Trench warfare malaria in Korea and Finland. Time scale for Finland has been moved 55 years forwards. Note: The population of South Korea is about 10 times that of Finland and the lowest absolute values for Finland were about the same as those for Korea. On the logarithmic scale 1 for Finland and 0.1 for Korea both represent 4 cases of malaria. The malaria situation in Finland was only marginally different from that in Korea when a new epidemic commenced. The pronounced decline of malaria in Korea should be compared with the urbanization rate.