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NOTES ON LARVAL FLUKES FROM CHINA 1 . 
By ERNEST CARROLL FAUST, Ph.D., 
Peking Union Medical College , Peking , China. 
(With Plates XXI and XXII.) 
In connection with a survey carried on during the past three years to determine 
the helminth parasites of China and their incidence in various parts of the 
country, I have had occasion to examine several thousand molluscs, particularly 
gasteropods, with a view to ascertaining the degree of their infection with larval 
flukes. Examinations thus far have been made in the areas around Peking, 
Yli Tai Ho (Shansi Province), Wuchang (Hupeh Province), Changsha (Hunan 
Province) and Kiukiang (Kiangsi Province). In Peking examinations have 
been fairly continuous during the entire period; in the other centres only 
summer examinations were possible. 
The host species represented in the investigations, together with the 
localities where they were found, the numbers examined, and the parasites 
obtained, are presented in Table I. I am greatly indebted to Mr Bryant Walker, 
of Detroit, Michigan, and Mr Frank C. Baker, of the Natural History Museum, 
Urbana, Illinois, for identification of the hosts. 
While the Peking molluscs show an average incidence of infection which 
compares favourably with that of the more humid areas in China, analysis 
of the data reveals a distinct seasonal variability. During the winter the only 
parasites present are encysted agamostomes and these are relatively few. 
However, from the latter part of March to the 1st June, there is a rapid 
development of larval flukes. This period represents the migratory season of 
birds, so that it is more than likely that the infection is an extra-territorial one 
superimposed on the area. This belief is borne out by considerable confirmatory 
data. Birds caught during their migration through North China especially 
in the spring, are heavily parasitised by flukes, while very few animals 
indigenous to the Peking area have an appreciable infection with this group 
of worms. Moreover, the infection-incidence of snails of the area is lowered 
during the summer but reaches a second peak in the autumn following the 
return of birds to the south. 
On the other hand, the records from the Yangtze valley indicate just the 
reverse. In most cases the parasitisation of the mollusc is not overwhelmingly 
1 Contribution from the Parasitology Laboratory, Department of Pathology, Peking Union 
Medical College. 
