This document discusses yellow fever, a viral hemorrhagic disease transmitted by Aedes mosquitoes. It is caused by a flavivirus that primarily affects monkeys but can infect humans. The disease causes liver and kidney damage that can lead to jaundice, hemorrhaging, and death in 20-50% of cases. It is found in tropical areas of Africa and South America. Prevention relies on vaccination and controlling the Aedes aegypti mosquito vector through environmental management and insecticides.

1. DR.R.TAMILARASI
DEPT.OF COM. MEDICINE.
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2. INTRODUCTION:
 Zoonotic disease
Caused by ARBOVIRUS.
Principally affects monkeys.
Transmitted by Aedes Mosquitos.
 Hemorrhagic fever with severe HEPATIC and RENAL
involvement.
 Jaundice with hemorrhagic manifestations like black vomit
(xekik), epistaxis and melena may be present.
 May progress to albuminuria, anuria, shock, agitation, stupor
and coma.
Death between 5th and 10th day of illness.
Fatality rate : 80%
Survivors have long lasting immunity.
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3. CLINICAL FEATURES AND COMPLICATIONS
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4. PROBLEM STATEMENT
• 45 Countries in AFRICA (32 Countries) and LATIN
AMERICA (13 Countries ) – 900 million population is at
Risk.
• 2 lakh cases and 30,000 deaths each year.
• Small number of imported cases in yellow fever free
countries.
• ASIA – didn’t report case. But at risk.
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5. YELLOW FEVER CONQUEST, 1793
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6. EPIDEMIOLOGICAL DETERMINANTS
 AGENT FACTORS:
1) Agent: GROUP B - TOGAVIRUS- FLAVIVIRUS FIBRICUS.
2) Reservoirs:
Forest cycle→ monkeys and forest mosquitoes.
Urban cycle→ man and Aedes aegypti mosquitoes.
3) Period of communicability:
→ Man: 3-4 days of illness.
→ Mosquitoes: after “ the extrinsic incubation period”- 8 to 12
days. Trans ovarian transmission- extended dry season in
absence of susceptible hosts.
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7. HOST FACTORS: all age and both sex.
• Wood cutters and hunters are more prone.
• First attack→ long lasting immunity.
ENVIRONMENTAL FACTORS:
• CLIMATE: >24 deg C needed for the multiplication of virus in
mosquito.
• Relative humidity: >60%.
• Urbanization,travel & expanding population - closer to jungles.
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8. MODES OF TRANSMISSION
Three cycles of transmission:
1. Jungle yellow fever
2. Intermediate yellow fever
3. Urban yellow fever
Sylvatic or Jungle yellow fever:
• In tropical rain forests – monkeys infected by wild mosquitoes.
• Occasional human cases in young men working in forest.
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9. Intermediate yellow fever:
• Humid and semi humid areas.
• Semi domestic mosquitoes infect both monkeys and
humans.
• Small scale epidemics occur.
• Common type of outbreak in Africa.
• Severe epidemic can occur if infection introduced into
heavily populated area and unvaccinated people.
Urban yellow fever:
• Large epidemics occur.
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10. INVESTIGATION
• Complete heamogram
• LFT,RFT
• Urine analysis
• Liver biopsy –contraindication -hemorrhage
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11. TREATMENT
• No specific treatment .
• Supportive care – treat dehydration ,fever .
• Secondary bacterial infections - antibiotic .
INCUBATION PERIOD:
3 - 6 days.
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12. CONTROL OF YELLOW FEVER
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13. CONTROL OF JUNGLE YELLOW FEVER
• Uncontrollable in jungle.
• Virus maintains itself in the animal kingdom.
• Mosquito control is difficult can be considered only in
restricted areas .
• Vaccination of man with 17D vaccine.
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14. CONTROL OF URBAN CYCLE
THE 17 D VACCINE:
 Live attenuated vaccine developed from non-
virulent 17 D strain grown in chick embryo and
subsequently freeze dried.
 Dosage: Single dose of 0.5 ml irrespective of
age given subcutaneously over the insertion of
deltoid.
 Immunity: from 7th day-35 years.
 WHO recommends revaccination after 10
years.
 Mild post vaccinal reactions: myalgia, head
ache, low grade fever in 2.5% of vaccinees(5 –
10 days after vaccination). Anaphylaxis is rare.14

15. 17 D VACCINE:
• Highly Heat sensitive. Stored below 0oc (+5oc - -30oc )
• Keep away from sunlight.
• Reconstituted with cold physiological saline.
• Discard if not used within half an hour.
• Cholera and yellow fever vaccine interfere with each
other if given together or within 3 weeks.
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16. Contraindication:
1. Child under 9 mon ,or under 6 months during an epidemic .
2. Pregnant women – except during a yellow fever out break
when the risk of infection high
3. People with severe allergies to egg protein
4. People with severe immunodeficiency caused by
symptomatic HIV /AIDS or other causes or in the presence of
thymus disorder.
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17. VECTOR CONTROL:
Aedes is peri - domestic in habits
1) Anti adult and anti larval - source reduction and health
education to ensure community
participation/fogging
2) Personal protection: use of repellents, mosquito nets, coils.
SURVEILLANCE:
(Clinical, Serological, histopathological and entomological)
In Endemic Areas.
• “ AEDES AEGYPTI INDEX” → percentage of houses and
their premises in a limited well-defined area showing actual
breeding of Aedes aegypti larva.
• It should not be more than 1% in endemic areas.
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18. INTERNATIONAL MEASURES:
• INDIA is a RECEPTIVE AREA for YF → “ an area in which
YF does not exist, but where conditions would permit its
development if introduced”.
• Introduction can be possibly done by
i) MOSQUITOES. ii) TRAVELLERS
• Mosquito control:
• Aircrafts and Ships(from endemic areas): Aerosol spraying
with prescribed insecticide
• Airports and Seaports: area of 400 metres around them
should be kept free from breeding of mosquitoes.
• Aedes aegypti index should be kept below 1%.
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19. TRAVELERS:
• Should present a Valid VACCINATION CERTIFICATE.
(Including Infants)
• Validity of the certificate: 10 days after vaccination upto 10
years.
• If traveler arrives before certificate becomes valid- isolation till
becomes valid.
• If certificate not available – quarantine for 6 days.
• Issued by officially designated centers with official stamp of
MINISTRY OF HEALTH, GOVT. OF INDIA.
REFERENCE CENTERS:
1) National Institute of Virology, Pune.
2) Central Research Institute, Kasauli.
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20. Designated centres
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21. Thank you
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