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.
Yellow fever blood, hence the Spanish name for yellow fever, "vómito negro" ("black vomit"). There may also be kidney failure, hiccups, and delirium. The toxic phase is fatal in about 20% to 50% of cases, making the overall fatality rate for the disease about 3.0 to 7.5%. However, the fatality rate of those with the toxic phase of the disease may exceed 50%. Surviving the infection provides lifelong immunity, and normally no permanent organ damage results. Yellow fever is caused by the yellow fever virus, a 40– to 50--wide enveloped RNA virus, the type species and namesake of the family "Flaviviridae". It