Yellow Fever Could Spread From Brazil

  • A nurse vaccinates a toddler against yellow fever at a public health clinic in Rio de Janeiro, Brazil, Thursday, March 16, 2017. Rio state’s Health Department says that it has confirmed the first two cases of yellow fever in the state. (AP Photo/Renata Brito)

Top infectious disease experts are warning about a rapidly spreading outbreak of deadly yellow fever in Brazil that could hit parts of the United States. The danger would be most acute if the virus starts spreading by the same mosquito that transmits Zika.

The outbreak in Brazil has been underway since December, mostly in rural areas in the southeastern part of the country. It’s primarily in jungle areas, where forest-dwelling mosquitoes are spreading the virus mainly to monkeys. But an increasing number of people have been infected, making it Brazil’s worst yellow fever outbreak among humans in decades. There are at least 326 confirmed cases, including 220 deaths, with hundreds of additional cases under investigation, according to the Pan American Health Organization.

Writing March 8 in the New England Journal of Medicine, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said experts are concerned because the number of yellow fever cases is much higher than what’s typically reported in this part of Brazil. Officials are also worried because these areas are close to major urban centers like Rio de Janeiro and Sao Paolo, where tens of millions of people live and where city-dwelling Aedes aegypti mosquitoes could start spreading the disease in a human-to-human cycle.

Although there is a highly effective vaccine for yellow fever, it is not routinely given in Brazil’s major urban centers, they said. But millions of Brazilians have been vaccinated this year as health authorities scramble to prevent the outbreak from turning into an epidemic.

Aedes aegypti is the same mosquito species that transmits Zika, dengue and chikungunya, viruses related to yellow fever.

“The concern now is that there are a considerable number of these jungle cases, and there’s always the possibility — although it’s very unlikely — that some of these infected people in the jungle” will travel to an urban area…