Yellow fever is a viral hemorrhagic disease transmitted by infected mosquitoes that is endemic in parts of Africa and Latin America. It causes symptoms ranging from fever, jaundice, and kidney failure. Around 15-20% of infected individuals develop a life-threatening toxic phase with high mortality. Diagnosis is clinical or via liver biopsy. Treatment focuses on symptom management and prevention of secondary infections. Vaccination provides long-term immunity and is recommended for travelers. Pakistan is at risk due to suitable environmental conditions and lack of population immunity, so control relies on surveillance, vaccination, and prevention of international spread.

1. AB RAJAR
ASSOCIATE PROFESSOR
COMMUNITY MEDICINE

2. INTRODUCTION
• Yellow fever, known historically as yellow jack, yellow
plague, or bronze john.
• It is an acute infectious disease of short duration, with sudden
onset,fever,headache,prostration,nausea,epistaxis,buccal bleeding,
hematemesis,malena and jaundice.
• Pulse rate is slow, albuminuria and leucopenia are present.
• Fatality rate varies from 5% to 40%.

3. INTRODUCTION
• Yellow fever is a hemorrhagic
condition that can lead to a high
fever, bleeding into the skin, and
cell death in the liver and
kidneys.
• If enough liver cells die, liver
damage occurs, leading to
jaundice, a condition in which
the skin takes on a yellowish
color

4. KEY FACTS
• Yellow fever is an acute viral hemorrhagic disease transmitted by
infected mosquitoes.
• The "yellow" in the name refers to the jaundice that affects some
patients.
• Up to 50% of severely affected persons without treatment will die
from yellow fever.
• According to the recent analysis, there are an estimated 84 000–170
000 cases and up to 60 000 deaths due to yellow fever per year.
• The virus is endemic in tropical areas of Africa and Latin America, with
a combined population of over 900 million people.

5. GLOBAL DISTRIBUTION

6. EPIDEMIOLOGY OF YELLOW FEVER
• AGENT FACTORS:
• Flavi virus Fibricus.
• Toga Virus family.
• Group B Arbovirus.

7. Epidemiology of yellow fever
• RESERVOIR OF INFECTION::
• Monkeys, forest mosquitoes like Aedes African & Aedes
Simpsons while in case of URBAN cycle Man (sub-clinical ,clinical
cases ) & Aedes aegypti mosquitoes.
• PERIOD OF COMMUNICABILITY:
• 3-4 days while Mosquito for life is capable of transmission.

8. EPIDEMIOLOGY OF YELLOW FEVER
HOST FACTORS:
• Age:
• All age group,
• Sex:
• Both sexes,
• Occupation:
• Wood cutters, Hunters.
• Immunity:
• One attack provides life long immunity if person survive.

9. Epidemiology of yellow fever
ENVIRONMENTAL FACTORS:
• Climate & Temperature: Hot & Humid(60%).
• Social Factors: Urbanization, close approximate to Jungle cycle, Long
travels.

10. EPIDEMIOLOGY OF YELLOW FEVER
• MODES OF TRANSMISSIONS:
oJUNGLE CYCLE:
• Monkeys are reservoir of infection.
• Vectors are Aedes Africans, Aedes Simpsoni.
oURBAN CYCLE:
• Man is the reservoir of infection.
• Vector is Aedes aegypti(a peri-domestic mosquito).
INCUBATION PERIOD:
• 3-6 days but it may be as long as 9 days.

11. CLINICAL FEATURES
• CLINICAL FEATURES ARE IN TWO STAGES:
A. ACUTE STAGE: ( ABOUT 80 - 85% )
B. TOXIC/LIFE THREATENING STAGE: (15 -20%).

12. CLINICAL FEATURES
• ACUTE STAGE:
• In the early, acute stage, the individual may experience:
• Aching muscles (back and knees),
• High fever,
• Dizziness,
• Headache, loss of appetite,
• Nausea, shivers, or chills,
• Vomiting.
• These symptoms usually disappear within 7 to 10 days but
around 15% of people enter a second stage, or toxic.

14. CLINICAL FEATURES
• TOXIC/LIFE THREATENING STAGE:
• Recurring fever, abdominal pain,
vomiting.
• Sometimes with blood tiredness
• Sluggishness,
• Lethargy, jaundice,
• Kidney failure, liver failure.
• Hemorrhage delirium,
• Seizures, and sometimes coma,
• Arrhythmias, or irregular
heartbeats,
• Bleeding from the nose, mouth,
and eyes
• Between 20 percent and 50 percent of people who develop toxic stage
symptoms die within two weeks.

15. DIAGNOSIS:
• Symptoms of Yellow Fever are also identical to that of malaria,
typhoid, and dengue.
• Diagnosis is made on clinical grounds & in fatal cases by Liver biopsy,
• Blood tests must be done in order to properly diagnose Yellow Fever.

16. TREATMENT
Treatment for Mild Cases.
• Drink plenty of water
• Bed rest
• Take acetaminophen (not aspirin) for the pain and discomfort
Treatment for Severe Cases
• Hospitalization required
• Blood replacement.
• Medication to prevent and control seizures, nausea
• Prevention of secondary infections
• Yellow fever patients should be protected from further mosquito
exposure for up to 5 days after the onset of fever.

17. METHODS OF CONTROL
PREVENTIVE MEASURES:
Control of an aegypti breeding,
• Eliminate unnecessary artificial collection of water.
• Use of insecticides in water tanks & reservoirs.
• Use of Larvicidal fish.
Intensive vaccination programmes aimed at persons living in rural
areas nearer to Yellow fever forests.
Active immunization of exposed persons & all travelers entering or
leaving known areas of infections.

18. VACCINATION
• Live attenuated 17 D vaccine,0.5ml,S/C single dose provides at
least 10 years protection, and the person may be protected for life.
• The vaccine is deemed to be safe for patients aged between 9 months
and 60 years.
• Any patient over 60 years of age should discuss whether to have the
vaccine with a doctor.
• It is important for travelers to have the vaccination.
• After 30 days, 99 percent who receive the vaccination have complete
protection.
• A booster dose of yellow fever vaccine is not needed.

19. VACCINATION
• PEOPLE WHO ARE USUALLY EXCLUDED FROM VACCINATION INCLUDE:
• Infants aged less than 9 months;
• Pregnant women – except during a yellow fever outbreak when the risk of
infection is high;
• People with severe allergies to egg protein; and
• People with severe immunodeficiency due to symptomatic HIV/AIDS or other
causes, or who have a thymus disorder.

20. 2. VECTOR CONTROL
VECTOR CONTROL:
 All mosquito control measures.
 Notify the Health authorities.
Quarantine :6-days.
Investigation of contacts & source of infection.
Treatment: Symptomatic.

21. C. SURVEILLANCE
• WHO uses Aedes aegpti index.
• It should be less than 1%.

22. Pakistan a “Receptive area”…
• PAKISTAN is a” Yellow fever receptive area “i.e. an area where Yellow
fever does not exist, but where conditions would permit its
development if once introduced.
• The population of Pakistan is unvaccinated & susceptible to Yellow
fever.
• The vector,Asdes aegypti is found in abundance, monkeys here are
also susceptible.
• Environmental factors are favorable for the growth of Aedes aegypti
& hence for virus of Yellow fever.

23. Pakistan a “Receptive area”…
• The only missing link in the chain of transmission is the virus of Yellow
fever.
• The virus can enter in Pakistan by:
1. Infected travelers.
2. Infected mosquito.
3. Infected animals.

24. INTERNATIONAL MEASURES
• Notification of” WHO” & of adjacent countries by the Government
where Yellow fever is present.
• Prevent carriage of infected A.aegypti by international public carriers,
by thorough spraying of planes & ships with insecticide spray.
• Animal Quarantine: Monkeys arriving from Yellow fever areas should
be quarantined for 7 days.
• International travelers: Travelers from endemic areas must possess a
valid international anti-Yellow fever vaccination certificate is required
before they enter in “receptive area”.

25. INTERNATIONAL MEASURES
• If he/she does not have this certificate, then he/she is placed in
quarantine for 6 days.
• Air ports & sea ports are kept free from breeding of insect vector over
an area of at least 400m.
• Vaccination of travelers from Pakistan to yellow fever endemic areas
to prevent infection.