An epidemic of meningococcic meningitis started in the port of Valparaiso, Chile, in June 1941 and extended from there until it reached Santiago, the capital, three to four months later. However, it was during the year 1942 that the largest number of cases was observed. Valparaiso is surrounded by hills which are close to the sea. Most of its 200,000 inhabitants live on these hills, in poor hygienic conditions. Santiago, the capital of the most pleasant and civilized country in South America, as John Gunther wrote in his book "Inside Latin America," is a city of 1,290,000 inhabitants and is located about 80 miles (129 kilometers) southeast of Valparaiso, close to the first peaks of the Andes range. The total number of cases recorded in Santiago from September 1941 to July 3, 1943 was 4,464. The average population of Santiago for these years was 1,290,000, and on this basis there