Abstract
Malaria is endemic over a wide area of the earth's surface. Although popularly associated with tropical or subtropical countries, it occurs as far north as the south of Sweden and Lake Ladoga in Russia and as far south as Bechuanaland, Swaziland and Natal in South Africa and the Argentine in South America. Though most frequent in low-lying districts it may be found at altitudes as great as 6000–9000 ft.