ORGANISM IDENTIFICATION: Helminths

Why do helminth larvae need to be identified to the species level; shouldn't all larvae recovered in stool be that of Strongyloides stercoralis?

Although helminth larvae in stool are normally Strongyloides stercoralis, there is always the possibility that in fresh stool hookworm eggs have continued to mature and may hatch before the stool is processed and/or placed in fixatives. It is important to make sure that the larvae seen are, in fact, the rhabditiform (non-infectious) larvae of S. stercoralis rather than larvae of hookworm.