In addition to the high incidence of malaria among the American millitary in Vietnam, there has been a progressive increase in the number of imported cases occurring in such persons following their return to the United States. Most of these cases are due to Plasmodium vivax infection. The combined chloroquine-primaquine tablet, taken once a week for 8 consecutive weeks, is effective for radical cure for vivax infection, and all returnees supposedly complete this course of therapy. This study was made to assess the effectiveness of this prophylactic program. A questionnaire survey was made of 671 Army officers and enlisted men regarding malaria prophylaxis. Of the total group, 70% failed to complete the full course of therapy. The rate of failure among officers and enlisted men was nearly equal. There was no predominant cause for failure, but common reasons given included 1) forgetting to take medication, 2) loss of pills, 3) not receiving sufficient number of pills, and 4) untoward side-effects of therapy. Persons stationed in “high-risk” malaria areas were more likely to complete therapy successfully, although previous clinical malaria did not improve the success rate in such affected persons. This extremely high failure rate of the current malaria chemoprophylaxis program would appear to be a significant factor contributing to the high incidence of imported malaria occurring in the United States.
U. S. Army Medical Research Unit, Presidio of San Francisco, California 94129.