30
STUDIES
ON
NASAL
SCHISTOSOMIASIS
[Vol. XXIV, Part I,
The incidence and distribution of both the infections were also worked out by
examining population samples of diagnostic material in several locations. An
account is given of the incidence of these infections in two different localities, with
observations on age and sex incidence. Each focus of infection is fairly well circums-
cribed.
2. Investigations have proved beyond doubts that cattle are the chief definitive
hosts of Schistosoma nasale and while all ages and sex seem to contract the infection
equally, if exposed to it, older animals and males are the chief sufferers and carry
the disease owing to their more frequent contacts with infected foci.
3. A study of the molluscan fauna of the areas in relation to the incidence of the
disease indicates that Limnaea luteola and L. auricularia race rufescens are the
intermediaries of schistosomiasis and fascioliasis respectively.
All available fresh-water snails in the areas surveyed are specifically determined
and recorded with illustrations.
4. The very fragile nature and quick hatchability of S. nasale eggs are indicated.
5. In determining the prevalent species of Fasciola in the area it was found that
it was a new species of the genus, Fasciola indica Varma 1953, quite distinguishable
from either F. hepatica or F. gigantica.
6. Some control measures of practical value, both preventive and curative, are
suggested. In this connection it is also considered necessary that ecological aspects
of the molluscan vectors and their relationship with the parasites be studied in detail,
as they are likely to prove of great value in eradicating the infections.
7. Cercariae indicae LVII Sewell [1922], are reported from another host, Indo-
planorbis exustus, in the district of Saharsa of this State. Also, a new cercaria
belonging to 'Agilis' group of Sewell [1922], is reported from Indoplanorbis exustus.
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