• *Capillaria*

There are several species of *Capillaria* that occur in poultry in **Figure 3**. Male *capillaria* are 15–25 mm length and female *capillaria* are 35–80 mm long filamentous worms (females). Males only have one spicule, and many also have an early form of a bursa. The size of the eggs varies depending on the species; they contain bipolar plugs and thick shells. Important species include*; C. annulata, C. anatis and C. contorta. Capillaria annulata* and *Capillaria contorta* occur in the crop and esophagus. In the lower intestinal tract, there may be several different species but usually, *Capillaria obsignata* is the most prevalent. These species may cause thickening and inflammation of the mucosa. The life cycle of this parasite is direct. The adult worms may be embedded in the lining of the intestine. The eggs are laid and passed in the droppings. The created embryo will take 6 to 8 days, the eggs are infective to any other poultry that may eat them. The most severe damage occurs within 2 weeks of infection [29]. Approximately 1 cm (0.39 in) long, adult *Capillaria* are "threadlike" worms that are extremely thin.

**Figure 2.** *Anterior end Sublura sp. [29].*

*Poultry Farming: New Perspectives and Applications Chapter – Parasitic Diseases of Chickens DOI: http://dx.doi.org/10.5772/intechopen.109962*

### **Figure 3.** *Adult male of Capillaria sp. [31].*

Their barrel-shaped eggs contain clear pugs on each pole and can only be seen under a microscope. There are various different *Capillaria species*, and each one infests a certain area of the chicken. Some species, including *C. annulata* and *C. contorta*, can infiltrate the esophagus and crop, thickening and inflaming the mucous membranes. Other pathogens, including *C. bursata, C. caudinflata*, and *C. obsignata*, attack the lower intestinal tract and cause inflammation, bleeding, and erosion of the intestinal lining. *Capillaria* can be lethal to the chicken if they are present in large enough quantities.
