Yellow fever virus
From IDWiki
Background
Microbiology
- RNA virus and member of the Flaviviridae family
Epidemiology
- Worldwide, about 200,000 cases and 30,000 deaths annually
- Vectors include Aedes aegypti (urban cycles in Africa and South America), Aedes africanus (sylvatic cycles in Africa), other Aedes species mosquitoes (intermediate savanna cycles in Africa), Haemagogus and Sabethes species mosquitoes (sylvatic cycles in South America)
Clinical Manifestations
- Spectrum of illness from asymptomatic to fatal
- Acute illness starts with fever, chills, headache, backache, myalgias, arthralgias, nausea, vomiting, photophobia, mild jaundice, and epigastric pain
- After the acute illness subsides, about 85% of infections are resolved, and 15% progress
- In those who progress, a brief remission of hours to days is followed by return of symptoms with progression to renal failure, hemorrhage, and thrombocytopenia
Vaccine-Related Disease
- Yellow fever vaccine-associated neurotropic disease, which includes meningoencephalitis, Guillain-Barré syndrome, and acute bulbar palsy
- Yellow fever vaccine-associated viscerotropic disease, which causes multi-organ failure similar to wildtype virus
| YEL-AND | YEL-AVD | |
|---|---|---|
| Incubation period | 7 to 21 days | 2 to 5 days |
| Rate | 0.8 per 100,000 doses | 1 per 100,000 doses |
| Risk factors | age <6 months
age >60-70 years |
age >60 years
thymus disease |
| Prognosis | full recovery | 65% mortality |
Management
- Supportive care
Prevention
- A live attenuated vaccine strain is available, with a single dose provided at least decades of and possibly life-long immunity
- Antibodies develop within 28 days
- Contraindications
- Allergy to any component of the vaccine
- Immunocompromised state, including HIV with CD4 <200 or <15%, B-cell deficiency (except isolated IgA deficiency, IgG subclass deficiency, and specific antibody deficiency), and combined B- and T-cell deficiency
- Infants less than 6 to 9 months of age, due to the high risk of neurotropic disease following immunization
- People age 60 years and older, due to the high risk of adverse events following immunization
- Booster doses may stll be given, if indicated
- Pregnancy and breastfeeding
- Thymus disease, including thymoma, thymectomy, and myasthenia gravis, given the high risk of viscerotropic disease
- Moderate or severe acute illness
- Booster doses
- No longer routinely indicated
- May be indicated if the original dose was given when the recipient was unlikely to mount a full immune response
- Vaccinated during pregnancy, while on immunosuppressants, or other immunocompromise like HIV
- One-time booster for most, and booster every 10 years for HIV
- Hematopoietic stem cell transplant since last vaccination
- One-time full dose
- Last dose was fractional, given improperly, undocumented, or underdocumented
- One-time full dose
- Vaccinated during pregnancy, while on immunosuppressants, or other immunocompromise like HIV
- May be indicated for individuals at particularly high risk of exposure
- Travel to an area experiencing an outbreak
- Frequent or prolonged travel to areas with high endemicity, particularly West Africa
- One-time booster if 10 or more years since primary vaccination
- May be indicated for individuals with regular and ongoing exposure
- Laboratory workers working on yellow fever virus
- Booster every 10 years unless antibody titres confirm ongoing immunity
- Vaccination can cause YF vaccine-associated neurotropic disease and YF vaccine-associated viscerotropic disease
