Contents
In this article we will look at:
- What is yellow fever?
- How does yellow fever occur?
- What are the symptoms of yellow fever? How is yellow fever diagnosed?
- What are the complications of yellow fever?
- What is the treatment for yellow fever?
You can click on any of the links above to navigate to the section of your interest.
What is yellow fever?
Yellow fever is a highly serious, potentially fatal, mosquito-borne disease caused by the flavivirus. The virus is transmitted by infected species of Aedes, and Haemagogus mosquitoes. The mosquito becomes infected when it bites an infected human or an animal (especially a primate).
The disease is endemic and intermittently an epidemic in parts of Africa and tropical South America. Severe cases of yellow fever can cause high fever, internal haemorrhaging, and liver and kidney damage. Often liver damage results in severe jaundice, causing yellowing of the skin and eyes, and hence the name ‘yellow fever’.
As yellow fever is associated with acute haemorrhages, if you notice any symptoms matching those of this disease in yourself, or in any family member, you need to contact your family physician or a general physician without delay to avoid any fatal consequences.
How does yellow fever occur?
The flavivirus which causes yellow fever enters the system of a mosquito replicates in its body and spreads to its salivary glands. Soon after, when the mosquito feeds on a person, the virus gets transmitted to the person. It travels through his body and spreads to various glands in the body. It enters the bloodstream and causes inflammation of the blood vessels, causing them to swell and leak. This affects the blood flow in the body and can cause the body to go into a state of shock, as the organs do not receive the required amount of oxygenated blood.
The incubation period of the flavivirus in a human being varies from 3 to 6 days, following which there is an abrupt onset of chills, fever, muscle and joint pains and headache.
After a day or so, other symptoms soon catch up which includes facial flushing, deep red tongue, loss of appetite, and shivering. These symptoms stay for 3 to 4 days and in most cases disappear.
The patient begins to improve.
A small percentage of patients ( 15% to 25% ), however, see a return of the fever after around 24 hours of recovering from initial symptoms, and develop jaundice, and haemorrhagic symptoms.
Abdominal pain occurs coupled with vomiting. They may also bleed from the mouth, nose, or eyes. 50% of the patients who enter the toxic phase die within 7 - 10 days.
People who have suffered from yellow fever and recovered will be immune to the disease for the rest of their lives.
There is no cure for yellow fever, however, it can be prevented through vaccination. Though, not everyone is eligible for the yellow fever vaccine. The exceptions include:
- infants within 6-8 months of age
- people with a severe allergy to any part of the vaccine, including eggs, chicken proteins, or gelatin
- people who have had a severe reaction to a previous dose of yellow fever vaccine
- people HIV/AIDS or any other disease that affects the immune system
- people with a weak immune system due to cancer or other medical conditions
- people with Thymus disorder
- adults 60 years of age and older
- pregnant women and nursing mothers
What are the symptoms of yellow fever? How is yellow fever diagnosed?
The symptoms of yellow fever occur three to six days after the exposure to the virus. It develops faster than dengue, malaria, or chikungunya.
The initial symptoms at the onset of this disease match those of the common flu and include:
- headaches
- muscle and joint pains
- chills
- high fever
The second phase of this fever is an acute phase and the symptoms that appear in addition to the above include:
Post this phase, most of the patients recover. However, 15% to 25% of the patients encounter a third phase, which is the toxic phase and can often be fatal. Prior to this phase, the symptoms of the second phase disappear for a period of around 24 hours. They then reappear with new severe conditions such as:
- decreased urination due to kidney damage
- abdominal pain
- vomiting
- jaundice (liver damage), which causes yellowing of the skin and eyes
- hepatitis (inflammation of the liver)
- vomiting (sometimes with blood)
- internal bleeding (haemorrhaging)
- heart rhythm problems
- seizures
- delirium
- bleeding from the nose, mouth, and eyes
- multiple organ failures
According to the statistics received by the World Health Organisation, 50% of the patients who reach the third phase die, while the other half recovers.
Diagnosis
Diagnosis of yellow fever can be a complicated process due to the fact that the symptoms match a variety of other ailments, such as flu, severe malaria, typhoid, leptospirosis, or viral hepatitis.
A general physician will usually look at your symptoms and ask whether you travelled recently to any place where yellow fever is active.
A specialized blood test, which is exclusively done for the diagnosis of yellow fever, may reveal specific antibodies, which are virus-specific, produced in response to the particular infection. Further specific antibody testing, such as plaque reduction neutralization test (PRNT) will be done to confirm the yellow fever diagnosis.
What are the complications of yellow fever?
The complications of yellow fever can be highly severe often causing death. Some of these include:
- jaundice
- internal bleeding (haemorrhaging)
- heart rhythm problems
- seizures
- delirium
- coma
- bleeding from the nose, mouth, and eyes
- multiple organ failures
What is the treatment for yellow fever?
There is no specific medication to treat yellow fever. At the most you will be hospitalized and provided supportive care which includes, providing fluids, oxygen if needed, replacing any blood loss, providing dialysis in event of kidney failure, and treating any other complications if they arise. The treatment is more focused on providing you relief from the symptoms of yellow fever such as dehydration, bleeding or haemorrhaging, muscle and joint pains and so on.
You may be quarantined depending on your condition. And if treated at home, the doctor will ask you to stay safe from mosquito bites, by using a mosquito net, or mosquito repellent cream, to avoid spreading the disease to others.
Questions answered by trusted doctors
Did you know?
No case of yellow fever in India
Despite the presence of arbo-viral diseases like Dengue, Japanese Encephalitis, West Nile Fever, Kyasanur Forest Disease and Chikungunya, India has thankfully not seen a single case of yellow fever for decades now.
Yellow fever active areas
Yellow fever is endemic in 33 countries in Africa and 11 countries in South America.
200,000 cases of yellow fever occur annually
Approximately 200,000 cases of yellow fever occur annually and 90% of them occur in Africa.
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