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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. • Bovine babesiosis is a major tick-borne disease which needs prevention alternatives. • Imidocarb prevents symptoms, but its role in allowing seroconversion is uncertain. • Most cattle needed three treatments or more (> 84 days) to seroconvert. • About 8 % never seroconverted, and 41 % became immune only to one Babesia species. • Imidocarb is a valuable resource, but does not guarantee seroconversion for babesiosis. [ABSTRACT FROM AUTHOR]

Background: Acaricide resistance in cattle ticks is a significant concern in (sub)tropical regions, particularly Brazil. The Larval Packet Test (LPT) is the standard laboratory bioassay for resistance diagnosis, which requires triplicates of seven acaricidal dilutions plus controls to cover larval mortalities ranging between 0 and 100%. The value of the LPT lies in providing resistance ratios based on the ratio between the LC50 calculated with potentially resistant and susceptible ticks. However, LC50 ratios are difficult to translate into practical advice for farmers. Moreover, LPT requires laboratory facilities to maintain susceptible tick colonies, and it takes 6 weeks to obtain the larvae to be tested by LPT derived from engorged female ticks collected from cattle in the field. Our novel approach was twofold: first, we upgraded the LPT to the Resistance Intensity Test (RIT) by adopting the latest WHO guidelines for resistance detection in mosquitoes, which combines a 1 × recommended dose with 5 × and 10 × concentrated doses to reveal low, moderate and high resistance intensity, respectively. This reduced the number of test papers and tick larvae and, more importantly, provided relevant information on the resistance level. Our second innovative step was to abolish testing larvae entirely and expose partly engorged adult ticks to the same acaricidal doses immediately after removing them from cattle in the field. This resulted in the Rapid Tick exposure Test (RaTexT®), wherein partly engorged adult ticks were exposed to an acaricide-impregnated, specially designed matrix providing test results within 24 h. This approach directly compared resistance detection in tick larvae in the RIT with resistance in adult ticks in RaTexT®. Methods: Laboratory validation was conducted in Brazil with resistant and susceptible colonies of Rhipicephalus microplus ticks. For field validation, adult R. microplus ticks collected from different cattle farms in Brazil were evaluated for resistance to RaTexT®, and the results regarding their larval progenies were compared with those for the RIT. Partly engorged adult ticks derived from cattle infested with laboratory and field strains of R. microplus were exposed to deltamethrin in RaTexT® containers, which contained six rows of four interconnected compartments, accommodating five to eight semi-engorged female ticks with a preferred size ranging between 5 and 8 mm. The corresponding larvae of each strain were exposed in the RIT to the same deltamethrin concentrations in filter papers. Results: In RaTexT®, mortality in adult ticks from a resistant strain of R. microplus from Seropédica in Brazil was 38.4%, 54.2% and 75.0% at the 1 ×, 5 × and 10 × doses of deltamethrin, respectively. In RIT, mortality of larvae from the same resistant strain was 2.0%, 4.9% and 19.5% at 1 ×, 5 × and 10 × doses, respectively. The results of RaTexT® and RIT agreed since both tests identified a high level of resistance based on a cut-off of 90% mortality. In RaTexT®, mortality of adult ticks from a susceptible strain originating from Porto Alegre was 73.8%, 92.9% and 97.6% at the 1 ×, 5 × and 10 × doses, respectively. In RIT, mortality of larvae from the susceptible strain was 95.2%, 95.2% and 96.8% at the 1 ×, 5 × and 10 × doses, respectively. Interestingly, both tests identified a low number of unexpected resistant individuals in the susceptible strain since the mortality of neither larvae nor adults reached 100%. This effect remained unnoticed in the LPT, wherein a resistance ratio of 159.5 was found based on the LC50 of the resistant strain divided by the LC50 of the susceptible strain. Next, RaTexT® was compared with RIT using adult and larval ticks derived from three field strains of R. microplus in Brazil. RaTexT® detected high levels of resistance to deltamethrin in adult ticks in all strains, which was confirmed in larvae tested by the RIT. Both tests agreed on the same resistance level with significantly lower mortality rates in larvae than in adult ticks. Conclusions: RaTexT® is a novel rapid pen-site test for detecting acaricide resistance in adult livestock ticks. It potentially replaces laborious tests using larval ticks and provides results within 24 h relevant to acaricide resistance management of livestock ticks. [ABSTRACT FROM AUTHOR]

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 . [ABSTRACT FROM AUTHOR]

Ornithodoros brasiliensis , also known as the mouro tick, is an argasid tick only found in the highlands of Southern Brazil. O. brasiliensis parasitism is associated with severe reactions in its hosts ranging from local pruritus and pain to systemic disturbances. Recently, the re-emergence of O. brasiliensis parasitism in humans and dogs drew attention to the clinical findings induced by its bite, which are poorly understood and described. Moreover, rare experimental data about tick bite effects under controlled conditions were available. Thus, this study aimed to describe clinical and pathological findings induced by O. brasiliensis bites in experimentally parasitized rats. Ticks feed for ∼40 min in rats, and their weight increased by approximately four times after the blood meal. Rats bitten by five adult ticks showed hyperemia of the oral/ocular mucosa, piloerection, tachypnea, claudication, ocular and nasal discharge, pruritus, and swollen and erythemic lesions. A large hemorrhagic lesion was observed on rat skin in tick attachment sites, reaching ∼17 mm in diameter 12 h after a bite. Bitten rats also presented an increased bleeding tendency (∼50%) 6 h after a tick bite, evaluated by the tail-cut rat model of bleeding. Blood samples of bitten rats were taken, and clinical pathology analysis showed significant alterations in the eosinophil and basophil counts, in creatine phosphokinase (CPK) and CPK MB fraction, and lactate dehydrogenase (LDH) activity, and fibrinogen level. Histopathological analysis revealed marked subcutaneous hemorrhage, edema and slight muscle degeneration at the bite site. Also, muscle degeneration and necrosis were observed in the myocardium of bitten rats 72 h after bites by histopathology and immunohistochemistry against troponin C. This work showed the ability of O. brasiliensis to cause severe disturbances in experimentally parasitized rats, compatible with a tick toxicosis syndrome. This observation associated with the re-emergence of O. brasiliensis parasitism makes this parasite as a public health hazard in southern Brazil. [ABSTRACT FROM AUTHOR]

The cattle tick Rhipicephalus (Boophilus) microplus is one of the most harmful parasites affecting bovines. Similarly to other hematophagous ectoparasites, R. microplus saliva contains a collection of bioactive compounds that inhibit host defenses against tick feeding activity. Thus, the study of tick salivary components offers opportunities for the development of immunological based tick control methods and medicinal applications. So far, only a few proteins have been identified in cattle tick saliva. The aim of this work was to identify proteins present in R. microplus female tick saliva at different feeding stages. Proteomic analysis of R. microplus saliva allowed identifying peptides corresponding to 187 and 68 tick and bovine proteins, respectively. Our data confirm that (i) R. microplus saliva is complex, and (ii) that there are remarkable differences in saliva composition between partially engorged and fully engorged female ticks. R. microplus saliva is rich mainly in (i) hemelipoproteins and other transporter proteins, (ii) secreted cross-tick species conserved proteins, (iii) lipocalins, (iv) peptidase inhibitors, (v) antimicrobial peptides, (vii) glycine-rich proteins, (viii) housekeeping proteins and (ix) host proteins. This investigation represents the first proteomic study about R. microplus saliva, and reports the most comprehensive Ixodidae tick saliva proteome published to date. Our results improve the understanding of tick salivary modulators of host defense to tick feeding, and provide novel information on the tick-host relationship. [ABSTRACT FROM AUTHOR]

Abstract: 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, 50ppm 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 2.5ppm 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 &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Ornithodoros brasiliensis is a nidicolous tick only found in the southern Brazilian highlands region. O. brasiliensis parasitism is frequently associated with toxicosis syndrome, which can lead to severe reactions, ranging from local pruritus and pain to systemic disturbances both in humans and dogs. One of the most frequent findings associated with an O. brasiliensis bite is a slow healing lesion at the site of tick attachment, which can take several weeks to heal. This work tested the hypothesis that an O. brasiliensis salivary gland homogenate is able to modulate the skin wound-healing process in vivo, using a model of excisional skin lesion in rats, which are divided into two groups: (1) control group and (2) treated group, which topically received salivary gland homogenate equivalent to the protein amount of one whole salivary gland (≈5 μg protein). The hypothesis that O. brasiliensis salivary gland homogenates interfere with endothelial cell proliferation, a key role phenomenon in wound healing, was also tested. O. brasiliensis salivary gland homogenates significantly delay skin wound healing. The time to full healing of skin lesions in control rats was 15 days, contrasting with 24 days in rats topically treated with O. brasiliensis salivary gland homogenates. The calculated HT (healing time to recover 50 % of the wound area) for control groups was 3.6 days (95 % CI, 3.2-3.9) and for salivary gland treated rats was 7.7 days (95 % CI, 7.0-8.4). Salivary gland homogenates have a strong cytotoxic activity on cultured endothelial cells (LC, 13.6 mg/ml). Also, at sublethal concentrations (≤3 mg/ml), salivary gland homogenates have a remarkable anti-proliferative activity (IC 0.7 mg/ml) on endothelial cells, equivalent to ≈0.03 salivary gland pairs, an activity which seems to be much greater than reported for any other tick species. This is the first report about the biological activities of O. brasiliensis salivary compounds and provides the first in vivo evidence to support the concept of wound-healing modulation by tick salivary secretions. Results shown here contribute to an understanding of O. brasiliensis tick toxicosis syndrome, and also increase our knowledge of tick salivary bioactive compounds. [ABSTRACT FROM AUTHOR]

Abstract: The tick Rhipicephalus (Boophilus) microplus is a blood-sucking ectoparasite of cattle that severely impairs livestock production. Studies on tick immunological control address mostly single-antigen vaccines. However, from the commercial standpoint, so far no single-antigen vaccine has afforded appropriate protection against all R. microplus populations. In this context, multi-antigen cocktails have emerged as a way to enhance vaccine efficacy. In this work, a multi-antigenic vaccine against R. microplus was analyzed under field conditions in naturally infested cattle. The vaccine was composed by three tick recombinant proteins from two tick species that in previous single-vaccination reports provided partial protection of confined cattle against R. microplus infestations: vitellin-degrading cysteine endopeptidase (VTDCE) and boophilus yolk pro-cathepsin (BYC) from R. microplus, and glutathione S-transferase from Haemaphysalis longicornis (GST-Hl). Increased antibody levels against three proteins were recorded after immunizations, with a distinct humoral immune response dynamics for each protein. Compared to the control group, a statistically significant lower number of semi-engorged female ticks were observed in vaccinated cattle after two inoculations. This reduction persisted for 3 months, ranging from 35.3 to 61.6%. Furthermore, cattle body weight gain was significantly higher in vaccinated animals when compared to control cattle. Compared to the single-antigen vaccines composed by VTDCE, BYC or GST-Hl, this three-antigen vaccine afforded higher protection levels against R. microplus infestations. [Copyright &y& Elsevier]

Abstract: Porcine circovirus 2 (PCV2) is the primary causative agent of porcine circovirus disease (PCVD). PCVD is an emerging disease that has been reported worldwide, associated with wasting, lymphoid depletion, enteritis, pneumonia, vasculitis, ischemic lesions, and necrotizing dermatitis. Although PCVD causes considerable economic losses, the pathogenesis of PCV2 has not been fully understood. The aim of the present work was to study the participation of hemostatic system and of vascular endothelium in PCV2 infection, as well as their possible role in PCVD pathogenesis. Our results showed that naturally PCV2-infected swine displayed a prothrombotic state in vivo, since a diminished coagulation time (recalcification time, activated partial thromboplastin time and prothrombin time), a higher platelet aggregation ability (despite a diminished platelet blood count), and an increased thrombin plasma activity (associated with a reduced fibrinogen level) were observed. The PCV2-infected animals showed vasculitis and positive staining for PCV2 antigen in capillary vessels. Furthermore, PCV2-infected endothelial cells displayed an activated phenotype, characterized by an increase in cell surface procoagulant activity. Moreover, the PCV2-infected endothelial cells pre-treated with exogenous thrombin displayed an increased viral load. This work reports, for the first time, the role of the hemostatic system and of endothelium in the pathogenesis and infectivity of PCV2. The study reinforces the importance of the phenomena which occur during PCV2 infection, and affords a better knowledge of the mechanisms behind the pathophysiology of PCVD. [Copyright &y& Elsevier]

Abstract: Envenomation caused by Lonomia obliqua is a public health hazard in Southern Brazil. Envenomed victims present severe hemorrhagic syndrome that can progress to intracranial hemorrhage and death. To understand the mechanisms that lead to hemorrhage, we investigated the platelet dysfunction and blood coagulation disturbances following experimental envenomation in rats. L. obliqua bristle extract was injected (s.c.) and blood collected at different times post-venom administration for determination of platelet response and analysis of blood coagulation. Rats presented hypofibrinogenemia and platelet hypoaggregation in platelet rich plasma (PRP). After addition of exogenous fibrinogen to PRP, platelet hypoaggregation was not corrected. Interestingly, normoaggregation was observed when platelets were separated from plasma. In addition, incubation of plasma from envenomed rats inhibits aggregation response of normal washed platelets. These results indicate that an aggregation inhibitor is generated in plasma during envenomation. Moreover, rats presented an increase in nitric oxide plasmatic levels which coincided with maximum inhibition in platelet aggregation. Animals also showed blood incoagulability and a significant increase in thrombin, plasmin and urokinase plasmatic activities. Despite this intravascular thrombin generation, only a slight decrease in platelet numbers was detected. Certainly, the platelet hypoaggregation and blood incoagulability described herein contribute to systemic bleeding observed in patients. [Copyright &y& Elsevier]

Background: One bioassay for detecting acaricide resistance in livestock ticks is the adult immersion test (AIT), wherein engorged ticks are briefly immersed into a solution of a particular acaricidal compound and examined for mortality, their egg-laying capacity and offspring hatchability in vitro. Usually, the recommended label dose or an established discriminating dose of an acaricide is used to determine high mortality (≥ 95%) of susceptible tick strains. Such a test intends to detect the presence of resistance in a tick population. However, the adult immersion test does not directly translate the bioassay results to the predicted efficacy in the field. In this paper, we used the AIT as an initial screening bioassay supplemented with the resistance intensity test (RIT), a novel larval-based bioassay, wherein the resistance level can be determined and translated to the expected field efficacy. This was done by adopting World Health Organisation (WHO) guidelines for resistance detection in mosquitoes, which combines a 1 × recommended dose with 5 × and 10 × concentrated doses to reveal low, moderate and high resistance intensity, respectively. Methods: Engorged Rhipicephalus microplus ticks were collected from cattle at six different ranches across Rio Grande do Sul, Brazil, as part of the state's acaricide resistance surveillance program. Groups of adult ticks from each field collection were subjected to the AIT from each field sample. Additionally, engorged female ticks from each ranch were allowed to lay eggs, and their larval progeny aged 14 to 28 days were then used in the RIT. Deltamethrin and a combination of cypermethrin, chlorpyrifos and piperonyl butoxide were used in both tests, and the results were statistically analysed. Results: The in vitro efficacy of deltamethrin against adult ticks in the AIT ranged between 8.74% and 25.38%. The corresponding RIT results on their larval progeny indicated a high resistance level. In the immersion test, the in vitro efficacy of the combination of cypermethrin, chlorpyrifos, and piperonyl butoxide against adult ticks ranged between 49.31% and 100%. The corresponding RIT results on their larval progeny indicated a similar response ranging from fully susceptible to low or moderate resistance. The Pearson correlation coefficient (r = 0.883) showed a high correlation between tick mortality at the 1 × recommended concentrations of acaricides in both tests. Conclusions: The resistance intensity test is a valuable addition to the range of bioassays currently available for detecting acaricide resistance by determining the level of acaricide resistance. This is relevant to whether or not to continue using a particular acaricidal class for controlling cattle ticks. [ABSTRACT FROM AUTHOR]

The cattle tick Rhipicephalus (Boophilus) microplus (Canestrini, 1887) (Ixodida, Ixodidae) is responsible for significant economic losses in bovine production in tropical and subtropical regions worldwide. Control of this tick predominantly involves the use of chemical acaricides; however, their indiscriminate use has led to the selection of resistant populations. A survey on tick populations was conducted in the state of Rio Grande do Sul, in Brazil, to assess the prevalence of multiple resistance to acaricides in cattle farms. Additionally, questionnaires were administered to identify potential risk factors associated with multiple resistance to acaricides. In total, 176 farms with a bovine population of ≥40 cattle were randomly assigned for tick sampling. The resistance to six acaricidal compounds was investigated by bioassays. A larval packet test was performed for amitraz, chlorpyrifos, cypermethrin, fipronil and ivermectin. Fluazuron was screened using an adult immersion test. Multiple resistance to acaricides (i.e., resistance to three or more compounds) was detected in 173 samples, representing 98% of the total samples. Among these samples, 125 (71%) showed resistance to all six compounds tested. Additionally, we classified the resistance intensity into four levels (I to IV) based on the quartile distribution of the bioassay data. Ten samples (6%) showed high and very high levels (III and IV) of resistance to all six compounds tested. Three variables were significantly associated with multiple resistance to the six acaricides tested: (i) use of injectable acaricides to control ticks, (ii) application of more than five acaricide treatments per year, and (iii) farms with larger herds (≥232 animals). These results regarding widespread resistance and the emergence of multiple resistance to acaricides ticks are alarming and highlight the significant challenge of tick control in southern Brazil. [ABSTRACT FROM AUTHOR]

Background: Brown dog ticks (Rhipicephalus sanguineus sensu lato) are vectors of pathogens adversely affecting the health of dogs in many regions of the world. The three-host life cycle of R. sanguineus s.l., with all stages feeding on dogs, can lead to an uncontrolled build-up of large tick populations if not controlled by acaricides. However, frequent tick control on dogs using acaricides has led to the emergence of resistance to permethrin and fipronil. Currently, the larval packet test (LPT) is the standard tick resistance test, which is laborious, requires laboratory facilities, and takes at least 6 weeks before larvae derived from engorged female ticks can be tested. Our novel approach is to expose semi-engorged adult ticks to acaricides immediately after removing them from dogs, obtaining results within 24 h. Methods: Adult ticks from three laboratory colonies of R. sanguineus s.l. were tested in RaTexT®, a rapid tick exposure test in which ticks were confined to small compartments and exposed to an acaricide-impregnated, specially designed matrix. Resistance was confirmed by testing larvae derived from the same laboratory colonies using the LPT. RaTexT® was also used to determine the susceptibility of R. sanguineus acaricides in dog shelters. Results: RaTexT® detected resistance to permethrin in adult R. sanguineus s.l. ticks from two Brazilian laboratory colonies compared to a susceptible laboratory strain originating in Greece. Resistance was confirmed by LPT testing of larvae from the same colonies with resistance factors between 2.2 and 3.1. All laboratory strains were susceptible to fipronil. A suspected case of fipronil resistance at a dog shelter in Caxias do Sul, Brazil, was resolved within 24 h by testing adult ticks in RaTexT® and could be attributed to improper treatment. Conclusions: RaTexT® is a valuable tool for monitoring the development of resistance to synthetic pyrethroids or phenylpyrazoles in tick-infested dogs. [ABSTRACT FROM AUTHOR]

Canine rangeliosis is a tick-borne disease caused by the protozoan Rangelia vitalii, which has only been reported in South America. With this knowledge, we hypothesized that neotropical foxes could act as asymptomatic natural carriers of R. vitalii. To test this, we captured 44 free-ranging foxes and investigated the presence of R. vitalii DNA, and whether the infected animals presented any clinical findings or hematological changes. Eight foxes (18%), seven Cerdocyon thous (7/27-25%), and one Lycalopex gymnocercus (1/17-5%) were positive for R. vitalii. All foxes were clinically healthy and showed no hematological abnormalities. Thus, we propose that neotropical canids, particularly C. thous, could be the natural carriers of R. vitalii. [ABSTRACT FROM AUTHOR]

Rabies virus (RABV) may infect wildlife, domestic mammals, and humans worldwide, and outbreaks have been associated with population declines of wild carnivores. Although RABV infection has been considered almost invariably fatal, there has been growing evidence of non-lethal RABV exposure in wildlife. The aim of this study is to investigate the occurrence of RABV antibodies, as evidence of non-lethal exposure to the virus in free-living wild canids and felids from the Brazilian Pampa. Animals were live-trapped in three protected and two unprotected areas in Southern Brazil, and the presence of antibodies against RABV was verified by the RFFIT test. A total of 98 specimens without clinical signs of disease were live-trapped: 35 Cerdocyon thous, 23 Lycalopex gymnocercus, 29 Leopardus geoffroyi, 11 Leopardus wiedii. Thirteen out of 98 wild carnivores were considered seropositive to RABV: five C. thous, one L. gymnocercus, five L. geoffroyi, and two L. wiedii. All five localities where animals were sampled had at least one seropositive individual. The results support previous conclusions regarding the possible involvement of C. thous in the rabies ecology and expand the findings of RABV-seropositivity in free-living wildlife, representing the first record for the following species: L. gymnocercus, L. geoffroyi, and L. wiedii. Our findings also suggest that RABV circulation and non-lethal exposure in Neotropical wild carnivores may be more common than previously assumed. Furthermore, rabies and its sylvatic cycle should be taken into account in any conservation effort for wild carnivores. [ABSTRACT FROM AUTHOR]

Reports of Rhipicephalus microplus resistant populations worldwide have increased extensively, making it difficult to control this ectoparasite. The adult immersion test, commonly used to screen for acaricide resistance, produces the results only after 40 days of the tick collection because it needs the eggs to be laid and larvae to hatch. The present study aims to develop an automatic method, based on deep learning, to predict the hatching of R. microplus larva based on egg morphology. Initially, the time course of embryonic development of tick eggs was performed to discriminate between viable and non‐viable eggs. Secondly, using artificial intelligence deep learning techniques, a method was developed to classify and count the eggs. The larval hatching rate of three populations of R. microplus was evaluated for the software validation process. Groups of three and six images of eggs with 12 days of embryonic development were submitted to the software to predict the larval hatching percent automatically. The results obtained by the software were compared with the prediction results of the hatching percentage performed manually by the specialist and with the results of the hatching percentage of larvae obtained in the biological assay. The group with three images of each population submitted to the software for automatic prediction of the larval hatching percent presented mean values of 96.35% ± 3.33 (Piracanjuba population), 95.98% ± 3.5 (Desterro population) and 0.0% ± 0.0 (Barbalha population). For groups with six images, the values were 94.41% ± 3.84 (Piracanjuba population), 95.93% ± 2.36 (Desterro population) and 0.0% ± 0.0 (Barbalha population). Biological assays showed the following hatching percentage values: 98% ± 1.73 (Piracanjuba population); 96% ± 2.1 (Desterro population); and 0.14% ± 0.25 (Barbalha population). There was no statistical difference between the evaluated methods. The automatic method for predicting the hatching percentage of R. microplus larvae was validated and proved to be effective, with considerable reduction in time to obtain results. [ABSTRACT FROM AUTHOR]

Environmental changes may expose primates to new pathogens. We investigated two zoonotic protozoa, Trypanosoma cruzi and Leishmania infantum, to which free-living primates may be exposed in Rio Grande do Sul State, Brazil. We evaluated risk factors associated with species, sex, age group, and biome in howler monkeys and assessed whether eight landscape metrics of forest fragments influence the monkeys' exposure to the pathogens. To do this, we tested serum from 96 howler monkeys (61 Alouatta caraya and 35 Alouatta guariba clamitans) by using an indirect hemagglutination assay (IHA) for T. cruzi and an indirect fluorescence antibody test (IFAT) for L. infantum. In the IHA for T. cruzi, 51% (49/96) were seropositive, with titers from 1:16 to 1:256. We found that A. caraya in the Pampa biome is more susceptible to exposure to T. cruzi than A. g. clamitans in the Atlantic Forest biome, but none of the landscape metrics, sex, or age were significantly related to exposure. No samples were positive for L. infantum. This may suggest that the conditions of the Pampa biome, where A. caraya occurs, are more conducive to the presence of Trypanosoma cruzi vectors, exposing the howler monkeys to infection. However, further serological tests are needed confirm our results. We hope our findings encourage future studies focused on identifying and isolating T. cruzi in primates and understanding the eco-epidemiological role that wildlife plays in transmitting and maintaining protozoa in the wild environment. [ABSTRACT FROM AUTHOR]

Procellariiformes includes pelagic seabirds that only use land for breeding; and also, these sites mostly occur in insular habitats. These peculiar habits make the investigation of hemoparasites a challenging issue. Thus, the data on the blood parasites of Procellariiformes are still scarce. In the order Piroplasmida, 16 species of Babesia have been described in terrestrial birds and seabirds. However, there is no register for Babesia spp. in procellariiform seabirds. Hence, the objective of this survey was to investigate the occurrence of Babesia spp. in these seabirds. A total of 220 tissue samples from 18 different seabird species were analyzed; the samples comprised blood and fragments of liver and spleen. The samples were obtained from live rescued animals and carcasses found along the southern coast of Brazil. Polymerase chain reaction (PCR) was conducted, followed by phylogenetic analysis. Only one blood sample yielded a positive result, from an adult female Thalassarche chlororhynchos (Atlantic yellow-nosed albatross). The sequence obtained showed the highest identity with sequences of Babesia spp. of birds from the South Pacific, and the isolate was named Babesia sp. strain Albatross. In the phylogenetic analysis, the sequence was grouped within the Babesia sensu stricto group, and further still into a subgroup including Babesia spp. of the Kiwiensis clade (parasites from birds). The phylogenetic analysis also showed that Babesia sp. strain Albatross clustered apart from the Peircei group, a clade that includes Babesia spp. from seabirds. As far as it is known, this is the first report of Babesia sp. in procellariiform seabirds. Babesia sp. strain Albatross may constitute a novel variant of tick-borne piroplasmids associated with the Procellariiformes order. [ABSTRACT FROM AUTHOR]

The environments in which neotropical primates live have been undergoing an intense fragmentation process, constituting a major threat to the species' survival and causing resource scarcity, social isolation, and difficulty in dispersal, leaving populations increasingly vulnerable. Moreover, the proximity of wild environments to anthropized landscapes can change the dynamics of pathogens and the parasite‐host‐environment relationship, creating conditions that favor exposure to different pathogens. To investigate the previous exposure of free‐living primates in Rio Grande do Sul State (RS), southern Brazil, to the bacterial agents Leptospira spp. and Brucella abortus, we investigated agglutinating antibodies against 23 serovars of Leptospira spp. using the microscopic agglutination test and B. abortus acidified antigen test in primate serum samples; 101 samples from primates captured between 2002 and 2016 in different forest fragments were used: 63 Alouatta caraya, 36 Alouatta guariba clamitans, and 02 Sapajus nigritus cucullatus. In addition, the forest remnants where the primates were sampled were characterized in a multiscale approach in radii ranging from 200 to 1400 m to investigate the potential relationship of previous exposure to the agent with the elements that make up the landscape structure. The serological investigation indicated the presence of antibodies for at least one of the 23 serovars of Leptospira spp. in 36.6% (37/101) of the samples analyzed, with titers ranging from 100 to 1600. The most observed serovars were Panama (17.8%), Ballum (5.9%), Butembo (5.9%), Canicola (5.9%), Hardjo (4.9%), and Tarassovi (3.9%); no samples were seropositive for Brucella abortus. Decreased forest cover and edge density were the landscape factors that had a significant relationship with Leptospira spp. exposure, indicating that habitat fragmentation may influence contact with the pathogen. The data generated in this study demonstrate the importance of understanding how changes in landscape structure affect exposure to pathogenic microorganisms of zoonotic relevance. Hence, improving epidemiological research and understanding primates' ecological role in these settings can help improve environmental surveillance and conservation strategies for primate populations in different landscapes. Highlights: Free‐living primates in Rio Grande do Sul showed agglutinating antibodies to different Leptospira spp. serovars in the microscopic agglutination testDecreased forest cover in the landscape within a 200 m radius of the forest fragment was associated with primate exposure to Leptospira spp.Increased edge density in the landscape within a 1400 m radius of the forest fragment was associated with lower primate exposure to Leptospira spp. [ABSTRACT FROM AUTHOR]

Hemoplasma infection significantly impacts felines health, yet there is a research gap regarding free-ranging wild small felids. Therefore, this study aimed to investigate the occurrence of hemoplasma in Leopardus geoffroyi and Leopardus wiedii in southern Brazil. For this purpose, we conducted molecular research for Mycoplasma spp. based on the 16S rRNA gene in 79 blood samples from captured wild felids. When positive, the samples were submitted to species-specific reactions for Mycoplasma haemofelis (Mhf), ' Candidatus Mycoplasma haemominutum' (C Mhm), and ' Candidatus Mycoplasma turicensis' (C Mt). A total of 39/79 samples were positive for at least one species of hemoplasma. The frequencies found by hemoplasma species were: 39.2 % (31/79) for Mhf , 17.7 % (14/79) for C Mhm, and 20.2 % (16/79) for C Mt. Factors such as species, sex, age, pelage, capture season, ectoparasite presence, and co-infection with another Mycoplasma were not associated with hemoplasma infection. This study provides the first evidence of circulating hemotropic mycoplasmas in free-living L. geoffroyi and L. wiedii in southern Brazil. • This is the first report of hemoplasma in free-rangging small cats in Brazil. • Leopardus geoffroyi and Leopardus wieddi are potential reservoirs of hemoplasmas. • Mycoplasma haemofelis presented a higher occurrence between hemoplasmas species. [ABSTRACT FROM AUTHOR]

In the present study, we evaluated and compared the in vitro biological parameters of the evolutionary stages of R. microplus (female, eggs, and larva) from two extreme regions of Brazil: Santa Rita (SR) northeast region and Bagé (BG) southern region. For this, all stages were maintained at 23, 27, and 32°C with a relative humidity (RH) of 65, 80, and 100%. The mean incubation period was 43.7 to 53.7 days (SR population) and 59.0 to 56.1 days (BG population) at 23°C and 18.0 to 19.3 days (SR population) and 16.8 to 21.2 days (BG population) at 32°C. Eggs incubated at 23°C (65, 80, and 100% RH) of SR and BG populations showed a similar egg hatching percentage (P > 0.05). The egg hatching percentage of the SR population (30.5 to 98.0%) was always higher than that of the BG population (8.7 to 85.5%; P < 0.05) when incubated at 32°C and 65, 80, or 100% RH. Deleterious effects on the larval survival period from SR and BG were observed under all experimental conditions (temperature and RH), especially at 23 and 32°C. However, they were more intense on larvae at 32°C (all RH). Under 80 and 100% RH, the mean period of larval survival did not exceed 65 days, being shortest for the BG population (mean: 42.7 days [80% RH] and 55.1 days [100% RH]) compared with the SR population. [ABSTRACT FROM AUTHOR]

Leptospirosis and toxoplasmosis are re-emerging zoonosis caused by infection with pathogenic spirochaetes of Leptospira and the protozoa Toxoplasma gondii , respectively. Wild boars (Sus scrofa), an exotic invasive species in Brazil, could play a role in the diseases' epidemiological cycles, but this issue is still unexplored. This study aimed to evaluate the Leptospira spp. and T. gondii seropositivity in wild boars in Rio Grande do Sul state, south Brazil. Of evaluated animals, 16% (13/80) and 85% (52/61) had antibodies to T. gondii and Leptospira spp., respectively. Sex, weight, age, hunt location and season of hunt were evaluated by their association with seropositivity for both pathogens, but none of them had statistical significance. This study revealed that wild boars should be considered as a potential source of Leptospira spp. and T. gondii dissemination for humans and animal species in shared environments in Rio Grande do Sul state. • Wild boars can play a role in Leptospirosis and Toxoplasmosis cycle in Brazil. • 16% of wild boars had T. gondii antibodies. • 85% of wild boars had Leptospira spp. antibodies. • A great diversity of Leptospira spp. serovars were identified. • Wild boars may be sources of infection to other species in shared environments. [ABSTRACT FROM AUTHOR]

Abstract: Caterpillar envenomation has been an emergent health issue. Lonomia obliqua is a medically important animal that causes a hemorrhagic syndrome that can progress to acute renal failure, intracranial hemorrhage and death. In the past few years the molecular characterization of L. obliqua venom in addition to experimental models has provided fundamental information to the understanding of the envenomation syndrome. Herein studies from several authors which characterized the complex toxic-pharmacological actions of whole venom are reviewed. [ABSTRACT FROM AUTHOR]

The genus Bartonella comprises emerging bacteria that affect humans and other mammals worldwide. Felids represent an important reservoir for several Bartonella species. Domestic cats are the main reservoir of Bartonella henselae, the agent of cat scratch disease (CSD). It can be transmitted directly by scratches and bites from infected cats and via cat fleas. This study aims to investigate the circulation of Bartonella spp. in free-ranging Neotropical wild felids from Southern Brazil using serological and molecular methods. In this study, 53 live-trapped free-ranging wild felids were sampled, 39 Leopardus geoffroyi and 14 Leopardus wiedii, from five municipalities in the Rio Grande, do Sul state, southern Brazil. All captured animals were clinically healthy. Two blood samples of L. geoffroyi were positive, by PCR, for the presence of B. henselae DNA. Conversely, none of L. wiedii blood samples were positive when tested using PCR. Indirect immunofluorescence assay (IFA) showed that 28% of serum samples of wild felids were reactive (seropositive) for B. henselae by immunofluorescence, with titers ranging from 64 to 256. The results presented here provide the first evidence of a Bartonella-enzootic cycle involving L. geoffroyi and L. wiedii, which may account for the spillover of the emerging zoonotic pathogen B. henselae for the indigenous fauna in Southern Brazil. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Thymol and carvacrol biopolymeric formulations were effective against ticks. • Association with starch and glycerol provided a better effect of terpenes. • Further field studies are necessary to evaluate these biopolymeric formulations. [ABSTRACT FROM AUTHOR]

Spotted fever (SF) is a tick-borne disease associated with Rickettsia spp.. In the Pampa biome, Southern Brazil, cases of SF seem to be strongly linked with the practice of hunting wild animals. An investigation of rickettsiae in tick species found on wild animals could provide more information regarding the rickettsiosis enzootic cycle. The aim of this study is to describe the results of a molecular survey of Rickettsia spp. in the Neotropical deer tick, Haemaphysalis juxtakochi Cooley, 1946 (Acari: Ixodidae), from the Brazilian Pampa. Ticks were obtained from 14 road-killed gray brocket deer, Mazama gouazoubira (Artiodactyla: Cervidae), found in nine different municipalities of Rio Grande do Sul state, Southern Brazil. Ticks were processed individually to obtain genomic DNA, and then Rickettsia spp. was investigated using a set of PCR reactions that amplified the rickettsial fragments of the gltA, ompA, and htrA genes. Of the 24 tick samples tested, DNA of Rickettsia parkeri sensu stricto (s.s.) was found in 11 H. juxtakochi specimens collected in two different areas of the Brazilian Pampa. This is the first report of R. parkeri s.s. (the main agent associated with SF in the Uruguayan, Argentinian, and Brazilian Pampa) in H. juxtakochi ticks. These findings indicate that R. parkeri s.s. may be much more common and widely distributed in the Pampa biome than previously assumed. Moreover, H. juxtakochi ticks and gray brocket deer could participate in the potential spillover of R. parkeri s.s. from endemic to non-endemic areas in the South American Pampa. [ABSTRACT FROM AUTHOR]

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 210 A. 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. [ABSTRACT FROM AUTHOR]

Abstract: 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 &y& Elsevier]

“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. [ABSTRACT FROM AUTHOR]

The article presents an eco-epidemiologic investigation of Rickettsia parkeri based on the case of a 44-year-old female patient who developed tick-borne rickettsiosis as a result of wildlife hunting in Rio Grande do Sul, Brazil. The diagnosis was confirmed after performing paired serologic testing, actual investigation of the patient's house and taxonomic identification. The ticks included the species of Amblyomma (A.) dubitatum, Rhipicephalus sanguineus and A. tigrinum.

The expansion of urbanization on natural areas is increasing contact between human populations with wild animals. Wild carnivores can act as sentinel hosts or environmental health indicators. Thus, the aim of this work was to investigate the exposure of two major species of wild canids from Southern Brazil to selected pathogens. For that, we live-trapped free-ranging Cerdocyon thous and Lycalopex gymnocercus in five localities and determined the frequency of animals with antibodies against Toxoplasma gondii , Trypanosoma cruzi , Leishmania infantum , Neospora caninum , and Leptospira spp. Among the canids sampled, 23% (12/52) (95%CI: 13–36%) had antibodies against T. gondii , with titers ranging from 64 to 512. For T. cruzi , 28% (15/52) (95%CI: 18–42%) of sampled canids were seropositive, with titers ranging from 8 to 64. Concerning the protozoan pathogen N. caninum , a total of 5% (3/52) (95%CI: 2–15%) of wild canids had antibodies against it. None of the sampled canids showed the presence of antibodies against L. infantum. On the other hand, 44% (23/52) (95%CI: 31–57%) of the wild canids showed antibodies against Leptospira spp. The set of results presented here, show that free-ranging neotropical wild canids are exposed and have antibodies against to T. gondii , T. cruzi , Leptospira spp., and to a lesser degree to N. caninum. We found no evidence of L. infantum circulation among the studied populations. These results highlight some of the major pathogens which may represent risks for populations of these wild canids. The data that support the findings of this study are available from the corresponding author upon reasonable request. • Wild canids are major reservoirs of infectious diseases. • Few studies have addressed pathogens of Lycalopex gymnocercus. • Toxoplasma gondii and Leptospira spp. seem widespread among wild canids. • A third of canids were seropositive for Trypanosoma cruzi. • Neospora caninum seems rare, contrarily to North America. [ABSTRACT FROM AUTHOR]

• Here, we investigated the pathogens in fleas 61 from 350 Neotropical rodents. • Five genotypes of Bartonella sp. were identified in two species of fleas. • A novel Spotted Fever Group Rickettsia was found in rodent fleas. • This is the first description of a Spotted Fever Rickettsia in Neotropical fleas. The Neotropical region shows a great diversity of fleas, comprising more than 50 genera. The importance of the study of fleas is linked to their potential role as disease vectors. The aim of this study is to investigate the presence of Rickettsia spp. and Bartonella spp. in Neotropical fleas collected from wild rodents in Southern Brazil. From 350 rodents captured, 30 were parasitized by fleas. A total of 61 fleas belonging to two genera and six different species were collected (Craneopsylla minerva minerva, Polygenis occidentalis occidentalis, Polygenis platensis , Polygenis pradoi, Polygenis rimatus , and Polygenis roberti roberti). In 13 % of fleas of three different species (C. minerva, P. platensis , and P. pradoi) Rickettsia sp. DNA was found. Phylogenetic analysis of concatenated sequences of gltA , htrA , and ompA genes showed that Rickettsia sp. found in rodent fleas (referred as strain Taim) grouped together with Spotted Fever Group Rickettsia. In reference to Bartonella spp., five genotypes were identified in seven fleas of two species (C. minerva and P. platensis) and in five rodent spleens. Also, 207 frozen samples of wild rodents were screened for these pathogens: while none was positive for Rickettsia spp.; five rodent spleens were PCR-positive for Bartonella spp.. Herein, we show the detection of potential novel variants of Bartonella sp. and Rickettsia sp. in fleas collected of wild rodents from Southern Brazil. Further studies are needed to fully characterize these microorganisms, as well as to improve the knowledge on the potential role of Neotropical flea species as diseases vectors. [ABSTRACT FROM AUTHOR]

Anaplasma marginale is the causative agent of the severe bovine anaplasmosis. The tick Rhipicephalus microplus is one of the main vectors of A. marginale in tropical and subtropical regions of the world. After the tick bite, the bacterium invades and proliferates within the bovine erythrocytes leading to anemia, impairment of milk production and weight loss. In addition, infection can cause abortion and high mortality in areas of enzootic instability. Immunization with live and inactivated vaccines are employed to control acute bovine anaplasmosis. However, they do not prevent persistent infection. Consequently, infected animals, even if immunized, are still reservoirs of the bacterium and contribute to its dissemination. Antimicrobials are largely employed for the prophylaxis of bovine anaplasmosis. However, they are often used in sublethal doses which may select pre-existing resistant bacteria and induce genetic or phenotypic variations. Therefore, we propose a new standardized in vitro assay to evaluate the susceptibility of A. marginale strains to different antimicrobials. This tool will help health professionals to choose the more adequate treatment for each herd which will prevent the selection and spread of resistant strains. For that, we initially evaluated the antimicrobial susceptibility of two field isolates of A. marginale (Jaboticabal and Palmeira) infecting bovines. The least susceptible strain (Jaboticabal) was used for the standardization of an antimicrobial assay using a culture of Ixodes scapularis-derived tick cell line, ISE6. Results showed that enrofloxacin (ENRO) at 0.25, 1 or 4 μg/mL and oxytetracycline (OTC) at 4 or 16 μg/mL are the most efficient treatments, followed by OTC at 1 μg/mL and imidocarb dipropionate (IMD) at 1 or 4 μg/mL. In addition, this proposed tool has technical advantages compared to the previously established bovine erythrocyte culture. Thereby, it may be used to guide cattle farmers to the correct use of antimicrobials. The choice of the most suitable antimicrobial is essential to eliminate persistent infections, prevent the spread of resistant strains and help controlling of bovine anaplasmosis. Image 1 • A. marginale strains infecting calves exhibit distinct susceptibility to antimicrobials. • Evaluation of A. marginale antimicrobial susceptibility using an in vitro assay with tick cell line. • Assessment of the efficacy of novel antimicrobial drugs by in vitro assay. [ABSTRACT FROM AUTHOR]