RESUMO
In this study, we evaluated the therapeutic efficacy of diminazene diaceturate at a dose of 7 mg/kg (DA), imidocarb dipropionate at 4.8 mg/kg (IMD), isometamidium chloride at 0.5 and 1.0 mg/kg (ISM 0.5 and ISM 1.0) and combinations applied through different methods to treat Trypanosoma vivax in experimentally infected calves. Thirty male Girolando calves were kept indoors and infected intravenously with T. vivax trypomastigotes (approximately 1 × 106). On D-1, the calves were randomized based on the quantity of infecting parasites per animal, yielding six groups of five animals each: G1: positive control group without treatment; G2 animals treated with DA on Day 0 intramuscularly (IM); G3 animals treated with IMD on Day 0 and D + 14 subcutaneously; G4 animals treated with ISM 0.5 on Day 0 IM; G5 animals treated with ISM 1.0 on Day 0 IM; G6 animals received DA on Day 0 and ISM 1.0 on D + 14, both IM. Throughout 180 days, blood samples were collected for the evaluation of T. vivax using the Woo, Brener and PCR methods. The results indicated that the treatment protocols with DA and/or ISM 0.5 and ISM 1.0 had high efficacy (100 %) against T. vivax. Interestingly, cattle that received ISM remained free of parasites until D + 180. In contrast, animals treated with IMD had relapsed T. vivax detected on the 10th and 14th days post-treatment (DPT). Cattle that received ISM 1.0 did not exhibit relapsed T. vivax in the blood, even after reinfection performed on the 50th DPT. However, treatment with DA on Day 0 failed to prevent a new infection of T. vivax on the 50th DPT. The animals that received ISM 1.0 had a transient decrease in packed cell volume similar to that found in the control group. The reappearance of T. vivax in herds in Brazil treated with DA likely occurred due to the short half-life of the drug and not necessarily due to T. vivax resistance to DA.
Assuntos
Diminazena/análogos & derivados , Imidocarbo/análogos & derivados , Fenantridinas/farmacologia , Tripanossomicidas/farmacologia , Trypanosoma vivax/efeitos dos fármacos , Tripanossomíase Africana/prevenção & controle , Tripanossomíase Bovina/prevenção & controle , Animais , Bovinos , Diminazena/farmacologia , Relação Dose-Resposta a Droga , Imidocarbo/farmacologia , MasculinoRESUMO
In July 2000, Heads of State of the 36th Session of the Organisation for African Unity signed a potentially important declaration on African trypanosomiasis, urging member states "to act collectively to rise to the challenge of eliminating the problem through concerted efforts in mobilising the necessary human, financial and material resources required to render Africa tsetse-free within the shortest time possible". To many, such an ambitious dream is received with some scepticism, recalling the doubts that surrounded a similar declaration signed in Brasilia in 1991, which paved the way for the Southern Cone Initiative against American trypanosomiasis (Chagas disease). True, the two diseases are quite different. But the operational challenges are quite similar, and there are sufficient biological parallels to suggest that the Latin American experience in controlling Chagas disease may provide a useful model for the control of African trypanosomiasis.
Assuntos
Controle de Insetos/métodos , Trypanosoma/crescimento & desenvolvimento , Tripanossomíase Africana/prevenção & controle , Tripanossomíase Bovina/prevenção & controle , Moscas Tsé-Tsé/crescimento & desenvolvimento , África Subsaariana/epidemiologia , Animais , Bovinos , Doença de Chagas/epidemiologia , Doença de Chagas/prevenção & controle , Humanos , Insetos Vetores , América do Sul/epidemiologia , Triatominae/crescimento & desenvolvimento , Tripanossomíase Africana/epidemiologia , Tripanossomíase Africana/parasitologia , Tripanossomíase Bovina/epidemiologia , Tripanossomíase Bovina/parasitologia , Moscas Tsé-Tsé/parasitologiaRESUMO
Trypanosoma vivax is a blood parasite of ruminants that was introduced into Latin America in cattle imported from Africa, possibly in the late 19th century. The parasite has now spread to ten of the 13 countries of the South American continent, often resulting in a severe wasting disease and death. Here, we review the current state of knowledge about this parasite and the problems faced by animal health agencies in controlling the disease.
Assuntos
Trypanosoma vivax , Tripanossomíase Bovina/epidemiologia , África/epidemiologia , Animais , Bovinos , América do Sul/epidemiologia , Tripanossomíase Africana/epidemiologia , Tripanossomíase Bovina/diagnóstico , Tripanossomíase Bovina/prevenção & controleRESUMO
An overview is presented of the results obtained with biodegradable sustained release devices (SRDs) containing a mixture of polymers and either isometamidium (ISMM) or ethidium. Under controlled laboratory conditions (monthly challenge with tsetse flies infected with Trypanosoma congolense) the protection period in SRD treated cattle could be extended by a factor 2.8 (for ethidium) up to 4.2 (for ISMM) as compared to animals treated intramuscularly with the same drugs. Using a competitive drug ELISA ISMM concentrations were detected up to 330 days after the implantation of the SRDs, whereas after i.m. injection the drug was no longer present three to four months post treatment. Two field trials carried out in Mali under heavy tsetse challenge showed that the cumulative infection rate was significantly lower in the ISMM-SRD implanted cattle than in those which received ISMM intramuscularly. Using ethidium SRD, however, contradictory results were obtained in field trials in Zambia and in Mali. The potential advantages and inconvenients of the use of SRDs are discussed and suggestions are made in order to further improve the currently available devices.
Assuntos
Implantes Absorvíveis/veterinária , Etídio/uso terapêutico , Fenantridinas/uso terapêutico , Poliésteres/uso terapêutico , Tripanossomicidas/uso terapêutico , Trypanosoma congolense/efeitos dos fármacos , Tripanossomíase Africana/veterinária , Tripanossomíase Bovina/prevenção & controle , Animais , Bovinos , Preparações de Ação Retardada/uso terapêutico , Fatores de TempoRESUMO
A 0.125 degree raster or grid-based Geographic Information System with data on tsetse, trypanosomiasis animal production, agriculturerkina> and land use has recently been developed in Togo. This paper addresses the problem of generating tsetse distribution and abundance maps from remotely sensed data, using a restricted amount of field data. A discriminant analysis model is tested using contemporary tsetse data and remotely sensed, low resolution data acquired from the National Oceanographic and Atmospheric Administration and Meteosat platforms. A split sample technique is adopted where a randomly selected part of the field measured data (training set) serves to predict the other part (predicted set). The obtained results are then compared with field measured data per corresponding grid-square. Depending on the size of the training set the percentage of concording predictions varies from 80 to 95 for distribution figures and from 63 to 74 for abundance. These results confirm the potential of satellite data application and multivariate analysis for the prediction, not only of the tsetse distribution, but more importantly of their abundance. This opens up new avenues because satellite predictions and field data may be combined to strengthen or substitute one another and thus reduce costs of field surveys.
Assuntos
Conceitos Meteorológicos , Moscas Tsé-Tsé , África Ocidental , Animais , Bovinos , Controle de Custos , Análise Multivariada , Dinâmica Populacional , Comunicações Via Satélite , Tripanossomíase Bovina/prevenção & controleRESUMO
The Brazilian Pantanal is a 138,000 km2 tropical seasonal wetland located in the center of South America bordering Bolivia and Paraguay. The Pantanal contains approximately 1100 cattle ranches, 3 million cattle, 49,000 horses and a unique diversity of wildlife. Cattle ranching is the most important economic activity in the Pantanal. This study explores the direct financial impacts of the adoption of seven treatment strategies for the control of Trypanosoma evansi in the Brazilian Pantanal. T. evansi adversely affects the health of the horse population in the region. Horses are indispensable to the cattle ranching industry in the Pantanal. Estimated costs include risk of infection, costs of diagnosis, alternative treatments, collecting animals for treatment, and costs of animal losses. The estimated total cost of T. evansi to the Pantanal region's cattle ranchers is about US$2.4 million and 6462 horses/yr. Results indicate that one preventive and two curative treatment strategies are financially justifiable. The best available technology for the treatment of T. evansi from an economic perspective is a curative treatment employed year-round. This treatment represents an annual net benefit of more than US$2 million or US$1845/ranch and spares about 5783 horses. It represents an annual net benefit of over US$200,000 and 600 horses relative to the currently most widely adopted strategy.