 Great progress was also made in the fight against endemic diseases; the numbers of reported cases of sleeping sickness went from 34,000 cases in 1931 to 1,100 cases in 1959, mainly by eradicating the tsetse fly in densely populated areas.All Europeans and Congolese in the Belgian Congo received vaccinations for polio, measles and yellow fever.Vast disease prevention programmes were rolled out, aimed at eradicating polio, leprosy and tuberculosis.