Yellow Fever

Overview

Yellow fever is a viral disease transmitted to people when they get bitten by mosquitoes carrying the virus. Symptoms of this disease include body aches, fever and so on. This viral disease can be fatal and can even take the shape of an epidemic, if not taken care of at the right time. However, proper vaccination can help prevent its development.

What is Yellow Fever?

Yellow fever causes the skin and the white portions of the eyes to turn yellow, giving the disease its name. It can cause damage to the internal organs such as the liver and may even prove to be fatal when the virus enters the human body. It has symptoms that are somewhat similar to the flu. However, with the right vaccine, people can prevent its occurrence.

Symptoms of Yellow Fever

The symptoms of yellow fever can be classified into less severe and more severe symptoms. Less severe symptoms, apart from fever, include muscle pain, headache, and loss of appetite. The infected person can also feel tired or nauseated. More severe symptoms include very high fever, jaundice (the skin and the whites of the eyes turn yellow), and haemorrhage (bleeding). Other severe symptoms include shock, liver failure, kidney failure, and death. It is possible to develop the disease without the appearance of prominent symptoms.

The signs and symptoms of yellow fever in the majority of the cases disappear after three to four days. However, some patients enter the second phase of this disease just within 24 hours of recovering from initial symptoms. This stage is more harmful as people might experience high fever along with problems in the liver and the kidneys. People might also develop jaundice and experience abdominal pain and dark urine alongside vomiting in this second stage. Bleeding from the mouth, eyes, nose, or stomach can occur too.

Causes of Yellow Fever

Yellow fever is caused by an arbovirus, a virus transmitted by mosquito bites. Aedes and Haemagogus mosquitoes transfer the virus into their bodies upon biting infected people and inject it back into the body of a healthy individual when biting them. There are 3 types of transmission cycles of this viral disease: sylvatic, intermediate and urban.

Sylvatic Yellow Fever: Sylvatic yellow fever spreads when wild mosquitoes bite monkeys and pass the virus on to other monkeys and humans.

Intermediate Yellow Fever: Intermediate yellow fever, the most common type of outbreak in Africa, spreads when semi-domestic mosquitoes infect monkeys and people.

Urban Yellow Fever: Urban yellow fever spreads when the infected individuals spread the virus into densely populated regions having high mosquito density and where people have very low immunity.

Yellow Fever Diagnosis and Tests

Yellow fever is hard to diagnose, particularly during the early stages. Someone who has been in an area with an outbreak and notices any symptoms should consult their doctor immediately. Doctors diagnose this disease by assessing recent travel activity, checking the symptoms, and prescribing blood tests. Polymerase Chain Reaction (PCR) testing of blood can sometimes detect the virus in the early stages of the disease. For the later stages, testing is done to check the presence of antibodies in the blood.

Yellow Fever Management and Treatment

There is no cure or treatment for this disease. However, doctors may advise getting lots of rest and drinking lots of fluids to manage the symptoms effectively. People should go to a hospital if they have a more serious form of the disease. The patients admitted may be sent home or referred for in-hospital management or require emergency treatment. They may also be sent on urgent referral depending on the signs and symptoms patients may experience or observe. Associated bacterial infections can be treated with antibiotics. Alongside, the treatment for dehydration, liver failure and kidney failure improves outcomes.

Preventive Measures for Yellow Fever

Vaccination is the most important and effective yellow fever prevention method. The vaccine is safe and a single dose provides life-long protection against the disease. There is no need for a booster dose. About 80-100% of the people getting vaccinated acquire effective immunity within 10 days and 99% of people get it within 30 days.

The side effects of the yellow fever vaccine are somewhat rare. However, some people usually are not suitable for vaccination. Infants aged less than 9 months, people aged 65 or older and pregnant women do not qualify for taking this vaccine.

If someone has had a severe allergic reaction to chicken, eggs, gelatin, or previous yellow fever vaccine they may also be excluded from taking the vaccine. People with severe immunodeficiency and someone with cancer and thymus disorder are not suitable for getting this vaccine.

Patients should see their doctors right away if they develop a side effect after taking the medicine. This vaccine in a few rare cases has caused a nervous system reaction, allergic reaction, and life-threatening illness.

There are some other preventive measures such as:

• Eliminating mosquito breeding locations by applying larvicides to water storage containers and places where stagnant water collects.
• Wearing clothing to minimise skin exposure and use insect repellants to avoid mosquito bites.
• Using screens on windows and doors, hanging mosquito nets over the beds to keep mosquitoes away, and avoiding going outdoors during peak mosquito hours.
• Keeping accurate records of international travel dates, locations and outdoor activities. This will be useful to identify a viral infection after returning from tours.

Myths and Facts Related to Yellow Fever

Yellow fever has some misconceptions around it. Some of these myths and facts that prove them wrong are:

Myth 1: You Can Only Get It From Getting Bit by Mosquitoes
Fact: The infection may be transmitted directly into the blood of healthy individuals through contaminated needles as well.

Myth 2: Yellow Fever is Not a Serious Disease Anymore
Fact: Medical science has advanced a lot since yellow fever was first detected. But it does not mean it is not a serious disease anymore. Healthy people can experience severe symptoms if the infection reaches an advanced phase due to a delay in treatment.