What is Yellow Fever?

Yellow fever (also known as American Plague) is an acute infectious disease caused by a virus and transmitted to humans by Aedes and Haemogogus mosquito. The disease is mainly confined to Africa and Central and South America. However, the disease has become less common due to regular vaccinations. The usual course of the illness is acute.

This tropical viral infection is termed ‘Yellow Fever’ because it can cause severe jaundice and turns the skin bright yellow. The virus is transmitted initially by mosquitoes from monkeys to humans and then by mosquitoes from person to person.

Symptoms

The symptoms appear suddenly within 3-5 days of the infected mosquito bite. There may be flu like illness in some cases while in others symptoms include abnormal bleeding, liver failure or kidney failure. Severe bleeding may lead to shock. Rarely, severe infection may lead to convulsions and coma.

Phases

The symptoms in first phase include acute onset of fever, headache, arthralgia, vomiting, relative bradycardia and leucopenia. Second phase is calm. Symptoms of the third phase show increasing fever with chills, orbital pain, photophobia, conjunctivitis, jaundice, hepatomegaly (enlargement of liver), hematemesis (vomiting of blood), malaena (blood in stool) and bleeding gums.

Diagnosis

Diagnosis is symptomatic and confirmation is done through blood test that detects the antibodies against the virus. Liver function tests are also abnormal along with fatty degeneration of liver.

Treatment

There is no specific treatment for yellow fever and the disease is fatal in almost 20-50% of the cases. One attack provides life long immunity. Supportive treatment includes fluid replacement and treating the complications.

Blood transfusion may be required in severe cases and dialysis is considered necessary in renal failure cases.

Prevention

Immunization provides protection for almost 10 years and is strongly recommended for people travelling to high-risk areas. Other steps include using insect repellants and proper clothing.