H. D. SRIVASTAVA                                   117

Trichinella spiralis. The infestation is acquired by eating raw or improperly
cooked pork containing the encysted larvae. Heavy infestations are often
fatal.

C. PARASITES WHICH LIVE AS ADULTS IN MAN AND AS ADULTS IN ANIMALS

The most important disease under this group is the well-known ' Hydatid '
caused by the bladder worm stage of Echinococcus granulosus of dogs, cats and
wild canidae. The intermediate hosts of this tapeworm are legion, almost any
mammal. There are a large number of trematodes of birds and mammals,
the cercariae of which actively penetrate into the skin and produce a marked
local reaction known as cercarial dermatitis. Analogous to this is the condi-
tion known as ' Creeping eruptions ' which is caused by a variety of parasites
of lower animals penetrating into the skin of man and finding the environment
unsuitable, move about in or under the skin. The commonest of such parasites
is the immature hookworm of dogs and cats.

Apart from the parasites which are injurious to man in one way or other,
there are several which by their presence render meat unfit for human con-
sumption, e.g., liverflukes, tapeworms, hydatid cysts, kidney worm and
Onchocerca sp. in muscles, etc.

Though there are at present no statistics to show the actual economic loss
due to helminths in this country, few will deny the importance of helminths as
factors determining the health of stock. The problems of veterinary hel-
minthology are highly complex. These parasites are highly specialised and
have acquired a high degree of adaptation to their peculiar modes of life.
The relations existing between them and their hosts are in all respects
governed by their life-history. A detailed knowledge of their life-histories is
necessary to determine the nature and extent of the pathological conditions
to which they give rise or to devise means of protection against them. As
development of science makes it possible to keep more and still more animals on
a limited area, so also does it make an increase in the number of their para-
sites possible. Unless helminth parasites are studied systematically and
thoroughly, the list of obscure and undiagnosed diseases, puzzling anaemias
and mysterious enlargement of organs will remain lengthy and will continue
to be a stumbling block in the conservation of animal health in this country.

                                        REFERENCES

Africa, C. M., Leon, W. De and Garcia, E. Y. (1935). Philip. J. Pub. Health 2,
Nos. 1-2, pp. 1-22.
— (1935). J. Philip. Is. Med. Assn. 15, 11, pp.
585-592.
—(1936). Ibid. 16, 1, pp. 22-26.
— (1936). Philip. J. Pub. Health 3, Nos. 1-2, 27.