Comparison of the efficacy of different methods to apply acaricides for control of Rhipicephalus (Boophilus) microplus

The present study compared the efficacy of different methods to apply an acaricide formulation to control Rhipicephalus (Boophilus) microplus. To compare the methods, an acaricide blend containing three active ingredients (a pyrethroid and two organophosphates) was used. In experiment 1 (farm 1: Goiânia, GO, Brazil), three methods were tested: a backpack sprayer (BS), power sprayer (PS) and spray race (SR). In experiment 2 (farm 2: São José do Rio Pardo, SP, Brazil), two methods were tested: BS and PS. In both experiments, 10 cattle with similar tick burdens were used. On day 0 in both experiments, the animals were treated with the acaricide. On day +1 (only in experiment 1), +3, +7, +14, +21, +28 and +35 (only in experiment 2), tick counts were performed to determine the control efficacy. The time application, pressure (KPa), volume applied (L) and ergonomic aspects of each spraying system were also evaluated. The adult immersion test (AIT) using three different acaricide blends (combinations of pyrethroid + organophosphate) was performed to compare the susceptibility of strains of each farm. In experiment 1, all treatments significantly reduced (p < 0.05) the number of ticks on the animals, and PS resulted in the greatest acaricide efficacy since day +1. In experiment 2, both treatments (PS and BS) reduced (p < 0.05) the tick burden, and as observed in experiment 1, PS resulted in the best reduction. The application times were 4.5, 150 and 330 s, while pressures were 306.8, 4,826.3 and 220.6 KPa for SR, PS and BS, respectively. In the AIT, the efficacy values were between 99.8 and 100% for the tick strain form farm 1 (Goiânia), while for tick strain from farm 2 (São José do Rio Pardo), the efficacy was between 67.2 and 80.9%. We conclude that the sprayer methods chosen influences the efficacy of the acaricide. All sprayer methods were efficient for acaricide application; the best efficacy was obtained using the PS, while the SR resulted in good efficacy and lower application time. The strain from farm 2 was less susceptible to all acaricides tested.

Spatial distribution and risk factors for sheep toxoplasmosis in Goiás, Brazilian Cerrado Region

The present study aimed to evaluate the spatial distribution and risk factors for infection by Toxoplasma gondii in sheep in the state of Goiás, located in the central-western region of Brazil. Through the immunofluorescence antibody test (IFAT), the seroprevalence of anti-T. gondii antibodies was analyzed in 1000 blood serum samples obtained from sheep in all macro and micro regions of the state of Goiás. Data related to sex, age of the animals, size of the farm, type of farm, water source, veterinary assistance, replacement of the herd, presence of domestic cats, presence of wild cats and presence of other wild animals were obtained at the sampling time. The differences between the seroprevalences obtained in relation to the variables analyzed were estimated using Pearson's chi-square test (χ2). The odds ratio (OR) values for each risk factor evaluated were statistically analyzed with a confidence interval of 95%. Positivity for IgG anti-T. gondii was observed (titer ≥64) in 34.3% (343/1000) of the samples, which ranged from 26.9% (31/115) to 44.2% (53/120) and from 21.8 (12/55) to 55.2% (16 / 29), respectively in the analyzed mesoregions and microregions. In all investigated regions of the State of Goiás, serum-reactive animals were detected with the age of the animals, the source of water, the form of replacement of the herd and the presence of domestic cats and wild animals risk factors statistically associated with the occurrence of T. gondii in animals.

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.

Investigation of fecal egg counts versus worm burden and helminth fauna in cattle treated or not with macrocyclic lactones in a tropical region

Gastrointestinal nematodes negatively impact the health and productivity of livestock. Macrocyclic lactones (MLs) are the most common class of chemicals used in helminth control programs, however, their intense use is accelerating the development of parasite resistance. For cattle, little is known regarding the relationship between fecal egg counts (FECs) and the helminth population inside the animal's gastrointestinal tract and so this study evaluated the correlation between FEC and worm burden in cattle treated or not with MLs (ivermectin 200 μg/kg, ivermectin 630 μg/kg, abamectin 200 μg/kg, doramectin 700 μg/kg and moxidectin 200 μg/kg). Animals were necropsied to determine if there were any modifications to the proportions of worm species due to chemical treatment. FECs of ML-treated and untreated animals showed significant (p ≤ 0.05 and R² ≥0.70) positive linear correlations and substantial or perfect strength-of-agreement (LCCC ≥ 0.61) with total worms present, all of which were Haemonchus placei and Cooperia punctata. However, this correlation and strength-of-agreement did not occur when the efficacy of MLs was ≥80 % against these helminths. Among the active MLs tested, moxidectin had the weakest relationship between FEC and worm burden, except for H. placei. Analysis of the helminthological fauna found an increase of H. placei (35.6 % = 95 % CI 35.4-35.6) and a consequent decrease of C. punctata (52.5 % = 95 % CI 52.3-52.6) in untreated animals, when compared to studies carried out over 20-40 years ago, but this proportion was reversed for ML-treated animals (C. punctata 64.5 % = 95 % CI 64.4-64.8; H. placei 30.8 % = 95 % CI 30.6-30.8). It is possible that MLs mitigate this effect in the field and that C. punctata remained prevalent in cattle in different regions of Brazil.

FIRST REPORT OF GENUS Cryptosporidium IN CERVIDS SPECIES: Mazama americana, Mazama nana AND Blastocerus dichotomus

We analyzed Cryptosporidium spp. in fecal samples of wild cervids (Ozotoceros bezoarticus, Blastocerus dichotomus, Mazama nana, Mazama americana, and Mazama bororo) from many Brazilian regions, a fact unprecedented in the literature. Sniffer dogs were used to collect 936 fecal samples of cervids from 14 Brazilian localities. Cervids species were identified using polymerase chain reaction (PCR) performed from genomic DNA extracted from 563 fecal samples of Ozotoceros bezoarticus, Blastocerus dichotomus, Mazama nana, Mazama americana, and Mazama bororo. Cryptosporidium spp. oocyst screening was performed using malachite green negative staining. Nested PCR (nPCR) protocols targeting the 18S rRNA and GP60 genes followed by genetic sequencing were performed for Cryptosporidium spp. detection and Cryptosporidium parvum subtyping, respectively. Nested PCR targeting actin gene and genetic sequencing were performed in samples with non-identified Cryptosporidium species by 18S rRNA amplicon sequencing. The association between the occurrence of Cryptosporidium and the presence of bovines in the same locality was evaluated using Fisher's exact test. The positivity rates of diagnostic methods were compared by McNemar test and the Kappa correlation coefficient. The prevalence rates of Cryptosporidium spp. in cervids were 1.42% (8/563) and 0.36% (2/563) by nPCR and malachite green negative staining, respectively. C. parvum IIaA16G3R1 isolate was identified in three fecal samples from M. americana, two from M. nana and one from B. dichotomus. Cryptosporidium ryanae were found in one sample from B. dichotomus. We identified a new Cryptosporidium genotype, named Cryptosporidium deer genotype BR, from one M. americana fecal sample.

Cryptosporidium parvum in brown brocket (Mazama gouazoubira) from Brazil: First report of the subtype IIaA16G3R1 in cervids

This research had as objective to evaluate the occurrence and to characterize genetically the infections by Cryptosporidium in Mazama gouazoubira. By a non-invasive harvest methodology using trained sniffer dogs to locate fecal samples of cervids, 642 fecal samples were obtained from six Brazilian localities. The cervids species responsible for the excretion of each fecal sample were identified by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), using the mitochondrial cytochrome b target gene (cyst b) and the restriction enzymes Sspl, AflIII and BstN. From this identification, 437 fecal samples of M. gouazoubira were selected for research of Cryptosporidium spp. performed through negative staining with malachite green and polymerase chain reaction (nPCR), with the subunit of 18S rRNA gene, followed by sequencing the amplified products. In the samples that were diagnosed the presence of parasite species with zoonotic potential, genotyping was also performed using nPCR with the subunit of GP60 gene. Statistical analysis consisted of the Fisher exact test to verify the association of the presence of the enteroparasite in relation to the presence of cattle in each locality, and the McNemar tests and Kappa correlation coefficient used to compare the results obtained between the two diagnostic techniques. In the fecal samples of M. gouazoubira the occurrences of Cryptosporidium were diagnosed in 1.6% (7/437) and 1.1% (5/437), respectively, through nPCR and microscopy. Cryptosporidium. parvum was diagnosed in 100% (7/7) of the samples submitted to sequencing (18S gene). The IIaA16G3R1 subtype was diagnosed in five of the C. parvum samples submitted to genotyping (GP60 gene). This is the first world report of C. parvum in M. gouazoubira and subtype IIaA16G3R1 in cervids.

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.

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.

Investigation of Toxoplasma gondii in semen, testicle and epididymis tissues of primo-infected cats (Felis catus)

This study aimed to investigate the presence of Toxoplasma gondii in semen, testicle and epididymis tissues of cats experimentally infected by this coccidium. A total of 12 male felines without a definite breed that were of reproductive age and serologically negative for T. gondii were selected and distributed to the following three experimental groups: GI, inoculated with 600 tissue cysts of the P strain of T. gondii (isolate III); GII, inoculated with 2×10⁵ tachyzoites of the RH strain (isolate I); and GIII, not inoculated (control group). Prior to inoculation (day -7 and 0) and on post inoculation days (PIDs) 7, 14, 21, 28, 42, 56, and 70, all felines were subjected to assessments of anti-T. gondii IgG by indirect immunofluorescence (IIF) and assessments of parasitemia. Collection of semen (electroejaculation) was performed on the specified dates, followed by nested PCR and bioassays in mice to detect T. gondii. On PID 70, all 12 felines were orchiectomized, and the presence of the parasite in the testicles and epididymides was evaluated by nested PCR, murine bioassay, and histopathological and immunohistochemical analyses. All felines inoculated with T. gondii (GI and GII) seroconverted to the toxoplasmic infection after PID 14; on PID 7, seroconversion of three felines (P4, RH2 and RH4) could observed, and all exhibited detectable titers by PID 64. The GII felines exhibited greater serological titers compared with GI felines. The maximum serological titer (IgG) was observed in feline RH3 (titer 1024), while in other experimental felines, a maximum titer of 256 was detected. Parasitemic peaks were diagnosed in all felines of groups I and II from PIDs 7-42. A total of five parasitemic peaks were diagnosed in GI and nine in GII. In none of the experimental time points was the presence of T. gondii diagnosed in seminal samples collected from the felines or in the testicle or epididymis tissues collected from these animals. Thus, sexual transmission in domestic cats does not appear to be a major route of T. gondii infection, possibly demonstrating the tendency of this protozoan to develop a response directed to the formation and excretion of oocysts in the feces of these definite hosts, which act as its main route of perpetuation in the environment.

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.

Occurrences of Oestrus ovis parasitism in necropsied sheep in the Umuarama microregion, Paraná, Brazil

Between January 2007 and September 2013, 71 sheep belonging to 12 farms in the Umuarama microregion, State of Paraná, were evaluated regarding presence of Oestrus ovis larvae, during necropsies. The farms from which these animals originated were visited and the owners and employees were interviewed. Occurrences of O. ovis parasitism in sheep were diagnosed for the first time on this microregion. Of the 71 animals, 12 (16.9%) were parasitized by O. ovis, with mean intensity of 2.25 larvae per infested head (1 to 8 larvae/infested head). There was a high correlation (0.81, p=0.0346) between the number of larvae and the macroscopic lesions observed in these animals' nasal cavities, such that sheep with more than 3 larvae may contain mucupurulent secretions or epistaxis. From the interviews conducted, it was found that all the farm owners were applying chemical parasite control methods (helminths and/or O. ovis), administered to all animals in the herds every 30 days (91.6% of the producers), using derivatives of macrocyclic lactones and/or benzimidazoles/imidazothiazoles. Further studies need to be conducted in this particular region, in an attempt to elucidate the prevalence of O. ovis parasitism in herds.

Endoparasites of horses from the Formiga city, located in center-west region of the state of Minas Gerais, Brazil

With the aim of studying the endoparasite fauna of horses from the Formiga city, located in center-west region of the state of Minas Gerais, 25 animals that were naturally infected with helminths were evaluated. By means of parasitological necropsies, different endoparasites were found. The subfamily Cyathostominae presented the highest incidence, followed by Trichostrongylus axei, Oxyuris equi, Triodontophorus serratus, Strongyloides westeri, Strongylus edentatus, Habronema muscae, Parascaris equorum, Probstmayria vivipara, Strongylus vulgaris, Gasterophilus nasalis, Anoplocephala magna and Anoplocephala perfoliata. In the present study, if the species Probstmayria vivipara was not considered in the prevalence, the frequency of Cyathostominae was equivalent to 94.85%. The results obtained in this study allowed us to detect and identify different species of helminths in horses, and confirmed the high incidence of nematodes belonging to the subfamily Cyathostominae in the center-west region of Minas Gerais.

Effect of a spray formulation on the reproductive parameters of a susceptible population of Rhipicephalus (Boophilus) microplus

The number of studies emphasizing the possible damage that acaricidal spray formulations can cause on engorged female ticks' reproductive parameters is small. The present study evaluated the deleterious effects of a spray formulation (dichlorvos 60% + chlorpyrifos 20%) on the reproductive parameters of a susceptible population of Rhipicephalus (B.) microplus females, using the Stall Test. The ticks were allocated randomly to treatments according to the mean numbers of females detached from each cow on days -3, -2 and -1 and the cattle pen location. The numbers of engorged female ticks that naturally detached from the cattle were counted daily from day 1 to day 30. For each group, 20 detached engorged female ticks or the available number collected daily were evaluated regarding reproductive parameters. Associations of organophosphates demonstrated elevated acaricidal efficacy, as well as deleterious effects on the reproductive parameters of R. (B.) microplus females. The engorged female weight (days 1 to 7), weight of egg masses (days 5 to 10) and larval hatching percentage (days 5 to 19) were decreased (P ≤ 0.05). It is possible that a formulation can lead to deleterious effects on R. (B.) microplus females when the tick population analyzed shows elevated sensitivity towards a particular formulation. However, further studies need to be conducted.

A comparison of three different methodologies for evaluating Rhipicephalus (Boophilus) microplus susceptibility to topical spray compounds

This study aimed to compare three different methodologies (Adult Immersion Tests, field trials with naturally infected animals, and a Stall Test using artificially infested cattle) to evaluate the efficacy of two topical formulations that we administered as whole body sprays (15% Cypermethrin+30% Chlorpyriphos+15% Fenthion-Colosso(®) FC 30, Ouro Fino Agronegócios; and 60% Dichlorvos+20% Chlorpyriphos-Ectofós(®), Vallée Saúde Animal Ltd.), against a susceptible strain of Rhipicephalus (Boophilus) microplus. To achieve this objective, two natural infestation trials were conducted, as well as two artificial infestation trials (Stall Tests) and two Adult Immersion Tests (AIT). The AIT results showed that both spray formulations achieved 100% efficacy against R. (B.) microplus fully engorged females. However, when observing results obtained by field trials (natural infestations) and Stall Tests, none of these topically applied compounds reached 100% efficacy or affected the reproductive capacity of the fully engorged female ticks. Additional studies must be conducted to compare these in vivo methodologies with different in vitro techniques, such as the Larval Packet Test. However, based on results obtained here, we can conclude that depending on the spray formulations used, the AIT can overestimate acaricidal efficacy and values of reproductive efficiency of such compounds against R (B.) microplus. Specifically, when dealing with spray formulations in the Stall Tests, the period of residual action can increase because these animals are sheltered from contact with environmental factors that might interfere with the efficacy of the products tested. It may be necessary to take in vivo trial results into consideration (such as field trials with naturally infested animals or Stall Tests) to standardize a specific in vitro assay, such as the Adult Immersion Test.

Nematode resistance to ivermectin (630 and 700μg/kg) in cattle from the Southeast and South of Brazil

Two high doses of ivermectin (630μg/kg and 700μg/kg) that are sold commercially in Brazil were evaluated in dose-and-slaughter trials with 144 naturally nematode-infected cattle from eight regions within the states of Minas Gerias, São Paulo and Rio Grande do Sul in Brazil. Treatment groups were based on fecal egg counts 1, 2, and 3days before treatment; all animals studied had a minimum egg count of at least 500 eggs per gram of feces (EPG). Post-mortem analyses were conducted on day 14. The highest levels of resistance to ivermectin were found for Haemonchus placei, Cooperia punctata and Oesophagostomum radiatum; all populations of H. placei were resistant to the 630μg/kg dose, and 67% were resistant to 700μg/kg; 86% of C. punctata were resistant to the 630μg/kg dose, and 33% were resistant to 700μg/kg. A combined analysis revealed that 57% of O. radiatum were resistant to the lower dose of ivermectin. H. placei, C. punctata and O. radiatum, in order, were the nematode populations with the highest indices of resistance, whereas Trichostrongylus axei was the most susceptible to 630 and 700μg/kg dosages of ivermectin. The results of helminthic resistance to ivermectin for different populations of H. placei and C. punctata described in the present study support previous literature data, in which a small decrease in the average parasitic burden of C. punctata and a consequent increase of H. placei were observed in cattle from the Southeast, South and Center-West regions of Brazil.

Effects of fluazuron (2.5 mg/kg) and a combination of fluazuron (3.0 mg/kg) + abamectin (0.5 mg/kg) on the reproductive parameters of a field population of Rhipicephalus (Boophilus) microplus on experimentally infested cattle

The current study assessed the deleterious effects of two formulations of fluazuron (2.5 mg/kg fluazuron and a combination of 3.0 mg/kg fluazuron + 0.5 mg/kg abamectin) on the reproductive parameters of engorged Rhipicephalus (Boophilus) microplus females that naturally detached from experimentally infested cattle in two experiments. Based on the obtained results, it can be concluded that fluazuron (2.5 mg/kg) showed deleterious effects only on the hatchability percentage in the period of 2-7 post-treatment days of this ectoparasite's engorged females. On the other hand, the fluazuron (3.0 mg/kg) + abamectin (0.5 mg/kg) combination presented harmful effects over reproductive parameters of this tick species. Further studies should be performed with a known tick population (reference susceptible strain) to determine the effect of these formulations on the reproductive parameters and to elucidate if this field population is fluazuron resistant.

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.

Assessing resistance of ivermectin and moxidectin against nematodes in cattle naturally infected using three different methodologies

The objective of this study was to evaluate the accuracy of the faecal egg count reduction test (FECRT) and the faecal egg count efficacy test (FECET) to assess the resistance status of ivermectin (630 μg/kg) and moxidectin (200 μg/kg), using the controlled efficacy test as a reference, and whether the results of the EPG are equivalent to the efficacy results from the parasitological necropsies. Two experiments were conducted. The results demonstrate that it was not possible to demonstrate that the EPG values were equivalent with the ivermectin and moxidectin efficacy obtained by parasitological necropsies, mainly if the phenomenon of parasites resistance is not advanced in a determined field population. Maybe the FECET technique would be possibly better than the FECRT. The high anthelmintic efficacy of 200 μg/kg moxidectin, in naturally infected cattle, against field population of nematodes that are resistant to 630 μg/kg ivermectin, was observed in this study.

Detection of Cryptosporidium parvum oocysts in calf fecal samples by direct immunofluorescence assay

The aim of this study was to produce a conjugate containing anti-Cryptosporidium parvum polyclonal antibodies and standardize a Direct Immunofluorescence Assay (DIF) for detecting C. parvum oocysts in fecal samples from calves. In order to obtain anti-C. parvum polyclonal antibodies, two New Zealand rabbits were immunized with a purified solution of C. parvum oocysts and Freund's adjuvant. Purification of the immunoglobulin G (IgG) fraction was performed by means of precipitation in ammonium sulfate and chromatography using a DEAE-cellulose column. The anti-C. parvum polyclonal antibody titer was determined by means of the enzyme-linked immunosorbent assay (ELISA). The rabbit anti-C. parvum IgG fraction was conjugated with fluorescein isothiocyanate and standardization of the DIF was performed using various dilutions of conjugate on slides positive for C. parvum oocysts. The cross-reactivity of the anti-C. parvum conjugate was tested using oocysts of Cryptosporidium serpentis, Cryptosporidium andersoni, Escherichia coli, Eimeria sp., and Candida sp. An anti-C. parvum conjugate was successfully produced, thus allowing standardization of DIF for detection of Cryptosporidium oocysts in fecal samples. Cross-reactivity of anti-C. parvum polyclonal antibodies with C. andersoni and C. serpentis was also observed.