively, triggered by high infestations on animals. More than six insecticide/acaricide treatments were applied yearly in all cattle ranches controlling horn flies and in 76.5% of the ranches controlling the cattle tick. Pesticide products were applied mostly by manual backpack sprayers (63.6%) without restraining the animals in 45.5% of ranches. Product dilution following manufacturer's recommendations was performed by 45.5% of interviewees, but 63.6% of them used lower doses per animal than technically recommended. Associations of organophosphates and pyrethroids were the main products used to control both parasites. Although pesticide use was a routine practice, the use of personal protective equipment (PPE) was not common among surveyed people. Most interviewees were able to recognize epidemiological characteristics of the parasites; however, parasite control measures adopted at most cattle ranches tend to jeopardize the efficacy of products, susceptibility of parasites and sustainability of control programs.

Farmers' perception about parasitic otitis in Gyr breed from three states of Brazil / Percepção de criadores de Gir a respeito da otite parasitária de bovinos em três estados brasileiros, 2009

This study aimed to know the perception of Gir cattle breeders and farm employees about parasitic otitis and practices regarding methods of treatment and control. A questionnaire was applied on specific topics about the disease. The results showed that the otitis occurred in 25 (89.3%) of the 28 farms studied, where the main etiologic agents were the nematodes Rhabditis spp. The majority of the farmers regarded the disease as a serious problem, mainly in cattle older than eight years of age. About half of the respondents did not observe a correlation between season and prevalence of the otitis; however, 30.8% reported an increase of its incidence during the rainy season. In addition to various methods and products for the rhabditiosis treatment, a lack of standardized preventive or curative protocols was found, suggesting insufficient knowledge about control of the disease.

Este estudo objetivou conhecer a percepção de criadores e responsáveis técnicos de rebanhos bovinos da raça Gir frente à otite parasitária, inclusive suas práticas relativas aos métodos de controle e tratamento. Utilizou-se um questionário contendo tópicos específicos relacionados à doença. Os resultados mostraram que a otite esteve presente em 25 (89,3%) das 28 propriedades estudadas, sendo os nematóides do gênero Rhabditis o principal agente etiológico encontrado. A maioria dos entrevistados considerou a doença como um sério problema do rebanho, ocorrendo principalmente nos animais com mais de oito anos de idade. Cerca de metade dos entrevistados não observaram correlação entre a época do ano e maior prevalência da doença, por sua vez, 30.8% deles relataram o aumento da frequência de casos de otite durante a estação chuvosa. Verificou-se, além da grande variedade de métodos e produtos para o tratamento da rhabditiose, a ausência de padronização dos protocolos preventivos ou curativos, sugerindo conhecimento insuficiente a respeito do seu controle.

Genetic diversity patterns of Haemonchus placei and Haemonchus contortus populations isolated from domestic ruminants in Brazil.

Parasitic nematodes of the genus Haemonchus infect a range of ruminant hosts and are of major veterinary and economic importance. In this study, the genetic variability of seven isolates of Haemonchus placei and Haemonchus contortus was evaluated using the mitochondrial gene cytochrome oxidase subunit I and the nuclear gene b-tubulin isotype 1. A total of 156 specimens were obtained from cattle, sheep, goat and buffalo herds raised on commercial properties from the southern and southeastern regions of Brazil and identified to the species level by sequencing of the nuclear internal transcribed spacer 2. Thirty-four percent of the specimens were identified as H. placei and 66% as H. contortus. Cattle were the preferred hosts for H. placei, whereas H. contortus was most frequent in the other three ruminant species. Analysis of genetic differentiation between isolates revealed that high rates of gene flow are operating among populations of both nematode species, including among those from different ruminant host species. Populations of H. placei were less polymorphic and presented a lower frequency of single nucleotide polymorphisms associated with benzimidazole resistance compared with H. contortus. In line with the low amount of genetic structure observed among isolates, alleles of b-tubulin 1 associated with benzimidazole resistance were present at relatively high frequencies of 5­20% in isolates of H. contortus from farms that never used this class of anthelmintic. The results presented here are consistent with the hypothesis of multiple origins of alleles associated with benzimidazole resistance, with the trade of animals among properties acting as the main factor promoting the spread of anthelmintic resistance.

Coxiella symbiont in the tick Ornithodoros rostratus (Acari: Argasidae).

In the present study, the presence of tick-associated bacteria and protozoa in Ornithodoros rostratus ticks (adults, nymphs, and eggs) from the Pantanal region of Brazil were determined by molecular detection. In these ticks, DNA from protozoa in the genera Babesia and Hepatozoon, and bacteria from the genera Rickettsia, Borrelia, Anaplasma, and Ehrlichia were not detected. Conversely, all tested ticks (100%) yielded PCR products for 3 Coxiella genes (16S rRNA, pyrG, cap). PCR and phylogenetic analysis of 3 amplified genes (16S rRNA, pyrG, cap) demonstrated that the agent infecting O. rostratus ticks was a member of the genus Coxiella. This organism grouped with Coxiella symbionts of other soft tick species (Argasidae), having different isolates of C. burnetii as a sister group, and these 2 groups formed a clade that grouped with another clade containing Coxiella symbionts of hard tick species (Ixodidae). Analysis of tick mitochondrial 16S rRNA gene database composed mostly of tick species previously shown to harbor Coxiella symbionts suggests a phylogenetic congruence of ticks and their Coxiella symbionts. Furthermore, these results suggest a very long period of coevolution between ticks and Coxiella symbionts and indicates that the original infection may have occurred in an ancestor common to the 2 main tick families, Argasidae (soft ticks) and Ixodidae (hard ticks). However, this evolutionary relationship must be confirmed by more extensive testing of additional tick species and expanded populations.

A novel Rickettsia infecting Amblyomma dubitatum ticks in Brazil.

A total of 130 adult free-living ticks of Amblyomma cajennense and 9 free-living Amblyomma dubitatum were collected in the surroundings of the Pampulha Lake, within Belo Horizonte city, state of Minas Gerais, south-eastern Brazil. Each adult tick was tested for rickettsial infection by PCR protocols targeting the rickettsial genes gltA, htrA, and ompA. All the 130 A. cajennense ticks were negative by PCR. In contrast, all 9 A. dubitatum ticks were shown to contain rickettsial DNA. PCR products were sequenced, generating identical sequences for each gene among the 9 ticks, which were shown to contain a novel agent, here designated as Rickettsia sp. strain Pampulha. Phylogenetic analyses inferred from the 3 rickettsial genes (gltA, htrA, ompA) showed that Rickettsia sp. strain Pampulha segregated in the same cluster with R. tamurae, R. monacensis, and several other unclassified rickettsial strains; however, strain Pampulha is a unique Rickettsia strain for the New World, since its closest relatives, according to 3 genes (gltA, htrA, and ompA), are all from the Old World. Because A. dubitatum eventually bites humans, further studies are necessary to determine the potential pathogenicity of Rickettsia sp. strain Pampulha to humans.

[Comparison of different sampling traps for Dermanyssus gallinae (Acari: Dermanyssidae) (de Geer, 1778)]. / Comparacao da eficiencia de diferentes armadilhas utilizadas para a captura de Dermanyssus gallinae.

This work aims to compare the performance of corrugated paper and "taquaril" bamboo (Phyllostachys sp.) straw traps for collecting (in sampling) Dermanyssus gallinae in a metal cages battery laying hens. The presence of eggs in the two trap models were compared using a Qui-square test and a proportion confidence interval test. Total daily values of mobile instars gathered in each type of trap were compared using the Wilcoxon's test. The amount of traps containing eggs was not different in neither of the traps (p < 0,05). The number of mobile instars sampled at every two days per trap model was different (p

Comparação da eficiência de diferentes armadilhas utilizadas para a captura de Dermanyssus gallinae (Acari: Dermanyssidae) (de Geer, 1778) / Comparison of different sampling traps for Dermanyssus gallinae (Acari: Dermanyssidae) (de Geer, 1778)

O presente trabalho teve como objetivo comparar a eficiência de armadilhas de papel corrugado com a de armadilhas de colmo de bambu taquaril (Phyllostachys sp.) seco na captura de Dermanyssus gallinae, presentes em uma bateria de gaiolas de metal utilizadas na criação de galinhas de postura. A presença de ovos no interior de cada tipo de armadilha foi comparada por meio do teste de Qui-Quadrado e pelo intervalo de confiança para duas proporções. Os valores das somas de estágios móveis nas diferentes armadilhas a cada intervalo de tempo foram comparados utilizando-se o teste de Wilcoxon. A proporção de armadilhas contendo ovos não foi diferente nos dois tipos de armadilha (p < 0,05). O número total de estágios móveis capturados durante a coleta a cada dois dias de intervalo em cada tipo de armadilha foi diferente (p < 0,01), enquanto que as contagens, nas armadilhas de papelão, apresentaram distribuição normal e foram superiores aos valores de espécimes móveis capturados nas armadilhas de bambu.

This work aims to compare the performance of corrugated paper and "taquaril" bamboo (Phyllostachys sp.) straw traps for collecting (in sampling) Dermanyssus gallinae in a metal cages battery laying hens. The presence of eggs in the two trap models were compared using a Qui-square test and a proportion confidence interval test. Total daily values of mobile instars gathered in each type of trap were compared using the Wilcoxon's test. The amount of traps containing eggs was not different in neither of the traps (p < 0,05). The number of mobile instars sampled at every two days per trap model was different (p < 0,01). Counting in the corrugated paper traps showed a Gauss distribution histogram and was superior to the values of the bamboo straw traps.

An outbreak of malignant catarrhal fever in Murrah buffaloes in Minas Gerais, Brazil / Surto de febre catarral maligna (FCM) em búfalos da raça Murrah no estado de Minas Gerais

An outbreak of Malignant Catarrhal Fever (MCF) resulted in death of five female buffaloes and one domestic cow from the same farm. Four buffaloes died 10-15 days after the appearance of clinical signs, while the fifth was euthanized in extremis, after similar clinical signs. Histopathological lesions included multifocal histiolymphocytic epicarditis, myocarditis and lymphocytic interstitial pneumonia, which are commonly seen in cases of MCF in buffaloes. Furthermore, lymphocytic vasculitis centered in the adventitia, with occasional fibrinoid necrosis in the muscular layer, was found in the kidneys, liver, spleen, lymph nodes and brain. Nucleotide sequencing of DNA fragments from the central nervous system amplified by PCR revealed 98 percent similarity with known OHV-2 sequences from Genbank. Additionally, PCR analysis also revealed the presence of OHV-2 DNA in the peripheral mononuclear blood cells of two clinically healthy buffaloes. The diagnosis of MCFwas based on epidemiological, clinical, gross and histopathological findings and on the results of a semi-nested PCR followed by nucleotide sequencing.

É relatado um surto de febre catarral maligna (FCM) em Minas Gerais, que resultou na morte de 5 búfalas e uma vaca de uma mesma propriedade. Quatro búfalas morreram com 10-15 dias após o início dos sinais clínicos e uma búfala foi sacrificada in extremis, após manifestar sinais clínicos semelhantes. O exame histopatológico revelou lesões comumente observadas em búfalos com FCM como epicardite e miocardite histiolinfocítica multifocal e pneumonia linfocítica intersticial. Além disso, vasculite linfocítica, principalmente na camada adventícia, com necrose fibrinóide da camada muscular, foi observada no rim, fígado, baço, linfonodos e cérebro. A seqüência de nucleotídeos amplificada pela técnica de PCR revelou 98 por cento de homologia entre o fragmento de DNA amplificado da amostra do sistema nervoso central (SNC) da búfala com seqüências de OHV-2 previamente depositadas no Genbank. Adicionalmente, a técnica de PCR revelou a presença do DNA viral no sangue total de 2 búfalas, clinicamente sadias. O diagnóstico de FCM foi baseado em dados epidemiológicos, clínicos, patológicos, histopatológicos e semi-nested PCR.

Tripanosomatides like Trypanosoma theileri in the cattle tick Boophilus microplus.

Findings of epimastigotes forms of a tripanosomatide is reported in the hemolymph of the cattle tick Boophilus microplus in the state of Rio Grande do Sul, southern Brazil. Morphological evidences suggest they are similar to Trypanosoma theileri, a species described as non pathogenic to cattle, and usually transmitted by tabanids.

Ritmo de queda de Rhipicephalus sanguineus (Acari: Ixodidae) de cães artificialmente infestados / Drop off rhythm of Rhipicephalus sanguineus (Acari: Ixodidae) of artificially infested dogs

O ritmo de queda de Rhipicephalus sanguineus (Latreille) foi avaliado para duas populações do Brasil; uma de Monte Negro, Estado de Rondônia, e outra de Belo Horizonte, Estado de Minas Gerais. Infestações artificiais com carrapatos das duas populações foram realizadas em cães domésticos mantidos em laboratório, sob o regime de luz: escotofase de 12:12 h. O padrão de queda de larvas ingurgitadas do hospedeiro se caracterizou pelo desprendimento de quantidades semelhantes de carrapatos em períodos de luz e de escotofase ou com um predomínio de queda durante o período de luz. No caso de ninfas e fêmeas ingurgitadas, a maioria dos carrapatos se desprendeu dos cães durante o período de escotofase, em todos os casos observados. Desta forma, é possível que em condições naturais, a maioria das ninfas e fêmeas adultas de R. sanguineus tendem a se desprender dos cães durante o período noturno, ao passo que larvas ingurgitadas se desprendem em proporções maiores durante o período diurno. Com base nestes dados, sugere-se que os locais onde os cães freqüentam durante a noite (onde possivelmente estará a maior parte da população de vida livre de R. sanguineus) sejam priorizados com os tratamentos ambientais utilizando-se produtos carrapaticidas.

The present study evaluated the drop-off rhythm of Rhipicephalus sanguineus (Latreille) ticks from two populations from Brazil, one from Monte Negro, state of Rondônia, and another from Belo Horizonte, state of Minas Gerais. Artificial infestations with ticks were performed on dogs in the laboratory, held in a light: scotophase regimen of 12:12 h. Larval drop-off rhythm was characterized by similar number of engorged larvae detaching during both periods of light and scotophase, or by a larger number of larvae detaching during the light period. In contrast, most of the engorged nymphs and females detached from dogs during the scotophase period. These results indicate that under natural conditions, most of R. sanguineus engorged nymphs and females detach from dogs during the night period, whereas engorged larvae detach in higher proportions during daytime. Based on these data, tick control measures, encompassing environmental treatments with acaricide, should be indicated. The control measures are especially indicated in places where dogs spend or visit during the night period, since these places possibly harbor most of the free-living stages of R. sanguineus.

[Control of Rhipicephalus sanguineus (Latrielle, 1806) (Acari: Ixodidae) in the kennel of the UFMG Veterinary School, Belo Horizonte, Minas Gerais, Brazil]. / Controle de Rhipicephalus sanguineus (Latrielle, 1805) (Acari: Ixodidae) no canil da Escola de Veterinária da UFMG, Belo Horizonte, Minas Gerais, Brasil.

The present work was aimed at proposing a control measure for Rhipicephalus sanguineus in a naturally infected kennel of 72 m(2) of the UFMG Veterinary School with 25 dogs of different breeds. A sensitivity test to acaricide products was applied in a sample of R. sanguineus. Out of the acaricide products tested: 12.5% Amitraz (product 1); 2% Alfamethrin and 60% Dichlorvos association (product 2); 5% Deltamethrin (product 3) and the association between 77.6% Trichlorfon, 1.0% Coumaphos and 1.0% Cyfluthrin (product 4); only 1 and 4 products showed 100% efficacy. Amitraz (12.5%) was used for controlling R. sanguineus in the surrounding of the kennel, on which four treatments every seven days were carried out in the facilities. For parasitic R. sanguineus, a single topical treatment was used: Flumetrin 1.0% pour-on on all the 25 dogs. This control measure significantly reduced the population of R. sanguineus within the kennel. A slight infestation was observed in the seventh month after treatment. A new application of 12.5% Amitraz was done in the kennel as well as a new topical treatment with Flumetrin 1.0% pour-on on the dogs. The control procedure proposed in the present study was an emergency measure and its effectiveness was checked through environmental surveys throughout a one-year period.

Tripanosomatides like Trypanosoma theileri in the cattle tick Boophilus microplus / Tripanosomatídeos similares a Trypanosoma theileri no carrapato dos bovinos Boophilus microplus

Findings of epimastigotes forms of a tripanosomatide is reported in the hemolymph of the cattle tick Boophilus microplus in the state of Rio Grande do Sul, southern Brazil. Morphological evidences suggest they are similar to Trypanosoma theileri, a species described as non pathogenic to cattle, and usually transmitted by tabanids.

Descreve-se a ocorrência de formas epimastigotas de um tripanosomatideo na hemolinfa do carrapato do bovino Boophilus microplus no Estado do Rio Grande do Sul. Evidências morfológicas sugerem tratar-se de Trypanosoma theileri , espécie descrita como não patogênica aos bovinos e que usualmente é transmitida por tabanídeos.

Controle de Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) no canil da Escola de Veterinária da UFMG, Belo Horizonte, Minas Gerais, Brasil / Control of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) in the kennel of the UFMG Veterinary School, Belo Horizonte, Minas Gerais, Brazil

O presente estudo teve como proposta controlar uma infestação natural de Rhipicephalus sanguineus em um canil pertencente à Escola de Veterinária da UFMG, com uma área de 72 m² e 25 cães de diversas raças. Um teste de sensibilidade a produtos acaricidas foi aplicado em uma amostra de carrapatos capturados no canil. Dos produtos testados: Amitraz 12,5 por cento (Produto 1); uma associação de Alfametrina 2 por cento e Dichlorvós 60 por cento (produto 2); Deltametrina 5 por cento (produto 3) e uma associação de Trichlorfon 77,6 por cento, Coumaphós 1 por cento e Cyfluthrin 1 por cento (produto 4); somente os produtos 1 e 4 apresentaram 100 por cento de eficácia. O Amitraz 12,5 por cento foi utilizado no controle dos estádios de R. sanguineus presentes no ambiente do canil, com um esquema de 4 aplicações a cada 7 dias de intervalo. Para os estádios parasitários, um único tratamento com Flumetrina 1.0 por cento pour-on foi empregado em todos os animais. A inspeção e o monitoramento do ambiente e dos animais foram realizados durante um período de um ano. Estas medidas de controle reduziram significativamente a população de carrapatos dentro do canil. O canil não apresentou infestação pelo carrapato nos seis meses seguintes aos tratamentos. Uma infestação leve foi observada no 7º mês pós-tratamento, quando foi realizada uma nova aplicação de Amitraz 12,5 por cento no ambiente do canil e um novo tratamento com Flumetrina 1.0 por cento pour-on nos animais, com resultados satisfatórios.

The present work was aimed at proposing a control measure for Rhipicephalus sanguineus in a naturally infected kennel of 72 m² of the UFMG Veterinary School with 25 dogs of different breeds. A sensitivity test to acaricide products was applied in a sample of R. sanguineus. Out of the acaricide products tested: 12.5 percent Amitraz (product 1); 2 percent Alfamethrin and 60 percent Dichlorvos association (product 2); 5 percent Deltamethrin (product 3) and the association between 77.6 percent Trichlorfon, 1.0 percent Coumaphos and 1.0 percent Cyfluthrin (product 4); only 1 and 4 products showed 100 percent efficacy. Amitraz (12.5 percent) was used for controlling R. sanguineus in the surrounding of the kennel, on which four treatments every seven days were carried out in the facilities. For parasitic R. sanguineus, a single topical treatment was used: Flumetrin 1.0 percent pour - on on all the 25 dogs. This control measure significantly reduced the population of R. sanguineus within the kennel. A slight infestation was observed in the seventh month after treatment. A new application of 12.5 percent Amitraz was done in the kennel as well as a new topical treatment with Flumetrin 1.0 percent pour - on on the dogs. The control procedure proposed in the present study was an emergency measure and its effectiveness was checked through environmental surveys throughout a one-year period.

[Drop off rhythm of Rhipicephalus sanguineus (Acari: Ixodidae) of artificially infested dogs]. / Ritmo de queda de Rhipicephalus sanguineus (Acari: Ixodidae) de cães artificialmente infestados.

The present study evaluated the drop-off rhythm of Rhipicephalus sanguineus (Latreille) ticks from two populations from Brazil, one from Monte Negro, state of Rondônia, and another from Belo Horizonte, state of Minas Gerais. Artificial infestations with ticks were performed on dogs in the laboratory, held in a light: scotophase regimen of 12:12 h. Larval drop-off rhythm was characterized by similar number of engorged larvae detaching during both periods of light and scotophase, or by a larger number of larvae detaching during the light period. In contrast, most of the engorged nymphs and females detached from dogs during the scotophase period. These results indicate that under natural conditions, most of R. sanguineus engorged nymphs and females detach from dogs during the night period, whereas engorged larvae detach in higher proportions during daytime. Based on these data, tick control measures, encompassing environmental treatments with acaricide, should be indicated. The control measures are especially indicated in places where dogs spend or visit during the night period, since these places possibly harbor most of the free-living stages of R. Sanguineus.

Biological parameters of ticks (Amblyomma cajennense Fabricius, 1787) under field and laboratory conditions in Pedro Leopoldo, State of Minas Gerais, Brazil.

This study evaluated the biological parameters of the duration of the pre-oviposition and egg incubation periods and maximum survival of unfed larvae, under field and laboratory conditions, with the aim of providing support for more rational measures for controlling Amblyomma cajennense. This study was conducted at the Experimental Farm of the Veterinary School of the Federal University of Minas Gerais. Every 14 days, from September 1997 to March 1998 and from October 1998 to April 1999, six netted tubes containing engorged females were kept on pasture of Brachiaria decumbens that was up to 60 cm high and another six were kept in a BOD glass chamber (27 degrees C, 80% relative humidity). For both groups, 84 and 72 females were used during the first and second observation periods, respectively. The duration of the pre-oviposition period was similar under both conditions (5-7 days). Significant differences were seen between the duration of the egg incubation period under field conditions (56 to 60 days) and under BOD conditions (34 to 39 days); and between the maximum survival of the unfed larvae under field conditions (14 months) and under BOD conditions (9.5 months). These suggest that behavioral diapause was occurring. The long survival of unfed larvae in pasture needs to be considered when implementing Amblyomma cajennense control programs.