What are the recommendations for preventing and treating yellow fever in North America?

Yellow Fever Prevention and Treatment in North America

Yellow fever vaccination is recommended for persons aged ≥9 months who are traveling to or living in areas at risk for yellow fever virus (YFV) transmission in South America and Africa, as there is no specific treatment for yellow fever disease. 1

Disease Overview

• Yellow fever is a mosquito-borne viral disease endemic to sub-Saharan Africa and tropical South America, causing an estimated 200,000 clinical cases and 30,000 deaths annually 1
• Clinical manifestations range from asymptomatic infection to severe disease with jaundice and hemorrhagic manifestations 1
• The case-fatality ratio for severe yellow fever with hepatorenal dysfunction is 20%-50% 1
• Yellow fever is not endemic to North America, but prevention is critical for travelers to endemic regions 1

Prevention Recommendations for North American Travelers

Vaccination Guidelines

• Yellow fever vaccine is recommended for:

  • Persons aged ≥9 months traveling to or living in areas at risk for YFV transmission in South America and Africa 1
  • Laboratory personnel who might be exposed to virulent YFV or concentrated preparations of YF vaccine virus 1

• Vaccination should be administered at least 10 days before travel to endemic areas to ensure immunity 1

• Proof of vaccination (International Certificate of Vaccination or Prophylaxis) is required for entry into certain countries and is valid for 10 years 1

Personal Protective Measures

• All travelers should take precautions to avoid mosquito bites, including: 1
  • Using EPA-registered insect repellents containing DEET, picaridin, IR3535, or oil of lemon eucalyptus 1
  • Wearing permethrin-impregnated clothing 1
  • Staying in accommodations with screened windows or air conditioning 1

Vaccination Considerations

Contraindications

• The following are contraindications to yellow fever vaccination: 1
  • History of severe allergic reaction to vaccine components or previous dose
  • Age <6 months
  • Thymus disorder associated with abnormal immune function
  • Primary immunodeficiencies
  • AIDS or symptomatic HIV infection with severe immunosuppression
  • Immunosuppressive and immunomodulatory therapies
  • Malignant neoplasms
  • Transplantation

Precautions

• Healthcare providers should carefully consider precautions before administering yellow fever vaccine to: 1
  • Infants aged 6-8 months
  • Adults aged ≥60 years
  • Pregnant women
  • Breastfeeding women
  • Persons with asymptomatic HIV infection and moderate immune suppression

Medical Waivers

• If vaccination is contraindicated, healthcare providers may issue a medical waiver: 1
  • Complete the "Medical Contraindications to Vaccination" section of the International Certificate of Vaccination or Prophylaxis
  • Provide a signed and dated letter on letterhead stating the contraindication
  • Include the official yellow fever vaccination center stamp 1
  • Inform travelers that a waiver may not be accepted by all countries 1

Risk Assessment

• Evaluation of a traveler's risk should consider: 1
  • Immunization status
  • Planned itinerary (specific locations)
  • Season of travel
  • Duration of exposure
  • Occupational and recreational activities
  • Local rate of virus transmission at the time of travel

Current Challenges

• Vaccine shortages have been reported worldwide, presenting challenges for travelers requiring vaccination 2
• Travelers should plan well in advance to ensure vaccine availability 3

Important Caveats

• Yellow fever cannot be eradicated as it is a zoonotic disease with a sylvatic cycle involving monkeys and mosquitoes 4
• The risk of importation and spread to non-endemic regions has increased due to:
  • Increased density and distribution of the urban mosquito vector (Aedes aegypti) 5
  • Increased international air travel 5
• North American healthcare providers should maintain vigilance for yellow fever in returning travelers from endemic regions 3