64 
Bilharziasis 
As we suggested in 1916, the ideal procedure would be to confine those cases 
known to be infested with bilharzia that have returned to Australia to sewered 
areas, at all events till they have learned to appreciate their potential danger 
to any community. These suggestions, we understand, have been carried out. 
These measures alone might appear sufficient to prevent the disease ever 
becoming endemic in Australia, but such is really not the case. We have met 
with fully 20 cases styled “Latent Bilharziasis.” These patients have either 
no symptoms at all, or their symptoms have been so slight as to be entirely 
disregarded. Nevertheless, the examination of their excreta has revealed the 
presence of lateral or terminal spined ova. It is in infestations with S. mansoni 
that latency is most frequently seen. Most of these “latent” cases were diag¬ 
nosed in a routine examination of a large number of sera by means of the speci¬ 
fic complement deviation test for this disease. They have been more fully dealt 
with in previous publications. ( Journ. Roy. Army Med. Corps, iv. and vi. 1919.) 
From the above it will be seen that the existence of the disease in people 
who are unaware of, or neglect the signs of, its presence, considerably compli¬ 
cates the problem of the prevention of the spread of this disease into a com¬ 
munity. It is the carrier problem over again! 
(2) The destruction of intermediary hosts. The destruction of the molluscan 
fauna of a country, such as Egypt, would lead to the disappearance of bil¬ 
harziasis in man and of a number of “trematode diseases affecting animals. 
In a country with an intensive system of irrigation, such for instance as 
Egypt, the molluscan fauna becomes a universal and persistent scourge. Many 
measures have been proposed for the eradication of the intermediate snail hosts. 
Dr C. Todd, the Director of Public Health, informs us that several years 
ago the possibility of reducing the molluscan fauna by means of ducks and 
wild fowl was carefully considered, but the idea was rejected as impracticable 
for Egypt 
More recently, Major T. Cherry has advocated this method as applicable 
to Australia. While it is possible that the presence of ducks and other wild 
fowl might materially help to diminish the number of molluscs in localized 
water areas, it is far from being the solution of the problem of Egyptian 
bilharziasis, and at most can only be regarded as a possible accessory measure. 
In 1915, Leiper, in his “suggestions for the eradication of the disease in 
Egypt,” proposed that the annual rotations in the supply of water enforced 
by the Government from April to August in Lower Egypt, should be utilized 1 
to destroy the molluscan fauna. 
During the periodical stoppages of water supply for 15 days, the canals 
become dry except for small puddles. By the systematic use of destructive 
chemical reagents, Leiper suggested that the number of contained molluscs 
could be considerably reduced. It may be that methods of this sort, if they 
could be attempted, would be possible for the smaller, but not for the large 
canals. There are obviously many grave objections to this scheme, as the whole 
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