Yellow fever is an acute viral hemorrhagic disease transmitted by infected mosquitoes that originated in Central Africa. It causes symptoms like fever, jaundice, and in severe cases significant bleeding. While most cases resolve, 15% of infections progress severely and can result in death within 7-10 days. The virus is a positive-sense RNA flavivirus about 50-60nm in diameter. Diagnosis involves testing for viral RNA or antibodies in the blood. Vaccines can prevent yellow fever, but supplies of one major vaccine may be limited in the near future.

1. Yellow Fever
Virus

2. • An acute viral hemorrhagic
disease
• Family: Flaviviridae
• Genus: Flavivirus
• Originated in Central Africa
• 84 000–170 000 cases and
up to 60 000 deaths
What is Yellow Fever?

3. What is Yellow Fever
• Angola
2015:1975 suspected
cases , 258 deaths
• YFV is transmitted by infected
mosquitoes and ticks

4. History of Yellow Fever
• Originated in Central Africa
• Spread to east and west Africa, and to Americas
• First outbreak in Yucatan peninsula, Mexico, 1648.
• 1975 suspected cases and 258 deaths in Angola,
2015.

5. • Sylvatic (or jungle)
Transmission
• Intermediate
Transmission
• Urban
Transmission
Transmission Cycles

6. • The incubation period is 3–6 days.
• Yellow eyes
• Headache
• Backache
• Vomiting
• Bleeding
• Death occurs on day 7–10 of
illness.
Signs and symptoms

7. About 15% of cases, the
disease progresses to a
more severe form, with
fever, jaundice, renal
failure, and hemorrhagic
manifestations.
Signs and symptoms

8. • Positive-sense, single-stranded,
RNA enveloped flavivirus
• 50-60 nm diameter.
Viral Structure

9. Viral Structure
• Capsid protein C
• Membrane protein M
• E proteins
• Nonstructural protein 1
• NS2A protein
• NS2B and NS3
• NS5

10. Diagnosis
Blood tests (RT-PCR) can sometimes detect the virus
in the early stages of the disease. In later stages of
the disease, testing to identify antibodies is needed
(ELISA and PRNT).
• Virus Detection or Isolation

11. Diagnosis
• Serological test
The detection of IgM antibody by ELISA capture in
a single sample provides a presumptive diagnosis,
with confirmation by a fourfold or greater rise in
titer of neutralizing antibody between acute phase
and convalescent phase serum samples.

12. Treatment
• Patients should be hospitalized for supportive care and
close observation.
• Rest, fluids, and use of pain relievers and medication to
reduce fever may relieve symptoms of aching and fever.
• Care should be taken to avoid certain medications, such as
aspirin or other nonsteroidal anti-inflammatory drugs,
which may increase the risk of bleeding.
• Yellow fever patients should be protected from further
mosquito exposure for up to 5 days after the onset of fever.

13. Prevention
Yellow Fever Vaccine
• YF-Vax
Licensed in the United States, but it has
announced that YF-Vax will be unavailable from
mid-2017 to mid-2018 because of delays in the
production process.

14. Prevention
• STAMARIL
It is registered and distributed in over 70
countries. However, it is considered
investigational in the US, as it is not a US-
licensed product.

15. Thank You!
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