Yellow fever known as "mosquito inspectors" fiercely worked to combat yellow fever throughout Rio by spraying, exterminating rats, improving drainage, and destroying unsanitary housing. Ultimately, the city's sanitation and renovation campaigns reshaped Rio de Janeiro's neighborhoods. Its poor residents were pushed from city centers to Rio's suburbs, or to towns found in the outskirts of the city. In later years, Rio's most impoverished inhabitants would come to reside in "favelas". During 1920–23, the Rockefeller Foundation’s International Health Board undertook an expensive and successful yellow fever eradication campaign in Mexico. The IHB gained the respect of Mexico’s federal government because of the success.
History of yellow fever The entire Mississippi River Valley from St. Louis south was affected, and tens of thousands fled the stricken cities of New Orleans, Vicksburg, and Memphis. An estimated 120,000 cases of yellow fever resulted in some 20,000 deaths. Memphis suffered several epidemics during the 1870s, culminating in the 1878 epidemic (called the Saffron Scourge of 1878), with more than 5,000 fatalities in the city. Some contemporary accounts said that commercial interests had prevented the rapid reporting of the outbreak of the epidemic, increasing the total number of deaths. People still did not understand how the disease developed or was transmitted, and