SUB-DRAINAGE AS APPLIED TO 
THE ANTI-MALARIAL CAMPAIGN 
ON THE ISTHMUS OF PANAMA 
BY 
HENRY SIMMS 
SAJilTAIV ENGINEER. GOLD COAST, FORMERLY CANAL ZONE, PANAMA 
iReceived for publication 30 October^ 1908^ 
With the growing interest at present taken in anti-malarial work, 
and in view of the large works being at present carried out as a result 
of a fuller realisation of its commercial value, it is believed that the 
value of any information on the results of the practical application of 
successful methods not in general use is sufficient warrant for this 
article. It must be remembered that the methods described are the 
outcome of experience with the somewhat unusual tropical climate 
and topography prevailing on the Isthmus of Panama. The rainfall 
is very heavy, averaging about 180 inches on the Atlantic coast and 
80 on the Pacific. The rainy season lasts from May to December, 
inclusive. 
Ordinary methods in the design of sub-drainage for agricultural 
purposes are not applicable. For the agriculturist the object aimed 
at is the removal of subsoil water. For Anopheline extermination 
the object is to remove all water from the surface, and all puddles 
formed by seepage water, however small. All wet places should become 
thoroughly dry at least once every ten days. Here this must be 
accomplished in the face of continuous rains. An engineer without a 
knowledge of the habits of the Anophelines in question (in this case 
^dlia albimanus, C. argyritarsis, and C. tarsimaculata) would not 
be well equipped for the work. T he results obtained by the sub 
drainage work are shown by its effect on the fever rate. This rate 
shows the number of cases sent to the hospitals monthly as a 
percentage of the number of employees appearing on the rolls of the 
Commission. 
At the start of work on the Canal, in the spring of 1904, all the 
energies of the Sanitary Department were directed towards the 
suppression of yellow fever and to the cleaning of the two ports of 
