RESUMEN
Four groups (A, B, C and D) of 10 naïve rats were used to compare the virulence of isolates of a strain of Trypanosoma brucei before and after the development of diminazene aceturate resistance. Group A rats were uninfected (controls). Group B rats were infected with a trypanosome isolate unexposed to the drug, while groups C and D rats were infected with two different drug-resistant isolates of the same strain. Rats in the three infected groups each received 10(6) trypanosomes intraperitoneally. Prepatent periods were longer (P<0.05) in groups C and D than in group B. The parasitaemic periods in groups B, C and D were similar, but group C and D rats differed from group B rats in surviving longer, and in showing lower degrees of parasitaemia, anaemia and hepatomegaly. No differences were noted between group C and D rats. Thus, diminazene aceturate resistance appeared to reduce the virulence of T. brucei.
Asunto(s)
Diminazeno/análogos & derivados , Tripanocidas/farmacología , Trypanosoma brucei brucei/patogenicidad , Tripanosomiasis/veterinaria , Animales , Diminazeno/farmacología , Resistencia a Medicamentos , Femenino , Masculino , Ratas , Tripanocidas/uso terapéutico , Trypanosoma brucei brucei/efectos de los fármacos , Trypanosoma brucei brucei/aislamiento & purificación , Tripanosomiasis/tratamiento farmacológico , Tripanosomiasis/prevención & control , Virulencia/efectos de los fármacosRESUMEN
Four groups (A, B, C and D) of 10 rats were used to determine the effect of comparatively high doses of diminazene aceturate on diminazene aceturate-resistant Trypanosoma brucei and the pathogenic effect of relapse infection. Group A rats were uninfected (controls) while group B, C and D rats were inoculated intraperitoneally with 0.5 x 10 (6) diminazene aceturate-resistant T. brucei and treated with diminazene aceturate at 14.0, 17.5 and 21.0mg/kg body weight, respectively, on day 14 post-infection (PI) as a single intraperitoneal injection. Prepatent periods and also levels of parasitaemia were comparable in groups B, C and D. Packed cell volume (PCV) decreased in the infected groups by day 14 PI and returned to pre-infection values by day 63 post-treatment (PT). Anaemia was comparable in groups B, C and D. Relapse parasitaemia occurred in six rats in group B on day 70 PT and in five rats in each of groups C and D on day 77 PT. The PCV of the rats with relapse infection decreased progressively up to day 105 PT, when the experiment was terminated, whereas the PCV of rats without relapse did not. The levels of anaemia and parasitaemia on day 14 post-relapse were significantly higher (P<0.05) than the levels obtained on day 14 PI in the same animals. Thus, comparatively high doses of diminazene aceturate failed to cure drug-resistant T. brucei infection in 50-60% of infected rats and relapse infections were more severe than the primary infections before treatment.
Asunto(s)
Diminazeno/análogos & derivados , Diminazeno/uso terapéutico , Tripanocidas/uso terapéutico , Trypanosoma brucei brucei/patogenicidad , Tripanosomiasis Africana/tratamiento farmacológico , Animales , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Resistencia a Medicamentos , Eritrocitos/efectos de los fármacos , Eritrocitos/patología , Femenino , Hematócrito , Masculino , Parasitemia/tratamiento farmacológico , Ratas , Recurrencia , Trypanosoma brucei brucei/efectos de los fármacosRESUMEN
A monoclonal antibody against a plasma membrane antigen of Trypanosoma rhodesiense was used for the detection of T brucei group-specific circulating antigen in 24 adult local dogs experimentally infected with T brucei brucei strain 8/18. Ten of the dogs were splenectomised and the remainder non-splenectomised (intact). Five dogs each from the splenectomised and intact groups were inoculated intravenously with trypanosomes. The infected dogs developed trypanosomiasis between days 4 and 8 after infection. The circulating antigens were detected as early as six days after infection and remained high until two weeks after treatment, when the circulating antigen declined. The detection of the antigens showed the existence of infection unlike the antibody test. The treatment of the infected dogs with diminazene aceturate (Berenil; Hoechst) at a dose of 7.0 mg/kg on day 21 after infection cleared all the parasites but elevated the circulating antigen levels. The antigen capture enzyme-linked immunosorbent assay is a useful diagnostic tool for complementing parasitological diagnosis, for detecting infection in the field and for ascertaining the efficacy of trypanocidal drugs.
Asunto(s)
Anticuerpos Monoclonales , Antígenos de Protozoos/análisis , Enfermedades de los Perros/diagnóstico , Esplenectomía/veterinaria , Trypanosoma brucei brucei/inmunología , Tripanosomiasis Africana/veterinaria , Animales , Antiprotozoarios/uso terapéutico , Diminazeno/análogos & derivados , Diminazeno/uso terapéutico , Enfermedades de los Perros/tratamiento farmacológico , Enfermedades de los Perros/inmunología , Perros , Ensayo de Inmunoadsorción Enzimática/veterinaria , Femenino , Masculino , Trypanosoma brucei brucei/efectos de los fármacos , Trypanosoma brucei rhodesiense/inmunología , Tripanosomiasis Africana/diagnóstico , Tripanosomiasis Africana/tratamiento farmacológico , Tripanosomiasis Africana/inmunologíaRESUMEN
Twenty adult mongrel dogs of both sexes were used. Ten of the dogs were splenectomised and the remaining dogs were left intact. Five dogs each from the splenectomised and non-splenectomised (intact) animals were infected intravenously with Trypanosoma brucei brucei while the rest served as uninfected controls. All the infected dogs developed trypanosomosis between Days 4 and 8 postinfection. The packed cell volume, haemoglobin concentration, total red blood cell count and white blood cell count decreased progressively indicating anaemia and leucopenia. The absolute reticulocyte counts were increased. Splenectomy enhanced fever, reticulocytosis and parasitaemia but delayed the onset of anaemia and leucopenia. It also shortened the prepatent period of the infection. The treatment of the infected dogs with diminazene aceturate (Berenil at the dose rate of 7.0 mg kg-1 body weight on Day 21 postinfection cleared the parasites in blood within 24 h and resulted in complete reversal of all the haematological aberrations observed. Splenectomy did not enhance or inhibit the recovery rate in the animals after treatment.