Abstract
The relationships between estimates of tsetse challenge and trypanosome prevalence in trypanotolerant and susceptible cattle were examined at sites of the African Trypanotolerant Livestock Network. Estimates of tsetse challenge were determined as the product of tsetse relative densities, their trypanosome infectionTates and the proportions of feeds taken by them from cattle. Trypanosome prevalence in both trypanotolerant and susceptible breeds of cattle was estimated from monthly examination of groups of ear-tagged cattle. Regression equations between estimates of trypanosome prevalence and tsetse challenge were fitted using an arcsin transformation of trypanosome prevalence and a log10 transformation of tsetse challenge. Highly significant relationships between estimates of tsetse challenge and trypanosome prevalence were found for sites with trypanotolerant cattle (P < 0.0001) and sites with susceptible cattle (P < 0.01). Mean trypanosome prevalence at a given level of tsetse challenge was at least twice as high in susceptible as in trypanotolerant cattle. The slopes of the regression lines for the two groups of cattle were significantly different (P < 0.05). The results confirm the superior ability of trypanotolerant cattle to withstand tsetse challenge in the field. The curves obtained for the two groups of cattle illustrate the necessity in tsetse control campaigns for a major reduction of tsetse populations to take place before significant decreases in trypanosome incidence in livestock can be achieved.
Résumé
Les relations entre les estimations de la pression glossinaire, et la prévalence trypanosomienne chez le bétail trypanotolérant et trypanosensible ont été examinées sur les sites du Réseau Africain d’Etudes du Betail Trypanotolerant. Une estimation de la pression glossinaire a été obtenue en calculant le produit de la densité relative de tsétsés, du taux d’infection trypanosomienne, et de la proportion de repas de sang pris sur le bétail. La prévalence trypanosomienne chez le bétail a été obtenue par l’examen parasitologique mensuel de groupes d’animaux identifiés par boucle auriculaire. Les équations de régression entre les estimations de la prévalence trypanosomienne et la pression glossinaire ont été déterminées aprés transformation logarithmique de la pression glossinaire (log10) et transformation arcsin de la prévalence trypanosomienne. Il existe une relation hautement significative entre les estimations de la pression glossinaire et la prévalence trypanosomienne dans les sites du Réseau comportant du bétail trypanotolérant (P<0.0001) et dans les sites comportant des animaux sensibles (P<0.01). La prévalence trypanosomienne moyenne pour un niveau donné de pression glossinaire est au moins deux fois plus élevée chez le bétail sensible que chez le bétail résistant. Les pentes des équations de régression pour les deux types de bétail sont significativement différentes (P<0.05). Ces résultats confirment la capacité du bétail trypanotolérant de supporter la pression glossinaire naturelle. Les courbes obtenues pour les deux groupes d’animaux illustrent la nécessité d’une réduction considérable de la population glossinaire au cours des campagnes de lutte, pour qu’un effet significatif sur l’incidence des trypanosomoses chez le bétail soit obtenu.
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Leak, S.G.A., Collardelle, C., Couubaly, L. et al. Relationships between Tsetse Challenge and Trypanosome Prevalence in Trypanotolerant and Susceptible Cattle. Int J Trop Insect Sci 11, 293–299 (1990). https://doi.org/10.1017/S1742758400012704
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DOI: https://doi.org/10.1017/S1742758400012704