Rapid risk assessment: Outbreak of yellow fever in Brazil, 25 January 2017

Risk assessment
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European Centre for Disease Prevention and Control. Outbreak of yellow fever in Brazil – 25 January 2017. Stockholm: ECDC; 2017.

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​On 6 January 2017, the Ministry of Health of Brazil notified the Pan American Health Organization of the occurrence of 23 suspected and probable cases of yellow fever, including 14 deaths in the state of Minas Gerais. As of 23 January 2017, three states in Brazil had reported confirmed cases of yellow fever. This document assesses the risk to EU/EEA countries and citizens associated with the ongoing outbreaks of yellow fever in Brazil.

Executive summary

In light of the current yellow fever outbreak in Brazil, this rapid risk assessment concludes that the risk of yellow fever transmission in the EU/EEA is currently very low as it depends on the virus being introduced by viraemic travellers to an area with an established, competent and active mosquito vector population. However, EU citizens travelling to, or living in, risk areas in Brazil should check their vaccination status and get vaccinated if necessary.

Update: On 26 January 2017, after the publication of the rapid risk assessment, the Regional Office for the Americas of the World Health Organization (PAHO) reported new municipalities at risk for yellow fever transmission in Bahia, Espirito Santo and Rio de Janeiro states. The list of these municipalities is available on the PAHO/WHO website.

Subsequently, PAHO/WHO encourages national authorities to advise  travellers to the newly defined areas at risk of yellow fever transmission be vaccinated for yellow fever at least 10 days prior travel and apply measures to avoid mosquito bites.

On 6 January 2017, the Ministry of Health of Brazil notified the Pan American Health Organization of the occurrence of 23 suspected and probable cases of yellow fever, including 14 deaths. In this current outbreak, and as of 23 January, three states (Espírito Santo, Minas Gerais and São Paulo) have reported over 60 confirmed cases of yellow fever, in comparison to six confirmed cases in Brazil in 2016. Notably, Espírito Santo was previously considered an area of low risk.

Rapid risk assessment conclusions

This outbreak should be carefully monitored as the establishment of an urban yellow fever cycle would have the potential to quickly affect a large number of people. Therefore, EU/EEA Member States should consider a range of options for response.

EU citizens who travel to, or live in, areas where there is evidence of periodic or persistent yellow fever virus transmission, especially those in outbreak-affected regions, are advised to:

  • Be aware of the risk of yellow fever in endemic areas of Brazil, particularly in the states with confirmed autochthonous cases: Minas Gerais, Espírito Santo and São Paulo;
  • Check their vaccination status and get vaccinated if necessary. Vaccination against yellow fever is recommended from nine months of age for people visiting, or living in yellow fever risk areas. An individual risk benefit analysis should be conducted prior to vaccination, taking into account the season (December to July in Brazil), destination, duration of travel and the likelihood of exposure to mosquitoes (e.g. rural areas, forests).
  • WHO publishes a list of countries, territories and areas with yellow fever vaccination requirements and recommendations, which includes the Brazilian states of Minas Gerais, Acre, Amapá, Amazonas, Distrito Federal (including the capital Brasília), Goiás, Maranhão, Mato Grosso, Mato Grosso do Sul, Pará, Rondônia, Roraima and Tocantins, and designated areas of Bahia, Paraná, Piauí, Rio Grande do Sul, Santa Catarina and São Paulo. Vaccination is also recommended for travellers visiting Iguazu Falls.
  • Given the geographical extension of the outbreak to states previously considered low risk, such as Espírito Santo, in addition to considering recommending vaccination in line with the WHO recommendations on yellow fever vaccination related to the states listed above, Member States should also consider recommending yellow fever vaccination for travellers aged over nine months going to rural areas in Espírito Santo.
  • Take measures to prevent mosquito bites indoors and outdoors, especially between sunrise and sunset when Aedes mosquito vectors are most active. These measures include:
  • the use of mosquito repellent in accordance with the instructions indicated on the product label;
  • wearing long-sleeved shirts and long trousers;
  • sleeping or resting in screened or air-conditioned rooms, or using mosquito nets at night and during the day.

To reduce the risk of adverse events following immunisation, healthcare practitioners should be aware of the contraindications and follow the manufacturers’ advice on precautions before administering yellow fever vaccine.

Over the past 10 years in the Americas, human cases of yellow fever have been reported in Argentina, Bolivia, Brazil, Colombia, Ecuador, Paraguay, Peru and Venezuela.