Spatial distribution of Toxoplasma gondii in cows and associated risk factors.

The aim of the present study was to evaluate the spatial distribution of the prevalence of T. gondii in cows using the indirect immunofluorescence assay and determine associated risk factors. Serum samples were collected from 2970 cows on 263 rural farms in 223 municipalities. A questionnaire was administered to herd owners to collect data for the evaluation of risk factors associated with this disease. Mean seroprevalence of T. gondii in cows was 8.48% (95% CI: 7.48 to 9.49). The microregions with the greatest likelihood (p ≤ 0.05) of having infected animals were Anápolis, Ceres, São Miguel do Araguaia, the Federal District, Anicuns, and Vão do Paraná. The purchase of females or males for reproductive/breeding purposes was significantly associated (p ≤ 0.05) with the prevalence of T. gondii in these regions. A positive correlation (0.7618; p = 0.047) was found between the prevalence of T. gondii and total area in hectares of forests in these regions, suggesting that wild cats may be disseminating T. gondii at these sites. The present results highlight the importance of considering the meat from these animals to be an important infection route for humans who eat raw or undercooked food.

Biological parameters for Rhipicephalus microplus in the field and laboratory and estimation of its annual number of generations in a tropical region.

The present study aimed to evaluate biological parameters of Rhipicephalus microplus in the non-parasitic phase in both field and laboratory conditions. It also aimed to assess correlations between duration (in days) of these parameters and climatic variables (humidity, rainfall, and soil temperature) and to estimate the annual number of generations of R. microplus in a tropical region. The non-parasitic phase of R. microplus in field and laboratory conditions was evaluated throughout the course of two years. A pasture was infested with engorged female of R. microplus, and biological parameters, including female pre-oviposition, female oviposition, egg mass incubation, larval pre-hatching phase, larval maturation, and larval longevity, were evaluated concomitantly with the collection of data on climatic conditions. The same parameters were also evaluated in a climatized chamber in the laboratory. The total duration of the non-parasitic phase in the field was longer in the dry season (1st and 4th life-cycle repetitions) than in the rainy season (2nd, 3rd, and 5th repetitions). Tick biological parameters for the non-parasitic phase in the laboratory were similar to those obtained in the field during the rainy season. The evaluated biological parameters were influenced mainly by environmental and ground-level temperatures, which modified egg mass incubation, larval pre-hatching, and larval longevity periods and, consequently, the total duration of the non-parasitic phase of the tick. The annual number of generations for the tick was estimated at five per year, which is alarming because it represents an increase, and so new studies into strategic control are needed.

Experimental infection of calves with Haemonchus placei or Haemonchus contortus: Assessment of clinical, hematological and biochemical parameters and histopathological characteristics of abomasums.

The present study had the primary objective of evaluating clinical, hematological and biochemical parameters, as well as observing anatomical and histopathological characteristics of abomasums, from calves prime-infected with Haemonchus contortus or H. placei. Ten male Holstein newborns were subdivided in three groups (GI placebo; GII infected with H. contortus; GIII inoculated with H. placei). Eye mucosa staining was evaluated. Hematological and biochemical tests were performed on animals. The euthanasia of all ten experimental calves was performed on the 42nd day post-inoculation. Fragments were collected from each of all 10 abomasums for histopathological analysis. Discrete submandibular edema was diagnosed in animals from both infected groups (H. contortus or H. placei). However, there were no significant changes (P > 0.05) in the color of the ocular mucosa of calves from all three experimental groups across the entire experimental period. Hematological and biochemical changes diagnosed on animals could not be linked to infections by species of Haemonchus spp. Regarding histopathological exams, it was possible to diagnose hypertrophy, hyperplasia, binucleated cells, inflammatory infiltrate, multifocal hemorrhage and edema in abomasums from calves of both groups infected with H. placei and H. contortus. It can, thus, be concluded that not only are calves susceptible to infections by both Haemonchus species, but they can also present clinical changes and similar anatomic histopathological lesions independent of being infected by Haemonchus placei or Haemonchus contortus. These results reflect a negative effect on helminth control by mixed grazing between sheep and cattle, especially when using calves.

Acaricidal effects of fluazuron (2.5 mg/kg) and a combination of fluazuron (1.6 mg/kg) + ivermectin (0.63 mg/kg), administered at different routes, against Rhipicephalus (Boophilus) microplus parasitizing cattle.

The present study aimed to evaluate the acaricidal efficacy of fluazuron (2.5 mg/kg), administered as a pour-on, in comparison to an injectable formulation containing fluazuron (1.6 mg/kg) + ivermectin (0.63 mg/kg), against Rhipicephalus (Boophilus) microplus in naturally and experimentally infested cattle. Two studies were conducted with different tick strains, one with artificial infestations (Stall Test, using leight animals per group) and one with natural infestations (utilizing ten animals per group). In both studies, the animals were randomized, according to average tick counts performed on days -3, -2 and -1, into four groups: T01, negative control (saline solution); T02, pour-on fluazuron (2.5 mg/kg); T03: subcutaneous fluazuron (1.6 mg/kg) + ivermectin (0.63 mg/kg); and T04 subcutaneous ivermectin (0.63 mg/kg). Based on obtained results, and considering the utilized tick strains, it was possible to conclude that the pour-on fluazuron (2.5 mg/kg) formulation demonstrated high acaricidal efficacy, with protection periods ranging from 49 to 77 days against Rhipicephalus (Boophilus) microplus. On the other hand, for the injectable fluazuron (1.6 mg/kg) + ivermectin (0.63 mg/kg) formulation, it was not possible to observe elevated anti-R. (B.) microplus effect on both artificial and experimental infestation studies. Results observed for this combination were similar or inferior to those obtained by subcutaneous ivermectin (0.63 mg/kg). Future studies with this formulation containing fluazuron (1.6 mg/kg) + ivermectin (0.63 mg/kg), regarding pharmacokinetic and/or bioavailability profiles, or even studies analyzing both this active principles separately, are needed, seeking to better understand the effects of such combination against Rhipicephalus (Boophilus) microplus parasitizing cattle.

Historic of therapeutic efficacy of albendazol sulphoxide administered in different routes, dosages and treatment schemes, against Taenia saginata cysticercus in cattle experimentally infected.

The present study aimed to notify the history of albendazole sulphoxide (ALB-SO) and albendazole (ALBZ) efficacy against Taenia saginata cysticercus (Cysticercus bovis) parasitizing experimentally infected bovines. A total of 11 efficacy trials were performed between the years of 2002 and 2010. In order to perform these trials, animals were individually inoculated with 2×10(4) eggs of T. saginata in each study's day zero (D0). For every trial, a positive control group (untreated infected animals) and a negative control group (animals that were neither infected nor treated) were used. ALB-SO or ALB were administered in the different dosages, in different days of treatments. In a last study with this formulation, this active principle was administered orally, mixed with the mineral supplement, on the 60th DPI, in a dosage of 30mg/kg. In all trials, on the 100th DPI, all animals were euthanized and submitted to the sequenced slicing of 26 anatomical segments (fragments of approximately five millimeters) for the survey of T. saginata cysticercus. With the obtained results it is possible to verify that in the first trials, conducted in 2002, ALB-SO reached, independently of dosage and treatment scheme, efficacies superior to 98% (arithmetic means). The trials conducted in 2005 (2.5mg/kg on the 30th, 60th, and 90th DPI) obtained values of efficacy all inferior to 60%. In 2008, the trials with 2.5 and 7.7mg/kg demonstrated efficacy values inferior to 40%, for both dosages and treatment schemes (30th/60th/90th DPI and 60th DPI). When this formulation was administered orally on the dosage of 30mg/kg on the 60th DPI, the efficacy against T. saginata cysticercus reached 88.28%. ALB administered orally showed efficacy values of 0.0%, 29.88% and 28.64% in the dosages of 5, 10 and 15mg/kg, respectively, using the treatment schemes described above for each dosage. Based on the results of these trials, conducted in an eight year period (2002-2010) using the sequenced slicing method for evaluating the efficacy of the aforementioned formulations against T. saginata cysticercus, it is possible to observe that, amongst the few molecules used in the chemotherapic treatment against T. saginata larvae, ALB-SO, administered in varied routes, dosages and treatment schemes, the studies conducted in 2008, 2009, and 2010, have a low therapeutic efficacy against C. bovis in Brazil, while ALBZ had insignificant efficacy values against T. saginata larvae parasitizing experimentally infected bovines. However, future studies using molecular biology will be necessary to assess whether the difference on the efficacy of the ALB-SO can be related to strain or another specific factor.

Toltrazuril + fenbendazole for cattle: Pharmacokinetics and efficacy against Eimeria spp. and gastrointestinal nematodes.

The present work evaluated the pharmacokinetics and efficacy of the association of 15cmg/kg toltrazuril +5cmg/kg fenbendazole against Eimeria spp. and gastrointestinal nematodes (GINs) in calves of different regions of Brazil (Center-West, Southeast, and South). A total of seven experiments were carried out, five of which determined formulation efficacy against Eimeria spp., considering the following aspects: therapeutic, preventive, metaphylactic, and residual efficacy. Therapeutic efficacy experiments for GINs were carried out by parasitological necropsy. The toltrazuril + fenbendazole association demonstrated ≥95% efficacy against Eimeria spp. for 21 days post-treatment (DPT). When used preventively and metaphylatically, the same association demonstrated ≥97% efficacy against E. zuernii, E. ellipsoidalis, E. cylindrica, E. bovis, E. wyomingensis and E. auburnensis. Toltrazuril + fenbendazole administered seven days before challenge was 100% effective against all these Eimeria species. Results of therapeutic, preventive, metaphylactic and residual efficacies can be related to the pharmacokinetic results, especially considering toltrazuril sulfone, which was detected in animal plasma for a longer period than the parent compound. Toltrazuril + fenbendazole achieved 100% anthelminthic efficacy against the GINs Haemonchus placei (L4), Cooperia pectinata and Oesophagostomum radiatum; 99.94% against adult H. placei; and 99.98% against C. puntacta. The association of toltrazuril + fenbendazole, associated with other measures, is an important and suitable tool for the control and treatment of Eimeria spp. and GINs in young cattle.

Effects of macrocyclic lactones on the reproductive parameters of engorged Rhipicephalus (Boophilus) microplus females detached from experimentally infested cattle.

The present study therefore assessed the deleterious effects of MLs (ivermectin, abamectin, doramectin and moxidectin) on the reproductive parameters of engorged Rhipicephalus (Boophilus) microplus females that naturally detached from experimentally infested cattle in two experiments. The following reproductive parameters of engorged female ticks were analyzed: female weight, egg mass weight, percentage of hatchability, percentage of reduction in oviposition, percentage of reduction in hatchability, reproductive efficiency and percent control/efficacy of formulations with respect to reproductive parameters. In the experiment I, statistical analysis of the data grouped into 5-days intervals revealed that pour-on application of abamectin (500 mcg/kg) had significantly (p ≤ 0.05) reduced engorged female weight, egg mass weight and percent hatchability on days 6-15, 6-20 and 11-20 post-treatment (p. t.) compared to the respective data for detached and pre-selected engorged females in the control group. The abamectin, demonstrated 33.41% of reduction in oviposition, 6.77% in hatchability and abamectin efficacy was of 13.99%. In the experiment II, statistically significant reductions (p ≥ 0.05) were observed in animals treated subcutaneous with ivermectin (630 mcg/kg), doramectin (700 mcg/kg) and moxidectin (1000 mcg/kg) relative to the control for days 6-40, 6-48 and 6-40 p. t., respectively. Ivermectin reduced hatchability only on days 16-20 p. t., whereas doramectin significantly reduced (p ≤ 0.05) hatchability on days 6-10 and 16-35 p. t. For moxidectin, deleterious effects on hatchability were observed on days 16-35 p. t. The percent reductions in oviposition of engorged female ticks were 46.31%, 62.17% and 61.02% with ivermectin, doramectin and moxidectin treatments, respectively. The percent efficacy of the formulations on the reproductive parameters of engorged female ticks was 21.22% for ivermectin, 36.03% for doramectin and 35.45% for moxidectin. Among the MLs assessed, doramectin and moxidectin had the highest acaricidal efficacies and the most deleterious effects on the reproductive parameters of engorged R. (B.) microplus females. However, future studies will be necessary to assess the extent to which these effects, along with acaricidal activity, can be used to control the ectoparasite in cattle.

First report of the efficacy of a fluralaner-based pour-on product (Exzolt® 5%) against ectoparasites infesting cattle in Brazil.

BACKGROUND: This study describes the effectiveness of a novel active pharmaceutical ingredient, fluralaner (isoxazoline class), against important ectoparasites infesting cattle in Brazil. METHODS: A total of 13 studies involving a 5% fluralaner-based pour-on formulation (Exzolt 5%; further referred to as Exzolt) were conducted. Specifically, the effectiveness of this formulation was studied against Rhipicephalus microplus (6 studies), Cochliomyia hominivorax larvae (4 studies), Dermatobia hominis larvae (1 study) and Haematobia irritans flies (2 studies). RESULTS: The therapeutic efficacy of Exzolt was found to exceed 98% at 4 days post treatment (DPT), while persistent efficacy (> 90% efficacy) against repeated infestations of R. microplus was observed for up to 79 DPT. In field studies, ≥ 98% therapeutic efficacy was demonstrated at all study sites by 7 DPT, and a persistent efficacy (> 90% efficacy) was observed for 42, 49 or 56 DPT. Exzolt prevented C. hominivorax eggs from developing to the larval stage, thus mitigating the development of myiasis in cattle naturally and artificially infested with this screworm. The efficacy of Exzolt against D. hominis larvae was 98% at 3 DPT, while persistent efficacy (> 90% effectiveness) was found to last for up to 70 DPT. Against H. irritans, Exzolt showed therapeutic efficacy (≥ 90%) within the first day of treatment at both study sites, while persistent efficacy (≥ 90%) was observed for 7 DPT at one site and for 21 DPT at the other site. CONCLUSIONS: Overall, the results from these studies confirm that Exzolt is therapeutically efficacious against the most important ectoparasites infesting cattle in Brazil. The novel active pharmaceutical ingredient, fluralaner, provides a new treatment option for farmers to control cattle ectoparasites, especially where there is resistance to other chemical classes. In addition, an effective control of ectoparasites will improve overall cattle health and well-being as well as production.

First report of Giardia duodenalis in pet rabbits in Brazil.

Giardia duodenalis is a flagellate protozoan that multiplies in the small intestine of a wide variety of hosts, animals and humans. It has a worldwide distribution, however it is considered a neglected disease by the World Health Organization (WHO). Nowadays, rabbits are being chosen as pets, especially by children. There are already reports of the occurrence of G. duodenalis in rabbits from other countries, but research has not been carried out in Brazil yet. Thus, the objective of our work was to verify the occurrence and molecularly characterize G. duodenalis that affect pet rabbits, through the polymerase chain reaction (PCR) in the northwest region of the state of São Paulo, Brazil. Fecal samples from 100 rabbits were collected, which later underwent a process of DNA extraction and amplification by nested-PCR (nPCR), using the SSU rRNA gene, and ß-giardin (bg), glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) to determine the assemblage. A questionnaire was answered by the owners with information about gender, age, deworming, diarrhea, water source, food, place of residence and contact with other animals. From those samples, 40 were positive for G. duodenalis. Good quality of the SSU rRNA gene by nPCR were obtained from two samples. For the first time, we report the occurrence of G. duodenalis assemblage A on pet rabbits in Brazil.

Canine visceral leishmaniasis and Rhipicephalus sanguineus: evaluation and comparison of classical techniques.

The aim of this study was evaluating the association and correlation between the diagnostics tests used for Leishmania spp. detection in dogs and ticks. We evaluated 99 dogs and 990 Rhipicephalus sanguineus. In dogs, we used bone marrow aspirates and lymph node fine-needle aspiration biopsy (FNAB) for direct parasitological examinations and real time-polymerase chain reaction (RT-PCR) and collected blood samples for enzyme-linked immunosorbent assays (ELISA). In ticks, two laboratory techniques [immunohistochemistry to lipophosphoglycan (IHC) and RT-PCR] were performed in the intestine, ovaries and salivary glands. With respect to the measurement of diagnostic performance in dogs, lymph node RT-PCR proved to be the best test followed by ELISA and bone marrow RT-PCR. In ticks, intestine IHC were considered as a gold standard for diagnosis of leishmaniasis with intestinal RT-PCR being the best diagnostic test. To arrive at the correlation between laboratory techniques for dogs and their ticks, we evaluated the diagnostic test used for dogs with tests performed in R. sanguineus, which used lymph node FNAB as the gold standard. The intestine IHC technique showed strongest association. We demonstrated that the best tissue for Leishmania spp. detection in dogs was the lymph node and the intestine in case of ticks. As for laboratory techniques, the isolated analysis of each species presented a strong agreement between immunohistochemistry and RT-PCR when compared to its gold standard. In addition, we concluded that the immunohistochemistry of ticks' intestines was a better technique for diagnosing Leishmania spp. in R. sanguineus, thereby showing almost perfect correlation with the lymph node FNAB.

Strategic control of cattle co-parasitized by tick, fly and gastrointestinal nematodes: Is it better to use ecto + endoparasiticide or just endectocide formulations?

Ticks, flies, and gastrointestinal helminths (GINs) significantly affect cattle productivity; thus, ectoparasiticide, endoparasiticide, and endectocide drugs have commonly been used for their control. The study aimed to compare the technical (parasites counts), productive, and financial effects of a treatment protocol comprising ecto- + endoparasiticides formulations (T01: fluazuron 2.5 mg/kg + fipronil 1.25 mg/kg and fenbendazole 5 mg/kg; n = 15) to a treatment with one formulation of endectocide (T02: ivermectin 450 µg/kg + abamectin 250 µg/kg; n = 15) over 308 days under field conditions in crossbred cattle co-parasitized by Rhipicephalus microplus, Haematobia irritans, and GINs. Bovine weight gain and return on investment (ROI) were also evaluated. Bovines from T01 received four treatments against the cattle tick and two against two GINs. For T02, four treatments were performed. Animals from T01 gained 15.4 kg more than T02 and provided a comparative ROI of 15.8. In cattle co-parasitized with R. microplus, H. irritans, and GINs, the treatment protocol used in this study with ecto- + endoparasiticidal action formulations showed better technical results regarding parasite counts and productive and financial data than the strategic treatment protocol using only an endectocide formulation.

Tick infestation level interferes with spray formulation (organophosphate + pyrethroid) efficacy against Rhipicephalus microplus.

Due to the scarcity of information regarding the control of Rhipicephalus microplus on bovines with different tick burdens, tick counts and the efficacy of a commercial spray formulation (aspersion bath with organophosphate + pyrethroid) were evaluated for animals with a low and high tick burdens for 35 days in a stall test. Thirty-two crossbreed Bos taurus indicus x Bos t. taurus experimentally infested with R. microplus larvae were divided into four groups: T01 high infestation control, T02 high infestation treated, T03 low infestation control, and T04 low infestation treated. The bovines were kept individually in pens and R. microplus females were collected daily. All data were statistically analyzed with a significance level of 5% (P ≤ 0.05). For linear regressions, variables with P≤0.05 and the highest coefficients of determination (R2 ≥ 0.70) were considered the best descriptors. The reliability level was 95%. Tick counts differed (P<0.0001) between T01 and T02 (high infestation control vs. treated), except at day 2 (P >0.05) post-treatment, and efficacy ranged from 85.2 to 50.6%. The number of collected engorged females was lower (P<0.0001) for T04 than for T03 (low infestation treated vs. control) animals from day 3 to 29, and efficacy ranged from 95.2 to 69.8%. In addition, tick burden and efficacy were negatively correlated for both the group of animals with a high tick burden (r = -0.5256; p = 0.0012; R² = 0.2762) and the group of animals with a low tick burden (r = -0.9817; p < 0.0001; R² = 0.9638). In conclusion, a high tick burden on bovines decreases the efficacy of the tested spray acaricide.

Toxoplasma gondii: infection natural congenital in cattle and an experimental inoculation of gestating cows with oocysts.

Two studies, of a natural infection and an experimental infection, were performed in order to study congenital transmission of Toxoplasma gondii in cattle. In the first study, 50 fetuses were harvested from gestating cows that were eutanasied at a municipal slaughterhouse in Jaboticabal, São Paulo state, Brazil. In the second study, 11 gestating cows were divided into four groups for inoculation with T. gondii: GI consisted of three cows inoculated with 1.0 × 10(5) oocysts during their first trimester of gestation; GII consisted of three cows inoculated with 1.0 × 10(5) oocysts during their second trimester of gestation; GIII consisted of three cows inoculated with 1.0 × 10(5) oocysts during their last trimester of gestation; and GIV consisted of two control cows, one during its first and the other during its second trimester of gestation. In both studies, the presence of T. gondii was confirmed both indirectly by immunofluorescence assay (IFAT). In the natural infection experiment, 18% (9/50) of the gestating cows were confirmed to have specific antibodies (IFAT--1:64) against T. gondii. The bioassay was able to diagnose the presence of T. gondii in the tissue samples from three calves. In the second experiment, the nine cows from groups I, II and III presented with specific antibodies (IFAT) against T. gondii. In contrast, T. gondii could not be detected by IFAT, histopathological examination or the bioassay in any of the nine calves born to cows experimentally infected with T. gondii oocysts. Based on the results from both studies, we conclude that congenital infection of T. gondii in cattle, while infrequent, does occur naturally. The pathogenicity of the strain of T. gondii may influence the likelihood of this route of transmission.

Establishment and characterization of a cell line (RBME-6) of Rhipicephalus (Boophilus) microplus from Brazil.

Tick cell lines have already proved to be a useful tool for obtaining more information about possible vector species and the factors governing their ability to transmit a pathogen. Here, we established and characterized a cell line (RBME-6) derived from embryos of Rhipicephalus microplus from Brazil. Primary tick cell cultures were prepared in L-15B medium supplemented with 20% fetal bovine serum and 10% tryptose phosphate broth. The cell monolayers were subcultured when they reached a density of approximately 8 × 10 5 cells/mL (95% viability). Only after the sixth subculture were cells thawed from storage in liquid nitrogen successfully. Cytological analyses were performed using live phase contrast microscopy and cytocentrifuge smears stained with Giemsa, while periodic acid-Schiff and bromophenol blue staining techniques were used to detect total polysaccharides and total protein, respectively . No DNA from Anaplasma spp., Anaplasma marginale, Babesia spp., Bartonella spp., Coxiella spp., Ehrlichia canis, Rickettsia spp. or Mycoplasma spp. was detected in the cells through PCR assays. In addition, we performed chromosomal characterization of the tick cell line and confirmed the R. microplus origin of the cell line through conventional PCR and sequencing of a fragment of the mitochondrial 16S rRNA gene. In conclusion, we established and characterized a new cell line from a Brazilian population of R. microplus, which may form a useful tool for studying several aspects of ticks and tick-borne pathogens.

Does bathing affect tick and flea burdens and ectoparasiticide effectiveness of a spot-on formulation (fipronil + (S)-methoprene) for dogs?

This work evaluated tick and flea burdens and the efficacy of a single topical application of 10% fipronil + 9% (S)-methoprene spot-on against experimental infestations of Rhipicephalus sanguineus sensu lato and Ctenocephalides felis felis on dogs that were submitted to regular baths for 56-days post-treatment. Four treatments (n = 24) were evaluated: no chemical treatment and no bathing (T01); no chemical treatment + bathing (T02); chemical treatment and no bathing (T03) and chemical treatment + bathing (T04). Dogs were infested with adult ticks and fleas seven days pre-treatment (-7). The ectoparasites were then counted and removed on day -5, followed by a new infestation on day -2 and treatment on day 0. Ticks and fleas were then counted without removal on day 1 and counted with removal on day 2. The dogs were then repeatedly infested with both ectoparasites on days 5, 12, 19, 26, 33, 40, 47 and 54 post-treatment. Baths and ectoparasite counts with removal were performed every 48 h before and after experimental infestation, respectively. Animals of T04 had lower (P ≤ 0.05) tick burden than animals from T01 and T02 from day 2 to day 28. For fleas, the counts varied among days of the study. Dogs from T03 presented lower (P ≤ 0.05) flea burden than dogs from T01 from day 1 until day 56. The same was true for T04 when compared to T01 from day 1 to day 42. Animals of T02 greater (P ≤ 0.05) flea burden than animals of T04 in all dates post treatment. In addition, dogs from T02 presented higher (P ≤ 0.05) flea burden than T01 from day 7 to day 28 and from day 49 to day 56. In sum, the efficacy of the spot-on formulation used declined over the time against both ectoparasites. The efficacy for ticks ranged from 0.0 to 96.5% and 0.0 to 98.52% for T03 and T04, respectively. While for fleas, the efficacy of the formulation ranged from 67.41 to 100% for T03 and 40.18 to 100% for T04. So, bathing dogs that were not treated increased C. f. felis burden but not R. sanguineus s. l. burden. The residual efficacy of the product had a shorter duration against these ectoparasites for dogs that received subsequent bathing.

Viability of Haemonchus placei parasitism in experimentally infected young goats.

The present study aimed to evaluate the viability of Haemonchus placei parasitism in experimentally infected goats. For that, 14 75 days old kids male Saanen kids were placed in one of the four experimental groups: GI - infected with 5000 H. placei L3 (n = 4); GII - infected with 5000 H. contortus L3 (n = 4); GIII - infected with 2500 H. contortus L3 + 2500 H. placei L3 (n = 4), and GIV - control, inoculated with distilled water (n = 2). Each kid received, orally, the infective dose in a single inoculum. Based on daily fecal egg counts, the average pre-patent period was determined as 24 days for H. contortus, and 31 days for H. placei. Regarding the Haemonchus spp. recovered at necropsy, the experimental groups GI, GII, and GIII had, respectively, an average of 25.5, 619.5, and 724.75 (120 H. placei, and 604.75 H. contortus) adult specimens, and no immature forms. Under the conditions of this study, the viability of goat infection by H. placei was confirmed, although, with low susceptibility. Nevertheless, the parasitism of this helminth species was more intense when associated with H. contortus. This fact indicates that in common grazing between cattle and young goats, when the latter end up ingesting both Haemonhcus species, especially in a mixed infection, H. placei may also parasitize them.

Experimental infection of calves with Haemonchus placei and Haemonchus contortus: Assessment of parasitological parameters.

The present study evaluated the viability and possible effects of Haemonchus contortus infections in experimentally prime infected calves, comparing them to infections by Haemonchus placei. Ten male Holstein newborns were used. All calves were individually weighed for subsequent group formation, in which two animals were kept as a control group, inoculated with water (GI); four animals were inoculated with 10,000 third stage (L3) Haemonchus contortus larvae (GII); and the remaining four calves were inoculated with 10,000 third stage (L3) H. placei larvae (GIII). All experimental animals were necropsied on the 42nd day after inoculation. Based on results obtained by the present study, it can be concluded that bovine calves were susceptible to infections by both Haemonchus species (placei and contortus). H. contortus presented an inferior pre-patent period when compared to H. placei. No significant difference (P>0.05) was observed between Haemonchus burdens recovered from both infected groups (GII and GIII). Moreover, H. contortus females maintained an egg production rate similar to H. placei females in young animals, which can contribute to pasture contamination by both Haemonchus species. This could possibly lead to negative reflexes on helminth control based on a mixed pasture with bovines and ovines, especially when it involves younglings.

Susceptibility of Rhipicephalus (Boophilus) microplus to fluazuron (2.5mg/kg) and a combination of novaluron (2.0mg/kg)+eprinomectin (0.36mg/kg) in field studies in Brazil.

The present study aimed to determine the susceptibility of 32 R. (B.) microplus populations from Southeast, Midwest and South regions of Brazil, to fluazuron (2.5mg/kg), administered topically (pour-on). Additionally, five populations (Southeast and Midwest regions) of the southern cattle tick were evaluated using in vivo field studies, regarding their susceptibility to a new combination of novaluron (2.0mg/kg)+eprinomectin (0.36mg/kg), administered subcutaneously, compared with two positive controls (fluazuron 2.5mg/kg and eprinomectin 0.5mg/kg), both administered topically (pour-on). Selected bovines were allocated to treatment groups on day 0, and block formation was based on arithmetic means of female ticks (4.5-8.0mm long) counted on three consecutive days (-3, -2 and -1). To evaluate therapeutic and residual efficacies of these formulations, tick counts (females ranging from 4.5 to 8.0mm long) were performed on days 3, 7 and 14 post-treatment, continuing on a weekly basis until the end of each experiment. Results obtained throughout this study, utilizing field efficacy trials, allowed us to conclude that four R. (B.) microplus populations (including two in the Southeast and two in the Midwest regions) could be diagnosed as resistant, or with low susceptibility, to fluazuron (2.5mg/kg). Such fact was detected in farms where owners applied products containing this active component on cattle for at least five years, with treatment intervals of 30-55days during the rainy season. Nonetheless, in vitro studies should be performed in order to reinforce in vivo results obtained on the present study. Regarding efficacy indexes obtained by the association of eprinomectin and the novel molecule novaluron against R. (B.) microplus, none of the trials managed to obtain efficacies superior to 48%. Such results, allied to data obtained by different researchers and previously published in literature, reinforce the perception that maybe these formulations containing novaluron, in the administered dosages and treatment routes, may not be effective tools for controlling R. (B.) microplus. However, future studies must be conducted in order to support such hypothesis. Additionally, all five R. (B.) microplus populations were diagnosed as resistant, or with low susceptibility, to eprinomectin (0.5mg/kg) as well. Even though fluazuron, administered topically (pour on), is still an excellent active principle to be used against R. (B.) microplus, resistance management strategies should be quickly implemented in order to keep selection pressure in Brazil at a minimum level for this compound.

Population dynamics and evaluation of the partial selective treatment of crossbreed steers naturally infested with Rhipicephalus (Boophilus) microplus in a herd from the state of Minas Gerais in Brazil.

The present study aimed to evaluate the population dynamics of Rhipicephalus (Boophilus) microplus over a period of 13 months on a rural property located in the state of Minas Gerais in southeastern Brazil. Animals were treated for ticks indoors by whole body spraying when R. (B.) microplus had an average count equal or more than 30 ticks. The study also evaluated the possibility of a partial selective treatment for bovines to control R. (B.) microplus in which only a percentage of the population would be treated (specifically those bovines with tick counts of ≥20. Moreover, we examined the percentage of the population of R. (B.) microplus present on experimental bovines that did not come into contact with the chemical compounds used in the partial selective treatment. We concluded that in this particular region of Brazil, the crossbreed steers support up to five R. (B.) microplus generations per year and that the number of generations was primarily affected by the pluviometric precipitation. We sprayed the bovines with chemicals seven times during the course of the study. The results of the partial selective treatment method revealed that during the rainy and the dry periods, 42.1% to 60.0% and 61.9% to 79.2% of the animals, respectively, fulfilled the criteria to receive a chemical treatment to reduce the number of cattle ticks. In consideration of the need to slow the development of tick resistance with the chemical compounds used in the spraying treatment, the results showed that the percentage of animals that did not require treatment is not relevant. This was evidenced by the result that bovines that presented tick counts of ≥20 during the dry and rainy periods represented 91.5% and 90.6% of the total recorded R. (B.) microplus populations, respectively. Only 8.7% of the tick population remained free from exposure to acaricides during the 13 months of the study, which is an important point when considering the adoption of the partial selective treatment method. Future studies with larger herds must be conducted on these topics; however, our results suggest that the partial selective treatment method most likely will not slow the development of resistance in this R. (B.) microplus population against the chemical compound used in this study.

Spatial distribution and risk factors for Toxoplasma gondii seropositivity in cattle slaughtered for human consumption in Rondônia, North region, Brazil.

The present study aimed to evaluate Toxoplasma gondii seroprevalence in cattle slaughtered for human consumption from rural properties in the state of Rondônia, North region, Brazil; the seroprevalence was determined using indirect immunofluorescence assays (IFATs). Additionally, spatial distribution and risk factors associated with toxoplasmosis were also analyzed. Of the 1000 cattle serum samples examined, 53 (5.3%) were determined to be seropositive for T. gondii with antibody titers (IgG) ≥64. In regard to results of the studied risk factors (presence of cats, cats with free access to cattle, breeding system, animal's gender, consumption of raw milk by humans on the property and cattle abortion in the last 12 months) and the odds ratio (OR) of each of these factors influencing cattle to acquire toxoplasmosis, only animals raised on a feeder/stocker/backgrounder system presented a higher probability of being seropositive for T. gondii (OR≥1, P=0.04) than cattle raised only in a feeder/stocker system. There was no association between the occurrence of reproductive problems and T. gondii seropositivity. Based on results obtained in the Brazilian state of Rondônia, it could be concluded that the presence of cats and their contact with cattle on each property, cattle breeding purpose and cattle abortion in the last 12 months were not considered risk factors for T. gondii infection in cattle. Considering that the presence of T. gondii was detected in animals slaughtered in the state of Rondônia, consuming raw or undercooked meat from seropositive cattle should be considered a route of transmission of T. gondii to humans. However, the prevalence of toxoplasmosis diagnosed in cattle from this state (5.30%) is lower than the prevalence of toxoplasmosis observed in South, Southeast and Center-West regions of Brazil, which may vary between 48.5% and 71.0%. The low prevalence of toxoplasmosis in cattle is highlighted in Rondônia, which is the sixth largest state for cattle slaughtering in Brazil and is responsible for producing 20% of all cattle meat exported by Brazil.