McDougald L R, Hu J
Department of Poultry Science, University of Georgia, Athens 30602, USA.
Avian Dis. 2001 Apr-Jun;45(2):307-12.
The effect of concurrent cecal coccidiosis infections on severity of Histomonas meleagridis (blackhead disease) in chickens was investigated in a series of experiments. Cecal lesions from H. meleagridis were severe in all inoculated control groups and did not appear to be affected by the introduction of Eimeria tenella infection. However, the severity of liver lesions and number of birds positive for liver lesions of H. meleagridis increased significantly with the presence of E. tenella. The increase was similar when 10(3) or 10(4) oocysts of E. tenella were given and was the same when oocysts were given at the same time as H. meleagridis or 4 days prior. The liver lesions increased directly as doses of H. meleagridis increased from 7.5 x 10(3) cells to 30, 100, or 300 x 10(3) when E. tenella was given along with H. melelagridis but not when H. meleagridis was given alone. Administration of a live coccidiosis vaccine containing very low levels of E. tenella also gave a significant boost to liver lesions but at a much lower level than that observed with larger doses of E. tenella. The positive relationship between infections of cecal coccidiosis and H. meleagridis in chickens suggests that such dual exposure may contribute to increased clinical outbreaks of blackhead disease in chickens under field conditions.
在一系列实验中，研究了同时感染盲肠球虫病对鸡的火鸡组织滴虫（黑头病）严重程度的影响。在所有接种的对照组中，火鸡组织滴虫引起的盲肠病变都很严重，似乎不受柔嫩艾美耳球虫感染引入的影响。然而，随着柔嫩艾美耳球虫的存在，火鸡组织滴虫引起的肝脏病变严重程度和肝脏病变阳性鸡的数量显著增加。当给予10³或10⁴个柔嫩艾美耳球虫卵囊时，增加情况相似；当与火鸡组织滴虫同时给予卵囊或在其前4天给予时，情况相同。当与火鸡组织滴虫一起给予柔嫩艾美耳球虫时，肝脏病变随着火鸡组织滴虫剂量从7.5×10³个细胞增加到30、100或300×10³个细胞而直接增加，但单独给予火鸡组织滴虫时则不会。给予含有极低水平柔嫩艾美耳球虫的活球虫病疫苗也显著促进了肝脏病变，但程度远低于用较大剂量柔嫩艾美耳球虫观察到的情况。鸡的盲肠球虫病感染与火鸡组织滴虫感染之间的正相关关系表明，这种双重感染可能导致田间条件下鸡黑头病临床暴发增加。
