Yellow Fever
Yellow fever is a viral disease, which is now largely confined to Equatorial Africa and Central South America. There are 200,000 estimated cases – with 30,000 deaths – per year. Thirty-three African countries are affected, with a total human population at risk of around 500 million.
The virus is incubated in the body for between three to six days before the start of the disease phase. This can involve fever, muscle pain, headache, shivering and loss of appetite, nausea and /or vomiting. After a few days, most patients improve and their symptoms disappear.
However, 15% enter a ‘toxic’ phase within 24 hours. Fever reoccurs, the patient develops jaundice – thus the “yellow” in the name – and kidney function deteriorates. Half of the patients in the toxic phase die within 10-14 days.
Transmission
The virus which causes yellow fever is one of a group of viruses known as the arboviruses. Humans and monkeys are infected by being bitten by the yellow fever mosquito (Aedes aegypti) which lives in a range of ecosystems from rain forests to urban environments.There is no specific treatment for yellow fever, but it is one of the few arboviruses for which an effective vaccination is available. A single dose usually provides protection for at least 10 years. Certain countries require proof of vaccination before allowing entry.