Yellow fever

Yellow fever is a disease that causes fever and yellowness of the white part of the eyes. It is caused by a virus which enters the human body through the bite of a specific type of mosquito called Aedes egypti species. This is different from the mosquito whose bite causes malaria- female anopheles mosquito.

Yellow fever is very common in areas where the environment encourages the breeding of mosquitoes. It is common in some countries in Africa –Nigeria inclusive as well as some parts of Southern America. However due to availability of yellow fever vaccines, the number of infections have drastically reduced worldwide.

Symptoms of yellow fever

Some individuals may have yellow fever without having symptoms, others may have some symptoms which resolve after a few days. Those who have symptoms may experience the following:

  • Fever
  • Headache
  • Body pains
  • Nausea and vomiting
  • Poor appetite

Those with a severe form of the disease (15 to 25%of those infected) will experience worsening of the above symptoms after the initial resolution. This is also when they get to notice change in the color of their sclera (the white part of the eyes), which occurs due to destruction of liver cells. The liver is involved in production of substances (clotting factors) that should make the blood to clot when there is an injury but due to the destruction of the liver cells, the clotting factors are not produced and therefor e, one starts to bleed from different body parts.

They may also experience the passage of dark-coloured urine, bleeding from the mouth, nose or eyes as well as bleeding under the skin (petechial, purpura). Abdominal pain and bleeding from the gastrointestinal tract (stomach and intestine) are also common at this stage. They may vomit blood or dark vomitus (altered blood) and pass dark stool (altered blood) that feels like coal tar. This bleeding from different parts of the body will eventually cause a reduction in blood flow to the kidneys leading to kidney failure. There could also be bleeding in the brain (stroke). This stage is usually fatal if not treated promptly with intravenous fluids and blood/blood products.

Diagnosis of yellow fever

The diagnosis is usually confirmed by blood and urine test. In the late stages of the disease they may test for antibodies against the virus in the blood.

How to prevent yellow fever

This can be prevented by

  • Avoiding mosquito bites
  • Keeping your environment clean and free from stagnant water and other breeding sites for mosquitoes such as empty cans and bottles, tires etc.
  • Wearing long-sleeved clothes and use mosquito repellant creams if you can’t avoid being in a place where you may get bitten by a mosquito.

Yellow fever vaccine

Taking the vaccine. A single dose is usually sufficient however, booster doses may be given during an outbreak. A single dose of the vaccine confers lifetime immunity which usually would kick in within ten days of getting the vaccine for most people. Almost all persons vaccinated would develop immunity by the thirtieth day post vaccination.

yellow fever vaccine
Yellow fever vaccine Credit: Novikov Aleksey/ Shutterstock

Side effects of yellow fever vaccine

  • Sore injection site
  • Muscle ache
  • Headache
  • High temperature
  • rarely, some people have allergic reaction to ingredients in the injection

Which countries require yellow fever vaccine?

Some countries require that you have a yellow fever vaccine before entry. You can find a list of countries that require it here.

Yellow fever vaccination certificate

Some countries require that you provide a yellow fever certificate called the International Certificate of Vaccination or Prophylaxis (ICVP) before entry. Get one when you have your vaccine and keep it safe.

Cost of yellow fever vaccine

The yellow fever vaccine cost between £60 and £100 in the UK.

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