カンジダ症は酵母様真菌による日和見感染症で、主にCandida albicansが分離され、多くの場合は特に何の影響も与えないのですが、二次的に増殖して影響を与えます。C.tropicis、C.parapsilosis、C.glabrata、C.rugosaなども時に分離されます〔Cafarchia et al.2006,Anna Glushakova et al.2023,Brilhante et al.2013,Moretti et al.2000,Ugochukwu et al.2022〕。
カンジダ属の酵母菌は人および様々な動物の消化管の正常な微生物叢の一般的な構成菌で、出芽によって増殖し、条件によっては菌糸に近い姿(偽菌糸)をとることもあります。酵母から菌糸形態への移行は、真菌が病原性状態に入ったことを示すという報告もあります〔Arné et al.2020,Tartor et al.2022〕。
発症要因
カンジダ菌は組織損傷、免疫抑制、長期間または不適切な抗菌療法などの素因により、微生物叢の不均衡が生じ、過剰増殖が促進されます〔Arné et al.2020〕 。免疫力が不十分な雛や幼若鳥、他の疾病に罹患しての免疫不全の鳥に見られ〔Gupta et al.1994〕、また手乗りのための挿し餌の流動食に含まれている過剰な糖質や澱粉が酵母菌の生育に最適になることもあります〔Wyatt et al.1975,Magalhaes et al.2019〕。抗菌薬を投与されている鳥やビタミンA欠乏は微生物叢が崩れやすくなり、粘膜の防御機構を混乱させる可能性があります。
好発鳥種
ガチョウ、アヒル、ブロイラー、ホロホロ鳥、キジ、ウズラ、ハト、オウム、猛禽類など多くの鳥種で報告されています〔Domán et al.2021,Donnelly et al.2019,Liu et al.2018,Magalhães et al.2019,Pitarch et al.2017,Sokół et al.2018,Wang et al.2022,Wyatt et al.1975〕 。
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