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sheep and goats is Haemonchus contortus and in cattle Mecistocirrus digitatus.
Fourie [1931] compared the anaemias of haemonchosis in sheep to that caused
by daily withdrawal of blood from the jugular vein and found the two anaemias
to be haematologically identical. In 1934, Martin and Ross attempted
to estimate the amount of blood withdrawn by Haemonchus contortus from the
amount of phosphorus eliminated with the eggs of the worms. It was found
that even in moderate infestations about 30 c.c. of blood was used daily by the
worms. This is the minimal figure and probably the actual amount would be
several times more. Apart from the larvae of certain roundworms which pass
through the lungs during their course of migration in the body, there are several
worms which have their final habitat in the lungs, and produce marked pul-
monary symptoms. Lungworms are specially dangerous in calves, sheep and
goats. Another worm which is particularly dangerous to young animals is
the ascarid parasite of calves and foals. Though, in the adult stage, amphis-
tomes are practically harmless, they are highly pathogenic in their immature
stages which are passed in the duodenum and intestine. The immature stages
of amphistomes, specially of Cotylophoron cotylophorum, are often responsible
for alarming symptoms, such as persistent foetid diarrhoea, oedema of the
submaxillary space, intestinal haemorrhage and general unthriftiness, etc.,
and consequent high mortality. Recently, two other important diseases of
bovines have been found to be due to helminths. They are nasal schistoso-
miasis and cutaneous microfilariasis. Besides the above, whipworms,
intestinal nodule worms and tapeworms are often responsible for much damage
to ruminants.
POULTRY
Helminths do considerable damage to poultry. Instances are not rare
when most of the birds in a flock are lost as a result of worm infestations. The
most harmful trematode of poultry is the one—Prosthogonimus sp.—found
in the oviducts of birds. The worm, which usually lives in the Bursa fabricii,
enters the oviduct in laying birds and is responsible for acute inflammation
resulting in the production of abnormal eggs and discharge of albumen. Owing
to irritation, retroperistaltic movements are set up in the oviduct causing bro-
ken eggs, egg contents and parasite material to enter the peritoneal cavity
and giving rise to acute peritonitis which is often fatal. The eggs, if laid, are
soft-shelled. Birds are often infested with large numbers of tapeworms of
varying degree of pathogenicity. Taeniasis in poultry may be responsible for
marked enteritis, rapid wasting and death. Raillietina tetragona and R.
echinobothrida cause the formation of nodules resembling those of tuberculosis.
Apart from causing general loss of condition due to haemorrhage and enteritis,
the large roundworms of poultry cause shrinking of the thymus gland and a
decrease in blood sugar, increasing thereby the susceptibility of birds to certain
infectious diseases, such as roup. The gapes are most dangerous to chicks, in
which they give rise to dyspnoea and asphyxia, besides progressive emaciation.
The stomach worms of poultry produce marked irritation, inflammation,
ulceration and nodules in the gizzard and proventriculus. The nodules at
E