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Understanding Yellow Fever: Symptoms, causes, and treatment

Dr. Ajay KohliApr 19, 2024

Yellow Fever, a haemorrhagic disease, causes epidemics in tropical and subtropical regions of Central and South America and Africa, resulting in considerable illness and death. Symptoms are typically self-limiting, but complications involve severe organ damage, bleeding, and sometimes death. Unfortunately, no treatment for Yellow Fever exists, though a vaccine is recommended for travellers to high-risk areas to prevent Yellow Fever transmission. Read ahead to know more about this disease.




What is Yellow Fever?

Yellow Fever is caused by a virus belonging to the Flaviviridae family. The disease is transmitted to humans by the bite of an infected Aedes mosquito (particularly A. aegypti) that also transmits dengue, Zika, and chikungunya viruses. It is called "Yellow Fever" because, in severe cases, the skin turns yellow in colour, just like in jaundice. The current estimate indicates that Yellow Fever claims 30,000 lives every year globally. 

Signs and symptoms of Yellow Fever

Many people do not develop symptoms once they contract the virus. However, if a person does, it takes 3 to 6 days for the illness to manifest. During this time, they will suffer the unexpected onset of:

  • Fever and chills

  • Severe headaches

  • Muscle and joint pains

  • Vomiting

  • Loss of appetite

  • Severe back pain

In most instances, people tend to feel better after 3 to 5 days of infection. But, in some (1 in 5 patients), the disease progresses to a more toxic stage after the initial symptoms resolve. 

At this stage, the patient will have the following.

  • Extremely high fever

  • Jaundice (yellowing of the skin and eyes, hence the name)

  • Bleeding from the eyes, mouth, nose, and stomach 

  • Abnormal heartbeat 

  • Kidney failure accompanied by black urine 

  • Seizures

  • Sudden loss of thinking and confusion 

  • Coma

Death is possible within 7 to 10 days in half of those who develop severe symptoms. For those who survive, recovery can take a long time, often with life-threatening sequelae. 


What causes Yellow Fever?

Yellow Fever is primarily transmitted via mosquito bites, principally the Aedes aegypti and Haemagogus species. These mosquitoes are active both day and night, and thrive in even the cleanest water present around human settlements. The virus is acquired when an uninfected mosquito bites a previously infected person or animal, such as a monkey. It then enters the mosquito's circulation and travels to its salivary glands. When a new human or a monkey is bitten by this infected mosquito, the virus enters the host's bloodstream, and the symptoms develop soon after.

Treatment for Yellow Fever

Yellow Fever has no effective treatment. That is why, if you are sick with Yellow Fever with more severe symptoms, you may need to go to the hospital for extensive supportive care and hydration.

Your supportive care will focus on providing the following.

  • Restoration of bodily fluids

  • Oxygen support

  • Substitution of lost blood

  • Dialysis for renal insufficiency

  • Antibiotic therapy for secondary infections

  • Pain treatment using traditional medications

Moreover, do not take aspirin and other nonsteroidal anti-inflammatory medicines such as ibuprofen unless prescribed, as these medications can raise the risk of bleeding.

Diagnosis of Yellow Fever

Diagnosing Yellow Fever is often challenging, especially in the initial stages of infection, because it can be easily confused with a wide range of diseases, such as the following.

That is why your doctor may ask questions about your recent travel and probably would do a blood test to confirm the diagnosis. 

During the procedure, your blood will be evaluated by:

  • Polymerase Chain Reaction (PCR) to detect the virus directly in the blood in the initial stages of infection).

  • ELISA to identify virus-specific antibodies in the later infective stages.

The blood tests will also demonstrate rising white blood cell counts (leukopenia), indicating progressive infection. Other investigations will be ordered depending on which organ is involved.

How can I prevent Yellow Fever? 

Vaccination is the most important means to combat the Yellow Fever virus. Not only is the vaccine safe, but a single dose can provide 99% protection when taken within 30 days of the onset of symptoms. 

With few exceptions, the vaccine is recommended for those living in or travelling to areas endemic to Yellow Fever. 

Preventing exposure to mosquito bites is another important measure for those who cannot be vaccinated but are travelling in areas with Yellow Fever transmission. For such individuals, the CDC recommends taking the following steps.

  • Use insect repellent containing DEET or Picaridin, specifically around midmorning, late afternoon, and dusk, when the activity of Aedes mosquito peaks.

  • Wear light-coloured long sleeves, and trousers to protect your arms and legs.

  • Stay in well-screened and air-conditioned accommodations.

  • Sleep under a mosquito net when you are outdoors or in a room without window and door screens. 

  • Remove stagnant water in and around spaces like tyres, buckets, toys, pools, birdbaths, flowerpots, and trash containers, or put larva-killing chemicals to prevent mosquito breeding.

Risk factors for Yellow Fever

The risk of catching the illness is undeniably high for anyone who visits a location where mosquitoes continue to thrive and spread the virus. For example, the risk of infection for unvaccinated travellers to West Africa is approximately 50 per 1,00,000 persons. Of those who become severely infected, one in five dies, says CDC.

So, if you wish to travel to an area that is currently experiencing an outbreak, talk to your doctor about being vaccinated before travelling. Yellow Fever can infect anyone. But old adults and people with compromised immune systems are at a greater risk of severe patient outcomes. 

Frequently Asked Questions (FAQs)

Here’s a list of common queries about Yellow Fever and their answers.

Is Yellow Fever a notifiable disease?


In compliance with the WHO's International Health Regulation, Yellow Fever must be reported as soon as it is detected. Therefore, it is a notifiable disease.

How does Yellow Fever affect your body?


When the Yellow Fever virus (also known as bunyavirus infection) enters the body, it damages key organs: the liver, kidneys, heart, and digestive system. Subsequently, two phases of symptoms occur. The first phase is marked by a flu-like illness that lasts 3 to 5 days. While the next phase is more toxic, where the disease returns vigorously, causing jaundice, bleeding of the gums, nose, and mouth, bloody vomiting, and sometimes, shock.

Who is most at risk for getting Yellow Fever?


People who have a higher chance of contracting Yellow Fever include the following.

  • Individuals living in or travelling to locations where Yellow Fever is seen in humans or monkeys 

  • Infants younger than 9 months

  • Pregnant females

  • Laboratory workers

  • Older adults

  • People with severe immunodeficiency

Should I worry about Yellow Fever when I travel out of the country?


Before travelling abroad, it is usually best to consult a doctor about your risk of contracting an infection that is common in other countries. However, the odds of you acquiring Yellow Fever depend partly on the destination, season, outdoor activities, and transmission rate at the time of travel. Hence, you are advised to get vaccinated against Yellow Fever before visiting Yellow Fever-endemic regions.

What is the chance of my recovery if I get infected with Yellow Fever?


The chances of recovery are good if you are familiar with the common symptoms of Yellow Fever. Because then, you can seek medical help and save yourself from succumbing to any serious complications.

How long should you wait after getting vaccinated?


Preferably,  wait for 10 days to give enough time for the vaccine to take full effect. Again, if you have had the MMR vaccine, wait at least 4 weeks before receiving the Yellow Fever vaccine.







Disclaimer: The content on this page is generic and shared only for informational and explanatory purposes. Please consult a doctor before making any health-related decisions.


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