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 vaccine Book that between 1970 and 2002 only "nine cases of yellow fever were reported in unvaccinated travelers from the United States and Europe who traveled" to West Africa and South America, and 8 of the 9 died. However, it goes on to cite "only 1 documented case of yellow fever in a vaccinated traveler. This nonfatal case occurred in a traveler from Spain who visited several West African countries in 1988". The first attempts to develop a yellow fever vaccine followed the opening of the Panama Canal in 1912, which increased global exposure to the disease. The Japanese bacteriologist Hideyo