83 
BILHARZIASIS IN NATAL. 
By F. G. CAWSTON, M.D. (Cantab.). 
CONTENTS. 
PAOE 
Introduction.83 
History.84 
Experiments in Natal ..85 
Recent researches ...... 86 
Distribution ........ 86 
Fresh-water snails of Natal ...... 87 
Further experiments in Natal . . . . . 88 
Prognosis .......... 89 
Life insurance ... .... 89 
Treatment .... ... 92 
Conclusions ..93 
INTRODUCTION. 
In the following pages I shall endeavour to describe the present state of our 
knowledge of Bilharziasis in Natal and the result of some personal observa¬ 
tions extending over the last seven years. The investigations of the Bilharzia 
Mission to Egypt 1 have drawn attention to the various forms of cercariae 
which infest .several species of fresh-water snail in African rivers. The 
cercariae which give rise to Bilharzia disease in Egypt are furcocercous 
cercariae, i.e. they possess a tail which is divided for a greater or shorter 
portion of its length. They are characterised, further, by the absence of a 
pharynx at the commencement of the oesophagus. Similar cercariae are 
present in one of the species of fresh-water snail which abounds in the infected 
areas of Natal. 
In some localities, the custom of the South African natives in anointing 
the skin with grease and oil may be nature’s own preventative against the skin- 
infection through cercariae. During the visit of the Bilharzia Mission to Egypt 
it was observed that cercariae would attack all parts of the bodies and limbs 
of young rats and mice that were immersed in water containing them. 
As long ago as 1872, T. S. Cobbold was of opinion that the disease was 
caused as a result of drinking water containing snails or the little cercariae 
which are often present in snails from the rushes of slow-running streams or 
stagnant bathing-pools; but only recently has it been known that infected 
snails were so intimately associated with the disease. 
1 Journ. Roy. Army Med. Corps for 1915—July, August and September. 
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