Yellow fever.pptx

Menu © Community, Environmental & Occupational Medicine .Dept, ASU, 2013
VECTOR-BORNE DISEASES

Menu © Community, Environmental & Occupational Medicine .Dept, ASU, 2013
ILOs
By the end of this lecture, you should be able
to:
• Identify modes of transmission of Yellow fever
• Identify epidemiology of the disease
• Identify preventive measures

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
© Community, Environmental & Occupational Medicine .Dept, ASU, 2013
Identification
Yellow Fever
• An acute infectious
disease of short duration
and varying severity.
Typical attacks are
characterized by a dengue
like illness
• It is one of the
quarantinable diseases.
• It is a zoonotic disease
Identification
Definition

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Identification
Yellow Fever
• The mildest cases are clinically indeterminate.
• Typical attacks are characterized by sudden onset of:
Identification
Clinical Picture
Fever Headache
vomiting
Albuminuria,
anuria (acute
renal failure)
Jaundice
Leukopenia,
hemorrhage

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Identification
Yellow Fever
• Laboratory criteria:
4 fold or greater rise in yellow fever antibody titer in a
patient who has no history of YF vaccine and cross
reaction to other flaviviruses have been excluded
Demonstration of YF virus (antigen or genome) in tissue,
blood or other body fluid.
Identification
Diagnosis
( = or > ) 4x Y titer

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Identification
Yellow Fever
• Clinically compatible
• Supportive serology
• No history of YF vaccination
• No cross reaction to other flaviviruses
Probable
case
• Same as probable
• Demonstration of the virus
Confirmed
case
Identification
Reporting:

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Infectious
agent
Yellow Fever
• Yellow fever virus, a
flavivirus.
Infectious agent

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Epidemiology
• In Africa, sylvan yellow fever is endemic in Angola, Zaire, Zambia,
Tanzania, Uganda, Kenya and South Sudan.
• In the Americas, the disease is reported in Northern South America and
Amazon basin.
• No cases reported in Asia, Europe, North America and Australia.
Yellow Fever
Epidemiology

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Reservoir
Yellow Fever
Reservoir
In urban areas:
Man
in forest areas
(Jungle):
mainly
Monkeys

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Mode of
transmission
Yellow Fever
• By the bite of infected Aedes mosquito.
• Trans-ovarian transmission in
mosquitoes may contribute to
maintenance of infection. Once the
mosquito is infected it remains so for
life.
• Aedes aegypti mosquito can’t withstand
cold weather
Mode of transmission

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Mode of
transmission
Yellow Fever
In urban
areas:
Aedes aegypti
In the forest
(in Africa):
Aedes
africanus
in the
Americas:
Haemagogus
Mode of transmission
Vector: types

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Incubation
Period
Yellow Fever
The incubation period is:
6 days
Incubation period
1 6
Exposure to mosquito bite

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Period of
communicability
Yellow Fever
• Not communicable by contact or common vehicles.
• But the blood of patient is infective for mosquitoes shortly
before onset of fever and for the first 3-5 days of illness.
Period of communicability
Before onset of fever
& for 3-5 days of illness
Patient is infective to mosquito

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Susceptibility
& resistance
Yellow Fever
Susceptibility& resistance
1. Susceptibility:
Person
All ages affected,
but Adult males
working in forest
(hunters &
woodcutters) are
more exposed
Place
Disease is endemic
in: Sub-Saharan
Africa, Northern
South America
& Amazon
basin.
Time
Mosquito
breeding season

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Susceptibility
& resistance
• Transient passive immunity in infants born to immune
mothers may persist up to 6 months.
• Recovery from yellow fever is followed by life long
lasting immunity; second attacks are not reported.
Yellow Fever
Susceptibility& resistance
2. Resistance
6 months immunity
Life long lasting immunity

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Prevention &
Control
Yellow Fever
Prevention & Control
1. Prevention
A. General measures:
• Control of Aedes aegypti in urban yellow fever.
• Protective clothes, bed nets and repellent are advised for
persons not immunized and work in forests.
• Aircrafts leaving an infected area to receptive area should
be disinfected
• Quarantine measures for imported monkeys at receptive
areas.
• Periodic spraying of airports and surrounding receptive
areas.

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Prevention &
Control
Yellow Fever
1. Prevention
B. Specific measures: by active immunization
• A single S.C. injection of a 17 D vaccine containing viable
attenuated yellow fever 17 D strain virus.
• Validity of the vaccine: begins after 10 days and persists for at least
10 years. During this period of validation no cases have been
reported.
• Indications:
– Travelers to endemic areas or between endemic and receptive
areas.
– Those who work in jungles.
– Resident of endemic areas.

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Prevention &
Control
Yellow Fever
Traveler isolation (Quarantine)
• If a traveler arrives in a receptive area without a certificate, he is
isolated for 6 days from the date of leaving the last infected area.
• If a traveler arrives in a receptive area before completing 10 days of
vaccination, he is isolated until the certificate becomes valid, with
a maximum of 6 days.
1. Prevention

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Prevention &
Control
Yellow Fever
• Control measures concerning the patient:
– Isolation at any place. Prevent access of mosquitoes to patients
for at least 3-5 days.
– Notification to local health office then to WHO.
– Disinfection is not required.
– Treatment is symptomatic and correction of complications.
2. Control
x

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Prevention &
Control
Yellow Fever
• Control measures concerning the contacts:
Family and other contacts not previously immunized
should be vaccinated.
• Control measures concerning the environment:
Search for source of infection i.e. areas visited by patient
3-6 days before onset to locate focus of yellow fever.
2. Control

Identification
Infectious
agent
Epidemiology
Reservoir
Mode of
transmission
Incubation
Period
Period of
communicability
Susceptibility
& resistance
Prevention &
Control
Glossary Summary
Menu Quiz
Yellow Fever

Yellow fever.pptx

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