Identification of Eimeria species in field isolate
A total of 318 samples were collected from chicken farms in the Hubei and Henan provinces (Fig. 1). Each isolate was amplified with seven pairs of species-specific primers (Fig. 2). The specific identification results of each sample are shown in Table S2-1 and Table S2-2. We found that E. mitis (66.67%), E. tenella (46.86%), and E. necatrix (41.51%) were the most prevalent species in the Hubei and Henan provinces (Table 2). In the Henan province, E. mitis (78.57%), E. tenella (39.01%), and E. necatrix (36.26%) (n = 182) were the most common species, while in the Hubei province (n = 136) the most prevalent species were E. tenella (57.35%), E. mitis (50.74%), and E. necatrix (48.53%) (Table 2).
Table 2
The relative pathogenicity and occurrence (number and ranking) of Eimeria species detected on poultry farms sampled in Henan and Hubei Provinces. na = not applicable. Rankings 1–7 indicates most to least common
Eimeria species | Hubei (n = 136) | Henan (n = 182) | Henan and Hubei Provinces (n = 318) |
No. positive (%) | Rank | No. positive (%) | Rank | No. positive (%) | Rank |
Any Eimeria species | 133(97.79) | na | 176(96.70) | na | 309(97.17) | na |
Eimeria necatrix | 66(48.53) | 3 | 66(36.26) | 3 | 132(41.51) | 3 |
Eimeria brunetti | 13(9.56) | 7 | 8(4.40) | 6 | 21(6.60) | 7 |
Eimeria tenella | 78(57.35) | 1 | 71(39.01) | 2 | 149(46.86) | 2 |
Eimeria acervulina | 43(31.62) | 4 | 28(15.38) | 5 | 71(22.33) | 5 |
Eimeria maxima | 21(15.44) | 6 | 1(0.55) | 7 | 22(6.92) | 6 |
Eimeria mitis | 69(50.74) | 2 | 143(78.57) | 1 | 212(66.67) | 1 |
Eimeria praecox | 43(31.62) | 4 | 63(34.62) | 4 | 106(33.33) | 4 |
Geographically, the distribution of E. mitis and E. tenella in the Henan and Hubei provinces was more widespread than that of the other species. E. necatrix was mainly distributed in the northern (Anyang, Puyang, Hebi, and Xinxiang) and central (Zhengzhou and Xuchang) Henan and in the northeastern (Suizhou, Xiaogan, Huanggang, and Wuhan) and southwestern (Enshi Tujia and Miao Autonomous Prefecture and Yichang) Hubei (Fig. 3a). E. tenella was not detected in Kaifeng, Jiaozuo, Nanyang, and Shangqiu of the Henan Province (Fig. 3b) and Xiangyang of the Hubei province (Fig. 3c). Only the chicken feces samples from Yichang and Wuhan in the Hubei province did not show E. mitis (Fig. 3c). Additionally, we found that E. maxima was detected only in Sanmenxia of the Henan Province (Fig. 3b) and Wuhan, Huanggang, Suizhou, Xiaogan, Yichang and Enshi Tujia, and Miao Autonomous Prefecture in the Hubei province (Fig. 3c).
Mixed-species infections were common in the Hubei and Henan Provinces (Fig. 4a). The single Eimeria infection rate was lower in the Hubei province (15.44%) than in the Henan province (34.07%) (Fig. 4b), while the proportion of isolates mixed infected with two (Hubei versus Henan: 36.76% versus 26.92%), three (Hubei versus Henan: 29.41% versus 26.37%), and four (Hubei versus Henan: 12.50% versus 4.40%) species of Eimeria isolates was higher in Hubei than in Henan and the emergence of mixed coccidial infections involving six species of Eimeria appeared only in the Hubei province (2.21%) (Fig. 4b), especially in Suizhou and Huanggang (Fig. 4a). Therefore, it could be preliminary indicated that the Hubei province showed a higher proportion of mixed infections than the Henan province did.
Mixed-species infections were common irrespective of the type of the chicken; indigenous chicken was infected with one (indigenous chicken versus layers and broilers: 47.73% versus 22.67% and 12.24%) or two (indigenous chicken versus layers and broilers: 36.36% versus 29.33% and 34.69%) Eimeria spp. higher than layers and broilers. While indigenous chicken was infected with three (indigenous chicken versus layers and broilers: 6.82% versus 32.44% and 24.49%) or four (indigenous chicken versus layers and broilers: 4.55% versus 8.44% and 8.16%) Eimeria spp. lower than layers and broilers; the emergence of mixed infections involving six Eimeria spp. appeared in the layers (1.33%). It could be preliminary concluded that indigenous chicken showed a lower degree of mixed infections than layers and broilers (Fig. 4c).
Sulfachloropyrazine sodium (SC) sensitivity of Eimeria
In this study, among the 94 isolates selected (Table S3), 53 were from the Henan province and 41 were from the Hubei province. We found that 25 of the isolates—16 Henan and nine from Hubei—had an ACI of less than 160, indicating that these strains were fully resistant. ACI of 24 strains—16 Henan and eight from Hubei—was 160–180, indicating that these strains were partially resistant. The ACI of the other strains was > 180, indicating that these strains were not resistant (Table 3).
Table 3
༎Summary information of Anticoccidial index (ACI)
District | Henana | Hubeib | Total |
ACI༜160 | 16 | 9 | 25 |
160 ≤ ACI༜180 | 16 | 8 | 24 |
ACI ≥ 180 | 21 | 24 | 45 |
Total | 53 | 41 | 94 |
a Henan, Henan Province, China; b Hubei, Hubei Province, China |
Geographically, we found that the sulfa-resistant Eimeria spp. were distributed in the central (Zhengzhou, Kaifeng, Xuchang, Luohe, and Zhumadian) and western (Sanmenxia, Luoyang, and Jiyuan) parts of Henan (Fig. 5). In Hubei, it was distributed in the northwest (Shiyan and Shennongjia Forest Area) and southeast (Xiantao, Xianning, and Huangshi).
Four urban areas in Henan (Hebi, Xinxiang, Shangqiu, and Nanyang) account for more than 50% sensitivity to sulfa drugs (ACI > 180). In Hubei, nine cities have a sensitivity of more than 50% to sulfa drugs, including Xiangyang, Suizhou, Huanggang, Wuhan, Ezhou, Yichang, Jingmen, Tianmen, and Jingzhou (Fig. 5).