Yellow fever as an outbreak in brown howler monkeys, which serve as a sentinel species for yellow fever, that then spread to men working in the jungle. No cases had been transmitted between humans by the "A. aegypti" mosquito, which can sustain urban outbreaks that can spread rapidly. In April 2017, the sylvan outbreak continued moving toward the Brazilian coast, where most people were unvaccinated. By the end of May the outbreak appeared to be declining after more than 3,000 suspected cases, 758 confirmed and 264 deaths confirmed to be yellow fever. The Health Ministry launched a vaccination campaign and was concerned
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