Yellow Fever's Evolution in the Western Hemisphere

Yellow Fever Outbreaks, 1800-1900 from Ian Read on Vimeo.

As far as I know, this is the first map to show regional yellow fever outbreaks during the nineteenth century, and certainly the first of its kind to be animated.  I recommend you enlarge the video to full screen for much better resolution.  Red dots indicate coastal infections, while the rarer inland infections are represented by yellow dots.  Infection location names are listed in the left column.

The area that yellow fever occupies shifts considerably, from most outbreaks before 1850 in the Caribbean, gulf region and American eastern seaboard.  After 1850, yellow fever remains active in the Caribbean, but there are many epidemics in South America, mainly Brazil while US outbreaks diminish noticeably.

The range of yellow fever changed when more and more ships brought African slaves, immigrants and California 49ers into Brazilian ports during the 1840s.  I believe these ships carried a dangerous stowaway that had disappeared from Brazilian shores for many decades:  the Aedis aegypti mosquito.  This mosquito is almost always the transmitter of the disease and it does best in urban areas where there are small collections of water and many non-immune human hosts.  Like the Asian Tiger Mosquito that is today partly blamed for the growing spread of West Nile virus in the US and Europe, the Aedis aegypti travel well in ship, trains and trucks, spreading the yellow fever virus when given the chance.