H. D.
SRIVASTAVA
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with the large intestinal round-worm. This age resistance is so marked that
the chickens, which are kept worm-free for the first three or four months of
life, can be safely run on infected ground with little danger of subsequent ill-
effects. In such birds the parasite experiences great difficulty in establishing
itself. The age resistance appears to be associated with certain growth in-
hibiting factors in the serum of the chicken, the nature of which is not definitely
understood. This resistance in the bird is further assisted by the development
of an acquired resistance in fighting the infestation.
The latter resistance
develops as a result of the larvæ attacking the intestinal wall which produces
a marked eosinophilia and a concentration of the blood leucocytes and the
cells of the reticulo-endothelial system in the intestinal wall. From the above,
it appears that few worms will survive to the adult stage in aged birds, which
have been exposed to repeated infestations with the parasite. But, in reality,
serious infestations in such birds are by no means uncommon. This is due to
the fact that the age and acquired resistance of the host to infestation breaks
down in some way or other. It has been demonstrated that the factors affect-
ing the general well being of the host, such as a diet deficient in vitamin-A
and-B and in animal protein, loss of blood, bacterial, protozoan and other
diseases, etc. break down the age and acquired resistance of the bird and
render it susceptible to infestation with these parasites.
The infestation with these worms is diagnosed by the finding of the eggs
in the faeces or of the parasite in a selected case on autopsy. The eggs of this
parasite should be distinguished from those of the caecum worm, which are
comparatively more rounded at either end with their sides less convex.
There are two methods of treating ascaridiasis in poultry: individual
and flock treatments. In the individual treatment, each bird receives the
required full dose of the drug, which ensures greater success ; while in the flock
treatment a number of birds are treated simultaneously by means of a vermi-
fuge which is mixed with the mash. Obviously the efficiency of the latter
method of treatment is comparatively low, for it is impossible to ensure the
intake of a requisite amount of the treated mash by each bird. Moreover,
an impaired appetite and the unpleasant taste of the treated mash render the
intake of a proper amount of it by each bird difficult. A number of drugs
have been used for the treatment of ascaridiasis in poultry. For the indivi-
dual treatment, the important drugs are a solution of nicotine sulphate (40 per
cent nicotine), Iodine Vermicide, oil of chenopodium, carbon tetrachloride
and tetrachlorethylene. In addition to these, a large number of others have
been employed with varying degrees of success.
In the treatment of ascaridiasis, several workers have obtained highly
satisfactory results with Blackleaf 40, which is a proprietary nicotine sulphate
compound containing 40 per cent nicotine. This drug, when given in
sufficient quantity to be effective, is toxic to the host and hence is used with
Lloyd's alkaloid reagent—a special type of Fuller's earth, which renders it
non-toxic. 6.6 c. c. (7 .92 gm.) of Blackleaf 40 and 16 gm. of Lloyd's reagent
are mixed and administered in doses of 350-400 mg., without any previous