Yellow fever Brazil. In March 2018, Brazil shifted its policy and announced it planned to vaccinate all 77.5 million currently-unvaccinated citizens by April 2019. Some countries in Asia are theoretically in danger of yellow fever epidemics (mosquitoes with the capability to transmit yellow fever and susceptible monkeys are present), although the disease does not yet occur there. To prevent introduction of the virus, some countries demand previous vaccination of foreign visitors if they have passed through yellow fever areas. Vaccination has to be proved by the production of a vaccination certificate which is valid 10 days after the vaccination and lasts for
Yellow fever they reach the liver and infect hepatocytes (probably indirectly via Kupffer cells), which leads to eosinophilic degradation of these cells and to the release of cytokines. Apoptotic masses known as Councilman bodies appear in the cytoplasm of hepatocytes. Fatality may occur when cytokine storm, shock, and multiple organ failure follow. Yellow fever is most frequently a clinical diagnosis, made from symptoms and where the infected person was before becoming ill. Mild courses of the disease can only be confirmed virologically. Since mild courses of yellow fever can also contribute significantly to regional outbreaks, every suspected case of yellow fever (involving