In 1853, Cloutierville, Louisiana, had a late-summer outbreak of yellow fever that quickly killed 68 of the 91 inhabitants. A local doctor concluded that some unspecified infectious agent had arrived in a package from New Orleans. In 1854, 650 residents of Savannah, Georgia, died from yellow fever. In 1858, St. Matthews German Evangelical Lutheran Church in Charleston, South Carolina, had 308 yellow fever deaths, reducing the congregation by half. A ship carrying persons infected with the virus arrived in Hampton Roads in southeastern Virginia in June 1855. The disease spread quickly through the community, eventually killing over 3,000 people, mostly residents of Norfolk and Portsmouth. In 1873, Shreveport, Louisiana, lost 759 citizens in an 80-day period to a yellow fever epidemic, with over 400 additional victims eventually succumbing. The total death toll from August through November was approximately 1,200.In 1878, about 20,000 people died in a widespread epidemic in the Mississippi River Valley. That year, Memphis had an unusually large amount of rain, which led to an increase in the mosquito population. The result was a huge epidemic of yellow fever. The steamship John D. Porter took people fleeing Memphis northward in hopes of escaping the disease, but passengers were not allowed to disembark due to concerns of spreading yellow fever. The ship roamed the Mississippi River for the next two months before unloading her passengers.Major outbreaks have also occurred in southern Europe. Gibraltar lost many lives to outbreaks in 1804, 1814, and 1828.
Barcelona suffered the loss of several thousand citizens during an outbreak in 1821. The Duke de Richelieu deployed 30,000 French troops to the border between France and Spain in the Pyrenees Mountains, to establish a cordon sanitaire in order to prevent the epidemic from spreading from Spain into France. Causes and transmission
Ezekiel Stone Wiggins, known as the Ottawa Prophet, proposed that the cause of a yellow fever epidemic in Jacksonville, Florida, in 1888, was astrological. The planets were in the same line as the sun and earth and this produced, besides Cyclones, Earthquakes, etc., a denser atmosphere holding more carbon and creating microbes. Mars had an uncommonly dense atmosphere, but its inhabitants were probably protected from the fever by their newly discovered canals, which were perhaps made to absorb carbon and prevent the disease. In 1848, Josiah C. Nott suggested that yellow fever was spread by insects such as moths or mosquitoes, basing his ideas on the pattern of transmission of the disease. Carlos Finlay, a Cuban doctor and scientist, proposed in 1881 that yellow fever might be transmitted by previously infected mosquitoes rather than by direct contact from person to person, as had long been believed. Since the losses from yellow fever in the Spanish–American War in the 1890s were extremely high, Army doctors began research experiments with a team led by Walter Reed, and composed of doctors James Carroll, Aristides Agramonte, and Jesse William Lazear. They successfully proved Finlays "mosquito hypothesis". Yellow fever was the first virus shown to be transmitted by mosquitoes.