Moloo S K, Sabwa C L, Baylis M
International Livestock Research Institute, Nairobi, Kenya.
Med Vet Entomol. 2000 Sep;14(3):290-9. doi: 10.1046/j.1365-2915.2000.00242.x.
In field studies, tsetse flies (Diptera: Glossinidae) feed more successfully on cattle infected with Trypanosoma congolense Broden (Kinetoplastida: Trypanosomatidae) than on cattle infected with T. vivax Ziemann or uninfected cattle. Here we describe the first laboratory investigation of this phenomenon. In the first experiment, caged Glossina pallidipes Austen were fed for 1 and 5 min on a Boran steer infected with T. congolense clone IL 1180 and on an uninfected steer. Feeding success was recorded in this way five times over several weeks. The same protocol was subsequently used in three additional experiments with the following combinations: G. pallidipes and a steer infected with T. vivax stock IL 3913, G. morsitans centralis Machado and a steer infected with T. congolense, and G. morsitans centralis and a steer infected with T. vivax. The four experiments were replicated once, making eight experiments in total. In three experiments there was increased tsetse feeding success, measured at 1 min, after a steer became infected (T. congolense, two experiments and T. vivax, one experiment). Analysis of all data combined found no significant differences in tsetse feeding success on the different groups of cattle prior to infection, but after infection tsetse feeding success was significantly greater on the infected cattle (P< 0.001). Trypanosoma congolense infection led to a greater increase in tsetse feeding success than T. vivax infection. The increase in feeding success was not related to changes in the level of anaemia, skin surface temperature or parasitaemia. A possible explanation is the effects of trypanosome infection on cutaneous vasodilation and/or blood clotting in infected cattle. When allowed to feed for 5 min, nearly all tsetse engorged successfully and effects of cattle infection on feeding success were not found.
在野外研究中，采采蝇（双翅目：舌蝇科）在感染刚果锥虫（动质体目：锥虫科）的牛身上取食比在感染活泼锥虫的牛或未感染的牛身上更为成功。在此，我们描述了对这一现象的首次实验室研究。在第一个实验中，将关在笼中的淡足舌蝇放在感染刚果锥虫克隆IL 1180的博拉公牛和未感染的公牛身上取食1分钟和5分钟。在几周内以这种方式记录取食成功率5次。随后，在另外三个实验中使用了相同的方案，组合如下：淡足舌蝇和感染活泼锥虫原种IL 3913的公牛、中喙采采蝇和感染刚果锥虫的公牛、中喙采采蝇和感染活泼锥虫的公牛。这四个实验重复了一次，总共进行了八个实验。在三个实验中，公牛感染后（刚果锥虫，两个实验；活泼锥虫，一个实验），采采蝇在1分钟时的取食成功率有所提高。对所有合并数据的分析发现，在感染前采采蝇在不同组牛身上的取食成功率没有显著差异，但感染后采采蝇在感染牛身上的取食成功率显著更高（P<0.001）。刚果锥虫感染比活泼锥虫感染导致采采蝇取食成功率的增加更大。取食成功率的增加与贫血水平、皮肤表面温度或寄生虫血症的变化无关。一种可能的解释是锥虫感染对感染牛皮肤血管舒张和/或血液凝固的影响。当允许采采蝇取食5分钟时，几乎所有采采蝇都成功饱食，未发现牛感染对取食成功率的影响。
