微孢子虫（学名：Microsporidia）为一门。它是由孢子形成的单细胞寄生虫。目前多于一百万种微孢子虫中的1500种版命名。微孢子虫只能寄生于动物宿主。大部份的动物物种都可以被微孢子虫寄生，包括人类。它多数感染昆虫，也是甲壳和鱼的常见疾病。一般的来说，已经命名的微孢子虫会专门感染指定的物种。而部分物种可能会感染人类，它们多是伺机感染原，在人体免疫力下降时才造成感染。

约有10%的物种是脊椎动物的病原。

医学导航 · 真菌病

真菌 · 分类

疾病

药物（抗真菌药）

This article describes a parasitic fungi group. For the ascomycete fungi genus, see Microsporum. For the green algae genus, see Microspora. For the beetle family, see Microsporidae.

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The Microsporidia constitute a group of spore-forming unicellular parasites. They were once considered protozoans or protists, but are now known to be fungi, or a sister group to fungi. Loosely 1500 of the probably more than one million species are named now. Microsporidia are restricted to animal hosts, and all major groups of animals host microsporidia. Most infect insects, but they are also responsible for common diseases of crustaceans and fish. The named species of microsporidia usually infect one host species or a group of closely related taxa. Several species, most of which are opportunistic, also infect humans.