Friday, March 10, 2017

YF in the Americas

5 ARBOviruses have been identified as reemerging infections in the Americas – dengue, West Nile virus, chinkungunya, Zika, and Yellow Fever. Yellow Fever virus especially has caused concern in brazil. The virus has caused 234 infectious and 80 deaths as of February 2017. Most of these infections have taken hold in rural areas and in the states of Minas Gerais, Espirito Santo, and Sao Paulo. They have found that this pattern of infection is disproportional to past years. Yellow Fever causes a non-specific influenza-like illness with an incubation period of three to six days. It also seems to have a bimodal pattern with symptoms disappearing and later reappearing.

A. Aegypti has been identified as a local vector, which especially concerning in urban areas. This is concerning because the Yellow Fever vaccine is not usually administered in these areas. This could lead to an epidemic in the densely populated area. Yellow Fever is thought to have originated in Africa and arrived in the Americas around the 1600s. In the Philadelphia outbreak of 1793 there was a 10% fatality of the total population. Today, fatality rates are around 20-60% in those with severe illness.

One concern is that the outbreaks in Brazil may lead to Yellow Fever outbreaks in the United States. Similar to Zika, which led to around 250 cases in the US, concerns about a similar Yellow Fever pattern has been expressed.
The Yellow Fever vaccine is live-attenuated virus vaccine that provides long-term protection in 99% of people. In 2015, due to outbreaks in Angola, the Democratic Republic of Congo, and China, there was exhaustion of the vaccine stockpile, which led to partial vacation administration. This practice was put in place to make the vaccine last. Unfortunately, there is no antiviral treatment for Yellow Fever. Yet, through vaccination and preventative measures – Yellow Fever has the potential to be controlled.

Gianna Nino-Tapias (’18)

References:Paules CI and Fauci AS. Yellow Fever – Once Again on the Radar Screen in the Americas. The New England Journal of Medicine (2017).

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