Volume 6, Issue 6
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



An evaluation of the ecological distribution of and in Puerto Rico was made, based on information obtained at 421 stations visited from March 1953 through May 1954.

The density of the population depended generally on the type of surface water. Large bodies of standing water afforded an unsuitable environment whereas all types of running water and associated marshes, as well as small ponds and water collections, abounded with snails. The geological formation was also an important ecological factor both physically and chemically, the inland alluvial deposits being ideal for the snail. The third most potent factor was rainfall, of which the pattern of distribution throughout the year was more important than the amount. Even distribution was favorable, but concentrated, heavy rain flushed the snails out of the streams.

The amount of infection of snails and men with was correlated on the one hand with the density of snails, and on the other with the degree of pollution of surface water by human excreta and the various ways in which man exposed himself to infection through contact with the contaminated water.


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