Comparative pathogenicity of single and mixed drug-resistant Trypanosoma brucei brucei and Trypanosoma congolense infections in rats.

Drug-resistant trypanosomes are widespread in sub-Saharan Africa and in conjunction with the drug-sensitive phenotypes cause a serious endemic wasting disease in animals. We evaluated the pathogenicity of single and mixed drug-resistant Trypanosoma brucei brucei and T. congolense isolates in 35 female rats, randomly divided into seven groups (1-7) of five rats. Group 1 was the uninfected control. Groups 2 and 3 were infected with drug-sensitive T. brucei brucei and T. congolense, respectively, whereas groups 4 and 5 were infected with multidrug-resistant T. brucei brucei and T. congolense respectively. Group 6 were infected with drug-sensitive T. brucei brucei and T. congolense while group 7 were infected with multidrug-resistant T. brucei brucei and T. congolense. Parasitaemia kinetics, haematological parameters, body weight, clinical signs, survival time, gross and histopathological changes in the spleen were evaluated. Parasitaemia occurred between day 3-9 post-infection in all the infected groups. Rats in groups 4 and 7 had markedly prolonged (p < 0.05) pre-patent period, days to first peak parasitaemia, survival time, and lower (p < 0.05) parasitaemia level than groups 2 and 6 rats while these parameters were comparable for groups 3 and 5 rats. Anaemia was noted in the infected groups but the severity did not vary amongst the infected groups. Severe clinical signs and splenic lesions were noted in rats infected with drug-sensitive trypanosome species compared to the multidrug-resistant species. Therefore, we conclude that the trypanosome isolates were pathogenic. However, the drug-sensitive T. brucei brucei and mixed drug-sensitive trypanosome infections were more pathogenic than their multidrug-resistant counterparts.

Comparative pathogenicity of drug-resistant and drug-sensitive Trypanosoma brucei and Trypanosoma congolense infections in Nigerian local dogs.

Animal trypanosomosis is an important endemic and wasting disease in sub-Saharan Africa. Its control relies on chemotherapy, and resistance to trypanocides has been widely reported. The pathogenicity of drug-resistant canine trypanosomes is not clear with scanty information available. Thus, this study assessed the comparative pathogenicity of drug-resistant and drug-sensitive Trypanosoma brucei and Trypanosoma congolense infections in dogs. Twenty Nigerian local dogs were used and were randomly assigned into five groups (A-E) of four dogs each. Group A served as the uninfected-control group, while groups B and C were infected with 106 drug-sensitive T. congolense and T. brucei. Groups D and E were infected with 106 multidrug-resistant T. congolense and T. brucei, respectively. The pre-patent period (PPP), clinical signs, level of parasitaemia (LOP), rectal temperature, body weight, packed cell volume (PCV), red blood cell count (RBC), haemoglobin concentration (HbC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), total leucocyte count (TLC) and survivability were assessed. Groups D and E had longer (p < 0.05) mean PPP than groups B and C. Also, group E dogs had lower (p < 0.05) mean LOP, longer (p < 0.05) mean survivability, and higher (p < 0.05) mean body weight, PCV, HbC and RBC than group C dogs. The clinical signs were very severe in group C dogs, compared to group E dogs. However, these parameters did not differ statistically between groups B and D. Thus, multidrug-resistant T. brucei was of lower pathogenicity than drug-sensitive T. brucei, while multidrug-resistant and drug-sensitive T. congolense had comparable pathogenicity following infection in dogs.

Evaluation of antitrypanosomal activity of Pterocarpus santalinoides L'H'erit ex DC hydroethanol leaf extract in rats experimentally infected with Trypanosoma brucei.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves of Pterocarpus santalinoides are used alone or with other plants by traditional healers in some Southern Nigerian and Ivorian rural villages to treat blood parasitic infections including trypanosomiasis and malaria. However, their efficacy and safety remains doubtful. AIM: To evaluate the antitrypanosomal activity of Pterocarpus santalinoides hydroethanol leaf extract (PSELE) in vitro and in vivo. MATERIALS AND METHODS: The phytochemical and acute toxicity studies of PSELE were performed using standard methods. Eleven different concentrations of the extract were screened for in vitro antitrypanosomal activity. For the in vivo study, twenty-five female albino rats were randomly assigned into five groups of five rats each. Group A was the uninfected and untreated group while groups B - E were infected intraperitoneally with 106 trypanosomes. Group C rats were treated once on day 11 post infection (PI) with 7 mg/kg diminazene aceturate while groups D and E rats were also treated on same day with 200 mg/kg and 400 mg/kg PSELE respectively for seven days. The level of parasitaemia (LOP), survivability, packed cell volume (PCV), total leucocyte count (TLC), total erythrocyte count (TEC), body weight and rectal temperature were used to assess the antitrypanosomal effect of PSELE. RESULTS: Phytochemical analysis revealed the presence of flavonoids, tannins, carbohydrates and reducing sugar. No sign of toxicity or mortality was observed following acute toxicity study at a single dose of 2000 mg/kg. The LC50 of PSELE was 0.0625 mg/ml. Parasitaemia was first detected on day 8 and all infected rats became parasitaemic on day 10 (PI). PSELE significantly reduced (p < 0.05) LOP, improved PCV, TEC and prolonged survival time of the rats compared with the infected untreated group B. CONCLUSION: It was therefore concluded that PSELE is safe, possesses some antitrypanosomal activity and may serve as a lead for the development of an effective alternative antitrypanosomal drug.