Yellow fever

Question 1

Yellow fever - organism

Answer 1

Single stranded RNA virus
Flavivirus
E protein used to internalise into cell
7 genotypesY

Question 2

Yellow fever - distribution

Answer 2

Found exclusive in Africa and South America

Question 3

Yellow fever - clinical disease

Answer 3

Short IP [3-6 days] - but may be longer
Asymptomatic or mild febrile illness in many cases:
-Headache, myalgia, lumbosacral pain, malaise, conjunctival infection

Some progress to toxic phase of infection
-0.8-7.5% will progress to this stage
-30-60% CFR

Question 4

Yellow fever - labs

Answer 4

Leucopenia
Neutropenia
AST elevated more than ALT [opposite in hepatitis]
Can develop leucocytosis in toxic disease secondary to hepatic necrosis

Question 5

Yellow fever - predictors of mortality

Answer 5

Older age >45 years
Neutrophilia
AST >3500
Hyperbilirubinaemia
High YFV RNA levels
Renal dysfunction

Question 6

Yellow fever - vaccine

Answer 6

YF-vaccine [17D]
-Live attenuated YFV
->90% protection after 10 days
>99% protection after 30 days
-Single dose probably provides life long protections

Question 7

Yellow fever - vaccine complications

Answer 7

Yellow fever vaccine-associated viscerotropic disease [YEL-AVD]

Vaccine-associated neurotropic disease:
-GBS
-Encephalitis

Question 8

Yellow fever - vaccine contraindications

Answer 8

<6 months
Confirmed anaphylaxis
Egg allergy
History of thymus disorder and thymectomy
Primary or acquired immunodeficiency

Question 9

Yellow fever - antiviral

Answer 9

No clear data on effective antivirals

Galidesivir
-Small molecule, antiviral, nucleoside analogue