RESUMO
BACKGROUND: Amblyomma cajennense is the main vector of Rickettsia rickettsii which causes Brazilian spotted fever. This adult tick preferably infests horses and capybaras, but has low host specificity during its immature stages, thus posing a threat to humans and dogs. In this study, the efficacy of sarolaner (Simparic™/Simparica®, Zoetis) when administered once orally to dogs at 2 mg/kg was evaluated against induced infestations of A. cajennense nymphs for up to 35 days after treatment. METHODS: Based on pretreatment tick counts, 20 dogs were randomly allocated to treatment with sarolaner (Simparic™) dosed at 2 mg/kg of body weight or a placebo on Day 0 of the study. Artificial infestations were performed using laboratory raised A. cajennense nymphs on study days -2, 5, 12, 19, 26 and 33. Efficacy was determined at 48 h post-treatment or post-infestation at each time point relative to the counts for dogs that received placebo. RESULTS: There were no adverse reactions to treatment. A single dose of sarolaner (Simparic™) provided 100% efficacy on study days 2, 7 and 14; and ≥ 99.6% on days 21, 28 and 35. Geometric mean live tick counts for sarolaner were significantly lower than those for placebo on all days (P < 0.0001). CONCLUSIONS: Under the conditions of the present study, sarolaner (Simparic™) administered once orally at 2 mg/kg provided 100% efficacy against existing infestations and ≥ 99.6% efficacy within 48 h against weekly challenges of A. cajennense for at least 35 days after treatment.
Assuntos
Vetores Aracnídeos/efeitos dos fármacos , Azetidinas/uso terapêutico , Doenças do Cão/tratamento farmacológico , Ixodidae/efeitos dos fármacos , Compostos de Espiro/uso terapêutico , Infestações por Carrapato/veterinária , Administração Oral , Animais , Vetores Aracnídeos/fisiologia , Azetidinas/administração & dosagem , Azetidinas/efeitos adversos , Brasil , Doenças do Cão/parasitologia , Cães , Ixodidae/fisiologia , Ninfa/efeitos dos fármacos , Ninfa/fisiologia , Carga Parasitária , Febre Maculosa das Montanhas Rochosas/transmissão , Compostos de Espiro/administração & dosagem , Compostos de Espiro/efeitos adversos , Infestações por Carrapato/tratamento farmacológico , Infestações por Carrapato/parasitologia , Fatores de Tempo , Resultado do TratamentoRESUMO
Because of the medical and veterinary importance of ticks and the wide use of synthetic chemical substances such as permethrin (active ingredient of Advantage® Max3 - Bayer)for their control, this study evaluated the effects of different concentrations (206, 1031 and 2062 ppm) of the acaricide on the salivary glands of Rhipicephalus sanguineus semi-engorged females. Results showed that permethrin is a potent substance that acts morpho-physiologically in the tick glandular tissue, causing changes in the acini shape intense vacuolation in acinar cells, and disruption of the tissue by cell death process, with subsequent formation of apoptotic bodies, especially at higher concentrations, thus precluding the accurate identification of different types of acini. Importantly, it is demonstrated that permethrin acts on salivary gland tissue, as well as affecting the nervous system, accelerating the process of glandular degeneration, and interfering with the engorgement process of female ticks, preventing them from completing the feeding process.
Assuntos
Acaricidas/toxicidade , Vetores Aracnídeos/efeitos dos fármacos , Permetrina/toxicidade , Rhipicephalus sanguineus/efeitos dos fármacos , Acaricidas/administração & dosagem , Animais , Vetores Aracnídeos/metabolismo , Vetores Aracnídeos/ultraestrutura , Relação Dose-Resposta a Droga , Feminino , Microscopia Eletrônica de Varredura , Permetrina/administração & dosagem , Rhipicephalus sanguineus/metabolismo , Rhipicephalus sanguineus/ultraestrutura , Glândulas Salivares/efeitos dos fármacos , Glândulas Salivares/metabolismo , Glândulas Salivares/ultraestruturaRESUMO
The objective of the present work was to evaluate the efficacy of a non-sulphur-based homeopathic preparation and a sulphur-containing natural product derived from Allium sativum (Linnaeus) against infestation by the cattle tick Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae). A total of 24 crossbred calves (7 : 8 Holstein : Zebu), aged 6-8 months and maintained in individual stables under tick-free conditions, were divided into three groups. Group 1 (control group) received no treatment; Group 2 was treated with 0.01 g/day of the homeopathic preparation Fator C&MC(®), and Group 3 was treated with 20 g/day of Enxofre-Allium sativum(®). After adaptation to the diet for 1 month, each calf was subjected to artificial infestation with 8000 R. (B.) microplus larvae (aged 7-14 days) twice per week over a 5-month period. Numbers of engorged females were recorded every 14 days and samples of freely released engorged females were collected at 14-day intervals commencing 3 months after the start of the experiment. The engorged females were weighed, incubated for 15 days under biochemical oxygen demand conditions at 27 ± 1 °C and relative humidity >85%, and the weights of the egg masses produced were recorded. Other biological parameters, including reproduction estimate, reduction in oviposition and efficiency of treatment, were determined. A significant reduction in the number of engorged females was detected on animals treated with Enxofre-Allium sativum(®) (Group 3) in comparison with the other two groups. The overall efficiency of the treatment with the sulphur-containing product was 64%, whereas that of the homeopathic preparation was 26%. Under the experimental conditions established, Enxofre-Allium sativum(®) can reduce the intensity of the R. (B.) microplus infestation.
Assuntos
Doenças dos Bovinos/tratamento farmacológico , Homeopatia/veterinária , Rhipicephalus/efeitos dos fármacos , Enxofre/uso terapêutico , Infestações por Carrapato/veterinária , Animais , Vetores Aracnídeos/efeitos dos fármacos , Bovinos , Doenças dos Bovinos/prevenção & controle , Relação Dose-Resposta a Droga , Feminino , Alho/toxicidade , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Enxofre/farmacologia , Infestações por Carrapato/tratamento farmacológico , Infestações por Carrapato/prevenção & controleRESUMO
Southern cattle ticks, Boophilus microplus (Canestrini) (Acari: Ixodidae), collected in Coahuila, Mexico, were determined to be resistant to permethrin. Discriminating concentration (DC) tests at the LC99 and 2X the LC99 of susceptible ticks produced 0 and 0.5% mortality, respectively, for permethrin. However, measured mortalities for coumaphos and amitraz acaricides were within the expected ranges. Polymerase chain reaction analysis of this strain detected a 99% frequency of homozygous resistant individuals in this strain.
Assuntos
Vetores Aracnídeos/efeitos dos fármacos , Resistência a Inseticidas/genética , Inseticidas , Ixodidae , Permetrina , Animais , Vetores Aracnídeos/genética , Bovinos , Cumafos , Feminino , Homozigoto , Ixodidae/genética , México , Canais de Sódio/genética , ToluidinasRESUMO
A cross-sectional study was carried out in order to investigate the association between management risk factors and the prevalence of organophosphate (OP) and synthetic pyrethroid (SP) resistance in Boophilus microplus ticks in Yucatan State, Mexico. Ninety-eight cattle ranches were randomly selected and a sample of 20-30 engorged female B. microplus ticks was collected at each. The modified larvae packet test was used to detect OP and SP tick resistance. A questionnaire was administered on each ranch. For risk factors, four reference types of response were used: Tuxpan (resistant to coumaphos, chlorfenvinphos and diazinon), Parkhurst (resistant to flumethrin, deltamethrin and cypermethrin), Lamington (resistant to flumethrin in absence of deltamethrin and cypermethrin) and Marmor (resistant to flumethrin and cypermethrin in absence of flumethrin). A primary screening was performed using 2 x 2 contingency tables of exposure variables. All variables with p < or = 0.20 were analyzed by a logistic regression. The prevalence of B. microplus resistance to OP and SP groups were 83.70% and 66.32%, respectively. The prevalence for a single chemical compound was: diazinon (80.60%), coumaphos (45.90%), chlorfenvinphos (35.70%), flumethrin (63.28%), deltamethrin (61.22%), and cypermethrin (59.18%). The prevalence type of response was: Tuxpan (34.16%), Parkhurst (58.16%), Lamington (4.08%), and Marmor (4.08%). The use of a different tick control program was the risk management factor associated with the Parkhurst type of response. It is concluded that the prevalence of cattle ranches with B. microplus resistant to OPs and SPs in Yucatan, Mexico, is a current problem, and a treatment interval of > or =6 times/year and use of a tick control program (macrocyclic lactones and pasture burn) different from standard recommended programs are risk factors associated with the Parkhurst type of response.
Assuntos
Vetores Aracnídeos/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Ixodidae , Controle de Ácaros e Carrapatos/métodos , Animais , Bovinos , Doenças dos Bovinos/tratamento farmacológico , Doenças dos Bovinos/parasitologia , Feminino , Ixodidae/efeitos dos fármacos , México/epidemiologia , Organofosfatos/farmacologia , Prevalência , Piretrinas/farmacologia , Fatores de Risco , Infestações por Carrapato/tratamento farmacológico , Infestações por Carrapato/veterináriaRESUMO
The effect of acaricide treatment of cattle on the infestation of the small Indian mongoose (Herpestes auropunctatus Hodgson) by Amblyomma variegatum (F.) was determined during a field evaluation of selected acaricides in Guadeloupe, French West Indies. From April 1990 to April 1991, cattle at one site were treated every 14 d with pour-on formulations of deltamethrin, flumethrin, or permethrin; and cattle at a second site were treated as per a local standard treatment using a spray formulation of coumaphos every 30 d. The protocol was then reversed, and from April to July 1991 cattle at the original standard treatment site were treated using the pour-on treatment. Mongooses were examined for ticks during February-March and July 1990 and 1991. The mean prevalence of infestation of mongooses by A. variegatum larvae was reduced from 41 to 27% during the February-March to July periods at the pour-on treatment sites but increased from 29 to 43% during the same periods at the standard treatment sites. The mean relative density of infestation by larvae decreased from 2.15 to 0.65 at the pour-on treatment sites and increased from 0.7 to 1.95 at the standard treatment sites during the same periods. Data on nymphal infestations were inconclusive, and mongooses were not infested by adult ticks. The infestation of mongooses by A. variegatum may be of importance as a short-term alternative host system for immature stages of this tick during an eradication program.