What is Yellow Fever
Yellow fever is a disease that is localized in Africa, and South and Central America. The disease causes a high fever and the yellowing of skin and the sclera (whites of the eyes). The disease was initially very hard to track as direct contact with sick patients did not spread the disease to health care workers. Later was discovered to be spread via mosquitoes after much confusion in the medical field at the time. Still 1000 cases are reported each year but this number could be considerably higher for unreported cases.
Symptoms can include:
- Headaches
- Delirium (severe confusion)
- Muscle aches
- Seizures
- Hepatitis
- Decreased urination
- Back pain
- High fever
- Loss of appetite
- Eye Redness
- Eye Sensitivity to light
- Mouth and nose bleeding
- Bradycardia (slowing of the heartbeat)
- Skin Jaundice (skin yellowing)
- Nausea and vomiting
- Abdominal pain
Why is this disease unique/ important
Yellow fever is unique in how it spreads which confused doctors at the time. Due to the fact that the disease spread only by mosquitos and the mosquito can only spread the disease after 10-12 days post biting an infected individual means the disease was very hard to track. Many unethical tests were performed to make discoveries as inoculation was still very new at the time. Earliest reports of this disease are thousands of years old in Africa but once colonization started the disease was able to travel over to the Americas and quickly became endemic to the area.
Vaccine Development:
Disease was eventually discovered to be able to infect monkeys which were used for testing in the 1920’s. Mice were also proven to be infectable if injected with the disease as well and would be used for other testing. Yellow fever in this testing mutated to a version where the lethality of this strain of the disease was lowered. This strain would then be used as the basis for the vaccine.
Vaccine importance today:
Yellow fever is endemic (Regularly found) in parts of Africa and South America due to infected monkey populations. However strict vaccine passports are implemented to prevent the spread from reaching parts of Asia and other humid locations so that the disease does not become endemic there as well. Yellow fever has the possibility to become endemic in any major population zone as long as mosquitoes can live year round and continuously feed on an infected population.
References
Sherman, I. W. (2007). Twelve diseases that changed our world. Washington, DC: ASM Press.