Albert Wulari Mbaya

The study evaluated the anthelmintic efficacy of the crude ethanolic extract of Diospyros mespiliformis (Ebenaceae) among Yankasa Sheep. Twenty-five (25) sheep were randomly selected and placed into five groups (A-E) of five animals each. The extract at dosages of 100 and 200 mg/kg resulted in 34.05 and 55.08% faecal egg reduction respectively. Haematological parameters (PCV, RBC, Hb, WBC, DLC, Platelet count and ESR) were significantly (ppHaemonchus contortus at the highest dosage tested. This finding supports the folkloric application of this plant as a vermifuge in trado-veterinary medical practices. Keywords: Haemonchus contortus; Diospyros mespiliformis; anti-helminth; ethanolic extract

Crude methanol, pet. ether, ethyl acetate, n-hexane, dichloromethane and aqueous extracts of various species of medicinal plants have shown significant in-vivo and in-vitro pharmacological activities against ecto, endo and haemoparasites. The scientific evaluations of the use of the plants as antiparasitic agents were based on the claims of folklore drawn from traditional healers from various communities across the world. The pharmacological activities of these plants were associated with the presence of various bioactive compounds such as alkaloids, flavonoids, saponins, glycosides, allicinine, harmala, harmaline, harman, tetrahydroharman, ursolic acid, terapines, tannins, phenolic compounds, embelin and brucine. These compounds were either found in the leaves, seeds, bulbs, flowers, stem, root barks or entire plant. In the in-vivo studies, plant extracts were tested using animal models such as mice, sheep, goats, cattle and dogs. The in-vivo anthelmintic activities of the plants were assessed by faecal egg out puts and post-mortem worm counts which in most instances achieved 70-90% priori levels with some of the plants. For haemoparasitic infections, parasitaemia clearance levels were used, while larvae and adult deaths were used to measure the activity of the plants against ectoparasites. For in-vitro activities, inhibitory concentration IC₅₀ values using the brine lethality test, micro dilution, flow cytometery and larval packet test were used to assess the efficacy of the plant extracts on the parasites in various cell cultures. Significant in-vitro activity of 99.8% at 3.1mg/ml was achieved with the ethanolic extract of Azadirachta indica. Many of the plants were found to be more potent and possessed similar mechanism of action as their novel synthetic drugs. Such breakthroughs have led to the development of less toxic, cheaper and readily available drugs. Worthy of note is the use of the fruit of the Thai plant Piper longum (PIPERACEAE) as part of a drug formulation used in India for the treatment of clinical giardiosis in human patients.

Reports on the clinico-pathology and mechanisms of trypanosomosis in free-living and captive wild animals showed that clinical disease and outbreaks occur more commonly among captive than free-living wild animals. This is because the free-living wild animals co-exist with the disease until subjected to captivity. In exceptional cases however, draught, starvation and intercurrent diseases often compromised trypanotolerance leading to overt trypanosomosis in free-living wild animals. Meanwhile, in captivity, space restriction, reduced social interactions, change in social herd structure, reduced specie-to-specie specific behaviors, altered habitat and translocation were the major stressors that precipitated the disease. The cumulative effect of these factors produced severe physiological and somatic stress leading to diminished immune response due to increased blood cortisol output from adrenal cortex. The major symptoms manifested were pyrexia, innapetence, increased respiration, anaemia, cachexia and death. At necropsy, pulmonary oedema, splenomegally, hepatomegally, lympadenopathy and atrophy of body fats were the gross changes encountered. At the ultra-structural level, the tissues manifested degenerative changes, haemorghages, necrosis and mononuclear cellular infiltrations. The mechanisms of cellular and tissue injuries were primarily associated with physical and metabolic activities of the organisms. From the foregoing, it is evident that stress is the underlying mechanism that compromises trypanotolerance in wild animals leading to severe clinico-pathological effects.

Une étude a été menée pour déterminer les effets chémothérapeutiques de l’hydrochlorure de mélarsamine (Cymelarsan®) et de l’acéturate de diminazène (Bérénil®) sur les paramètres biochimiques sanguins chez des gazelles au front rouge expérimentalement infectées par Trypanosoma brucei. Suite à la parasitémie des gazelles, les observations suivantes ont été faites : une augmentation significative (p < 0,05) de cortisol sérique, de l’alanine aminotransférase, de l’aspartate aminotransférase, de la bilirubine totale, de la créatinine, de l’urée, de l’acide urique et des lipides totaux, ainsi qu’une baisse significative des protéines sériques totales, du niveau de l’albumine et du glucose. En revanche, l’activité de la phosphatase d’alcaline a fluctué autour des valeurs normales (p > 0,05). Ces modifications biochimiques sont revenues à des valeurs proches de celles de la période de préinfection avant la fin de l’expérience chez les gazelles traitées avec 0,3 ou 0,6 mg/kg de poids vif (PV) de Cymelarsan ou 7,0 mg/kg de Bérénil. Les résultats semblent indiquer qu’un stress initial, associé à une augmentation du niveau du cortisol sérique et à son effet immunodépresseur pouvaient être responsable de l’installation et de l’expression clinique de l’infection chez les gazelles au front rouge. Par ailleurs, la sévérité des effets biochimiques produits expérimentalement a montré que la trypanotolérance chez les gazelles sauvages pouvait être compromise, surtout lorsque ces dernières étaient exposées au stress de la captivité. Les résultats ont aussi montré que le Cymelarsan à 0,3 ou 0,6 mg/kg PV et le Bérénil à 7,0 mg/kg PV étaient efficaces pour contrôler la maladie dans les conditions de l’expérience.