Without treatment, half of the patients who enter the second phase die within ten to fourteen days. Similar to yellow fever, malaria was transmitted to humans through mosquito bites, causing symptoms such as fever, fatigue and vomiting. Difficult to recognize at first, malaria continues to cause yellowing of the skin, convulsions and even death; These symptoms normally begin ten to fifteen days after being contracted. Malaria was introduced to America initially through slavery and killed millions of people between the 17th and 20th centuries. Throughout America's growth and expansion, several outbreaks of diseases both endemic and epidemic occurred, such as smallpox, measles, yellow fever, and malaria. From the Columbian Exchange and slavery, these diseases were introduced to the new world and spread like wildfires that devastated indigenous and non-indigenous populations. Most commonly known for the death toll among Native Americans, these diseases were so costly because of their low resistance, poor sanitation, and insufficient