What are the prevention and treatment options for yellow fever?

Yellow Fever Prevention and Treatment

Yellow fever has no specific antiviral treatment, making prevention through vaccination the most critical strategy for reducing disease risk and mortality. 1, 2

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 2
• 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 virus (YFV) has three transmission cycles: jungle (sylvatic), intermediate (savannah), and urban, all involving transmission between primates and mosquitoes 1

Prevention Strategies

Vaccination

• The primary prevention method is the live-attenuated 17D yellow fever vaccine 1
• Vaccination 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 workers who might be exposed to virulent YFV 1
• Vaccination should be administered at least 10 days before travel to ensure immunity 2
• A single dose provides long-lasting immunity, with protection considered valid for 10 years for international travel requirements 3

Contraindications to Vaccination

• Infants aged <6 months (absolute contraindication) 1
• Severe hypersensitivity to vaccine components 1
• Primary immunodeficiencies 2
• Thymus disorders 4
• Symptomatic HIV infection or CD4+ T-lymphocyte counts <200/mm³ 1
• Transplant recipients 2

Precautions for Vaccination

• Infants aged 6-8 months (only if travel to endemic areas cannot be avoided) 1
• Adults aged ≥60 years (higher risk of serious adverse events) 1
• Pregnant women (vaccination only if travel to endemic area is unavoidable) 1
• Breastfeeding women 2
• Asymptomatic HIV-infected persons with CD4+ T-lymphocyte counts of 200-499/mm³ 1

Personal Protection Measures

• Use EPA-registered insect repellents containing DEET, picaridin, IR3535, or oil of lemon eucalyptus 2
• Wear permethrin-treated clothing 2
• Stay in accommodations with screened windows or air conditioning 2
• Avoid outdoor activities during peak mosquito biting times 2

Treatment Approaches

• No specific antiviral treatment exists for yellow fever 1
• Management is primarily supportive care 1
• Recent case reports suggest sofosbuvir may have potential as an antiviral treatment in vaccine-derived yellow fever, but this is not yet standard practice 5
• Supportive care should focus on:
  • Fluid and electrolyte management
  • Fever control
  • Management of organ dysfunction 1

Special Populations

Travelers

• Risk assessment should consider immunization status, specific locations, season, duration of exposure, activities, and local transmission rates 2
• Travelers who cannot receive the vaccine due to contraindications should:
  • Consider changing travel plans to avoid endemic areas 1
  • If travel is unavoidable, obtain a medical waiver letter 1
  • Strictly adhere to mosquito bite prevention measures 1

Immunocompromised Persons

• Live yellow fever vaccine is generally contraindicated in immunocompromised individuals 1
• Patients on immunosuppressive therapies (including biological agents) should avoid vaccination 4
• Case reports document severe adverse events, including vaccine-derived yellow fever in immunocompromised patients 5

Practical Considerations

• International Certificate of Vaccination or Prophylaxis may be required for entry into certain countries 2
• Medical waivers can be issued for travelers with contraindications to vaccination 2
• Travelers, especially visiting friends and relatives (VFR), often seek vaccination <10 days before departure, which may not provide optimal protection 6