Heterakis gallinarum

                                                           Introduction

Heterakis gallinarum is a heavily prevalent poultry parasite that thrives in the ceca of various species of gallinaceous birds. It is a small roundworm, measuring between 4 and 15 mm long, in the family Heterakidae. Heterakis gallinarum has a direct life cycle not requiring an intermediate host to complete development, and it is generally believed that poultry raised at high density on litter are at greatest risk for accumulating large numbers of the nematode. This species typically only causes mild pathology that does not significantly affect bird performance. However, H. gallinarum is recognized as an economically important parasite by the poultry industry because its ovum serves as the vector for the protozoal parasite Histomonas meleagridis, the cause of histomonosis in poultry. Diagnosis of the nematode typically relies on fecal egg counts, which are prone to false negative diagnoses.

Common name	Caecal worm of poultry
Host	Fowl, Turkey, duck and Pea fowl
Location	Large intestine and Caecum

                                                        Gross

• Whitish small sized worm, 1.5 cm long.
• Large lateral alae extending down the side of the body.
• Oesophagus has strong posterior bulb having valvular apparatus.
• Tail end of male has large alae, circular precloacal sucker and 12 pairs of pedunculated papillare. Spicules are unequal, right one is slender and long. Left one is short and broad.
• Eggs are oval, smooth shelled.
                                                 Life cycle
    
  • Is direct, eggs developed into infective stage in 14 days. Infection of chicken by ingestion of egg containing L₂ stage.
  • L₂ hatch in the intestine move to caecal mucosa and remain there for 2 to 5 days and moult to L₃ in the lumen of caecum on 6^th day of infection.  
  • L₄ in 10 days and L₅ in 15 days. Prepatent period is 24 to 30 days, earthworm may act as transport host.
    
                                               Pathogenesis
  
  
  
  

  • Usually non pathogenic, but heavy infection cause thickening of caecal mucosa with petecheal haemorrhage on the surface.
  • The significance of the worm is that the protozoan viz. Histomonas meleagridis causing black head or entero hepatitis in turkeys is incorporated in the eggs of Heterakis galliarum.
    
    
                                      Diagnosis
    
    

    • Finding eggs in the feces.

    • gross examination of parasite
                                      Treatment
    
    
    

    • Phenothiazine is effective at the dose rate of one gram per bird.
    • Phenothiazine + Piperazine mixture is used to eliminate the mixed infections of H. gallinarum and A. galli.
    • Hygromycin B - 0.25% mix in feed is highly effective.
    • Mebendazole is also be used.

    
                                       Prevention
     
    
    

    • Strict sanitation of poultry houses is essential.
     
     

    

    Heterakis gallinarum egg