Changes

==== Life-Cycle ====

==== Life-Cycle ====

#Adult worms in tracheae and larger bronchi – females lay embryonated eggs

The adult worms are found in the trachea and the bronchi.  The female lays embryonated eggs, which are later coughed up and swallowed.  The eggs hatch during the passage through the intestinal system.  First stage larvae are passed in the faeces of the host. Development into L2, and later L3, occurs within the faeces on the pasture. 

#Embryonated eggs are coughed up and swallowed

 

#Eggs hatch during passage through the intestine

A new host is infected by ingestion of infective larvae whilst grazing.  These infective larvae are passed through the alimentary tract, where they penetrate the wall of the ingestine.  The larvae then migrate to the lungs, via the lymphatic system, or the blood circulation.  These ascend the respiratory tree, where they mature into adult lungworms.

#First stage larvae passed in fresh faeces (as ''D. viviparus'' is not a metastrongyloid, the larvae do not have an S-shaped tail like other lungworms)

 

#Development to second and third (infective) stage larvae in dungpat on pasture

The prepatent period is 3.5 weeks.

#Ingestion of infective larvae at grazing

#Infective larvae swallowed, pass through alimentary tract, penetrate wall of intestine and migrate via lymphatics → blood circulation → lungs

#Ascend respiratory tree and mature to adult lungworms. Prepatent period 3 and a half weeks

*''Dictyocaulus viviparus'' causes [[Respiratory Parasitic Infections - Pathology#Dictyocaulus viviparus|parasitic bronchitis]]

*''Dictyocaulus viviparus'' causes [[Respiratory Parasitic Infections - Pathology#Dictyocaulus viviparus|parasitic bronchitis]]