1793 Philadelphia yellow fever epidemic immune to the fever. Many of the slaves in Charleston in 1742 could have gained immunity before having been transported from Africa, by having been exposed to yellow fever in a mild case. People who survived one attack gained immunity. A total of 240 blacks died, in proportion to their population at the same rate as whites. Given the limited resources and knowledge of the times, the city's response was credible. The medical community did not know the natural history of yellow fever, a viral infection spread by the "Aedes aegypti" mosquito. Efforts to clean the city did not defeat
2016 Angola and DR Congo yellow fever outbreak mission to Angola was its first deployment. The team included "emergency medical teams, public health and medical coordination experts, mobile biosafety laboratories, medical evacuation planes and logistical support teams". Efforts to prevent international spread are confounded by the practice of selling falsified yellow fever vaccination certificates. The fake cards are sold to people who are required to have proof of vaccination after travel to areas where yellow fever is endemic. On 11 February 2016, the Pasteur Institute (WHO) in Senegal warned of fake yellow fever vaccine on the international market. With help from the World Health Organization (WHO), the Angolan