Last week, Drs. Anthony S. Fauci and Catharine I. Paules of the National Institute of Allergy and Infectious Diseases (NIAID) expressed concern about the Brazil yellow fever outbreak and the potential for spread to the United States in a Perspectives piece for the New England Journal of Medicine.

An Aedes aegypti mosquito prepares to bite a human. Image/USDA
An Aedes aegypti mosquito prepares to bite a human.

In the article they write:

As we have seen with dengue, chikungunya, and Zika, A. aegypti–mediated arbovirus epidemics can move rapidly through populations with little preexisting immunity and spread more broadly owing to human travel. Although it is highly unlikely that we will see yellow fever outbreaks in the continental United States, where mosquito density is low and risk of exposure is limited, it is possible that travel-related cases of yellow fever could occur, with brief periods of local transmission in warmer regions such as the Gulf Coast states, where A. aegypti mosquitoes are prevalent.

Early recognition may be difficult in countries such as the United States, where most physicians have never seen a case of yellow fever and know little about the clinical manifestations.

As with all potentially reemerging infectious diseases, public health awareness and preparedness are essential to prevent a resurgence of this historical threat.

On Tuesday, the European Centre for Disease Prevention and Control (ECDC) reported in a Rapid Risk Assessment a travel-associated case of yellow fever has been reported by the Netherlands in March 2017 after travel to Suriname.

During the past eight months, four travel-associated cases of yellow fever have been identified among EU travellers returning from South America. This represents a significant increase on four travel associated cases of yellow fever among EU travellers for the period of 1999 to July 2016.

This has prompted the ECDC to remind travellers of advice when going to areas with yellow fever:

  • Be aware of the risk of yellow fever in endemic areas throughout South America, including recently affected States in Brazil.
  • Check 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 period, destination, duration of travel and the likelihood of exposure to mosquitoes (e.g. rural areas, forests) as well as individual risk factors for adverse events following yellow fever vaccination.
  • Take measures to prevent mosquito bites indoors and outdoors, especially between sunrise and sunset when Aedes and sylvatic yellow fever 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/air-conditioned rooms or using mosquito nets at night and during the day.

LISTEN: Travel medicine: An interview with Dr. Christopher Sanford

Since December 2016, Brazil has reported 1,500 cases of yellow fever, including 371 confirmed, including 241 deaths of which 127 are confirmed. There is a 34 percent case fatality rate (CFR) among confirmed cases.