Yellow fever is a viral infection that earned its nickname because it causes sufferers to turn yellow— a symptom of jaundice. This mosquito-transmitted disease attacks a person’s liver during infection, which causes half of all its sufferers to die if left without medical treatment.
Though it is rarer than it once was, outbreaks still happen on a regular basis. 2018 marked the last major outbreak of yellow fever, and it took place in Brazil. The outbreak was thankfully contained before it spread to other countries.