Total Population at Risk (living in areas where malaria is still, or has recently been, endemic). Population Actually Protected in 1957 is Estimated to be at Least. * Estimated Source: WHO Report of Expert Committee on International Quarantine. International Protection Against Malaria WHO/IQ/67 Oct. '58. G. INSECT RESISTANCE The early successes with DDT and other new insecticides after World War II led to optimism and the hope that at least some of the insect vectors of disease might be eradicated. In 1947 and 1948, it became apparent that some insects of public health importance were becoming resistant to DDT. Starting with houseflies, which have since been reported resistant in more than 30 countries, the phenomenon was observed in other species of insects, including mosquitoes, lice, fleas, bedbugs, and cockroaches, with a total of 46 species now having been reported as resistant to one or another insecticide. This has had a definite impact on the progress of control operations against insect vectors. For example, important vectors of malaria (nine species of Anopheles), in 17 different countries have been confirmed as physiologically resistant to insecticides. For this reason personnel must be continuously at work developing new insecticides which will be economical, nontoxic to man, and adaptable to existing or new techniques of insect eradication. PHS Records Cumulative number of countries with confirmed physiologically resistant vectors of malaria Countries: Burma, El Salvador, French West Africa, Greece Cumulative number of arthropods of public health importance physiologically resistant to insecticides * Includes flies, mosquitoes, bedbugs, lice, fleas and cockroaches Sources: WHO Publications H. FILARIASIS The term filariasis encompasses a group of parasitic worm infections, two of which (Bancroft's filariasis and Malayan filariasis), involve the lymph glands and may result in tremendous swelling of the limbs and genitalia-termed elephantiasis. This deformity may partially or completely incapacitate the individual for productive work. More than 250 million people in the tropical areas of the world are believed to be infected. The greatest prevalence occurs in central Africa, parts of South America, southeast Asia, and the South Pacific islands. It is also reported in Central America and the West Indies, some parts of southern Europe, the Mediterranean coast of Africa, and in Japan and Korea. During World War II this disease assumed military significance when troops stationed in the South Pacific became infected. Experimental studies carried out in the Pacific area show that the disease can be effectively brought under control by the use of piperazine derivative drugs, provided treatment campaigns are organized on a mass basis. So far, however, the overall effort has been limited. Eventual success for worldwide control will depend upon the availability of funds and medical personnel to organize such campaigns in the various countries involved. |