Yellow fever known as "Sylvatic fever" and viral hemorrhagic fever or VHF is an acute tropical viral disease which is spread to humans by infected mosquitoes caused by a type of virus called a flavivirus.  It is an important cause of hemorrhagic illness. It is found only in parts of South America and Africa The yellow refers to the jaundice symptoms that affect some patients. There are two kinds of yellow fever, spread by two different cycles of infection.

• Jungle Yellow Fever: Jungle yellow fever is a disease which directly related to monkeys. It is spread from infected mosquitoes to monkeys in the tropical rain forest. It spread to the humans when humans are bitten by same mosquitoes which have been infected by monkeys. It is a rare disease and mainly occurs in persons who work in tropical rain forests.
• Urban Yellow Fever: It is spread by mosquitoes that have been infected by other people. "Aedes aegypti" is the type of mosquito that usually carries yellow fever from human to human. The mosquito bite one person and same mosquito bites another person.

There are 3 Stages of Yellow fever:

1. First Stage/Mild Stage: In first stage headache, muscle aches, fever, loss of appetite, vomiting, and jaundice are common.
2. Second Stage/Remission Period: After 3 -4 days, fever and other symptoms go away. Most people will recover at this stage.
3. Third Stage/Intoxication Period: In this stage Multi-organ dysfunction occur which includes liver and kidney failure, bleeding disorders/hemorrhage, brain dysfunction including delirium, seizures, coma, shock, and death.

 Other names of Yellow Fever: Yellow jack, Black Vomit or American Plague

 Causes of Yellow Fever
The major cause of Yellow Fever is mosquito. People get yellow fever from the bite of an infected female mosquito. The mosquito injects the yellow fever virus into the bite.

Possible Complications due to Yellow Fever:

• Coma
• Death
• Disseminated Intravascular Coagulation (DIC)
• Kidney failure
• Liver failure
• Parotitis
• Secondary Bacterial Infections
• Shock

Signs & Symptoms of Yellow Fever
Many yellow fever infections are mild, but the disease can cause severe, life-threatening illness. Symptoms start 3 to 6 days after being bitten by an infected mosquito. Symptoms of severe infection are:

• Arrhythmias
• Backache
• Bleeding
• Chills
• Coma
• Decreased Urination
• Delirium
• Headache
• Heart Dysfunction
• High Fever
• Jaundice
• Kidney/Liver Failure
• Muscle Aches
• Red Eyes, Face, Tongue
• Seizures
• Vomiting

A person with advanced yellow fever may show signs of liver failure, renal failure, and shock.

Complications of Yellow Fever
Yellow fever infection creates some complications during its toxic phase which includes:

• Coma
• Delirium
• Jaundice
• Kidney and Liver Failure

Yellow fever results in 20-50% cases of death of the infected people.

Diagnosis of Yellow Fever
Laboratory tests are required to diagnose Yellow fever. The disease may be difficult to distinguish from other illnesses, especially in the early stages.

• To diagnose properly, doctor will ask about your travel history, if you have traveled to areas where the disease is known to thrive.
• After that the doctor will perform the blood tests. In the laboratory, specific yellow fever virus antibodies can be detected in the blood.

Other tests which can be helpful in diagnosis of Yellow fever are:

• Cerebrospinal fluid tests
• Electrocardiograms (EKGs)

These individual tests will not definitely diagnose yellow fever, but they can be helpful.

Preventions of Yellow Fever
Yellow fever can be prevented by vaccination. Travelers should also take precautions against mosquito bites when in areas with yellow fever transmission.

• Avoid mosquito bites when traveling in tropical areas.
• Get vaccinated for yellow fever before travel.
• Spray living and sleeping areas with insecticide.
• Stay in well-screened areas as much as possible.
• Travelers should take steps to reduce contact with mosquitoes when outdoors and inside.
• Use a bed net when sleeping in a room.
• Use insect repellent on exposed skin.
• Use the bed net with the insecticide permethrin
• Wear long-sleeved clothing and long pants.

In order to minimize the chance of becoming infected by the yellow fever virus, it is important to learn yellow fever prevention strategies.

Treatments of Yellow Fever
There is no specific treatment for yellow fever. But the following treatment can help in reduction of symptoms: 

• Blood products for severe bleeding
• Dialysis for kidney failure
• Fluids through a vein
• High temperatures can be treated by cooling the patient and giving them appropriate medicines to lower the temperature
• Mild pain may be relieved with simple painkillers.
• Persons with yellow fever should rest and drink plenty of fluids.
• They should be kept away from mosquitoes for the protection of others.
• Dehydration can be treated with Oral Re-hydration Solution

Most people get better after a long recovery period. Serious cases of yellow fever need specialized hospital treatment. As there are no products that combat the virus itself, the doctor can only treat the symptoms.