RESUMEN
Four trials, three in the United States and one in South Africa, were conducted to evaluate the potential value of a novel self-medicating applicator in the passive control of gastrointestinal nematodes in cattle and deer, and of files and ticks on cattle using oil-based treatments. The results of the trials demonstrated that this applicator is an effective and practical device for the passive treatment of both deer and cattle for trichostrongyle infections using the endectocide, moxidectin (Cydectin. Fort Dodge Animal Health, USA), of cattle for hom fly (Haemotobia irritans) infestations using the insecticide, cyfluthrin (CyLence, Bayer AG, Germany) and of cattle for tick infestations (in particular Amblyomma hebraeum and Rhipicephalus appendiculatus) using the acaricides deltamethrin and amitraz (Delete All, Intervet, South Africa).
Asunto(s)
Animales Domésticos/parasitología , Animales Salvajes/parasitología , Antihelmínticos/administración & dosificación , Infestaciones Ectoparasitarias/veterinaria , Insecticidas/administración & dosificación , Parasitosis Intestinales/veterinaria , Administración Tópica , Animales , Bovinos , Ciervos , Combinación de Medicamentos , Infestaciones Ectoparasitarias/tratamiento farmacológico , Infestaciones Ectoparasitarias/prevención & control , Femenino , Parasitosis Intestinales/tratamiento farmacológico , Parasitosis Intestinales/prevención & control , Macrólidos/administración & dosificación , Masculino , Infecciones por Nematodos/tratamiento farmacológico , Infecciones por Nematodos/prevención & control , Infecciones por Nematodos/veterinaria , Nitrilos , Sinergistas de Plaguicidas/administración & dosificación , Butóxido de Piperonilo/administración & dosificación , Piretrinas/administración & dosificación , Distribución Aleatoria , Control de Ácaros y Garrapatas/métodos , Infestaciones por Garrapatas/tratamiento farmacológico , Infestaciones por Garrapatas/prevención & control , Infestaciones por Garrapatas/veterinaria , Toluidinas/administración & dosificaciónRESUMEN
The efficacy of an injectable microsphere formulation of ivermectin for control of the cattle tick, Boophilus annulatus (Say), was tested on 2 groups of 6 Hereford heifers held on separate 7-ha, tick-infested, buffel grass pastures. Cattle in one pasture were injected subcutaneously in the neck with a controlled-release microsphere formulation of ivermectin at the rate of 2.4 mg AI/kg body weight; the other group was injected with carrier only. Beginning 4 wk after injection and continuing throughout the remainder of the test (16 wk), no engorged ticks (> or = 5.5 mm) were found on any of the treated cattle, whereas large numbers of engorged ticks were found on the untreated controls. During this period, a few ticks were recovered from untreated sentinel animals placed in the treatment pasture during 7-8 wk after treatment, but none were recovered from animals exposed from 11-12 wk or 14-15 wk. Large numbers of B. annulatus ticks were found on untreated sentinel cattle placed in the control pasture during these same periods. Although the cattle, pastures, and tick habitat were approximately equal, the treated cattle gained an average of 77 kg compared with an average of 42 kg for the control group. This technology offers a possible alternative to the current official program of dipping and vacating pastures for eradication of Boophilus sp. infestations from the quarantine zone in southern Texas. Larger scale testing is needed to determine the potential of the injectable microsphere formulation and to optimize its use in eradication or control strategies.
Asunto(s)
Enfermedades de los Bovinos/tratamiento farmacológico , Enfermedades de los Bovinos/parasitología , Insecticidas/uso terapéutico , Ivermectina/uso terapéutico , Control de Ácaros y Garrapatas/métodos , Infestaciones por Garrapatas/veterinaria , Análisis de Varianza , Animales , Bovinos , Enfermedades de los Bovinos/sangre , Conducta Alimentaria , Femenino , Interacciones Huésped-Parásitos , Inyecciones Subcutáneas , Ivermectina/sangre , Microesferas , Infestaciones por Garrapatas/parasitología , Garrapatas/fisiologíaRESUMEN
Cattle infested with all parasitic life-stages of Boophilus microplus (Canestrini) were treated once with a pour-on formulation of fipronil at 0.25, 0.5, or 1.0% active ingredient (AI) to determine the therapeutic efficacy. Additionally, cattle were infested at weekly intervals for 13 consecutive weeks after treatment to determine the persistent effectiveness of the three concentrations. Results of therapeutic efficacy of fipronil showed that with each increase in concentration there was a corresponding and often significant (P < 0.05) decrease in the numbers, fecundity and fertility of engorged females. The overall control of the Index of Reproduction (IR) achieved at 0.25 and 0.5% AI was 86.2 and 94.3%, respectively, while the control of the IR at the 1.0% AI concentration was 99.7%. The persistent efficacy of fipronil, like the therapeutic efficacy, was also dose related. The 0.25% AI treatment failed to provide complete protection (100%) against larval reinfestation, although control of the IR remained high (> 95%) for the first 6 weeks after treatment. In contrast, at 0.5% AI the control of the IR remained at 100% for the first 4 weeks after treatment, and was > 90% for an additional 2 weeks (6 weeks posttreatment). The 1.0% AI concentration afforded the longest residual activity, providing virtually 100% protection against larval reinfestation for 8 weeks after treatment was applied. Based on the results, neither the 0.25 or 0.5% AI concentration completely eliminated the immature stages of the tick (nymphs and larvae) on the host at the time of treatment (therapeutic efficacy), and the residual activity (persistent efficacy) did not prevent reinfestation by larvae for long periods after treatment. While the 1.0% AI concentration provided both therapeutic and residual efficacy that would be suitable for use in the eradication program, caution is still warranted because a few engorged females detached for up to 25 days after treatment, although none reproduced after the 6th day.
Asunto(s)
Antiparasitarios/uso terapéutico , Enfermedades de los Bovinos/tratamiento farmacológico , Pirazoles/uso terapéutico , Infestaciones por Garrapatas/veterinaria , Garrapatas/efectos de los fármacos , Administración Tópica , Análisis de Varianza , Animales , Antiparasitarios/administración & dosificación , Antiparasitarios/farmacología , Bovinos , Enfermedades de los Bovinos/prevención & control , Femenino , Recuento de Huevos de Parásitos/veterinaria , Pirazoles/administración & dosificación , Pirazoles/farmacología , Distribución Aleatoria , Texas , Infestaciones por Garrapatas/tratamiento farmacológico , Infestaciones por Garrapatas/prevención & control , Garrapatas/fisiologíaRESUMEN
Four groups of cattle infested with Boophilus microplus (Canestrini) were each dipped in a different concentration of amitraz diluted from a 12.5% EC formulation to determine the efficacy and performance of the product in an 11,400 l dipping vat. Except for the period when heifers were dipped, animals were restrained in stanchions placed individually inside 3.3 x 3.3 m2 stalls within an open-sided barn. The amitraz in the vat was stabilized with hydrated lime to maintain a pH of ca. 12. Analyses of vat samples showed that concentrations of amitraz in the vat were 7.6 to 13% lower than the targeted concentrations of 0.010, 0.015, 0.020, and 0.025% active ingredient (AI) for dilutions prepared according to instructions on the manufacturer's label. The large quantity of hydrated lime added to the vat (10 kg/1000 l) interfered with the HPLC analysis of vat samples. Therapeutic efficacy of each of the four observed concentrations (0.0088, 0.0131, 0.0174, and 0.0231% AI) of amitraz was excellent (> 99% control). However, the rapid detachment of all ticks from an animal within a few hours after treatment with amitraz, that has been frequently observed, was not pronounced in the present study. Only 47% of the B. microplus detached in the first 4 h post-treatment, and 84% detached within the first 24 h. All of the treatments, except the lowest concentration, provided protection of cattle against re-infestation by B. microplus larvae for 14 days post-treatment. Possibly as a result of the formation of a compact layer of lime and amitraz on the bottom after the vat was undisturbed for six weeks, intense agitation was required to re-suspend the active ingredient.
Asunto(s)
Enfermedades de los Bovinos/tratamiento farmacológico , Insecticidas/uso terapéutico , Infestaciones por Garrapatas/veterinaria , Toluidinas/uso terapéutico , Animales , Bovinos , Relación Dosis-Respuesta a Droga , Femenino , Insecticidas/administración & dosificación , Infestaciones por Garrapatas/tratamiento farmacológico , Garrapatas/efectos de los fármacos , Toluidinas/administración & dosificaciónAsunto(s)
Academias e Institutos , Medicina Clínica , Investigación/tendencias , Medicina Clínica/clasificación , Educación Médica/tendencias , Humanos , National Institutes of Health (U.S.) , Investigación/economía , Investigación/estadística & datos numéricos , Apoyo a la Investigación como Asunto/economía , Apoyo a la Investigación como Asunto/tendencias , Estados UnidosRESUMEN
A study was conducted to determine the efficacy of cyhalothrin and lambdacyhalothrin as a whole-body spray and lambdacyhalothrin as a pour-on application on cattle infested with Boophilus microplus (Canestrini). A laboratory bioassay was also done with both spray formulations. Cattle were infested with all parasitic life stages of B. microplus, then treated with 0.007 or 0.01% (AI) concentrations of cyhalothrin as a spray; 0.005, 0.007, or 0.01% (AI) concentrations of lambdacyhalothrin as a spray, or 1% (AI) lambdacyhalothrin as a pour-on. As determined by calculations of the index of reproduction (IR), the 0.007 and 0.01% (AI) cyhalothrin provided 92.4 and 97.3% control, respectively; the 0.005, 0.007, and 0.01% (AI) lambdacyhalothrin provided 92.4, 98.2 (average of two treatments) and 99.3% control, respectively; and the lambdacyhalothrin pour-on treatment provided < 50% control. Bioassay results indicated lambdacyhalothrin to be twice as effective as cyhalothrin against B. microplus.
Asunto(s)
Enfermedades de los Bovinos/tratamiento farmacológico , Insecticidas/uso terapéutico , Piretrinas/uso terapéutico , Infestaciones por Garrapatas/veterinaria , Animales , Bovinos , Enfermedades de los Bovinos/parasitología , Nitrilos , Infestaciones por Garrapatas/tratamiento farmacológico , Infestaciones por Garrapatas/parasitologíaRESUMEN
A study was done at the USDA-ARS, Cattle Fever Tick Research Laboratory, Mission, Tex., to determine the efficacy of a 50% wettable powder (WP) amitraz formulation applied as a whole-body spray in a standard dip vat, and in a laboratory bioassay against Boophilus annulatus (Say) on cattle. A study also was done at the King Ranch in Kleberg County, Tex., to determine the stability of 50% WP amitraz in a dip vat under South Texas conditions Cattle were infested with all parasitic life stages of B. annulatus and were sprayed or dipped with a concentration of 0.025% amitraz. As determined by calculations of the index of reproduction, the whole-body spray treatment provided 86% control of the ticks and the dip treatment provided 99.8% control. Laboratory bioassay results compared favorably with those obtained with the dip vat treatment. Amitraz WP settled very rapidly in the freshly charged ranch vat. However, as more cattle were dipped and the vat became polluted with dirt and excrement, settling occurred much more slowly. Overall, amitraz remained stable in the vat during the test period.
Asunto(s)
Enfermedades de los Bovinos/tratamiento farmacológico , Insecticidas/administración & dosificación , Infestaciones por Garrapatas/veterinaria , Toluidinas/administración & dosificación , Administración Tópica , Aerosoles , Animales , Bovinos , Texas , Infestaciones por Garrapatas/tratamiento farmacológico , GarrapatasRESUMEN
White-tailed deer (Odocoileus virginianus L.) were evaluated as an alternate host for the cattle fever tick, Boophilus annulatus (Say). The total of adult female ticks recovered and associated reproductive parameters were compared between deer and bovine hosts. Significantly fewer ticks were recovered from deer than from cattle; this was attributed to the grooming behavior of the deer. The mean weight of ticks taken from deer (243.5 mg) was significantly less than that of ticks recovered from cattle (344.5 mg) with about 15% of the ticks from deer prematurely detached. Egg mass weight from the ticks recovered from deer (129.4 mg) was significantly less than that of ticks from cattle (172.1 mg). A significant difference was observed between the percentage hatch of the eggs of ticks from deer (63.1%) and ticks from cattle (76.7%). The index of reproduction was about 20 times greater for the ticks from the cattle than for the ticks from the deer. When the larval progeny of the ticks recovered from deer were reared on cattle, significantly fewer adult females were recovered than when larvae of ticks recovered from cattle were reared on cattle. This indicates a possible reduction in viability. All other parameters were comparable between the two groups. Thus, deer are biologically suitable hosts for B. annulatus, but significantly fewer ticks complete engorgement and those that complete engorgement have reduced fecundity.
Asunto(s)
Enfermedades de los Bovinos/parasitología , Ciervos/parasitología , Infestaciones por Garrapatas/veterinaria , Garrapatas/fisiología , Animales , Bovinos , Femenino , Infestaciones por Garrapatas/parasitologíaRESUMEN
The effect of selection pressure on the cholinesterase (AChE) activity of two strains of Boophilus microplus (Canestrini) resistant to coumaphos was monitored. Total AChE and protein was determined from three generations of resistant ticks and a susceptible strain. The effect of an AChE inhibitor, coroxon (the oxygen analog of coumaphos), was also determined. The resistance of the susceptible strain (Escondido) to coumaphos remained relatively unchanged throughout the study. The Tuxpan strain lost some of its resistance to coumaphos as the generations proceeded (AChE increased instead of decreased). The Tuxtla strain became more resistant to coumaphos as the generations proceeded (AChE increased).
Asunto(s)
Acetilcolinesterasa/metabolismo , Cumafos , Insecticidas , Garrapatas/enzimología , Animales , Resistencia a los InsecticidasRESUMEN
Ovicidal activity of coumaphos, diazinon, dioxathion, chlorpyrifos, and crotoxyphos applied topically at 0.125, 0.25, and 0.5% (AI) to 1-d-old, 10-d-old, and 20-d-old eggs of southern cattle tick, Boophilus microplus (Canestrini), was determined. All acaricides produced some disruption of hatching of eggs in all age classes. Coumaphos, diazinon, dioxathion, and chlorpyrifos were most effective in reducing egg hatch of 1-d-old eggs but had little effect against 10- or 20-d-old eggs. Although crotoxyphos was comparable with other acaricides in reducing hatch in 1-d-old eggs, it caused significantly greater mortality (greater than or equal to 94.6%) in 20-d-old eggs than other compounds tested. Crotoxyphos applied at 0.5% (AI) is the only acaricide tested that provided sufficient ovicidal activity in all three egg age classes (greater than or equal to 85% reduction of hatch).
Asunto(s)
Insecticidas , Garrapatas , Animales , ÓvuloAsunto(s)
Cumafos , Insecticidas , Garrapatas , Animales , Bovinos , Femenino , Resistencia a los InsecticidasRESUMEN
Studies were carried out to examine the effects of dietary fat and cholesterol on cholesterol homeostasis in man. 75 12-wk studies were carried out during intake of 35% of calories as either saturated or polyunsaturated fat, first low and then high in dietary cholesterol. Dietary fat and cholesterol intakes, plasma lipid and lipoprotein levels, cholesterol absorption and sterol synthesis in isolated blood mononuclear leukocytes were measured during each diet period. In 69% of the studies the subjects compensated for the increased cholesterol intake by decreasing cholesterol fractional absorption and/or endogenous cholesterol synthesis. When an increase in plasma cholesterol levels was observed there was a failure to suppress endogenous cholesterol synthesis. Plasma cholesterol levels were more sensitive to dietary fat quality than to cholesterol quantity. The results demonstrate that the responses to dietary cholesterol and fat are highly individualized and that most individuals have effective feedback control mechanisms.
Asunto(s)
Colesterol en la Dieta/metabolismo , Colesterol/metabolismo , Grasas de la Dieta/metabolismo , Células Cultivadas , Colesterol en la Dieta/administración & dosificación , Grasas de la Dieta/administración & dosificación , Ingestión de Energía , Grasas Insaturadas/administración & dosificación , Grasas Insaturadas/metabolismo , Retroalimentación , Homeostasis , Humanos , Absorción Intestinal , Lípidos/sangre , Lipoproteínas/sangre , Masculino , Monocitos/metabolismo , Esteroles/biosíntesisRESUMEN
A new technique called LDL-pheresis was used in patients to lower low-density lipoprotein cholesterol levels. This procedure combines continuous extracorporeal plasma separation with immunoadsorption of low-density lipoprotein on columns containing monospecific antibody to human apolipoprotein B. Six patients underwent a total of 164 procedures without significant side effects or nonspecific protein depletion. Acutely, LDL-pheresis lowered plasma cholesterol levels by removing up to 82 percent of the circulating low-density lipoprotein. Weekly LDL-pheresis combined with a portacaval shunt in a patient with homozygous familial hypercholesterolemia resulted in normalization of plasma cholesterol levels and rapid regression of skin xanthomata. Three of four patients with atherosclerotic coronary artery disease have noted improvement in their angina. LDL-pheresis appears to be a promising new technique capable of safely and efficiently lowering plasma low-density lipoprotein cholesterol levels.
Asunto(s)
Hipercolesterolemia/metabolismo , Técnicas de Inmunoadsorción , Lipoproteínas LDL/análisis , Adulto , Niño , Femenino , Humanos , Hipercolesterolemia/terapia , Técnicas de Inmunoadsorción/normas , Masculino , Persona de Mediana Edad , Intercambio PlasmáticoRESUMEN
Plasma high density lipoprotein (HDL) concentrations were increased in five hypercholesterolemic normoglyceridemic patients after removal of plasma low density lipoprotein (LDL) by LDL-pheresis. In each patient up to 80% of circulating LDL was removed by passing plasma through immunoadsorption columns containing antibody to apolipoprotein B immobilized to Sepharose. Rebound of LDL was slow after the procedure: 5-7 days in four non-familial hypercholesterolemic patients and greater than 14 days in one patient with homozygous familial hypercholesterolemia. Plasma HDL rose above the pretreatment baseline during the interval between treatments in four of the five patients. When treatments were repeated weekly, time-averaged plasma LDL was lowered by 40-70%, while plasma HDL cholesterol and apolipoprotein AI were increased up to 2-fold, depending on the degree of LDL lowering. Plasma HDL concentrations fell back to their baseline values when LDL-pheresis was stopped and rose again when treatment was restarted. Thus, LDL-pheresis may augment the therapeutic effectiveness of LDL lowering by raising plasma HDL levels and the concentration of HDL relative to LDL.