There are two reasons to have the vaccine:
The disease Yellow fever could easily spread out of Africa and South America into Asia and other parts of the world. This would be a serious problem. The YF areas are as follows
Generally everyone visiting the ‘at risk’ areas need to be vaccinated, however, the Yellow Fever guidelines are complicated.
Some countries have yellow fever only reported in part of the country (eg Brazil)
Some persons have medical conditions that would increase the risk of serious side effects from the YF vaccine. In that instance, the travel doctor may decide to issue a medical exemption certificate, or suggest you review your travel itinerary; death from Yellow Fever has occurred in unvaccinated tourists.
NOTE Reception staff at travel medicine centres are NOT able to give you detailed information about whether you need to have the YF vaccine for a particular trip, or whether it is safe for you to have the vaccine with your medical history. You cannot email these questions either as the reception staff are the ones answering emails.
You need to make an appointment to see a travel medicine specialist. You may be surprised that they can give you a lot of other information about how to stay healthy on your journey.