Efficacy of monthly treatment with oral fluralaner (Bravecto® 1-Month) against Tunga penetrans in dogs in Brazil: a randomized, double-blind, controlled field study

BACKGROUND

Tungiasis is a neglected tropical disease caused by the adult female sand flea (Tunga penetrans). Dogs are considered important reservoirs of T. penetrans in Brazil. The aim of this study was to determine the monthly insecticidal efficacy of a single oral administration of fluralaner at a dose of 10-18 mg/kg (Bravecto® 1-Month, also registered as Defenza® in some countries; MSD Animal Health) in dogs naturally infested with T. penetrans.

METHODS

This clinical trial was conducted in a rural community located in Ilhéus, Bahia, Brazil. A total of 64 dogs were selected and distributed in a completely randomized design between a treated group (TG) that received one single dose of Bravecto® 1-Month (Defenza®) and a negative control group (CG) that received no treatment. Each group was composed of 32 dogs. The evaluations took place on days 0, 7 ± 2, 14 ± 2, 21 ± 2, 28 ± 2, 35 ± 2, and 42 ± 2 post treatment, in which the dogs were inspected to evaluate the infestation stage and classify lesions associated with tungiasis. The primary efficacy was determined from the percentage of treated dogs free of fleas (stage II and III lesions) after administration of the formulation at each evaluation time. Secondary efficacy was based on the number of active lesions (stages II and III) in each group at each evaluation time. The clinical condition of the animals was defined based on the Severity Score for Acute Dog Tungiasis (SCADT), which is related to the number and severity of lesions.

RESULTS

The primary efficacy of the product was greater than 95.0% from days 7 to 21 and reached 100.0% between days 28 and 42, with a significant association between treatment and infestation decline (P < 0.025) between days 7 and 42. Secondary drug efficacy was greater than 99.9% from days 7 to 21, reaching 100.0% between days 28 and 42 (P < 0.05). The treated dogs also scored lower on the SCADT than the control animals did during the entire clinical evaluation period (P < 0.05).

CONCLUSIONS

A single administration of Bravecto® 1-Month (Defenza®) was effective in eliminating Tunga penetrans infestations, as well as in preventing parasitism for at least 42 days after treatment.

Effects of pasture management and supplementation on the productive performance of recently lambed ewes

The hypothesis was tested that the performance of lactating ewes is affected by the supplementation level and pasture management. Two supplementation levels (0.5 and 1.0% of body weight, BW) and two pasture managements (mowed and non-mowed) were tested. Forty adult ewes (2 years old) with an average weight at lambing of 62.97 ± 7.0 kg (day 0) and an average the body condition score of 2.5 points (day 0) were evaluated. Verminosis was monitored with periodic deworming. The number of eggs per gram of feces (EPG) of ewes at lambing was used as a covariate for performance assessments. Ewes lost an average of 7.5 kg over the 90 days post-partum (12% BW). The weaning rate was 53%. The body condition of the ewes was influenced by the post-partum period. The ewes mobilized their body reserves in the first 30 days of lactation. Mowing management negatively affected the nutritive value of the forage. Supplementation with 0.5% BW was sufficient for nutritional management post-partum. Pasture management (mowed vs. not mowed) cannot prevent post-partum weight loss. Supplementation levels and pasture management altered the morphological and chemical components of the pasture.

Efficiency of fluralaner pour-on in different strategic control protocols against Rhipicephalus microplus on Brangus cattle in a tropical area

BACKGROUND

The occurrence of higher winter temperatures in Brazilian areas with tropical and highland climates may result in a fifth peak of tick populations during winter in addition to the four generations previously described. Therefore, a strategic control protocol was developed with treatments in two seasons with the objective of controlling the generations of ticks that occur in spring/summer and those that occur in autumn/winter.

METHODS

The study was conducted in Mato Grosso do Sul, Brazil, from the beginning of the rainy season, November 2020, to October 2021. In a randomized block design, 36 calves were distributed into three groups: (i) negative control; (ii) traditional strategic control in one season (SC1S), at the beginning of the rainy season; and (iii) strategic control in two seasons (SC2S), at the beginning and end of the rainy season. The SC1S strategic control group was treated on day 0, November 2020, and twice more with intervals of 42 days. The SC2S group received three more treatments beginning on day 182, May 2021, with intervals of 42 days. All treatments consisted of 5% fluralaner (Exzolt® 5%) delivered via a pour-on dose of 1 mL/20 kg body weight. Counts of semi-engorged female ticks were performed on day 3 and every 14 days thereafter, and the animals were weighed at the same time.

RESULTS

Fluralaner showed a mean efficacy of more than 95% up to day 294. The two treated groups showed a decrease (P < 0.05) in the average number of ticks on day 3. In the SC2S group, the means were close or equal to zero throughout the study, while in the SC1S group, the means did not differ (P > 0.05) from those of the control group from day 231 onward. The final mean weight gain of each group was 76.40 kg, 98.63 kg, and 115.38 kg for the control, SC1S, and SC2S groups, respectively, differing (P < 0.05) from each other.

CONCLUSIONS

Therefore, three applications of fluralaner, with one application every 42 days from the beginning of the rainy season in the middle spring, resulted in effective tick control for 224 days. When three additional treatments were given in autumn/winter with intervals of 42 days between applications, tick counts were reduced throughout the year. This strategic control approach may be indicated in years with climatic conditions that allow that population peaks are expected to occur in the autumn/winter period.

Control of Rhipicephalus microplus on taurine cattle with fluralaner in a subtropical region

BACKGROUND

In Rio Grande do Sul, Brazil, a region with a subtropical climate, Rhipicephalus microplus is present in taurine cattle raised for beef and milk. In addition, ticks resistant to multiple acaricides are present in this region. Recently, fluralaner (isoxazoline) was launched on the market. Thus, there is a need to evaluate the effects of fluralaner for the control of R. microplus on taurine cattle. In addition, occurrence of myiasis by Cochliomyia hominivorax larvae after tick parasitism and weight gain of cattle during the experimental period were evaluated.

METHODS

Thirty naturally infested cattle were divided into two experimental groups: T01, treated with fluralaner (2.5 mg/kg) pour-on; T02, control. T01 received fluralaner on Days 0 (early summer in January), 42 and 84 (early autumn), whereas T02, a control group, received palliative treatment with a spray formulation when the group mean was ≥ 30 ticks. Counts of R. microplus females and calculation of the efficacy of fluralaner were performed on Days 3, 7, 14, 28, 35, 42, 56, 70, 84, 98, 112 and 126. The occurrence of myiasis was assessed throughout the study period. In addition, the weight, weight gain and daily weight gain of the animals were evaluated.

RESULTS

In the 12 evaluations performed, the parasitic load of T01 was near zero. Fluralaner showed 99.5% efficacy on the 3rd day after the first treatment and 100% efficacy from Day 7 to Day 126. Cochliomyia hominivorax larvae (n = 6; p = 0.0251) were found only in the control group (T02). At the end of the study, the animals subjected to treatments with fluralaner gained 32.8 kg more than the animals in the control group.

CONCLUSIONS

Application of fluralaner in summer and autumn, with 42-day intervals between treatments, was effective to control R. microplus on taurine cattle, which also gained more weight than control cattle. Additionally, no cases of myasis were documented in animals treated with fluralaner.

What is the optimal timing to initiate strategic control of Rhipicephalus microplus in taurine cattle in a tropical region?

Cattle tick control poses a significant challenge for livestock in tropical and subtropical regions. The objective of this study was to determine the most suitable timing to initiate a strategic tick control program and to identify the ideal number of acaricide treatments for adult taurine cattle (Bos taurus taurus) in a tropical region throughout the year. Three groups with 10 bovines each were performed: T01 (strategic treatment in late autumn/winter/late spring, every 28 days), T02 (strategic treatment to act in the "first tick generation" - early spring/summer/early autumn, every 28 days) and T03 (control). Tick counts (females 4-8 mm) were conducted every 14 days. If the tick burden in any group reached 30 or more during these counts, we applied an additional treatment. Over the course of a year, T02 required significantly fewer (p < 0.05) acaricide treatments than T01, with nine treatments for T02 and eleven for T01. Furthermore, during the tick counts, animals in T02 showed a lower tick burden compared to those in T01. Initiating the strategic tick control program in early spring, corresponding to the first tick generation, proved more effective than starting in autumn. This approach not only required fewer acaricide treatments but also resulted in a reduced tick burden. These benefits are particularly valuable in terms of animal welfare and managing acaricide resistance issues.

Efficacy of an oral formulation of afoxolaner and milbemycin oxime against Tunga penetrans in naturally infected dogs

BACKGROUND

The sand flea Tunga penetrans is one of the agents of tungiasis, an important parasitic skin disease affecting humans and several mammalian species. Tungiasis is mainly observed in disadvantaged rural and peripheral urban communities in Latin America and sub-Saharan Africa. The dog is a major reservoir of Tunga fleas. Hematophagous adult female Tunga spp. embed and grow in their host's epidermis and cause cutaneous inflammatory disorders. NexGard Spectra® is an orally administered endectocide for dogs, a co-formulation of the isoxazoline afoxolaner and the macrocyclic lactone milbemycin oxime. The objective of this study was to assess the efficacy of this product against canine tungiasis.

METHODS

A blinded, negative-controlled field trial was conducted in a Brazilian community known to be highly endemic for tungiasis. Sixty-six dogs naturally infected with live T. penetrans were randomly allocated to a treated group (44 dogs) and an untreated control group (22 dogs). In a first phase, dogs from the treated group were treated on days 0, 30, and 60. Efficacy was evaluated on the basis of the macroscopic parasitic skin lesions (Fortaleza classification) on days 7, 14, 21, 30, 45, 60, 75, and 90. In a second phase, to evaluate natural reinfections, all dogs were treated on day 90 and evaluated every 2 weeks thereafter until at least 30% of dogs were infected with live sand fleas.

RESULTS

During the first phase, efficacy (reduction in live sand fleas) of 92.4% was demonstrated on day 7. From day 14 until day 90, the efficacy of NexGard Spectra® was 100%. In the second phase, all dogs were free of live T. penetrans from 15 until 45 days after the day 90 treatment; 60 days post-treatment, 11% of dogs were reinfected, and 75 days post-treatment, 40% of dogs were reinfected.

CONCLUSIONS

NexGard Spectra® was demonstrated to be highly effective against canine tungiasis. In addition to an obvious beneficial effect on the health and welfare of the treated dog, the use of this product may have a one-health benefit on human cases by controlling the main reservoir of sand fleas.

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.

Selective versus strategic control against Rhipicephalus microplus in cattle: A comparative analysis of efficacy, animal health, productivity, cost, and resistance management

This study compared selective control versus strategic control against Rhipicephalus (Boophilus) microplus, under conditions of a real dairy farm. Strategic control requires that all animals be treated with acaricide at regular pre-determined intervals. Selective control only requires treatment of infested animals and only when they are at or above a pre-determined threshold. Tick counts on animals and in pasture were performed and the susceptibility of tick populations to the different treatment methods was evaluated at the beginning and end of the study using the Larval Packet Test, Larval Immersion Test, and Adult Immersion Test. Over the four years of the study strategic control was more advantageous than the selective control as the group experienced lower tick burden on animals and in pasture, absence of skin lesions and myiases, lower operating costs, treatments concentrated in fewer months of the year and lower resistance pressure.

Extruded urea levels in lamb supplementation in rainy tropical savanna conditions: the triad host-gastrointestinal nematodes-environment

The objective of this study was to evaluate the influence of increasing levels of extruded urea (EU, Amireia®) in the diet of lambs naturally infected by gastrointestinal nematodes on the interactions in the host-pasture-soil components in edaphoclimatic conditions of the tropical rainy savanna. A total of 60 Texel lambs with a mean initial weight of 20.7 ± 0.87 and mean age of 2.5 ± 0.70 months were distributed in a completely randomized design, in five treatments consisting of different levels of EU supplementation viz., 0, 6, 12, 18, and 24 g 100 kg^-1 live weight (LW). The performance of lambs, parasitological variables, gastrointestinal nematodes (NGIs), and larvae recovery in pasture and soil were evaluated. The highest animal performance was observed in animals that received 0 to 18 g kg^-1 LW (146.0 g day^-1) and the lowest in animals supplemented with 24 g kg^-1 LW (81.0 g day^-1) of EU. The body condition score (BCS) was similar in the animals (P > 0.05). Parasitic infection did not differ as a function of EU level (P > 0.05). Eggs of Haemonchus spp., Trichostrongylus spp., Cooperia spp., and Oesophagostomum spp. were found. The largest amount of larvae in the L1/L2 and L3 stages was recovered in the pastures occupied by the animals that received supplementation 0 g kg^-1 LW of EU (750 larvae), the smallest in those that the animals received 6 g 100 kg^-1 LW of EU (54 larvae). The presence of larvae in the L1/L2 stages changed significantly (P < 0.05) in the soil; in the other stages, it did not differ in the soil. Increasing levels of extruded urea do not influence the eggs per gram of feces (EPG) count. The 0 to 18 g 100 kg^-1 LW level maintains animal performance, BCS and FAMACHA^©. There is less dispersal of NGI larvae in pasture and soil when EU levels increase in the edaphoclimatic conditions of the rainy tropical savannah, which suggests that this supplement can be implemented in the diet of beef lambs, in addition to to be a lower cost nitrogen source.

Practical guide to the diagnostics of ruminant gastrointestinal nematodes, liver fluke and lungworm infection: interpretation and usability of results

The diagnostics of ruminant parasites remains one of the cornerstones for parasite control best practices. Field veterinarians have several techniques at their disposal (fecal egg count, coproculture, FAMACHA®, plasma pepsinogen, ELISA-Ostertagia, ELISA-Fasciola, Baermann and ELISA-Lungworm) for the identification and/or quantification of gastrointestinal nematodes, lungworms and liver fluke infecting small ruminants and cattle. Each of these diagnostic tools has its own strengths and weaknesses and is more appropriate for a specific production operation and/or age of the animal (young and adults). This review focuses on the usability and interpretation of the results of these diagnostic tools. The most advanced technical information on sampling, storage, advantages and limitations of each tool for different types of production operations and animal categories is provided.

Efficacy of oral fluralaner (Bravecto) against Tunga penetrans in dogs: A negative control, randomized field study in an endemic community in Brazil

The sand flea Tunga penetrans is one of the zoonotic agents of tungiasis, a parasitic skin disease of humans and animals. The dog is one of its main reservoirs. This negatively controlled, randomized, double-masked clinical trial evaluated the therapeutic and residual efficacy of fluralaner for treatment of dogs naturally infested with T. penetrans. Sixty-two dogs from an endemically affected community in Brazil were randomly assigned to either receive oral fluralaner (Bravecto chewable tablets) at a dose of 25 to 56 mg fluralaner/kg body weight, or no treatment (31 dogs per group). Dogs were clinically examined using a severity score for acute canine tungiasis (SCADT), parasitological examinations as defined by the Fortaleza classification, and pictures of lesions on days 0 (inclusion and treatment), 7 ± 2, 14 ± 2, 21 ± 2, 28 ± 2, 60 ± 7, 90 ± 7, 120 ± 7 and 150 ± 7. The percentage of parasite-free dogs after treatment was >90% between days 14 and 90 post-treatment with 100% efficacy on study days 21, 28 and 60. Sand flea counts on fluralaner treated dogs were significantly lower (p<0.025) than control dogs on all counts from day 7 to 120. The number of live sand fleas on treated dogs was reduced by > 90% on day 7, > 95% on days 14 and 90, and 100% from day 21 to 60, and with a significant difference between groups from day 7 to 120. From day 7 to day 120, mean SCADT scores were significantly reduced in treated dogs with a mean of 0.10 compared to 1.54 on day 120 in untreated dogs. Therefore, a single oral fluralaner administration is effective for treating and achieving long lasting (> 12 weeks) prevention for tungiasis in dogs.

Tungiasis is a dermatological disease that affects humans and animals infested with sand fleas (Tunga spp.), especially in communities exposed to contaminated sandy and dry soil, where living conditions are precarious and access to basic health is limited. These sand fleas penetrate host skin and cause severe acute and chronic injuries that can dramatically compromise the host’s health. Dogs are a primary reservoir and disseminator of these fleas in South America. In this clinical field trial, the efficacy of a single oral dose of fluralaner (Bravecto chewable tablets) was evaluated for treatment and prevention of tungiasis in dogs in an endemic area of Brazil. The treatment was assessed through absence of live sand fleas and resolution of characteristic tungiasis skin lesions. Fluralaner was 100% effective from the third to the eighth week post-treatment, eliminated live sand fleas and protected against new infestations during the study. Therefore, fluralaner proved to be an excellent therapeutic option for treatment and a highly effective control option for canine tungiasis.

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.

Poisoning of calves reared with cows treated with abamectin

The aim of the present study was to describe an outbreak of poisoning by abamectin in calves less than four months of age whose mothers were treated with a pour-on product containing this ingredient. The diagnosis was based on the history, clinical signs, absence of macroscopic and histopathological findings (characteristic of this type of poisoning) and the detection of abamectin in tissues of the animals submitted to necropsy. Based on this report, the recommendation is the use with caution of pour-on formulations containing abamectin on cows having given birth less than four months earlier.

Effects of supplementation on production and age anticipation at first mating of ewe lambs in tropical pastures

Studies on the rearing of ewe lambs in the Cerrado are scarce, so the objective was to evaluate the effects of protein-energy supplementation with 1.6 and 2.4% BW on the productive and reproductive performance of ewe lambs raised on pastures of Brachiaria brizantha cv. Marandu. Twenty-four Texel ewe lambs, with a mean age of 5 months, were distributed in two treatments with provision of energy protein supplementation at levels of 1.6 and 2.4% BW, formulated for average daily gains of 150 and 200 g/day for ewe lambs weighing 20 kg, respectively. The experimental delineation adopted was the completely randomized design, with fifteen repetitions per treatment. The performance of the ewe lambs was evaluated by weight at the beginning and end of the breeding season (BS), average daily gain (ADG), and total weight gain (TWG). The count of fecal eggs was performed monthly. The evaluation of the ewe lambs reproductive organs took place at 8 months of age. The fertility of the ewe lambs was detected by transrectal ultrasonography at the end of the BS. The supplementation level of 2.4% BW was higher for ADG and TWG; however, it did not influence the other performance characteristics. There was no effect of supplementation on the reproductive characteristics, parasite load, and nutrients of the pasture. Pasture nutrients were influenced by the month of use. Supplementation levels were not effective to ensure the reproductive success of 8-month-old ewe lambs.

Gastrointestinal nematode control programs in yearling Nellore heifers: Analysis of fecal egg counts, weight gain and reproductive indices

The objective of this study was to evaluate two different gastrointestinal nematode treatment regimens. Fecal egg counts (FECs), proportion of nematode genera, weight gain, body condition score and reproductive indices (estrous cyclicity, conception and pregnancy rates) were evaluated in yearling heifers after imposing two treatment regimens for gastrointestinal nematodes: T1 = 306 calves treated in May and November with 3.5 % doramectin (700 μg/kg) and August (Aug) with saline solution; and T2 = 307 calves treated in May with 3.5 % doramectin (700 μg/kg), in August with 1% moxidectin (200 μg/kg) and in November with 3.5 % doramectin (700 μg/kg). The animals were weighed, and feces were collected for conducting FECs and coproculture. There was imposing of three fixed-time artificial inseminations (TAIs), and estrous cyclic and pregnancy statuses were determined. Cooperia was the most frequent genus detected in both groups. Heifers of the T2, as compared to those in the T1 group, had fewer FECs in November (P ≤  0.05) and greater weight gain and average daily weight gain (P ≤  0.05) from August to November. There tended to be more heifers of the T2 than T1 group estrous cycling (P =  0.07) at the beginning of the breeding season as well as greater pregnancy rates (P =  0.03) and conception rates (P =  0.03) as a result of the second FTAI. The results indicate there is greater reproduction outcomes as a result of strategic control of gastrointestinal nematodes in yearling Nellore heifers using the T1 as compared with T2 treatment regimen.

Status of Rhipicephalus microplus resistance to ivermectin, fipronil and fluazuron in Mato Grosso do Sul, Brazil

Southern cattle tick resistance to pour-on and injectable acaricides has yet to be evaluated on a broader scope, and the paucity of information on the subject may hinder efforts to control this parasite. The objective of this study was to evaluate the resistance profile of ten populations of Rhipicephalus microplus to the acaricides fluazuron, fipronil and ivermectin in cattle herds in Mato Grosso do Sul, Brazil. The larval immersion test (LIT) was used to evaluate susceptibility to ivermectin and fipronil and the adult immersion test (AIT) was performed to evaluate fluazuron. Samples were randomly obtained in ten farms, and in general, we found resistance in five samples to fluazuron and in four samples to ivermectin and fipronil. Six samples showed incipient resistance to ivermectin and fipronil. Five of the ten evaluated samples showed resistance and/or incipient resistance to all the active ingredients, and the other five to two active ingredients. Among the samples classified as resistant, the average resistance ratio for ivermectin was 2.75 and 3.26 for fipronil. These results demonstrate the advanced status of resistance to the most modern chemical groups for the control of R. microplus in the state of Mato Grosso do Sul.

First report of Dermatobia hominis resistant to doramectin in cattle

The objective of this study was to evaluate the therapeutic efficacy of 1 % injectable doramectin to control Dermatobia hominis in naturally infested beef cattle in a farm with history of clinical parasitism after avermectin use. The study was conducted in a commercial beef cattle farm in Brazil. Twenty crossbred cattle (Nellore x Angus) were selected based on the minimum number of 10 live larvae. Assessment of infestation was performed based on tactile-visual inspection of the entire body of the animals. The animals were allocated to two experimental groups of ten animals each: treated group - dosed with doramectin 200 μg/kg live weight (LW), and control group - dosed with saline solution 1 mL/50 kg LW. Both treatments were administered subcutaneously in a single dose. After treatment, larval counts were performed at 1, 3, 7 and 14 days post-treatment (DPT). For the treatment to be considered efficient, it should reach an efficacy greater than or equal to 90 % by the 10th DPT and the average larval count in the treated animals should be statistically lower than the average larval count in the control group. The geometric means of larval counts at the beginning of the study were 27.2 and 26.3 for the control and treated groups, respectively. After 72 h of treatment, there was a significant reduction (p < 0.01) in the larvae counts of the treated group, extending to the 14th DPT, at which point maximum efficacy for doramectin (86.3 %) was obtained. After treatment, 90 % of the animals remained parasitized with live larvae on the 7th DPT and 70 % on the 14th DPT, while in the control group, all animals were infested on all dates. The administration of injectable doramectin was not effective in controlling D. hominis in naturally infested cattle.

The effect of Brachiaria brizantha cultivars on host-parasite-environment interactions in sheep naturally infected with gastrointestinal nematodes

The objective was to evaluate the effect of different cultivars of Brachiaria brizantha on the dynamics and concentration of the larval stages of gastrointestinal nematodes in the soil and forage strata, as well as their effects on the performance of naturally infected lambs. Overall, 48 90-day-old lambs with an initial weight of 19.04 ± 0.96 kg were observed. Moreover, a randomised block factorial design with four cultivars of Brachiaria brizantha (Marandu, Xaraés, Piatã and Paiaguás grasses) under intermittent stocking (with a pre-grazing canopy height of 40 cm and post-grazing canopy height of 20 cm) for two grazing cycles was used. The following variables were analysed: faecal egg counting, faecal culture, mean corpuscular volume, FAMACHA^© score, weight and body condition score, the recovery of larvae from pasture and soil samples, nutritional value and the production and structural components of forage. Lambs grazing Marandu grass demonstrated the highest level of nematode infection (P < 0.05). However, the nutritional value did not differ between cultivars. Marandu grass had the highest pasture density (P < 0.05), while Paiaguás grass had the highest percentage of dead material (P < 0.05). The various genera of gastrointestinal nematodes found in the faecal cultures, regardless of the cultivars, include Haemonchus (92.01%), Trichostrongylus (4.55%), Strongyloides (3.06%) and Oesophagostomum (0.37%). Lambs grazing Xaraés grass had the lowest body weight (P < 0.05). Furthermore, larvae concentrations were highest in Marandu and Paiaguás pastures; infective Haemonchus and Trichostrongylus larvae were recovered from pasture and soil samples. The different cultivars of Brachiaria brizantha produce diverse and relevant microclimatic conditions to contaminate soil, pastures and animals. Animal performance was not compromised despite the Marandu and Paiaguás cultivars having the highest levels of contamination and infection. Based on parasitological aspects, the Brachiaria brizantha cultivars Xaraés and Piatã are recommended for grass-based sheep production systems over the other cultivars since they contribute to the reduction of larval contamination and infection.

Clinical safety of lauric acid for cattle and its in vitro and in vivo efficacy against Rhipicephalus microplus

The aim of the present study was to test the in vitro acaricidal activity of saturated fatty acids (hexanoic, octanoic, decanoic, lauric, myristic, palmitic, octadecanoic, eicosanoic, docosanoic and tetracosanoic) against Rhipicephalus microplus and select a candidate compound for the subsequent determination of its clinical safety for mice and bovines as well as its in vivo efficacy (ethical clearance number 507/2013). None of the compounds exhibited in vitro larvicidal effectiveness, but acaricidal effectiveness was greater than 95 % in the adult immersion test at 40 mg/ml (hexanoic, octanoic, decanoic, lauric, myristic, palmitic and eicosanoic acids). After a second AIT evaluation of serial concentrations of the fatty acids, lauric and myristic acids were selected for the safety and in vivo efficacy assays. No adverse effect was found in the local lymph node assay in mice treated with lauric or myristic acid. Moreover, no clinical signs of systemic poisoning or dermatological, hematological or biochemical abnormalities were found in cattle after the topical application of 1 % lauric acid. In the dose determination test, the 1% solution of this compound exhibited 86% efficacy in cattle naturally infested by a field population of Rhipicephalus microplus susceptible to all chemical groups, except synthetic pyrethroids. The efficacy of 1 % lauric acid was 53.4 % in the dose confirmation test performed on another herd with a field R. microplus population resistant to all chemical groups of acaricides. In conclusion, fatty acids are potential bioactive compounds for the control of R. microplus. Topically applied lauric acid (C12) exhibits in vivo acaricide activity against adults, nymphs and larvae of R. (B) microplus and is safe for cattle.

Combination of quercetin and ivermectin: In vitro and in vivo effects against Haemonchus contortus

The aim of the present study was to evaluate the in vitro effect of quercetin combined with ivermectin (IVM) on Haemonchus contortus larvae and adults with different resistance profiles and demonstrate the in vivo anthelmintic action of this combination when used in sheep naturally infected. The effect of combination was evaluated based on the analysis of the mean effective concentration (EC50) obtained for larvae using the larval migration inhibition test and for adults using the motility test on females. The tests with larvae and adults were conducted using isolates with different degrees of susceptibility to IVM (sensitive, intermediate and highly resistant). The in vivo effect was evaluated based on the reduction in the egg count (FEC) and reduction in the count of adult helminths recovered after parasitological necropsy. Using the combination of quercetin with IVM, it was observed that in larvae, quercetin did not significantly reduce the EC50 for IVM in the sensitive and highly resistant isolates, but led to a significant reduction in the EC50 for IVM in the intermediate isolate. In adults, quercetin did not significantly reduce the EC50 for IVM in any of the isolates. No significant effect of the combination was found regarding the reduction in FEC or total count of parasites. The results of the in vitro and in vivo tests performed in the present study on quercetin activity underscore the importance of evaluating resistance-reversing agents among different stages of parasite development as well as among isolates with different resistance profiles. The action of quercetin combined with IVM on the motility of H. contortus larvae and adults was influenced by the degree of resistance and development stage of the parasite. The combination was effective only on intermediate resistant larvae. No action of the combination against adults was found. Moreover, this combination, when administered through the intra-abomasal route, was not effective at reducing the FEC and parasite load of naturally infected sheep.

Clinical and therapeutic aspects of an outbreak of canine trypanosomiasis

Trypanosomiasis caused by Trypanosoma evansi can seriously affect both domestic and wild animals. This article reports on an outbreak of canine trypanosomiasis on a farm in the Pantanal region of Brazil. The farm had 38 dogs, 20 of which died before receiving veterinary care. The remaining 18 dogs were underwent anamnesisn, clinical examination, hematological and biochemical evaluations. Blood smears and PCR analysis were performed for the diagnosis. The treatment protocols used according to the clinical recovery or parasitological cure of the dogs, using diminazene diaceturate, isometamidium chloride or quinapyramine sulfate. Post-treatment parasitological evaluation was performed by the microhematocrit technique. 7/18 dogs were PCR positive for T. evansi (confirmed by sequencing). There was clinical findings, which were consistent with both the acute and chronic stages of the disease in dogs. The infected dogs all exhibited at least one clinical sign of the disease. The hematological findings were compatible with trypanosomiasis, highlighting the hypochromic microcytic anemia as the main outcome. No treatment protocol was fully effective and the prolonged use of diminazene diaceturate caused the death of an animal. The trypanosomiasis can cause high rates of morbidity and mortality in dogs and difficulty in establishment an effective and safe therapeutic protocol.

Discovery of potential ovicidal natural products using metabolomics

Plant extracts are a potential source of new compounds for nematode control and may be an excellent alternative for the control gastrointestinal nematodes that are resistant to conventional anthelmintics. However, research involving natural products is a complex process. The main challenge is the identification of bioactive compounds. Online analytical techniques with universal detectors, such as high-performance liquid chromatography-mass spectrometry (HPLC-MS), together with metabolomics could enable the fast, accurate evaluation of a massive amount of data, constituting a viable option for the identification of active compounds in plant extracts. This study focused on the evaluation of the ovicidal activity of ethanol extracts from 17 plants collected from the Pantanal wetland in the state of Mato Grosso do Sul, Brazil, against eggs of Haemonchus placei using the egg hatchability test. The ethanol extracts were obtained using accelerated solvent extraction. The data on ovicidal activity, mass spectrometry and metabolomics were evaluated using HPLC-DAD-MS, partial least squares regression analysis (PLS-DA) and a correlation map (univariate correlation analyses) to detect compounds that have a positive correlation with biological activity. Among the ten metabolites with the best correlation coefficients, six were phenylpropanoids, two were triterpene saponins, one was a brevipolide, and one was a flavonoid. Combinations of metabolites with high ovicidal action were also identified, such as phenylpropanoids combined with the triterpene saponins and the flavonoid, flavonoids combined with iridoid and phenylpropanoids, and saponins combined with phenylpropanoid. The positive correlation between classes of compounds in plants belonging to different genera and biological activity (as previously identified in the literature) reinforces the robustness of the statistical data and demonstrates the efficacy of this method for the selection of bioactive compounds without the need for isolation and reevaluation. The proposed method also enables the determination of synergism among the classes, which would be impracticable using traditional methods. The present investigation demonstrates that the metabolomic technique was efficient at detecting secondary metabolites with ovicidal activity against H. placei. Thus, the use of metabolomics can be a tool to accelerate and simplify bioprospecting research with plant extracts in veterinary parasitology.

Molecular marker sequences of cattle Cooperia species identify Cooperia spatulata as a morphotype of Cooperia punctata

The genus Cooperia includes important parasites of ruminants and currently contains 34 accepted species. However, even for those species infecting livestock, there is a considerable lack of molecular information and many species are only identifiable using subtle morphological traits. The present study aimed to provide molecular data to allow diagnosis of Cooperia species infecting cattle. Partial sequences of two mitochondrial (cytochrome oxidase 2, 12S rRNA gene) and two nuclear genes (isotype 1 β tubulin gene including two introns, internal transcribed spacers (ITS) were obtained from morphologically identified specimens of Cooperia pectinata, Cooperia punctata and Cooperia spatulata as well as from larvae of pure Cooperia oncophora and C. punctata laboratory isolates. Pairwise identity of ITS-2 sequences was very high and it was the only region able to identify a specimen as Cooperia sp. However, the ITS-2 was unreliable for diagnosis at the species level. All other marker sequences could not unequivocally be allocated to the genus Cooperia but allowed clear species identification with the exception of the pair C. punctata/C. spatulata for which no significant differences were found for any marker sequence. Maximum-likelihood phylogenetic analyses of individual genes as well as a multi-locus analysis covering all four sequences confirmed that specimen identified as C. spatulata were randomly distributed throughout the C. punctata cluster and formed no group of their own. In contrast, the other Cooperia species formed clearly separated and statistically supported clusters. These data indicate that C. spatulata is most likely only a morphotype of C. punctata and the name should be considered a synonym. Combinations of nuclear and mitochondrial markers should be used to identify morphotypes or cryptic species to benefit from excellent barcoding properties of the latter but allowing proper phylogenetic analyses and controlling for lineage sorting that might occur for mitochondrial genotypes within a species.

Eimeria species in dairy and beef cattle of different ages in Goiás state, Brazil

Abstract This study aimed to identify the frequency of occurrence of Eimeria species in Holstein (taurine dairy cattle) and Nelore (zebu beef cattle) on 12 farms in the state of Goiás, Brazil. A total of 2,601 animals were evaluated, and the cattle were divided into the following age-group categories: up to three months old, four to eight months old, nine to 16 months old and cows. Fecal samples were collected directly from the rectum of all animals. None of the cattle presented any clinical signs of eimeriosis during the survey. From the results obtained, it could be concluded that higher rates of infection by Eimeria spp. were observed in Holstein cattle between the 1st and 16 th months of age and in Nelore cattle between the 1st and 8th months of age. Twelve and nine Eimeria species were diagnosed in Holstein and Nelore cattle, respectively. However, Eimeria zuernii was more prevalent in animals up to three months old, while Eimeria bovis was more common in the remaining categories (cattle aged four months and over). Future studies on the epidemiology and/or seasonality of infection by Eimeria species in cattle, from birth onwards, are needed in order to better understand the dynamics of E. zuernii and E. bovis occurrences, especially in cattle under three months of age.

EPIDEMIOLOGIA DE HELMINTOS GASTRINTESTINAIS EM BÚFALOS

Resumo Este trabalho objetivou avaliar a prevalência e a sazonalidade da infecção natural por parasitos gastrintestinais em bubalinos de aptidão leiteira de diferentes categorias, no município de Bandeirantes, Mato Grosso do Sul. Foram avaliados 41 búfalos da raça Murrah, divididos em três categorias, sendo 11 lactentes, com idade de 0 a 8 meses, 10 desmamados, de 8 a 18 meses, e 20 fêmeas adultas com idade superior a 18 meses. Os animais adultos apresentaram-se livres de parasitismo ou com carga parasitária muito baixa. A categoria lactente apresentou pico de contagem de ovos por grama de fezes (OPG=2038) em novembro, quando a precipitação acumulada foi de 69,3 mm e a temperatura 25,95 ºC, enquanto a menor contagem de ovos (167) ocorreu em maio, dois meses após pico de 234,68 mm e 20,59 ºC. Os búfalos desmamados apresentaram dois picos de OPG, de 1288 e 875, em setembro e junho, com precipitação de 41,45 e 18,4 mm e temperatura de 24,16 e 20,69 ºC, respectivamente. Foi observada correlação significativa (p=0,01) e negativa (r=-0,33) entre o OPG dos bezerros lactentes e precipitação pluviométrica. Os parasitos gastrintestinais mais frequentes foram Haemonchus sp. e Cooperia sp.

Avaliação da eficácia da lasalocida e de alguns fatores epidemiológicos de Eimeria spp. parasitando bezerros Nelore mantidos em regime de pastejo

RESUMO: A principal importância da eimeriose em bovinos, se deve ao baixo desempenho produtivo que os animais demonstram quando esta enfermidade apresenta-se sob a forma sub-clínica. Como objetivos, o presente trabalho avaliou a eficácia do uso da lasalocida sódica contra espécies de Eimeria spp. parasitando bezerros; avaliou também o desempenho ponderal dos animais submetidos aos diferentes tratamentos e analisou alguns fatores epidemiológicos que possam interferir na infecção por Eimeria nos bezerros. Foram utilizados 288 bezerros no dia 0 do estudo. Os animais pertencentes ao tratamento 01 receberam sal mineral proteinado de baixo consumo sem adição de lasalocida, enquanto que os bezerros do Tratamento 02 sal mineral proteinado de baixo consumo, com adição de lasalocida sódica, administrado via oral para bezerros dos quatro/cinco/seis meses até dez meses de idade. Colheita de fezes e pesagem dos animais foram realizadas nos dias 0 (antes do início do experimento), na desmama, 30 e 60 dias após desmama (DPD). A avaliação de alguns fatores epidemiológicos que pudessem ser relacionados com a infecção por Eimeria spp nos bezerros, como o desmame, sexo e época do ano, foram analisados neste estudo, levando-se em consideração os resultados encontrados durante todo estudo, para os 144 animais pertencentes ao grupo controle. Foram identificadas nove espécies de Eimeria nos bezerros em ordem decrescente: E. brasiliensis, E. wyomingensis, E. bovis, E. canadenses, E. zuernii, E. auburnensis, E. ellipsoidalis, E. pellita e E. cylindrica. Inesperadamente, diminuição na carga parasitária dos animais pode ser observada após o desmame. Mesmo a fazenda não adotando medidas de manejo que visam maior produtividade como a Inseminação Artificial em Tempo Fixo, que por sua vez acaba aumentando o número de nascimentos e unidade animal/hectare em uma determinada época do ano, elevado parasitismo pelo coccídio em questão foi diagnosticado nos bezerros pertencentes ao grupo controle. Talvez a época do ano em que o estudo foi realizado pode ter influenciado neste aspecto. As contagens de oocistos por grama (OoPG) de fezes para Eimeria dos animais tratados com lasalocida foram estatisticamente inferiores (P≤ 0,05) as do grupo controle após o início do estudo. O composto alcançou eficácia ≥ 95% contra o parasito em questão. No final do estudo, os animais que receberam lasalocida ganharam em média, 7,2kg a mais (P≤ 0,05) que os bezerros pertencentes ao grupo controle. Em propriedades que tem como objetivo a venda de bezerros logo após a desmama, recomenda-se o início do tratamento com a lasalocida, junto ao creep-feeding, a partir de três messes de idade, uma vez que diferencial no ganho em peso médio dos bezerros tratados foi significativamente (P≤ 0,05) mais elevado, em comparação ao grupo controle, após cinco meses de tratamento com o referido composto. Apesar de a lasalocida ser utilizada como um aditivo alimentar para animais, a diferença no ganho em peso vivo médio entre animais tratados com a lasalocida, em comparação a animais pertencentes ao grupo controle, também pode ser relacionada, em partes, a infecção dos animais por Eimeria spp., conforme discutido neste artigo, entretanto, futuros estudos devem ser conduzidos para comprovar esta hipótese.

Molecular characterization of Leishmania infantum in domestic cats in a region of Brazil endemic for human and canine visceral leishmaniasis

Leishmaniasis is a "neglected tropical disease" and serious public health issue in Brazil. While dogs are recognized as particularly important reservoirs, recent reports of domestic cats infected with Leishmania sp. in urban areas suggest their participation in the epidemiological chain of the parasite in endemic areas. The aim of this study was to screen domestic cats for Leishmania sp. infection in an area where human and canine visceral leishmaniasis are endemic, followed by the identification of the species circulating in cats. We collected peripheral blood, lymph-node aspirates and bone marrow from 100 adult animals, both male and female, and analyzed the samples using cytological and molecular (PCR) detection techniques. We detected Leishmania in 6% of animals, which were then analyzed by RFLP-PCR to identify the species. Leishmania infantum (synonym: L. chagasi), a species responsible for visceral leishmaniasis in humans and other animals, was identified from all six samples. Amastigotes were observed in the peripheral blood, bone marrow and lymph-node aspirates in 4 of the 6 PCR-positive animals. The presence of infected cats in endemic areas should not be neglected, because it demonstrates the potential role of these animals in the biological cycle of the pathogen.

First genetic identification of Cryptosporidium parvum subtype IIaA14G2R1in beef cattle in Brazil

The presence of Cryptosporidium spp. in a cattle herd registered with an outbreak of diarrhea was investigated and the the molecular subtyping of Cryptosporidium parvum was characterized. Fecal samples from 85 Nellore beef cattle (Bos indicus) were collected and examined with Ziehl-Neelsen modified staining method. Fifty-four cattle (63.52%) had Cryptosporidium spp. oocysts in their feces. Fragments of genes encoding the 18S ribosomal RNA subunit and a 60-kDa glycoprotein (gp60) were amplified by nested PCR accomplished in the 11 most heavily parasitized samples, and the amplicons were sequenced. Eight of the 11 analyzed samples were positive for 18S rRNA sequences and identified monospecific infections with C. parvum. Seven samples were positive for gp60 and identified subtypes IIaA15G2R1 (6/11) and IIaA14G2R1 (1/11). This report is the first for C. parvum subtype IIaA14G2R1 in beef cattle in Brazil.

Efficacy of extracts from plants of the Brazilian Pantanal against Rhipicephalus (Boophilus)microplus

This research evaluated the in vitro acaricidal activity of extracts from 21 plant species from the Pantanal of Mato Grosso do Sul. During stage I, a larval immersion test was performed using three extract concentrations (5%, 20%, and 40%). During stage II, we used only plants that showed over 95% efficiency at the 40% concentration in stage I in an amount sufficient for the adult immersion test. Aeschynomene denticulata, Angelonia hirta, Aspilia latissima, Caperonia castaneifolia, Centratherum punctatum, Crotalaria micans, Diodia kuntzei, Echinodorus paniculatus, Hyptis mutabilis, Lantana canescens, Melanthera latifolia, Ocotea diospyrifolia, Richardia grandiflora, Sebastiana hispida, Tocoyena formosa, Zanthoxylum rigidum, and Sesbania virgata (fruit extract) showed acaricidal activity against the larval stage ofRhipicephalus (Boophilus)microplus higher than 95% at a 40% (w/v) concentration, while Hippocratea volubilis and Randia armatashowed moderate efficacy and Croton glandulosus andSenna obtusifolia had no effect. The M. latifolia, A. hirta, R. grandiflora, and A. latissima raw extracts were evaluated for their activity against adults, and only A. hirta showed an efficacy close to 90%. Eighteen extracts had an efficacy of up to 95% against larvae at a 40% concentration, seven extracts were effective at 20%, and only one (Sebastiana hispida) was effective at a 5% concentration.