[Relationship between the viability and pathogenicity of Heterskis gallinarum and the intensity of invasion and age of the infested chickens].

It has been found that the survival rate of Heterakis worms in chickens aged from one to seven months is directly dependent on the number of Heterakis eggs that have gained access in them only in the case of lower numbers of infective eggs (10 and 50). At comparatively larger numbers of eggs (500 and 2500) the survival rate has been highest at the 3- and 4-month-old chickens, and the morphologic changes in this age group are most pronouncedly expressed. Investigations have shown that the greatest survival rate corresponds to the weakest increase in the leukocyte count and the amount of the gamma-globulins in the 3- and 4-month-old chickens. In the one- and 2-month-old ones the Heterakis infection has caused a strong increase in the leukocyte count, and in those aged 5-7 month-old there has been also an increase in the gamma-globulins. The biochemical indices and the morphologic changes have not in all cases been directly dependent on the age of the infected birds, the number of the infective eggs given, and the number of the Heterakis helminths that have survived. Heterakis injection caused by a greater number of eggs is present by worms of a smaller size. Chickens infected at the age of more than five months have worms among which the female samples are considerably more than the male ones as compared with the respective numbers found in one- to 4-month-old birds.