To evaluate activity of methanol extract of Achillea fragrantissima (meth) (A. fragrantissima) alone or in combination with diminazine aceturate (DA) against Trypanosoma evansi (T. evansi) in experimentally infected rats.

Sixty adult male Wister albino rats were divided equally into 6 groups (A–F). Rats in groups A–E were experimentally infected with T. evansi and those in group F were uninfected. The groups were treated respectively as follows: group A-with 3.5 mg/kg DA; group B- with 1 000 mg/kg meth A. fragrantissima; group C-3.5 mg/kg DA plus 500 mg/kg meth A. fragrantissima; group D-3.5 mg/kg DA plus 1 000 mg/kg meth A. fragrantissima. Group E was left untreated. Parasitemia, survivability, packed cell volume, hemoglobin concentration, total leucocytes count, lymphocyte count, and serum malondialdehyde and reduced glutathione (GSH) levels were estimated. Phytochemical screening of meth A. fragrantissima was also performed.

The phytochemical analysis of the meth A. fragrantissima indicated a higher content from polyphenolic tannins and non tannins and flavonoids. The efficacy percentage against trypanosomiasis in groups A – E was respectively as follows 80, 40, 90, 100, 0. The administration of meth-A. fragrantissima (1 000 mg/kg b.wt.) produced a moderate efficacy against trypanosomiasis. Untreated rats in group E died between 25 and 30 d post infection. The rats given DA and meth A. fragrantissima combinations (C and D) showed faster and higher recovery rates than the uninfected control and groups A and B. The initial reduction in packed cell volume, hemoglobin, total leucocytes count, increases in serum malondialdehyde and decreases in GSH levels were reversed by the treatments.

The administration of the methanol extracts of A. fragrantissima and DA combination therapy was more effective than each product alone in the treatment of rats infected with T. evansi and further studies are required to isolate more active ingredients.