How does infectious agent interact with the body to produce symptoms of yellow fever?

Yellow fever is a mosquito-borne viral infection caused by the yellow fever virus (YFV). The virus is transmitted to humans through the bite of an infected female Aedes aegypti or Aedes simpsoni mosquito.

After the virus enters the body, it replicates in the liver cells, causing damage and leading to the release of inflammatory mediators. These mediators cause fever, chills, headaches, muscle aches, nausea, and vomiting. In severe cases, the virus can also damage the kidneys, heart, and brain, leading to jaundice, bleeding, and ultimately death.

The incubation period for yellow fever is typically 3-6 days. The symptoms usually develop in two phases. The first phase, known as the "acute phase," lasts for 3-4 days and is characterized by the symptoms mentioned above. The second phase, known as the "toxic phase," occurs in about 15% of cases and is characterized by more severe symptoms, including jaundice, bleeding, and organ failure.

The yellow fever virus can also cause a mild infection known as "silent yellow fever." This occurs in about 80% of cases and is characterized by only mild symptoms, such as fever and headaches.

Treatment for yellow fever is supportive and includes measures to relieve symptoms and prevent complications. There is no specific antiviral treatment for yellow fever, but the disease can be prevented by vaccination. The yellow fever vaccine is safe and effective and is recommended for travelers to areas where the disease is endemic.