What disease was called yellow jack?

The disease called yellow jack was yellow fever.

Understanding Yellow Jack (Yellow Fever)

Yellow jack is an archaic but well-known common name for yellow fever, a serious infectious disease. This viral hemorrhagic fever has historically been responsible for significant outbreaks, particularly in tropical and subtropical regions of South America and Africa.

Key Characteristics of Yellow Fever

Yellow fever is caused by a virus transmitted primarily by mosquitoes. The disease has several historical aliases, reflecting its distinct and often severe symptoms, including the characteristic yellowing of the skin.

Here's a breakdown of its key aspects:

Aspect	Description
Disease Name	Yellow fever
Other Names	Yellow jack, yellow plague, bronze john
Specialty	Infectious disease
Symptoms	Symptoms can range from mild to severe, typically appearing 3 to 6 days after exposure. They often include: Fever Chills Muscle pain Headache Nausea and vomiting Yellow skin (jaundice) In severe cases, it can lead to bleeding, organ failure, and even death.
Causative Agent	Yellow fever virus (a flavivirus)
Transmission	Primarily through the bite of infected Aedes or Haemagogus species mosquitoes.

The name "yellow jack" likely stemmed from the yellow quarantine flag (known as the "yellow jack" flag) used on ships to indicate the presence of infectious disease, often yellow fever, aboard, or simply from the prominent symptom of jaundice, which causes the skin and eyes to turn yellow.