Histórico da febre amarela no Brasil e a importância da vacinação antiamarílica

The yellow fever (YF) is one of the biggest challenges to public health authorities, because it is a zoonosis and, therefore, it is difficult to be eradicated. YF is a non-contagious infectious disease of short duration caused by a virus. There are two forms of the disease: the urban yellow fever (UYF) and wild yellow fever (WYF), with main vectors Aedes genera and Haemagogus genera, respectively. Regarding pathogenesis, both forms of the disease may vary from asymptomatic to severe. The main measure of control of infection, after the vector control, was performed by vaccination with the 17D strain. This vaccine consists in attenuated virus and it is effective against re-infection by wild viruses; it confers immunity for, at least, 10 years, and is not recommended for immunocompromised patients. The main protective mechanism triggered by the vaccine is associated with the production of neutralizing antibodies, potent inducer of TCD4+ activation and proper integration between the innate and adaptive immunity. Vaccination is very important to prevent and control the disease, since it breaks the cycle of transmission from wild forms to the urban forms by generating a barrier of herd immunity. Once the YF vaccine with a high level of security has been showing an increase number of severe adverse reactions, it is necessary to improve the investigations about the security of the vaccine, particularly when it is indentified that different mechanisms of the immunity can influence the immunogenicity and reactogenicity of the vaccine in hosts considered immunocompetent.