Yellow Fever in Brazil

There is widespread concern that as the emerging Brazilian yellow fever outbreak threatens to spread from rural to urban areas, the number of those infected may greatly increase.

yellow feverBrazil has a very long history with yellow fever, but recent decades have seen a marked increase of infections, along with dengue fever, chikungunya and of course the Zika virus. The common thread linking these infections is the Aedes mosquito, responsible for transmitting ALL these infections. As is common with emerging epidemics, the true number of infections is unclear. This is because reported numbers include both those that are confirmed by  laboratory testing and also those that are simply suspected, but at present the picture is of over 500 possible infections of yellow fever in Brazil. Of those cases which have already received confirmatory tests, around 109 cases have been identified, including 40 fatalities. This underlines the serious nature of the disease, which can cause uncontrolled bleeding as well as liver failure in many patients, and often results in death.

This present outbreak started in the rural district of Minas Gerais, where the lion’s share of the cases have occurred so far. Infections have spread to neighbouring regions including areas that were previously thought to be at low risk of yellow fever, such as the coastal region of Espirito Santo. As the outbreak continues, the chief concern is that infected individuals may travel to major Brazilian cities where they can be bitten by local, previously uninfected mosquitos. Once these local, city mosquitos become infected with yellow fever, many thousands of subsequent human infections become possible  – as the Aedes mosquitos bite further people. As has occurred with the global spread of dengue and Zika, this same method of transmission of infection can also occur when an infected individual travels to their home country – and is bitten by  mosquitos in their own country, starting an epidemic.

To prevent spread of yellow fever to the cities in Brazil, mosquito control measures are already underway. In addition as there is an effective vaccination available for yellow fever, millions of doses of the immunisation are being sent to inoculate local people, protecting them against the consequences of infection. For those visiting Brazil, it is important to be vaccinated at least 10 days before entering the country. After having arrived, adopting effective mosquito-bite prevention strategies is crucial.

A Healix Bite Prevention eLearning Course is also available to inform and protect staff working abroad, please contact us for details at

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