Epidemiological monitoring of the last outbreak of yellow fever in Brazil An outlook from Portugal

Background: Yellow Fever (YF) is a high fatality rate disease (30-50%) caused by Flavivirus, present in some African and South American countries. In order to determine the magnitude and epidemiological distribution of YF cases, vaccination coverage and most affected regions in Brazil, a descriptive epidemiological study monitoring the last outbreak was undertaken in Portugal. Method: The Brazilian database Portal da Saude was used to collect data on cases of YF. We used Microsoft Excel on a weekly basis to update the suspected, confirmed and mortality cases as well as the case fatality rate and epizootics in non-human primates. Results: Case Fatality Rate was 33.6%. A total and 82% of confirmed cases were males. The outbreak predominantly affected two south-eastern states, Minas Gerais and Espirito Santo, both with a very low vaccination coverage. Conclusions: The last outbreak of YF was by far the largest observed over the last few decades! Until the emergence of this outbreak, Espirito Santo, Bahia and Rio de Janeiro were states of low risk for YF and the vaccine not previously recommended. The World Health Organization's Global Strategy to Eliminate Yellow Fever Epidemic (EYE) should be on the way, to prevent YF outbreaks in Brazil and other countries in Africa and South America.