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Pathogenicity and drug resistance of the Eimeria tenella isolate from Yiwu, Zhejiang province, eastern China

2023; Elsevier BV; Volume: 102; Issue: 8 Linguagem: Inglês

10.1016/j.psj.2023.102845

1525-3171

Hongchao Sun, Xinyao Su, Yuan Fu, Lili Hao, Zhou We, Zhijin Zhou, Jing Huang, Yimin Wang, Tuanyuan Shi,

Animal Nutrition and Physiology

Chicken coccidiosis can cause severe enteritis with high mortality, which causes serious economic losses to the global breeding industry each year. The most virulent strain is Eimeria tenella (E. tenella), but the infectivity of different E. tenella varies among geographic strains. At present, there are no reports related to the pathogenicity and drug resistance of E. tenella in Yiwu, Zhejiang province, China. A total of 600 faecal samples were collected from 10 farms in Zhejiang province, the overall oocyst prevalence was 54.2% (325/600). The prevalence was significantly higher (P<0.01) in chickens under 40 days (97.5%) than that in chickens between 60-85 days old (40.5%) and chickens over 90 days old (24.5%). E. tenella stain was isolated from fecal samples of chickens in Yiwu and the pathogenicity of this isolate were determined, and then we recorded the survival rate, bloody stool score, lesion score, average weight gain. The results showed that all of the chickens infected with 5 × 105 sporulated oocysts of E. tenella died after the 7th day of infection, the bloody stool score and average lesion score of chickens from group 1 (5 × 105), group 2 (5 × 104), group 3 (5 × 103) and group 4 (5 × 102) decreased successively; the average weight gain (g) and relative weight gain (%) increased successively; the weight gain of the low-dose coccidian infection groups (5 × 103 and 5 × 102) were higher than the other two groups (5 × 105 and 5 × 104) (P<0.05). Finally, The E. tenella isolate was tested for sensitivity to six anticoccidial drugs (sulfachloropyrazine sodium, amproline, toltrazuril, clopidol, salinomycin and nicarbazine) using four indexes including anticoccidial index (ACI), percent of optimum anticoccidial activity (POAA), reduction of lesion scores (RLS) and relative oocyst production (ROP). The results showed that this isolate have developed severe resistance to drugs of salinomycin and nicarbazine, moderate resistance to amproline and clopidol, slight resistance to toltrazuril, while the E. tenella isolate performed more sensitive to sulfachloropyrazine sodium.