output not only insures the conservation of 
the species, but indicates the existence of a 
relatively quick and easy way of leading the 
eggs to the outside world without striking 
symptoms. Thus the facility, with which the 
infection is overlooked, may be understood. 
Prognosis, Therapeutics and Prophyla- 
xis of Schistosomatosis. 
From our observations already refered 
to, one may conclude that in our country 
schistosomatosis is mostly not severe. GON- 
ZALEZ-MARTINEZ estimates that 45 9/0 of 
the infected show no clear symptoms and I 
think that in Brazil the proportion of unre- 
marked cases is rather higher than lower. On 
the other hand I dont know of any treatment 
for curing or improving this infection 15), 
while some of my observations show that 
these flukes may live for many years in the 
human body. Therefore our principal efforts 
must be directed to the prevention, rather 
than to the cure of this infection. 
Schistosomatosis is always dependent on 
water, either used for drinking or coming 
in contact witb the skin. As its infectiveness 
is necessarily connected with the presence of 
certain species of Planorbis, it is evident 
that prophylaxis ought to be directed in the 
first line against these intermediary hosts. 
The water collections might be cleaned by 
removing mud and aquatic vegetation and 
catching the specimens in sight, but these 
measures wili be often difficult or impossible 
just there where they are most needed. 
There are other measures for preventing 
the infection of the snails, which would also 
tend to eradicate the even more common 
and dangerous ankylostomum and necator in- 
fections. They are directed against the conta- 
mination of soil and water by human excre- 
ments. It is clear that sewers opening into 
rivers, the water of which is used for bathing 
and washing, could not be tolerated. 
If suspect water must be used, a stora- 
ge for 24-48 hours would be a sufficient pro- 
tection. Early in the morning the water is 
not likely to contain cercariae; taken near to 
129 
the surface and stored for a few hours it 
will lose any power of infection. The same 
may be achieved by heating (which need 
not attain the boiling point) or by desinfec- 
tion. According to LEIPER it is sufficient 
to heat the water up to 50 °/o or add one 
gramme of sodium bisulfite to the liter. 
The danger of bathing in stagnant 
water. 
Pianorbis (of the larger species) are found 
in waters with little or no current, not 
subject to complete evaporation and prefera- 
bly with floating or rooted water plants 
Such waters may be dangerous, when drunk, 
but would be avoided, when there is a choice 
in the supply of drinking water. But already 
the contact with the bare skin of legs and 
arms, as in fishing and washing, may cause 
more or less severe infection; however the 
greatest danger consists in total and prolon- 
gated immersion while bathing, as the chances 
of infection increase in proportion to the 
surface exposed and the time of contact. I 
know the history of several patients who 
were in the habit of bathing in stagnant 
water with water plants and ampullariae. 
These much larger snails are eatable and 
better known; they niay thus serve as indicators 
for suspect water. A few patients had even 
noticed the presence of Planorbis. In some 
places, for instance in Aracajú, Planorbis oli- 
vaceus may become so abundant in dry times 
that it is used for feeding pigs. There and 
also in Laranjeira, we found ponds, whose 
popular name indicates that people who bathe 
feel itching afterwards. This is quite a carac- 
teristic symptom of the penetration of the 
cercariae, as experiments in animals, princi- 
paliy in white rats, clearly show. 
To become infectious the water collections 
must be contaminated with Sch. eggs coming 
from the intestine of man or animals. This 
may happen at any time but mostly in con- 
sequence of showers and inundations. Of 
course the water must also contain specimens 
of Planorbis. At a sufficiently high tempera- 
ture, after 4—5 weeks, there may be infected 
