Yellow fever

 

Yellow fever is an acute viral hemorrhagic disease transmitted by a female mosquito (Aedes aegypti). It is an endemic disease in tropical and subtropical areas in South America and Africa, but not in Asia. Yellow fever is caused by the yellow fever virus which is a 40 to 50 nm enveloped RNA (ribonucleic acid) virus belonging to the Flaviviridae family.

 

 

Yellow fever virus enters the body of the female mosquito when it sucks the blood of an infected person. Viruses reach the stomach of the mosquito, and if the viral load is high, they replicate and get stored in the mosquito’s salivary gland which then causes infection.

 

 

Early stage symptoms include:

1. Headache

2. Muscle and joint ache

3. Fever

4. Flushing

5. Loss of appetite

6. Vomiting

7. Jaundice

After approximately 3 to 4 days, symptoms often go away briefly (remission).

During the period of remission, after 3 to 4 days, fever and other symptoms go away.

Period of intoxication causes multiple organ dysfunction which may include,

1. Heart failure

2. Liver and kidney failure

3. Bleeding disorders (blood in vomit or stools)

4. Hemorrhage

5. Brain dysfunction including delirium, seizures, coma, shock, and death in about 20% cases.

 

 

1. Your doctor shall ask you to get several blood tests such as complete blood count (CBC).

2. Enzyme-linked immunosorbent assay (ELISA) may help to find specific immunoglobulin M (IgM) against yellow fever during the acute phase of the disease.

3. Reverse transcription polymerase chain reaction where the genome of the virus is amplified can confirm the diagnosis.

4. Isolation of the virus and its growth in cell culture using blood plasma can also help in diagnosis. This can take 1 to 4 weeks.

 

 

Like other hemorrhagic fever there is no cure for this disease. However, symptomatic treatment with pain relief and rehydration is given to those infected. Hospitalization is advisable and intensive care may be necessary because of rapid deterioration in patients who are in intoxication phase.

 

 

1. Vaccination with the attenuated live vaccine (stem 17D) is recommended.

2. Reduce water build-up

3. Wearing clothing that fully covers the body

4. Use of mosquito repellents and nets