Hendrickx G, Napala A, Dao B, Batawui K, Bastiaensen P, De Deken R, Vermeilen A, Vercruysse J, Slingenbergh J H
FAO Trypanosomosis Project, Burkina Faso.
Vet Parasitol. 1999 Jul;84(1-2):13-31. doi: 10.1016/s0304-4017(99)00086-2.
This paper reports on an area wide study of all major variables determining the expression of trypanosomosis in cattle in the subhumid eco-zone of West Africa, taking Togo as an example. To enable systematic area-wide sampling, the country was divided in 311 grid-squares of 0.125 x 0.125 sides. Cross-sectional surveys were then conducted to generate maps or digital layers on cattle density, herd structure, ownership and breed. These data layers, except for the breed data, were subjected to a cluster analysis in order to define spatial patterns in animal husbandry systems. This analysis revealed two main systems: one is oriented towards integration with crop-agriculture and a second towards investment in cattle. These two systems could be further characterised by incorporating breed data. Zebu cattle and their crossbreeds are more favoured in the second system. The breed distribution map shows the actual situation but also serves to predict the outcome of progressive crossbreeding. An area wide trypanosomosis survey allowed the production of prevalence maps for Trypanosoma congolense, T. vivax and the associated packed cell volume (PCV) values. A simple curvi-linear relationship was established between vector density and disease prevalence. The regression between disease prevalence and PCV for taurine and zebu plus crossbreeds separately, revealed that taurine cattle maintain a comparatively high PCV level particularly in high prevalence scenarios. The relationship between the average herd PCV and cattle density suggests that herd PCV value may provide a mirror for the number of animals not kept because of the prevailing risk. The regression between agricultural intensity and cattle density subsequently in areas with decreasing herd PCV values reveals that the level of integration of cattle in crop production decreases with a decreasing PCV. Thus, despite the presence of taurine animals in Togo, the omnipresence of tsetse in particular Glossina tachinoides, remains a major obstacle to cattle raising and indirectly mixed farming development and intensification. It is argued that only with the present type of wide scale, spatial studies it becomes possible to clarify all the major variables influencing the expression of trypanosomosis. Spatial epidemiological studies at a macro level may form the basis for area wide trypanosomosis control in West Africa.
本文以多哥为例，报告了在西非半湿润生态区对决定牛锥虫病表现的所有主要变量进行的一项区域范围研究。为了进行系统的区域范围抽样，该国被划分为311个边长为0.125×0.125的网格方块。然后进行横断面调查，以生成关于牛密度、畜群结构、所有权和品种的地图或数字图层。除品种数据外，对这些数据图层进行聚类分析，以确定畜牧系统中的空间模式。该分析揭示了两个主要系统：一个以与作物农业结合为导向，另一个以牛养殖投资为导向。通过纳入品种数据可以进一步描述这两个系统的特征。瘤牛及其杂交品种在第二个系统中更受青睐。品种分布图显示了实际情况，也有助于预测渐进杂交的结果。一项区域范围的锥虫病调查得出了刚果锥虫、活跃锥虫的流行率地图以及相关的红细胞压积（PCV）值。在媒介密度和疾病流行率之间建立了简单的曲线关系。分别对黄牛和瘤牛及其杂交品种的疾病流行率与PCV进行回归分析，结果表明黄牛尤其在高流行情况下保持相对较高的PCV水平。畜群平均PCV与牛密度之间的关系表明，畜群PCV值可能反映了因当前风险而未饲养的动物数量。随后在畜群PCV值下降的地区，农业集约化程度与牛密度之间的回归分析表明，随着PCV的降低，牛在作物生产中的整合水平也随之降低。因此，尽管多哥存在黄牛，但采采蝇尤其是嗜人采采蝇的普遍存在，仍然是养牛以及间接的混合作物种植发展和集约化的主要障碍。有人认为，只有通过目前这种大规模的空间研究，才有可能阐明影响锥虫病表现的所有主要变量。宏观层面的空间流行病学研究可能构成西非区域范围锥虫病控制的基础。
