WHO Warns of Potential Yellow Fever Outbreak in Brazil

The World Health Organization (WHO) has issued a yellow fever outbreak warning after receiving notification from the Brazil Ministry of Health (MoH) that the country suspects a total of 12 cases of yellow fever from six municipalities in a single state.

All 12 cases are males living in rural areas, and are between the ages of seven and 53 years. The first patient presented with symptoms on December 18, 2016, with the rest of the patients presenting with symptoms after that time. Health professionals have collected samples from all patients and sent them to the State Reference Laboratory for diagnosis of yellow fever, dengue, hantavirus, malaria, and additional diseases. On January 12, 2017, Brazil updated WHO on the potential outbreak event, revealing that a total of 110 suspected cases have been reported from 15 different communities in the same state. Furthermore, 30 deaths were reported, with 10 of those deaths confirmed to have been a direct result of yellow fever infection.

WHO noted in its risk assessment of the event, “Yellow fever outbreak has previously been detected in Minas Gerais. The most recent outbreak occurred a 2002-2003, when 63 confirmed cases, including 23 deaths, were detected.” Regarding this potential outbreak, the organization emphasized that the disease could spread rapidly due to relatively low vaccination coverage in the area. WHO also noted that transmission of the viral illness might extend into other states, such as Espírito Santo and southern Bahia, where extensive vaccination did not occur because the areas were previously considered to be at a low risk of transmission. “The introduction of the virus in these areas could potentially trigger large epidemics of yellow fever,” WHO warned. If infected humans travel from the local areas of infection to other areas with Aedes aegypti mosquito populations, the cycle of human-to-human transmission could spread via an infected mosquito population. In addition to this, Brazil is also dealing with outbreaks of Zika virus, chikyngunya, and dengue.

The Centers for Disease Control and Prevention recommended in their 2016 Yellow Book that individuals traveling from the United States to Minas Gerais and designated areas of Bahia get vaccinated for yellow fever before travel. A WHO spokespeople emphasized that vaccination is “highly recommended as a preventative measure” for both travelers and residents of any country where the disease is present. Since 2015, yellow fever vaccines have been limited and there ordering restrictions have been put into place in the United States. It takes 12 months to produce a new supply of yellow fever vaccines, and the vaccine stockpile has been replenished twice in 2016 alone.

At time of publication, WHO had not yet recommended restricted travel and trade to Brazil due to the yellow fever outbreak. Brazil’s MoH has sent teams to Minas Gerais to investigate the situation. While there, the teams will look into options for controlling disease vectors, such as mosquitoes, and conduct a house-to-house immunization campaign in areas where the population is already infected. Adjacent states to Minas Gerais are in the process of completing “preparedness activities for a potential introduction of yellow fever,” WHO reported.