It is not perhaps generally realized that the United States maintains in the tropical countries under her control forces, large or small, of native troops. The efficiency of these troops compared with white troops serving under the same conditions and their relative liability to special diseases becomes a matter of considerable interest.
The Porto Rican regiment, of which the enlisted men are all natives, but the officers mostly American, was organized in February, 1901, and has served entirely in its own country. Since May, 1904, no American troops proper have served in Porto Rico, so that the comparisons with white troops refer to those serving in the Philippine Islands. For disease the admission and constantly non-effective rates of the Porto Ricans are slightly better than for white troops in the tropics, but their death and discharge rates are higher. Typhoid fever was very rare until 1906, when an outbreak occurred