As of 2013, Yellow Fever killed 78,000 people annually in Africa with a total of 130,000 severe cases. It is still considered endemic in 34 African and in 13 South American countries. There were 11 cases imported to China from Angola in 2016, potentially exposing a large and unvaccinated population in China. These Yellow Fever outbreaks and numbers represent a rising incidence of this preventable disease and an increasing risk to the entire population of the earth, whether in endemic areas or not. Due to this, we need to ensure we are much more familiar with this disease and how it is prevented.
This flavivirus is transmitted by Aedes and Haemogogus species of mosquitoes. As such, it is primarily found in tropical regions and at lower altitudes which will support the reproductive cycle needed for the mosquitoes to reproduce and spread the virus. A review of the CDC.gov travel website will show you endemic regions and areas (primarily sub-Saharan Africa and tropical South America). Many countries will require you to have proof of said vaccination if entering their boarders from an endemic country such as the South American or African countries, as mentioned above.
If not prevented, this disease can present in any number of ways. Many may not even realize they are infected as the signs may be non-specific and mild with symptoms such as a fever, chills and aching muscles (myalgias). About 12% will develop more severe symptoms such as jaundice (yellowing of the skin and eyes due to elevated bilirubin levels), hemorrhage (large amounts of bleeding) and eventually death in 30-60% of those effected in this manner.
If you are travelling to an endemic area, please ask your health care professional or travel medical advisor about obtaining the vaccine. There are contraindications to the shot and there have been shortages. As this is a virus with no specific treatment, the vaccine and taking precautions to prevent mosquito bites, is vital. If you have any questions, please feel free to leave them in the comments.