Yellow fever

Question 1

What is geographical distribution of yellow fever?

+ssRNA virus

Case fatality of 20-40%

Answer 1

Africa
SA
Carribbean

Question 2

YF not directly transmitted from human-human.

What are two life cycles?

Answer 2

Human-human via aedes aegypti in urban environments

Monekys to humans by Hameagogus mosquito - “jungle” yellow fever

Question 3

Virus enters via skin/ blood vessel, and spreads through body.

Which organs are affected?

Answer 3

Liver
kidneys
spleen
lymph nodes
heart

Question 4

What is incubation period?

Answer 4

3-6 days

Question 5

What are symptoms of yellow fever?

Answer 5

fever
nausea
vomiting
headache
myalgia

if liver involved - jaundice, renal failure, shock

Question 6

How does haemorrhage occur in YF?

Answer 6

Hepatitis leads to reduced synthesis of clotting factors, in combination with increased consumption

This leads to GI haemorrhage most commonly seen - melena/ haematemesis

Question 7

How to diagnose YF?

Answer 7

Reverse transcriptase PCR

IgM/ IgG - but note cross-reaction with other flavivirus

Post-mortem biopsy of liver - Councilman bodies

Question 8

What is treatment for YF?

How to prevent YF?

Answer 8

No specific treatment

17D vaccine - live. Provides lifetime protection

Vector control

Question 9

What are Councilman bodies, and where are they found?

Answer 9

Councilman bodies – an eosinophilic globule of apoptotic/ necrotic liver cells

Seen in many causes of hepatitis, but first discovered in Yellow Fever hepatitis