The meningeal worm (Parelaphostrongylus tenuis) is a nematode, also known as a roundworm, or meningeal worm, that parasitizes on a number of various ruminant species. White-tailed deer (Odocoileus virginianus) are the primary hosts for P. tenuis, which accounts for the extensive spread of this parasite throughout deciduous northeastern North America. The infected white-tailed deer rarely suffer any negative effects as a result of being infected by this parasite. However, infection can be detrimental to the neurological systems of cervids and camelids, such as moose, elk, and llamas (Bogaczyk et al., 1993; Duffy et al., 2002; Rickard et al., 1994; Samuel et al., 1992).

Physiology is commonly understood as the study of an animal’s anatomy and behavior, and how it works in relation to its environment. The infectivity of P. tenuis can only be understood by considering all of these fields. Therefore, it is important to understand the basic life stages of P. tenuis, as well as the pathway it follows in infecting its host, its host’s reactions, and ecological implications.