The life cycle is direct and similar to the other
Trichostrongyles. Arrested development is an important feature of the life cycle.
Cooperia are generally considered to be mild pathogens. They contribute secondary
effects to the primary pathogens Ostertagia and Haemonchus in parasitic
gastroenteritis. However, Cooperia punctata, pectinata and suranabada are
believed to be more pathogenic since they penetrate the mucosa during larval development
causing changes similar to those of intestinal species of Trichostrongylus.
Patterns of transmission are different depending on the species. In temperate climates
the patterns follow Ostertagia with winter hypobiosis at the L4 stage in the northern
hemisphere. In subtropical areas the patterns of transmission follow those of Haemonchus
with hypobiosis during the dry seasons.
A variety of clinical signs have been attributed to Cooperia species and these
include diarrhea, weight loss, anorexia and poor weight gains.
Cooperia infections are usually secondary contributors to parasitic gastroenteritis
caused by the more important nematodes, Ostertagia and Haemonchus. Therefore, they are
rarely diagnosed as monospecific infections. However, like most other trichostrongyles,
females pass strongyle-type eggs that may be found in host feces. The image to the right
shows strongyle-type eggs (including Cooperia) and a Nematodirus egg (A)
in a fecal sample.