Yellow Fever - History

History

The evolutionary origins of yellow fever most likely lie in Africa, with transmission of the disease from primates to humans. It is thought that the virus originated in East or Central Africa and spread from there to West Africa. As it was endemic in Africa, the natives had developed some immunity to it. When an outbreak of yellow fever would occur in an African village where colonists resided, most Europeans died, while the native population usually suffered nonlethal symptoms resembling influenza. This phenomenon, in which certain populations develop immunity to yellow fever due to prolonged exposure in their childhood, is known as acquired immunity. The virus, as well as the vector A. aegypti, were probably transferred to North and South America with the importation of slaves from Africa.

The first definitive outbreak of yellow fever was in 1647 on the island of Barbados. An outbreak was recorded by Spanish colonists in 1648 in Yucatan, Mexico, where the indigenous Mayan people called the illness xekik (black vomit).In 1685 Brazil experienced its first epidemic, in Recife.

Although yellow fever is most prevalent in so-called “tropical” climates, the Northern United States was not exempted from the fever. The first outbreak in English-speaking North America occurred in New York in 1668 and a serious outbreak afflicted Philadelphia in 1793. English colonists in Philadelphia and the French in the Mississippi River Valley recorded major outbreaks in 1669, as well as those occurring later in the eighteenth and nineteenth centuries. The southern city of New Orleans was plagued with major epidemics during the nineteenth century, most notably in 1833 and 1853. At least 25 major outbreaks took place in the Americas throughout the eighteenth and nineteenth centuries, including particularly serious ones in Cartagena in 1741, Cuba in 1762 and 1900, Santo Domingo in 1803, and Memphis in 1878. Major outbreaks have also occurred in southern Europe. Barcelona suffered the loss of several thousand citizens during an outbreak in 1821. Urban epidemics continued in the United States until 1905, with the last outbreak affecting New Orleans .

Due to yellow fever, in colonial times and during the Napoleonic wars, the West Indies were known as a particularly dangerous posting for soldiers. Both English and French forces posted there were decimated by the "Yellow Jack". Wanting to regain control of the lucrative sugar trade in Saint-Domingue, and with an eye on regaining France's New World empire, Napoleon sent an army under the command of his brother-in-law to Saint-Domingue to seize control after a slave revolt. The historian J. R. McNeill asserts that yellow fever accounted for approximately 35,000 to 45,000 casualties during the fighting. Only one-third of the French troops survived for withdrawal and return to France, and in 1804 Haiti proclaimed its independence as the second republic in the western hemisphere.

The yellow fever epidemic of 1793 in Philadelphia, which was then the capital of the United States, resulted in the deaths of several thousand people, more than nine percent of the population. The national government fled the city, including president George Washington. Additional yellow fever epidemics in North America struck Philadelphia, as well as Baltimore and New York in the eighteenth and nineteenth centuries, and traveled along steamboat routes of interior rivers from New Orleans. They have caused some 100,000–150,000 deaths in total.

In 1858 St. Matthew's German Evangelical Lutheran Church in Charleston, South Carolina suffered 308 yellow fever deaths, reducing the congregation by half. In 1873, Shreveport, Louisiana lost almost a quarter of its population to yellow fever. 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. The last major U.S. outbreak was in 1905 in New Orleans.

Ezekiel Stone Wiggins, known as the Ottawa Prophet, proposed that the cause of a Yellow fever epidemic in Jacksonville, Florida in 1888 was astronomical.

"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."

Carlos Finlay, a Cuban doctor and scientist, first proposed in 1881 that yellow fever might be transmitted by mosquitoes rather than direct human contact. 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, composed of doctors James Carroll, Aristides Agramonte, and Jesse William Lazear. They successfully proved Finlay's ″Mosquito Hypothesis″. Yellow fever was the first virus shown to be transmitted by mosquitoes. The physician William Gorgas applied these insights and eradicated yellow fever from Havana. He also campaigned against yellow fever during the construction of the Panama Canal, after a previous construction effort on the part of the French failed (in part due to the high incidence of yellow fever and malaria, which decimated the workers).

Although Dr. Reed has received much of the credit in American history books for "beating" yellow fever, Reed had fully credited Dr. Finlay with the discovery of the yellow fever vector, and how it might be controlled. Dr. Reed often cited Finlay's papers in his own articles and also gave him credit for the discovery in his personal correspondence. The acceptance of Finlay's work was one of the most important and far-reaching effects of the Walter Reed Commission of 1900. Applying methods first suggested by Finlay, the United States government and Army eradicated yellow fever in Cuba and later in Panama, allowing completion of the Panama Canal. While Dr. Reed built off of the research of Carlos Finlay, historian François Delaporte notes that yellow fever research was a contentious issue, and scientists, including Finlay and Reed, became successful by building off of the work of less prominent scientists, without giving them the credit they were due. Regardless, Dr. Reed's research was essential in the fight against yellow fever and he should receive full credit for his use of the first type of medical consent form during his experiments in Cuba.

The Rockefeller Foundation’s International Health Board (IHB) undertook an expensive and successful yellow fever eradication campaign in Mexico during 1920-1923. The IHB gained the respect of Mexico’s federal government because of the success. The eradication of yellow fever strengthened the relationship between the US and Mexico, which had not been very good in the past. The eradication of yellow fever was a major step toward better global health.

In 1927, scientists isolated the yellow fever virus in West Africa, which led to the development of two vaccines in the 1930s. The vaccine 17D was developed by the South African microbiologist Max Theiler at the Rockefeller Institute.This vaccine was widely used by the U.S. Army during World War II. Following the work of Ernest Goodpasture, he used chicken eggs to culture the virus and won a Nobel Prize in 1951 for this achievement. A French team developed the vaccine FNV (French neurotropic vaccine), which was extracted from mouse brain tissue but, since it was associated with a higher incidence of encephalitis, after 1961 FNV was not recommended. 17D is still in use and more than 400 million doses have been distributed. Little research has been done to develop new vaccines. Some researchers worry that the 60-year-old technology for vaccine production may be too slow to stop a major new yellow fever epidemic. Newer vaccines, based on vero cells, are in development and should replace 17D at some point.

Using vector control and strict vaccination programs, the urban cycle of yellow fever was nearly eradicated from South America. Since 1943 only a single urban outbreak in Santa Cruz de la Sierra, Bolivia has occurred. But, since the 1980s, the number of yellow fever cases have been increasing again and A. aegypti has returned to the urban centers of South America. This is partly due to limitations on available insecticides, as well as habitat dislocations caused by climate change, and partly because the vector control program was abandoned. Although no new urban cycle has yet been established, scientists fear that this could happen again at any point. An outbreak in Paraguay in 2008 was feared to be urban in nature, but this ultimately proved not to be the case.

In Africa, virus eradication programs have mostly relied upon vaccination. These programs have largely been unsuccessful, since they were unable to break the sylvatic cycle involving wild primates. With few countries establishing regular vaccination programs, measures to fight yellow fever have been neglected, making the virus a dangerous threat to spread again.