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Bovine babesiosis, caused by Babesia bovis or Babesia bigemina, is a major tick-borne disease affecting livestock. In regions with limited vaccine availability, imidocarb is widely used as a chemoprophylactic drug. Although it is assumed that chemoprophylaxis allows for the development of immunity shortly after treatment, the extent of seroconversion during the imidocarb administration protocol remains largely unexplored, with most investigations emphasizing symptom prevention. This research endeavors to verify the seroconversion rate (humoral immunity) of cattle undergoing imidocarb chemoprophylaxis while exposed to tick vectors in field conditions. Fifteen tick-naïve heifers were used, with twelve receiving imidocarb (experimental group) on day 0 of the experiment, and the remaining three serving as controls. On day one of the study, all animals were introduced into a tick-infested pasture. Subsequently, at 28-day intervals (days 28, 56, 84, 112, 140, and 168), the experimental group received imidocarb treatments (1.2 mg/Kg). The detection of antibodies against B. bovis and B. bigemina was performed using commercial ELISA kits. Throughout the study, all animals were exposed to natural infestation by Rhipicephalus microplus ticks. By the 56th day, after two imidocarb doses, 25 % of the experimental group had seroconverted for B. bovis, and 41 % for B. bigemina. By the 84th day, 66 % were seropositive for B. bovis and B. bigemina. By the 112th day, 75 % were seropositive for B. bovis. Notably, one heifer (8 %) failed to seroconvert for either species, while 41 % remained seropositive for only one Babesia species. These findings underscore certain limitations of the chemoprophylaxis protocol for bovine babesiosis. While the majority of treated cattle become seropositive for at least one Babesia species after four successive treatments, exposure to the parasite while receiving imidocarb chemoprophylaxis does not guarantee seroconversion for all treated animals., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The tick Rhipicephalus microplus is a parasite of great importance in cattle breeding. It is responsible for huge economic losses. The application of synthetic acaricides is used as a form of control. However, resistant strains have been selected over the years, making it necessary to search for new alternative formulations. The present study aimed to formulate biodegradable films impregnated with the terpenes carvacrol and thymol and evaluate their efficacy on larvae and adults of R. microplus through in vitro tests. The following formulations were prepared: Film 1 (starch based); Film 2 (based on starch and glycerol); Film 1 + Carvarcol or Thymol; Film 2 + Carvarcol or Thymol. Terpenes had a final concentration of 5.0 mg/mL. To evaluate the formulations on larvae, the immersion test was performed by dividing into six groups according to the concentration of terpenes: 5.0, 2.5, 1.25, 0.625, 0.313, 0.156 mg/mL and the control groups: 1% ethanol solution; 10% ethanol solution; Film 1; and Film 2. For the evaluations on adult ticks, ten experimental groups (n = 10) were used: 1) Carvacrol; 2) Film 1 + Carvacrol; 3) Film 2 + Carvacrol; 4) Thymol; 5) Film 1 + Thymol; 6) Film 2 + Thymol; 7) Distilled water; 8) 10% ethanol solution; 9) Film 1; and 10) Film 2. In experimental groups 1-6, carvacrol and thymol (free or incorporated in two different biodegradable film formulations) were evaluated at the same concentration (5.0 mg/mL). Each group of ticks was immersed in their respective solutions for five minutes. The results of the tests on larvae showed that the Film 1 + thymol and Film 2 + carvacrol formulations had the lowest lethal concentrations (0.076 and 0.255 mg/mL, respectively), values up to 9.0-fold lower than the monoterpenes tested outside the formulation. Carvacrol and thymol at the concentrations tested were effective in controlling engorged females with a percentage of 32.2% and 63.8%, respectively. When incorporated into biodegradable film formulations, these monoterpenes showed much greater efficacy. Film 1 + carvacrol and Film 2 + carvacrol with control percentages of 71.6% and 97.2%, respectively, while the formulations Film 1 + thymol and Film 2 + thymol showed values of 96.9% and 100.0%. The tick control activity of the biopolymer formulations with thymol and carvacrol was demonstrated through the high mortality rates of larvae and engorged females of the tick R. microplus. Therefore, the results obtained indicate that these formulations have great potential for tick control mainly because of the percentage of control up to 100% in engorged females in in vitro tests., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Livio M Costa Junior reports financial support was provided by Foundation for Research Support and Scientific and Technological Development of Maranhão. Livio M Costa Junior reports financial support was provided by Coordination of Higher Education Personnel Improvement. Livio M Costa Junior reports financial support was provided by National Council for Scientific and Technological Development. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The apicomplexan hemoprotozoan Theileria equi is a tick-borne pathogen that causes disease in equids, and together with Babesia caballi, causes equine piroplasmosis (EP). Many ticks are associated with EP around the world, and in South America three species may be related: Dermacentor nitens, Amblyomma sculptum, and Rhipicephalus microplus, as they are commonly found in horses. Among the species cited above, only R. microplus is found in Rio Grande do Sul state, Southern Brazil. In addition, this state has the only area legally free of R. microplus in Brazil. This study aimed to compare the seroprevalence for T. equi on farms located in a tick-free area (23 farms, 215 horses) and a tick-infested (25 farms, 141 horses) adjacent areas, as well as to identify potential risk factors for exposure to T. equi. Blood was collected from 356 horses from both areas, and later an indirect enzyme-linked immunosorbent assay was performed to detect anti-T. equi antibodies. Besides the blood collection, questionnaires and interviews were conducted in an attempt to identify potential risk factors. The R. microplus-free zone had 6% seropositive horses against 70% in the tick-infested zone. Previous observation of ticks on horses of the herd increased four times the odds of a horse to be seropositive for T. equi, and by three times if ticks were observed on cattle which share paddocks with horses on the farm. The results showed a large difference in T. equi seroprevalence between tick-infested and free areas, and also emphasized the relevance of R. microplus in the epidemiology of T. equi. The study also reveals the potential of the establishment of a T. equi-free zone for horse breeding in Southern Brazil., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The cattle tick, Rhipicephalus microplus, causes severe economic losses to beef and dairy production in several countries. The control of the cattle tick is based mostly on chemical acaricides. Currently, there are reports of tick populations resistant to all six classes of acaricides available on the market. The aim of this work was to evaluate two protocols for the control of the cattle tick, R. microplus, under field conditions. For that, an acaricide rotational-based approach and selective (partial)-based protocols were tested against a multi-resistant tick strain. Eighteen Brangus cattle were divided into three experimental groups: Group 1, a rotational-based approach aiming at six treatments per year (spring-spring period) using four different classes of acaricide (IPV6 protocol); Group 2, a selective (partial) and rotational-based protocol, in which only half of the animals with the highest tick counts were treated (IPV7S protocol); and Group 3 (non-treated). The protocols were able to maintain low tick infestation during the 57 weeks of study. The two experimental groups showed lower tick counts than the non-treated group, but not between them. Weekly efficacy of the experimental protocols reached 95% in Group 1 and 88% in Group 2. Herein, we proposed two protocols of cattle tick control (IPV6 and IPV7S) for use in multi-resistant tick populations in Southern Brazil., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

Amitraz is one of the most used acaricides for the control of ticks of domestic animals, however, extensive use of this active ingredient has favored the development of resistant populations of Rhipicephalus microplus worldwide. The possible mechanisms of metabolic and/or target-site alterations mechanisms of amitraz resistance were investigated in a Brazilian field population of R. microplus (São Gabriel strain). Bioassays with the synergists piperonylbutoxide, triphenylphosphate and diethyl-maleate were used to evaluate the metabolic mechanisms involved. Target-site insensitivity was investigated by amplification and sequencing of a fragment of the octopamine/tyramine (OCT/TYR) receptor gene. Piperonylbutoxide synergism (synergism ratio = 2.8) indicated the participation of the P450 pathway in the detoxification of amitraz. Previously reported single nucleotide polymorphisms that confer amino acid changes in the OCT/TYR receptor, threonine to proline (T8P) and leucine to serine (L22S), were found in the amitraz-resistant strain but not in the susceptible reference strain. The results suggest that amitraz resistance in the studied strain is multi-factorial and may result from cytochrome P450 detoxification and mutations in octopamine receptors., (Copyright © 2021 Elsevier GmbH. All rights reserved.)

Ticks are one of the main vectors of pathogens for humans and animals worldwide. However, they harbor non-pathogenic microorganisms that are important for their survival, facilitating both their nutrition and immunity. We investigated the bacterial communities associated with two neotropical tick species of human and veterinary potential health importance from Brazil: Amblyomma aureolatum and Ornithodoros brasiliensis. In A. aureolatum (adult ticks collected from wild canids from Southern Brazil), the predominant bacterial phyla were Proteobacteria (98.68%), Tenericutes (0.70%), Bacteroidetes (0.14%), Actinobacteria (0.13%), and Acidobacteria (0.05%). The predominant genera were Francisella (97.01%), Spiroplasma (0.70%), Wolbachia (0.51%), Candidatus Midichloria (0.25%), and Alkanindiges (0.13%). The predominant phyla in O. brasiliensis (adults, fed and unfed nymphs collected at the environment from Southern Brazil) were Proteobacteria (90.27%), Actinobacteria (7.38%), Firmicutes (0.77%), Bacteroidetes (0.44%), and Planctomycetes (0.22%). The predominant bacterial genera were Coxiella (87.71%), Nocardioides (1.73%), Saccharopolyspora (0.54%), Marmoricola (0.42%), and Staphylococcus (0.40%). Considering the genera with potential importance for human and animal health which can be transmitted by ticks, Coxiella sp. was found in all stages of O. brasiliensis, Francisella sp. in all stages of A. aureolatum and in unfed nymphs of O. brasiliensis, and Rickettsia sp. in females of A. aureolatum from Banhado dos Pachecos (BP) in Viamão municipality, Brazil, and in females and unfed nymphs of O. brasiliensis. These results deepen our understanding of the tick-microbiota relationship in Ixodidae and Argasidae, driving new studies with the focus on the manipulation of tick microbiota to prevent outbreaks of tick-borne diseases in South America., (Copyright © 2021 Elsevier GmbH. All rights reserved.)

The study of vectors and vector-borne diseases associated with ectoparasites from free-living Neotropical small wild felids is scarce, and the few existing studies on this theme focused on the genus Panthera, Paleartic species or in captive animals. For this reason, the aim of this study was to identify the diversity of ectoparasites and potentially associated Rickettsia and Bartonella species in free-ranging neotropical wild cats collected in the State of Rio Grande do Sul, southern Brazil. A total of 82 ticks, 10 fleas and 22 mites were collected from 18 Geoffroy's cats (Leopardus geoffroyi), 11 margays (Leopardus wiedii), two southern tiger cats (Leopardus guttulus), two jaguarundis (Herpailurus yagouaroundi), three ocelots (Leopardus pardalis) and two pumas (Puma concolor). We identified four tick species: Rhipicephalus microplus and three species from genus Amblyomma, the most frequent being Amblyomma aureolatum; three flea species corresponding to Ctenocephalides felis, Xenopsylla cheopis, and Pulex irritans; and one mite of genus Eutrombicula. In ectoparasites we found DNA of Rickettsia parkeri and Rickettsia asembonensis in ticks and DNA of Bartonella clarridgeiae, Bartonella sp. and R. asembonensis in fleas. Our results highlight the evidences of vectors and vector-borne agents in wild animals, and their potential wide distribution in the Pampa biome and the southernmost portion of the Atlantic Rainforest in Brazil., (Copyright © 2021. Published by Elsevier GmbH.)

The order Haemosporida is widely distributed parasitizing members of the Aves class. In birds of prey, infection with Plasmodium spp. parasites varies from an apathogenic form to a clinical syndrome. However, studies on Haemosporida in raptors from the neotropical region are scarce. The aim of this study was to investigate natural infection by Plasmodium spp., Haemoproteus spp. and Leucocytozoon spp. in free-ranging wild raptors from southern Brazil. For this, we sampled 206 individuals of 21 species: 94 live-trapped Southern Caracaras (Caracara plancus) and 112 raptors from other species that were brought to rehabilitation centers. The presence of infection was investigated using a nested-PCR for Haemosporida performed on blood samples. Overall, 56 out of 206 birds were positive for Plasmodium spp./Haemoproteus spp. Twenty-two percent (21/94) of the C. plancus samples were positive. Of the 112 wild raptors rescued, 31% (35/112) of those belonging to 15 other species tested positive. No sample was positive for Leucocytozoon spp. Herein, we demonstrated nine lineages of Haemosporidian parasites (eight Plasmodium sp. and one Haemoproteus sp.) in free-living species of Brazilian birds of prey, being six of them potential novel lineages. It suggests that information currently available on South-American haemosporidian from these birds greatly underestimate the potential lineage diversity in this region., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Rhipicephalus sanguineus sensu stricto (s.s.), the temperate lineage of the brown dog tick, is the most common tick found on dogs from urban areas in Rio Grande do Sul (RS) state, southern Brazil. Chemical treatments against ticks are important to control this pest, but can lead to selection for acaricide resistance. Unfortunately, little is known about acaricide resistance in this tick species in Brazil, although such information is very important to companion animal clinical practice. The objective of this study was to analyze acaricide susceptibility of R. sanguineus s.s. from the metropolitan area of Porto Alegre, RS. Engorged females ticks were collected in ten different locations, from naturally infested dogs or the environment (homes, shelters and kennels). The progenies were used in toxicological larval tests with deltamethrin, fipronil and ivermectin. Mortality data was used to determine the median lethal concentrations (LC50) for each tick population and resistance was characterized based on relative susceptibility of the different tick populations against each acaricide. Seven samples were considered resistant to deltamethrin, with resistance ratios (RR) ranging from 2.32 to 5.67. From five tick populations tested with fipronil, three were considered resistant, with RR varying from 2.56 to 13.83. For ivermectin, resistance ratios were lower, ranging from 1.54 to 2.97. The results reveal a notable variance of susceptibility to deltamethrin, fipronil and ivermectin in the R. sanguineus s.s. populations studied. This study documents for the first time the existence of acaricide-resistant populations of R. sanguineus s.s. in Brazil., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

More than seventy tick species have been reported in Brazil. Despite the emergence of tick-borne diseases in Neotropical region, there are still limited data available on tick species parasitizing humans in Brazil. Rio Grande do Sul is the southernmost state of Brazil, comprising the only part of Brazilian territory inside the Pampa biome, as well as the transition between subtropical and temperate zones. Here, we report on human parasitism by ticks in Rio Grande do Sul state between 2004 and 2017. Seventy cases of human parasitism by ticks were recorded, with a total of 81 tick specimens collected. These included 11 tick species belonging to three genera of Ixodidae (hard-ticks), Amblyomma, Haemaphysalis and Rhipicephalus; and one genus of Argasidae, Ornithodoros. The most prevalent tick species associated to cases of human parasitism were Amblyomma parkeri (24%), Rhipicephalus sanguineus sensu lato (22%), Amblyomma aureolatum (15%) and Amblyomma ovale (12%). A spatial analysis showed two major hot spots of human parasitism by ticks in Rio Grande do Sul state. The findings of this study highlight the need for permanent monitoring of human parasitism by ticks in order to provide a better understanding of tick and tick-borne disease eco-epidemiology, and the early identification of potential cases of tick-borne diseases, particularly in spotted fever endemic regions., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Rangelia vitalii is the etiologic agent of canine rangeliosis, a severe piroplasmosis that affects domestic dogs in Brazil, Uruguay and Argentina. While R. vitalii is one of the most pathogenic tick-borne pathogens for dogs in the world, its tick vector has remained unknown. The present study evaluated the vector competence of Rhipicephalus sanguineus sensu lato (both tropical and temperate species), Amblyomma aureolatum, Amblyomma ovale, Amblyomma tigrinum, and Amblyomma sculptum for R. vitalii. These six tick species were selected for the study because they comprise the main tick species infesting dogs within the distribution area of canine rangeliosis in South America. Acquisition feeding of the above six tick species was performed on domestic dogs showing clinical signs of canine rangeliosis, after being experimentally infected through intravenous inoculation or infestation with R. vitalii-infected ticks. Thereafter, engorged ticks were evaluated for transstadial and transovarial passages of R. vitalii through molecular analysis after molting or oviposition and egg hatching. The resultant ticks were evaluated for their competence to transmit R. vitalii to susceptible dogs. Among the six tick species, only A. aureolatum was able to acquire and perpetuate R. vitalii by transstadial and transovarial passages, as demonstrated by >5% infection rates of ticks after hatching or molting. When exposed to transmission feeding, only A. aureolatum ticks were competent to transmit R. vitalii to dogs, which became severely ill, and the results confirmed by molecular methods and blood smear examination to have acquired rangeliosis. Results of the present study, coupled with epidemiological data, indicate that A. aureolatum is a natural vector of R. vitalii. Our results also indicate that R. vitalii is the first Piroplasmorida agent to be transovarially transmitted in Amblyomma ticks., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Borrelia burgdorferi sensu lato (s.l.) complex includes the agents of Lyme disease/borreliosis in North America, Europe, and Asia, such Borrelia burgdorferi sensu stricto, Borrelia afzelii, Borrelia garinii, Borrelia bavariensis, Borrelia spielmanii, Borrelia bissettiae, and Borrelia mayonii. In 2013 B. burgdorferi s.l. was reported for the first time in the Neotropical region, from Ixodes aragaoi ticks in Uruguayan Pampa. In addition, from 2011 to 2016, 17 suspected human cases of borreliosis-like syndrome were reported in Rio Grande do Sul (RS) state, Brazil, which contains only part of country in the Pampa biome. The goal of this work is to report the results of a state surveillance program conducted in order to investigate the presence of B. burgdorferi s.l. in its classic vector, Ixodes spp. ticks, from the Brazilian Pampa. For this, we searched for Ixodes spp. ticks in 307 rodents from 11 municipalities of RS state. We then tested the ticks for the presence of B. burgdorferi s.l. DNA using PCR analysis. Of 35 Ixodes spp. ticks tested, one larva and one nymph of Ixodes longiscutatus ticks tested positive for Borrelia sp. DNA. The phylogenetic analysis of the flaB fragment grouped our samples (referred as Borrelia sp. haplotype Pampa) into B. burgdorferi s.l. group in a particular branch with other South American haplotypes, and this group was close to Borrelia carolinensis, B. bissettiae, and Borrelia californiensis. This is the first evidence of B. burgdorferi s.l. circulation in ticks of the genus Ixodes in Brazil. These results highlight the need for the implementation of public health policies for the diagnosis and prevention of potential cases of human borreliosis in Brazil. Further studies are needed to fill the gaps in our knowledge of the distribution, pathogenicity, reservoirs, and vectors of these emerging South American B. burgdorferi s.l. haplotypes., (Copyright © 2017 Elsevier GmbH. All rights reserved.)

Spotted fever is an acute febrile illness, which is considered severely underreported and misdiagnosed in the Brazilian Pampa, caused by tick-borne Rickettsiae. Here, we report an eco-epidemiological investigation of Rickettsia spp. in ticks from a spotted fever focus in Toropi, southern Brazil. Ticks were collected from capybara carcasses and processed individually to obtain genomic DNA. Rickettsia was investigated using PCR that amplified the rickettsial fragments of the gltA, ompA and htrA genes. DNA from Rickettsia parkeri was found in four of 14 Amblyomma dubitatum ticks collected from capybara carcasses in Toropi and the nearby municipality of Quevedos. We also tested 210A. dubitatum ticks obtained from road-killed capybaras of other localities from the Pampa biome; none of them were positive for Rickettsiae. Thus, in Rio Grande do Sul, two Rickettsia species can be potentially associated to spotted fever: Rickettsia sp. strain Atlantic Rainforest, associated with Amblyomma ovale ticks in the Atlantic Rainforest biome, and R. parkeri, associated both with Amblyomma tigrinum and A. dubitatum ticks in the Pampa biome. Our results reinforce that R. parkeri may be the agent associated with spotted fever in the Brazilian Pampa., (Copyright © 2017 Elsevier B.V. All rights reserved.)

"Candidatus Rickettsia asemboensis" is an obligate intracellular bacterium of the Rickettsiales order, genetically related to species belonging to the Rickettsia felis group, agents of flea-borne spotted fever. Here we report for the first time the detection of "Ca. R. asemboensis", a flea-associated organism, in Rhipicephalus sanguineus ticks. It is the first occurrence of this emerging bacterium in Brazil, which increases the geographical distribution of this R. felis-like agent., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The filamentous fungus Metarhizium anisopliae is an arthropod pathogen used in the biological control of pests in agriculture and livestock. The effect of the fungus M. anisopliae on ticks has been shown in experiments in vitro. The aim of the present study was to compare the susceptibility of different field isolates of Rhipicephalus microplus to M. anisopliae. A total of 67 field isolates were evaluated. Rhipicephalus microplus larvae were immersed in an M. anisopliae suspension (10 8 conidia/mL) for 5min. The median lethal times (LT 50 ) ranged from 2.6 to 24.9days. Mortality observed at the 15th day after treatment ranged from 26.3 to 100% in the tested samples. The effect of M. anisopliae on tick isolates was not associated with their susceptibility to any acaricide tested, animal stocking rate, cattle breed, rotational grazing, cultivated pasture, production system, presence of wet areas or biome. The integration of livestock and agriculture practices in the farm and the frequency of acaricide treatment seem to be associated with tick susceptibility to M. anisopliae. These results demonstrated that field populations of R. microplus show a high variation in their susceptibility to M. anisopliae., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

Acaricide resistance is a major obstacle to the control of Rhipicephalus microplus. Historically, the indiscriminate use of chemical compounds has contributed to the selection of populations resistant to different classes of acaricides. Therefore, multiple acaricide resistance is an important threat to the chemical control of the cattle tick. To investigate the occurrence and extent of multiple resistance to acaricides in Southern Brazil we performed larval tests with cypermethrin, chlorpyriphos, amitraz, fipronil and ivermectin on 104 cattle tick field samples from different ranches in Rio Grande do Sul, between the years 2013 and 2015. Adult immersion tests with a commercial formulation mixture of chlorpyriphos and cypermethrin were performed on 75 samples. Four levels of resistance were established according to the mortality of larvae: Level I: mortality between 82% and 95%; Level II: mortality between 57% and 82%; Level III: mortality between 25% and 57%; and Level IV: mortality lower than 25%. Resistance to cypermethrin was detected in 98.08% of the samples evaluated, mostly at resistance level IV. The frequency of samples resistant to amitraz, chlorpyriphos, ivermectin and fipronil was 76.92%, 60.58%, 60.58% and 53.85% respectively. Multiple resistance to three or more compounds was found in 78.85% of the samples. The results obtained in this study are alarming and reveal a new scenario for the challenge of tick control using chemicals. This is an issue of high importance to cattle production systems where this tick is responsible for a high economic impact., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

Ornithodoros Brasiliensis: Aragão is an endemic tick restricted to the highlands of the state of Rio Grande do Sul, Brazil. This species is very aggressive toward humans, causing fever, great pain and intense inflammatory response at the bite site. It is also very aggressive toward dogs, and tick toxicosis syndrome has been reported in this host. In order to elucidate the biology of this tick, the present study describes its life cycle under laboratory conditions, using guinea pigs as hosts for two generations. In the nonparasitic phase, the ticks were maintained in sand, in an incubator under controlled conditions. The larvae molted to the nymphal stage without feeding, and five nymphal stages (N1, N2, N3, N4 and N5) were observed in both generations. In both generations emergence of adults started from N3 when sex ratio was 0.85:1 (23 males and 27 females) in F1 and 0.63:1 (34 males and 54 females) in F2. For both generations, N4 generated more females, while N5 only produced females. The pre-ecdysis period of the nymphs ranged from 31.1 to 38.6 days. Two gonotrophic cycles were observed, and the first one presented a higher average number of eggs deposited (N=139) than the second (N=73.8). The mean duration of the life cycle (egg to egg) of O. brasiliensis was 215.4 days for the first generation and 195 days for the second., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

The efficacy of the fungus Metarhizium anisopliae to control ticks has been shown in several in vitro experiments. However, few studies have been undertaken in field conditions in order to demonstrate the applicability of its use as a biological control of ticks and its combination with chemical acaricides. The aim of the present study was to evaluate the efficacy of M. anisopliae to control an acaricide-resistant strain of Rhipicephalus microplus under laboratory and field conditions. First, the compatibility of M. anisopliae strain (TIS-BR03) with commercial acaricides and its potential to control the cattle tick were evaluated in vitro. In general, acaricide treatments had mild effects on fungus viability. In the field experiment, the median of treatment efficacy with acaricide only, M. anisopliae only and combination of M. anisopliae with acaricide were 71.1%, 56.3% and 97.9%, respectively. There is no statistical difference between groups treated with M. anisopliae and acaricide alone. Thus, in this work we have demonstrated the applicability of M. anisopliae use associated or not with chemical acaricides on field conditions in order to control an acaricide-resistant strain of the cattle tick R. microplus., (Copyright © 2015. Published by Elsevier B.V.)

Canine rangeliosis, caused by the piroplasmid protozoon Rangelia vitalii, is currently recognized as a reemerging disease that affects domestic dogs in Brazil. In the present study, piroplasmid infection was searched in wild canids (20 Cerdocyon thous and 4 Lycalopex gymnocercus) in Brazil. Molecular analysis, based on PCR and DNA sequencing of a portion of the 18S rRNA gene, revealed that 30% (6/20) C. thous were infected by R. vitalii. Blood and bone marrow samples from one of the R. vitalii-infected C. thous were inoculated into a domestic dog, which developed clinical rangeliosis that was confirmed by molecular tests. However, the C. thous donor showed no clinical, hematological or biochemical alterations, even though its R. vitalii infection status was confirmed for at least 80 days. These observations suggest that R. vitalii is not as highly pathogenic for C. thous as it is for domestic dogs. Phylogenetic analysis inferred by the 18S rRNA gene placed R. vitalii embedded in the clade 'Babesia sensu stricto', consisting of a number of species that represent truly the genus Babesia. It is proposed that the species R. vitalii should be transferred to the genus Babesia. The present study expands our knowledge on the natural history of R. vitalii, suggesting that it might have a natural cycle involving the wild canid C. thous. Further studies are needed to confirm that C. thous is a natural reservoir of R. vitalii in Brazil., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The control of the cattle tick Rhipicephalus microplus is based mainly on the use of chemical acaricides, which has contributed to the emerging problem of selection of resistant tick populations. Currently, there are six main classes of acaricides commercially available in Brazil to control cattle ticks, with fluazuron, a tick growth regulator with acaricidal properties, being the only active ingredient with no previous reports of resistance. Ticks (designated the Jaguar strain) were collected in a beef cattle ranch located at Rio Grande do Sul state, Southern Brazil, after a complaint of fluazuron treatment failure. To characterise the resistance of this strain against acaricides, larval tests were performed and showed that the Jaguar strain was resistant to all of the drugs tested: cypermethrin (resistance ratio, RR=31.242), chlorpyriphos (RR=103.926), fipronil (RR=4.441), amitraz (RR=11.907) and ivermectin (3.081). A field trial was conducted to evaluate the efficacy of fluazuron treatment in heifers that had been experimentally infested with the Jaguar or a susceptible strain. Between 14 and 28 days after treatment, the average efficacy in cattle experimentally infested with the susceptible strain was 96%, while for the Jaguar strain the efficacy was zero. Additionally, the Jaguar strain response to fluazuron was evaluated in vitro using a modified adult immersion test (AIT) and the artificial feeding assay (AFA). With the AIT, 50 ppm of fluazuron inhibited 99% of larvae hatching in the susceptible strain (POA) and less than 50% in the Jaguar strain. Results of the AFA showed a larval hatching rate of 67% at 2.5 ppm of fluazuron with the Jaguar strain; conversely, only 3% of larvae of the susceptible strain hatched at the same fluazuron concentration. The results showed here demonstrated the first case of fluazuron resistance in R. microplus and the first tick population resistant to six classes of acaricides in Brazil., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Ornithodoros brasiliensis, also known as the "mouro" tick, is an argasid tick found exclusively in the southern Brazilian highlands. O. brasiliensis parasitism is frequently associated with severe symptoms directly induced by the tick bite, a condition compatible with the definition of tick toxicosis. The objectives of this work include (i) the determination of the distribution of O. brasiliensis in farms located in the tick-endemic region, (ii) the description of the characteristics of O. brasiliensis habitats, (iii) the analysis of risk factors associated with O. brasiliensis, and (iv) the retrospective description of cases of human and animal parasitism by O. brasiliensis. Of the 30 farms included in this study, O. brasiliensis was identified on 5 farms (frequency 16.7%), in which several ticks found in high density buried in soil were collected. Information regarding the tick habitats and the local population was recorded. The data indicated that O. brasiliensis feeds on humans, dogs, armadillos (Dasypus hybridus), and possibly skunks (Conepatus chinga). The analysis of risk factors indicated that the presence of house basements with an unpaved (natural soil) floor on farms and insufficient sanitary conditions significantly enhanced the probability of identifying O. brasiliensis. Additionally, we describe retrospectively cases of tick parasitism in 28 humans and 11 dogs including the most common symptoms associated with tick toxicosis. This is the first study concerning O. brasiliensis epidemiology, distribution, and habitat, and the report represents the most comprehensive characterization of Ornithodoros bite-associated toxicosis syndrome., (Copyright © 2012 Elsevier GmbH. All rights reserved.)