Molecular identification of bloodmeal sources and trypanosomes in Glossina spp., Tabanus spp. and Stomoxys spp. trapped on cattle farm settlements in southwest Nigeria

The interactions of host, vector and parasite in bovine trypanosomiasis transmission cycles in southwest Nigeria are not yet well understood. Trypanosoma (Trypanosomatida: Trypanosomatidae) species infection prevalences and bloodmeal sources were determined in transmitting vectors of the genera Glossina (Diptera: Glossinidae), Tabanus (Diptera: Tabanidae) and Stomoxys (Diptera: Muscidae) collected using Nzi traps in cattle settlements in southwest Nigeria. Sequenced cytochrome B mitochondrial DNA segments obtained from vector digestive tracts identified bloodmeal sources from eight host species, namely human, cattle, hippopotamus, giraffe, gazelle, spotted hyena, long-tailed rat and one unidentified species. Overall, 71.1% [95% confidence interval (CI) 63.0-78.1], 33.3% (95% CI 21.9-47.0) and 22.2% (95% CI 16.2-29.9), respectively, of Glossina, Tabanus and Stomoxys flies were positive for trypanosomes. The observed trypanosome species were Trypanosoma vivax, Trypanosoma congolense, Trypanosoma brucei, Trypanosoma evansi, Trypanosoma simiae and Trypanosoma godfreyi. Trypanosome DNA was more prevalent in tsetse (34.8% Tr. vivax, 51.1% Tr. b. brucei, 5.2% Tr. congolense, 4.4% Tr. simiae and 24.4% mixed infections) than in other flies and the main determinants in all flies were seasonal factors and host availability. To the best of the present group's knowledge, this is the first report of Trypanosoma species in Tabanus and Stomoxys flies in Nigeria. It indicates that vector control programmes should always consider biting flies along with tsetse flies in the control of human and animal trypanosomiasis.

Ovicidal and larvicidal activity of Cassia alata leaf acetone extract and fractions on Haemonchus contortus: in vitro studies

CONTEXT

The failure of modern anthelmintics to control nematode parasites of sheep and goats is a reality on many farms in the tropical/subtropical regions of the world. This necessitates chemotherapeutic control alternatives and plant secondary metabolite with activity is one of those potential solutions.

OBJECTIVE

This study was design to evaluate the efficacy of solvent: solvent fractions of Cassia alata Gelenggang Besar (Leguminosae) leaf acetone extract against Heamonchus contortus Rudolphi (Trichostrongylidae).

MATERIALS AND METHODS

C. alata leaf was extracted with 70% acetone and fractions were obtained by solvent: solvent group separation procedures. The acetone extract and the fractions were tested by egg hatch assay (EHA) and larval development and viability assay to assess relative bioactivity against H. contortus eggs and larvae.

RESULTS

The extracts inhibited egg hatchability and killed infective larvae of H. contortus in a concentration-dependent manner. The best-fit LC(50) values were 0.562, 0.243, 0.490, 0.314, and 0.119 mg/mL for the acetone extract, chloroform, hexane, butanol and 35% water in methanol fractions, respectively, when tested against nematode eggs. The best-fit LC(50) values were 0.191, 0.505, 1.444, 0.306, and 0.040 mg/mL for acetone extract, chloroform, hexane, butanol and 35% water in methanol fractions, respectively, when tested against larvae. The 35% water in methanol fraction was the most active against the larvae and eggs of H. contortus demonstrating the lowest LC(50) values

DISCUSSION AND CONCLUSION

This study demonstrates that the leaf extracts of C. alata have anthelmintic activity; therefore it could find application in the control of helminths in livestock.

In vitro anthelmintic effect of Anogeissus leiocarpus (DC.) Guill. & Perr. leaf extracts and fractions on developmental stages of Haemonchus contortus

The anthelmintic effect of acetone leaf extract and fractions of Anogeissus leiocarpus was investigated to determine the relative efficacy of the components as anthelmintic against Haemonchus contortus (Rudolphi). The fractions were obtained by solvent-solvent group separation of the leaf extract. The fractions were evaluated for ovicidal and larvicidal activity by egg hatch inhibition assay and larval development viability assay. Best-fit LC(50) values for egg hatch test were 0.360, 0.316, 0.093, 0.219 and 0.196 mg/ml for the crude acetone extract, hexane, chloroform, butanol, and 35% water in methanol fractions, respectively. While the best-fit LC(50) values for larval development and viability test were 0.509, 0.162, 0.186, 0.288 and 0.130 mg/ml for the crude acetone extract, hexane, chloroform, butanol, and 35% water in methanol fractions, respectively. The 35% water in methanol fractions was the more active on larvae, although differences in activity between fractions were not significant (p>0.05). A. leiocarpus leaf extracts could find application in anthelmintic therapy in veterinary practice.

Anthelmintic activity of Spigelia anthelmia extract against gastrointestinal nematodes of sheep

In vitro (larval development assay) and in vivo studies were conducted to determine possible direct anthelmintic effect of ethanolic and aqueous extracts of Spigelia anthelmia towards different ovine gastrointestinal nematodes. The effect of extracts on development and survival of infective larvae stage (L(3)) was assessed. Best-fit LC(50) values were computed by global model of non-linear regression curve fitting (95% confidence interval). Therapeutic efficacy of the ethanolic extracts administered orally at a dose rate of 125, 250, and 500 mg/kg, relative to a non-medicated control group of sheep harbouring naturally acquired infection of gastrointestinal nematodes, was evaluated in vivo.The presence of S. anthelmia extracts in the cultures decreased the survival of L(3) larvae. The LC(50) of aqueous extract (0.714 mg/ml) differ significantly from the LC(50) of the ethanolic extract (0.628 mg/ml) against the strongyles (p < 0.05, paired t-test). Faecal egg counts on day 12 after treatment showed that the extract is effective, relative to control (one-way analysis of variance [ANOVA], Dunnett's multiple comparison test) at 500 mg/kg against Strongyloides spp. (p < 0.01), 250 mg/kg against Oesophagostomum spp., Trichuris spp. (p < 0.05), and 125 mg/kg against Haemonchus spp. and Trichostrongylus spp. (p < 0.01). The effect of the doses is significant in all cases, the day after treatment is also extremely significant in most cases, whereas interaction between dose and day after treatment is significant (two-way ANOVA). S. anthelmia extract could, therefore, find application in the control of helminth in livestock, by the ethnoveterinary medicine approach.

Anthelmintic efficacy of Nauclea latifolia extract against gastrointestinal nematodes of sheep: in vitro and in vivo studies

Direct effects of Nauclea latifolia extracts on different gastrointestinal nematodes of sheep is described. In vivo and in vitro studies were conducted to determine possible anthelmintic effect of leaf extracts of Nauclea latifolia toward different ovine gastro intestinal nematodes. A larval development assay was used to investigate in vitro, the effect of aqueous and ethanolic extracts of N. latifolia towards strongyles larvae. The development and survival of infective larvae (L(3)) was assessed and best-fit LC(50) values were computed by global model of non-linear regression analysis curve-fitting (95% CI). Twenty sheep harbouring naturally acquired gastrointestinal nematodes were treated with oral administration of ethanolic extracts at a dose rate of 125 mg/kg, 250 mg/kg and 500 mg/kg to evaluate therapeutic efficacy, in vivo.The presence of the extracts in the cultures decreased the survival of larvae. The LC(50) of aqueous and ethanolic extract were 0.704 and 0.650 mg/ml respectively and differ significantly (P<0.05, paired t test). Faecal egg counts (FEC) on day 12 after treatment showed that the extract is effective, relative to control (1-way ANOVA, Dunnett's multiple comparison test), at 500 mg/kg against Haemonchus spp, Trichostrongylus spp (p<0.05), Strongyloides spp (P < 0.01); at 250 mg/kg against Trichuris spp (P < 0.01) and ineffective against Oesophagostomum spp (p>0.05). The effect of doses is extremely significant; the day after treatment is sometimes significant while interaction between dose and day after treatment is insignificant (2-way ANOVA). N. latifolia extract could therefore find application in the control of helminth in livestock, by the ethnoveterinary medicine approach.

Anthelmintic Activity of Extracts of Spondias mombin Against Gastrointestinal Nematodes of Sheep: Studies In Vitro and In Vivo

This study was carried out to validate the efficacy of Spondias mombin, used locally as an anthelmintic, and to standardize the effective dose of the plant extract required for worm control in livestock. In vitro and in vivo studies were conducted to determine the direct anthelmintic effect of ethanolic and aqueous extracts of S. mombin towards different ovine gastrointestinal nematodes. A larval development assay (LDA) was used to investigate the in vitro effect of extracts on strongyle larvae. Another study was conducted in vivo to evaluate the therapeutic efficacy of the extracts administered orally at dose rates of 125, 250, 500 mg/kg to sheep naturally infected with gastrointestinal nematodes. Twenty sheep were selected on the basis of positive faecal egg counts (750 epg). The sheep were allocated randomly to a non-medicated control group (A) or to groups given 125 mg/kg (B), 250 mg/kg (C) or 500 mg/kg (D) of extract, respectively. Sheep in groups B-D were given extracts orally on two days. Individual faecal egg counts were performed on days 0, 3, 6, 9 and 12. The presence of S. mombin extracts in in vitro cultures of larvae decreased the survival of L3 larvae. The LC50 of the aqueous extract of S. mombin was 0.907 mg/ml, while the LC50 of the ethanolic extract was 0.456 mg/ml. This difference in LC50 was statistically significant (p > 0.05). The mean percentage faecal egg reduction of sheep drenched with 500 mg/kg S. mombin extracts was 15.0%, 27.5%, 65.0%, 65.0%, 100.0% against Haenmonchus spp., Trichostrongylus spp., Oesophagostomunm spp., Strongyloides spp. and Trichuris spp. respectively, on day 12. Extracts of S. mombin could find application in the control of helminths in livestock.

Evaluation of the anthelmintic activity of Khaya senegalensis extract against gastrointestinal nematodes of sheep: in vitro and in vivo studies

The anthelmintic effect of Khaya senegalensis is described. In vitro and in vivo studies were conducted to determine possible direct anthelmintic effects of ethanolic and aqueous extracts of K. senegalensis towards different ovine gastrointestinal nematode. A larval development assay was used to investigate in vitro, the effect of aqueous and ethanolic extracts towards larvae of strongyles. The LC50 values of the effects of both the aqueous and ethanolic extracts were calculated. Another study was conducted in vivo to evaluate the therapeutic efficacy of the extracts administered orally at a dose rate of 125, 250 and 500 mg/kg of sheep harbouring naturally acquired infection of gastrointestinal nematodes. The presence of K. senegalensis extracts in the cultures decreased the viability of larvae. The LC50 of the aqueous extract (0.69 mg/ml) is not significantly different (P >0.05, t-test) from the ethanolic extract (0.51 mg/ml). The activity of the extract is concentration dependent in vivo. Sheep drenched with 500 mg/kg K. senegalensis ethanolic extract had a mean faecal egg count (FEC) reduction of 88.82%. The extract of K. senegalensis could find application in anthelmintic therapy in veterinary practice.