A PRELIMINARY NOTE ON THE INCIDENCE OF
                    STRONGYLOIDES PAPILLOSUS WEDL, 1856

                                               IN INDIA

                                                    BY

                          S. N. VAIDYANATHAN, G.M.V.C.

Veterinary Assistant Surgeon, Parasitology Section, Madras Veterinary College,
                                                Madras

                        (Received for publication on 5 April 1941)

                                (With Plate I and 10 text figures)

                                        INTRODUCTION

THE genus Strongyloides Grassi, 1879, has an interesting feature among
nematodes. Its members exhibit in their life-cycle, an alternating genera-
tion of free-living and parasitic forms; the factors that contribute to cause
this transformation have not been definitely determined. Amongst parasitic
forms only females are known in all the species; the rarely found parasitic
males are only in the case of Strongyloides of the dog and man. The free-
living forms exhibit sexual differentiation. The parasitic forms occur in the
intestine of vertebrates, the free-living stages in the faeces of the host or in
the soil.

During the course of routine examination of calf dung, in the Parasito-
logy Section of the Madras Veterinary College, numerous ova considerably
larger than oocysts of coccidia and much smaller than the more common
strongyle ova were detected, varying in size from .044 to .052 mm. by .027
to .031 mm. In the fresh faeces, the eggs contained vermiform embryos.

In the faecal culture of calves that revealed these eggs, the infective
larvae of a Strongyloides species have been regularly seen. The cultures have
shown, besides, the free-living forms (females only) of a Strongyloides species
that agrees with the description given by Ransom [1911] for Strongyloides
papillosus. No males could be detected.

The post mortem examination of some of these bovines, whose faeces
contained eggs of the species, has revealed numerous parasitic females of
Strongyloides papillosus mixed up with the contents of the small intestine.

Cultures of dung from sheep brought for slaughter at the Madras
Slaughter House, have also shown the incidence of an infection with Strongy-
loides. A study of the free-living forms developing in them reveal that they
are identical with those met with in taurine faecal cultures.

                                            LITERATURE

Important life-history investigations on the human species (Strongy-
loides stercoralis Bavay, 1876) have been made during the last quarter of the
nineteenth century indirectly leading to furthermore experimental studies
of the present day. Quoting Faust [1937], from his review of the life-history
of Strongyloides, " it has been frequently demonstrated, the fundamental,
basic type of life-cycle of members of this genus involves an indirect mode of
development, with alternation of a parasitic and a free-living phase......
The indirect mode of development undoubtedly precedes the direct mode in

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