Trail J C, d'Ieteren G D, Viviani P, Yangari G, Nantulya V M
International Livestock Centre for Africa (ILCA), Nairobi, Kenya.
Vet Parasitol. 1992 May;42(3-4):213-23. doi: 10.1016/0304-4017(92)90063-f.
Relationships were evaluated between trypanosome infection as measured by antigen detection enzyme immunoassays (antigen ELISA), anaemia as determined by average packed red cell volume (PCV), and animal performance as assessed by daily weight gain in 99 N'Dama cattle in Gabon exposed to natural tsetse challenge at 11.5 months of age and recorded 14 times over a 13 week period. Approximately half the animals were found to be infected for an average of five of the 14 times that they were examined: 38% with Trypanosoma congolense, 13% with Trypanosoma vivax and 49% with a mixed infection. Trypanosoma congolense infections had significant deleterious effects on animal growth, while T. vivax infections did not. Animals found on several occasions to be infected with T. congolense had significantly lower PCV values than those demonstrated to be infected on fewer occasions. No relationship was found between mean optical density (OD) values in antigen ELISA and PCV values. Animals capable of maintaining PCV values, even when antigen ELISA positive on a high number of occasions, grew at the same rate as uninfected animals. Animals that could not maintain PCV values when infected had poorer growth. Antigen ELISA has the potential to increase the efficiency of selection of trypanotolerant N'Dama cattle under tsetse challenge in the field, in three main ways. (1) Accurate identification of trypanosome species, especially in mixed species infections, clarifies relations between infection, anaemia and animal performance. (2) Detection of animals antigenaemic without patent parasitaemia could allow individuals with superior ability to control trypanosome infection to be identified. (3) More accurate measurement of the proportion of time an animal is infected allows more accurate evaluation of its anaemia control capability.
通过抗原检测酶免疫测定法（抗原酶联免疫吸附测定，antigen ELISA）检测锥虫感染、通过平均红细胞压积（PCV）测定贫血以及通过日增重评估动物生长性能之间的关系，对加蓬99头恩达马牛进行了研究。这些牛在11.5月龄时面临自然采采蝇挑战，并在13周内记录了14次。大约一半的动物在14次检查中有平均5次被发现感染：38%感染刚果锥虫，13%感染活泼锥虫，49%为混合感染。刚果锥虫感染对动物生长有显著的有害影响，而活泼锥虫感染则没有。多次被发现感染刚果锥虫的动物的PCV值明显低于感染次数较少的动物。抗原酶联免疫吸附测定中的平均光密度（OD）值与PCV值之间未发现相关性。即使在抗原酶联免疫吸附测定多次呈阳性时仍能维持PCV值的动物，其生长速度与未感染动物相同。感染时无法维持PCV值的动物生长较差。抗原酶联免疫吸附测定有潜力通过三种主要方式提高在野外采采蝇挑战下选择耐锥虫恩达马牛的效率。（1）准确鉴定锥虫种类，特别是在混合感染中，可阐明感染、贫血与动物生长性能之间的关系。（2）检测无明显寄生虫血症但有抗原血症的动物，可识别出控制锥虫感染能力较强的个体。（3）更准确地测量动物感染的时间比例，可更准确地评估其贫血控制能力。
