Recent advances in malariology.

Some of the notable advances in malariology in the past quarter century have been (1) discovery of residual insecticides which ushered in the era of malaria eradication and led to the concept of global eradication of disease; (‘2) synthesis of antimalarial drugs, their use in the chemoprophylaxis and chemotherapy of malarias and appreciation of their values and limitations; (3) discovery of exe. erythrocytic stages in the life cycle of malaria parasites; (4) discovery of rodent plasmodial parasites and their successful transmission through mosquitoes; (5) emergence of drug-resistant plasmodia and insecticide-resistant mosquitoes and some understanding of their genetics; (6) transmission of human plasmodia to monkeys and vice versa; disclosure of multiple new facets of simian and rodent malarias; (7) recognition of the intricate structure of plasmodia through electron microscopy; (8) identification of abnormal hemoglobins and enzyme-deficient erythrocytes and their relation both to malaria and metabolism of drugs; (9) application of new immunologic and biochemical procedures to the study of pathophysiology and immunology of malaria; and (10) establishment of the World Health Organization (WHO) and other national and international agencies to correlate endeavors dealing with the health of nations. The mechanism of action of antimalarial drugs remains obscure. The efficacy of antimalarial drugs is largely dependent on the following factors: dosage; rapidity of drug absorption; degree of concentration of drug in the plasma, erythrocytes and tissues; rate of degradation and excretion of drug: the immune status of the host; and the species and geographical races of parasites involved. People differ greatly in their reactions to a specific infection and to a given course of antimalarial medication. Malaria is more severe and more refractory to chemotherapeutic agents in nonimmune subjects than in natives. Nonimmune subjects with primary infections require larger doses of drugs given over a longer period of time than those in relapse. Drug-host reactions determine the outcome of any therapy. Of the several 4-aminoquinolines available, chloroquine and amodiaquin are still adequate for the chemotherapy and chemoprophylaxis of malarias. Patients with relapsing malarias can best be treated by once daily administration of 15 mg. of primaquine base for fourteen consecutive days with concurrent administration of chloroquine (1,500 mg. base orally in three days). Resistance to drugs may be an innate genetic feature of the parasite, or it may be induced by exposure to subeffective doses of a single drug or one or another in a combination of drugs. Currently the best treatment for chloroquine-resistant falciparum malaria encountered in South Vietnam is a combination regimen with quinine, pyrimethamine and 4,4’-diaminodiphenylsulfone (DDS). Through the conjoined efforts of governments, the World Health Organization, the Rockefeller Foundation and other agencies, malaria has been eradicated from many countries. Nevertheless, 638 million people live in parts of the world in which the disease is still endemic. It is possible to control and even to eradicate malaria from these endemic foci through judicious use of antimalarials, antilarval measures, drainage, residual spraying and suppressive chemoprophylaxis. Global malaria eradication is the determined and dedicated goal of WHO.