Microsporidia

noun plural

Mi·​cro·​spo·​rid·​ia ˌmī-krō-spə-ˈrid-ē-ə 

: an order of spore-forming protozoans (class Microsporea) that are parasites of various invertebrate and vertebrate animals, that typically invade and destroy host cells, and that include some (as of the genera Enterocytozoon and Nosema) that cause infections in immunocompromised humans

microsporidian

-ē-ən 

adjective or noun