1920s: Malaria is a life-threatening, infectious disease. For instance, in 1914, around 600,000 Americans died after contracting malaria, primarily in the Mississippi River valley and along the East Coast. However, some of these fatal cases of malaria arose because doctors used the disease to treat another fatal disease, syphilis.

1990s: The World Health Organization estimates that there are 300 to 500 million cases of malaria reported each year, resulting in 1.5 to 2.7 million deaths. In developing countries, malaria is one of the leading causes of sickness and disease. The occurrence of malaria has actually risen in many countries in the last half of the 20th century. However, malaria poses little threat to western countries, such as the United States and Italy.In 1992, the United States reported 910 cases of malaria, but only seven of these were acquired in the country. Many of these cases occur among immigrant populations.

1920s and...