The assessment of nematodes as they generate and die is not a simple thing to do due in part to the complexity of the organism, and the fact that still relatively little is known about their physiology and internal biology. Indeed, the pathological changes in the internal organs of the worms are still only recognized in general terms. Obviously dead worms are easily recognized (when fractured, or calcified, etc.) but the lesser obvious changes can be difficult to detect and interpret. The point at which a worm can be defined as dead is not a simple matter; cessation of motility is currently the most commonly used parameter for this but it is not always a robust indicator and better indicators are needed. Various methods can be used to assess the presence, viability, and functionality of nematodes but these must be used with an understanding of the situation at hand and the specific questions being addressed. Careful use of appropriate statistics is essential given the complex nature of the target organism and the variability in the changes that can be seen within even one anatomical component of these worms. Histological assessment of the parasites present in both parasitized host tissues and isolated worms used in in vitro experiments can provide information that gives a more detailed understanding of the changes in nematodes as they degenerate and die. Understanding of the pathways nematodes follows as they degenerate naturally or under various external pressures, such as chemotherapy, remains a fascinating and potentially productive goal for investigation. Likewise, a complete understanding and definition of specific indicators that reflect parasite load, parasite viability, and damage, or reduced fecundity, will greatly help the fight against those nematode infections that currently cause significant burdens of disease in humans and animals.
Part of the book: Nematology