Microfilaria is the term used to refer to the larva of a certain parasitic nematode, i.e., filariae

when it is still in an early larval stage. These parasites are released into the bloodstream of

the host by the adult parasites. And hence, these embryonic larvae are usually found in the

blood of an infected person. This parasitic nematode, filariae, belongs to the family of

Onchocercidae. And they are the cause behind the diseases such as elephantiasis, river

blindness, Loa loa filariasis and so on.