Yellow Fever

Yellow fever is a severe disease caused by a flavivirus which is spread by mosquitoes in certain parts of Africa and South America especially areas covered with jungles and dense forests.

The flu-like illness is characterized by Jaundice and high fever. Jaundice is the yellowing of the eyes and skin, which is where the disease got the name ‘yellow fever.’

Causes of yellow fever

Yellow fever can only be contacted when one is bitten by an infected mosquito. These mosquitoes get infected by feeding on people and animals (like a monkey). They are only active during the day and are found in both rural and urban areas.

Thankfully, it isn’t a communicable disease; it can’t be passed directly through any form of human contact. However, there is no known cure for yellow fever, but it can be prevented with the yellow fever vaccine.

Regions at risk of yellow fever

As earlier mentioned, the disease can only be found in specific regions with favourable climate and dense jungles where the virus and mosquitos can survive.

About 90 per cent of the yellow fever outbreak is thought to occur in Africa where most deaths from the disease have been reported. It is found in Central and West Africa and some part of east Africa. Countries at risk of yellow fever include:

  • Angola
  • Benin
  • Burkina Faso
  • Burundi
  • Cameroon
  • The central African Republic
  • Chad
  • Republic of Congo
  • Cote d’Ivoire
  • The Democratic Republic of Congo
  • Equatorial Guinea
  • Ethiopia
  • Gabon
  • The Gambia
  • Ghana
  • Guinea
  • Guinea-Bissau
  • Kenya
  • Liberia
  • Mali
  • Mauritania
  • Niger
  • Nigeria
  • Rwanda
  • Senegal
  • Sierra Leone
  • Sudan
  • South Sudan
  • Togo
  • Uganda

The disease doesn’t cause outbreaks in most of South America, it is only found in regions with dense forest areas particularly the Amazon. Countries at risk of an outbreak include

  • Brazil
  • Peru,
  • Ecuador
  • Bolivia
  • Colombia
  • Venezuela
  • Argentina
  • Panama
  • Trinidad and Tobago
  • French Guiana
  • Guyana
  • Paraguay
  • Suriname

Yellow Fever Symptoms

The symptoms of yellow fever come in three stages; the first stage occurs within three to six days after exposure from a mosquito bite. Initial symptoms include;

  • Chills
  • Fever
  • Headache
  • Joint ache
  • Muscle aches

Acute/Remission stage

Most people tend to recover after the end of this stage which usually lasts for three to four days. Common symptoms for this stage include;

  • Shivers
  • Backache
  • Headaches
  • A loss of appetite
  • Nausea or vomiting

Severe/toxic stage

This stage is the most dangerous as half of the patients who develop symptoms of this stage die within 7 – 10 days.

More severe symptoms like Jaundice (the yellowing of the skin, eyes, and sometimes under the tongue) begin to surface after the 24 hours of recovering from the acute stage. Other symptoms include;

  • Kidney failure
  • Vomiting (sometimes with blood)
  • Abdominal pain
  • Delirium
  • Seizures
  • Bleeding from the eyes, nose, and mouth
  • Heart rhythm problems
  • Low white blood cell i.e. few immune cells

The good news is, only 15 per cent of people with the disease gets to this stage.


See your doctor immediately if you start developing symptoms of yellow fever. There are a few tests that can confirm your suspicion.

Urine test

This is a relatively new test that can spot the viral PCR (polymerase chain reaction) in the urine, making the diagnosis more practical. however, this test hasn’t gained worldwide recognition, even if it holds a lot of promise,

Antibody test

This is the most recognized, well-established test for yellow fever. It searches for the presence of protein immune to yellow fever in your blood. The presence of these immune proteins shows that either your body is fighting off or, it has effectively fought off the virus.

The dowside of this test, however, is that the results take around two to three weeks to get as it takes your body several days to produce a detectable amount of antibodies.

Viral PCR test

PCR (polymerase chain reaction) tests can spot the virus’ genetic material in your blood. It is seen as a stronger indicator of present infection than an antibody test as a positive PCR test means that you have the virus in your system.

However, one factor limiting the quality of this test is that RNA of the virus is easily detected at an early stage of infection but becomes harder to detect after several days. This can cause your test to come out negative even when you’re already infected.


Yellow Fever

Yellow fever has no specific antiviral treatment, but specific care to treat the symptoms of the disease can improve outcomes. This may include

Hydration. Patients need to be hydrated regularly with oral or IV fluids especially if they experience low blood pressure or vomiting.

Management of organ failure. when organs begin to fail due to the disease, those organs will need support to function properly as the condition improves. For instance, the work of the kidney can be replaced with dialysis, while breathing can be supported with a ventilator.

Pain. oral or injected pain relievers may be used to manage muscle or joint pains.

Fever control. Generally, yellow fever comes with low-grade fevers, but if you experience fevers that are higher than usual, you may need to take medications to lower your temperature.

Blood pressure support. for patients who are in shock, which happens when blood pressure is too low, blood pressure can be boosted with medications that constrict the blood vessels.

Yellow fever prevention

Vaccination is the surest way to prevent yellow fever because offers up to 95% protection to those who receive it.

The vaccine is extremely safe and its administered as a single shot which can last for up to 10 years. Those who live in endemic areas might already be immune or may have received the vaccination.

However, if you haven’t been vaccinated and you wish to travel to an area where yellow fever is endemic, then you need to visit a local travel clinic at least 10 days before your planned departure to get the vaccine.

The vaccine shouldn’t be administered to these set of people

  • Infants below 9 months
  • Adults above 59 years
  • Persons who have severe allergies gelatin, eggs or chicken protein.
  • Persons suffering from conditions that weaken the immune system like HIV, AIDS among others.

Other methods of prevention include; staying indoors and wearing cloths to protect your body during peak times when mosquitoes bite, sleeping under a mosquito net and also, using insect repellent.