this strain of plasmodium. It became apparent that another antimalarial was needed. Medical researchers concluded that DDS (4,-4�-diaminodiphenylsulfone), a drug long used in the, treatment of leprosy, seemed to be the most promising of many drugs under evaluation. Following intensive field tests on a priority basis in-country, it was found that the daily use of 25 milligrams of DDS, in addition to the standard chloroquine-primaquine weekly tablet, reduced the incidence of malaria by approximately one-half. This, therefore, became the operational regimen, and is now followed in tactical units operating in malaria risk areas in Vietnam.
Not only did the use of DDS, in conjunction with other antimalarials, reduce the incidence of malaria, but it also assisted greatly in lowering the incidence of relapse from a former high of almost 40 percent to a low of only 3 percent. Of equal importance, DDS aided in reducing the period of hospitalization by one-half, thus making it feasible to hold virtually all malaria patients in-country until fully recovered.
Infectious hepatitis did not pose a major problem. The incidence of this disease had been relatively low, and the disease in Vietnam was milder than in previous military experience. When the use of ISG, (immune serum globulin) to provide passive immunity was instituted in mid-1964, the incidence of the disease had already begun to decline from the 1962-63 experience.
In 1964, when there were relatively few U.S. troops in Vietnam, ISG was administered to all incoming troops as a precautionary measure. For both economic and medical reasons, the dose of ISG was reduced in early 1966, and in March of that year the program was further changed to administer ISG selectively to personnel on high-risk assignments or in key positions. No major problems developed from this change in policy and procedure. The lesson here is, of course, that all decisions must be evaluated constantly and changed with boldness and courage if the situation so dictates.
The exotic tropical diseases, endemic and epidemic in Southeast Asia, did not pose a problem in U.S. troops. Plague in the Vietnamese civilian, population pointed up, however, the shifting of disease patterns when the normal way of life of any peoples whose structure, economically or environmentally is altered. Vietnam is a rice-producing and rice-exporting country. Normally, the grain flowed from the rice bowls of the interior to the few major ports of the country. The rodents which infest the areas followed the path of the rice to the ports. There they were controlled; thus, the danger of a serious outbreak of plague was averted. During the war when, for economic reasons, the South Vietnamese began to import grain, a reverse situation was created. The rice was shipped from the ports into the countryside; the rodents followed the flow of the grain inland and created havoc in the form of increased incidence of
