May 2003 Yellow Fever and Its Influence on American History Yellow fever (YF) is a virus, transmitted by mosquitoes. The virus causes mild to severe, often deadly disease in humans. In many cases, infection is relatively mild with no symptoms whatsoever or maybe a slight fever. In more serious cases, symptoms occur 3 - 6 days after infection, beginning with the sharp onset of fever, chills, pain in the lower back and sometimes a rash develops on the chest. After 3 or 4 days most patients improve and their symptoms disappear. However, about 15% of these symptomatic cases of infection go from remission to a “toxic phase” within 24 hours. Fever reappears and the functioning of the liver and kidneys deteriorates. Symptoms are jaundice, internal hemorrhaging, bleeding from the mouth, nose, eyes, black vomit, and blood in the feces. Mortality of patients that experience the “toxic phase” of the disease ranges from 50 - 85%, depending upon the virulence of the virus and the susceptibility of the population.
The home of the yellow fever virus is western Africa where it is maintained, without any apparent adverse effects, in the monkeys of the high jungle canopy. The virus is transmitted amongst monkeys by a different specie of mosquito than the one that transmits the disease from person to person. Humans and monkeys are hosts, mosquitoes are the vector (transmitting agent) and reservoir of the virus. Once infected, survivors of the disease are immune for life.
Yellow fever is now endemic in Africa and South America. The mosquito vector, Aedes aegypti and the yellow fever virus is thought to have been introduced into the Americas by way of the African slave trade in the 1500's. Yellow fever ravaged Europeans in the New World. Because of Europe’s absence of exposure over the millennia, Europeans were especially susceptible to the effects of infection from this virus. In 1741, during an expedition to capture Peru and Mexico, British forces were reduced from 27,000 to 7,000 in a few short months by the dreaded disease they called “black vomit”. Coastal towns and cities in the United States were particularly vulnerable to YF in the seventeenth and eighteenth centuries.
Yellow fever has had far reaching effects on American History. In 1793 a mass evacuation of Philadelphia occurred when a YF epidemic killed 5,000 people about 10% of the population. What was to be the Capital of our newly formed nation was moved to what is now Washington, D.C.
In 1803 the French sold the Mississippi Valley region to the United States for $15 million, known as the Louisiana Purchase. In 1802, in its attempt to take over the West Indies, France lost over 50,000 soldiers, officers, doctors and sailors to YF, only 3,000 men from their original forces returned to France. With Napoleon’s largest expeditionary force thoroughly destroyed he was unable to establish control in this area of the New World. This situation precipitated Bonaparte’s decision to sell the territory of the Mississippi Valley to the United States.
Yellow fever continued to breakout in the United States, especially in the South. In 1851 Dr. Gorrie, a physician, who lived and practiced in Apalachicola, Florida, prescribed a cool environment for his YF patients because of their high fevers. This need stimulated Dr. Gorrie to invent the first ice making machine which led to the development of refrigeration and air conditioning.
In 1852 a YF epidemic occurred in New Orleans killing 8,000. In 1855 YF was nationwide, with outbreaks occurring sporadically for the next twenty years. The last extensive epidemic occurred in 1878, affecting 8 states especially Alabama, Louisiana and Mississippi. Over 20,000 people lost their lives. Because the cause of YF was unknown, every outbreak created alarm in the entire country, especially the South. Cities were deserted, commerce brought to a standstill, with local and regional economies destroyed. In fact, the entire industrial development of the South was stunted because of the region’s propensity to YF epidemics. Imagine living in a community where a large portion of the population was sick or dying from a disease that caused high fevers, black vomit, bleeding from every orifice, the sick turning yellow before dying and not knowing what caused the disease or how it was spread. Yellow fever was wiping out entire communities either by death, evacuation or both, chaos reigned. Fumigation of mail and newspapers was required, people wore vinegar soaked gauze over their nose and mouths, the shipping of cotton (the economic basis of the South) was forbidden from infected towns, bridges were burned, “infected” homes were burned, and the tearing up of railroad tracks was threatened to prevent people and goods from entering or leaving an area.
It was the continuing yellow fever epidemics that led to the formation of Health Departments in many states and the passage of Federal Quarantine Legislation by Congress in 1878. This legislation paved the way for Federal Government involvement in quarantine activities and the basis for the quarantine system the United States has today. Despite the strict quarantine measures that were instituted at the time, YF still occurred but the outbreaks stayed small.
During the brief Spanish-American War of 1898, which took place in Cuba, 968 American soldiers were killed in combat and over 5,000 died from disease, mainly YF. Luckily for the American army Spain sued for peace on July 17th, 1898. If the war had continued through the summer, the U.S. army might not have survived the next wave of yellow fever, its mortality rate was 85%.
In 1900, at an experimental station in Cuba, U.S. Army physicians James Carroll and Walter Reed discovered how YF was spread. By allowing an infected mosquito to feed on him, Dr. Carroll developed a severe case of YF, thus providing the proof Dr. Walter Reed needed to determine how YF is spread and what mosquito was involved in its transmission. The specific mosquito involved was known as the striped house mosquito, Aedes aegypti.
In 1904, the United States purchased the rights and properties from the French to construct a canal through the Isthmus of Panama. After 10 years and 20,000 deaths from YF, the French had given up on trying to build a canal and were happy to sell the project to the U.S. Now that the cause of YF was known, the Army sent surgeon Col. William Gorgas to Panama to institute control measures. Gorgas’s efforts quickly eradicated YF, paving the way for the construction of the Panama Canal.
The last epidemic of YF in the United States occurred in 1905 in New Orleans. Once the cause of the disease was determined, (the Aedes aegypti mosquito) the elimination of the mosquito’s habitat (man made containers) was easy. Yellow Fever has been eliminated from North America, Central America, Europe and the Caribbean Islands but still exists in tropical areas of Africa and South America because of the monkey populations. Presently, there are approximately 200,000 cases of YF, with 30,000 deaths, reported annually. Although YF has never been reported from Asia, the region is at risk because the appropriate primates and mosquitoes are present.
Yellow fever is controllable. A vaccine is available that provides immunity for at least 10 years and probably for life. To prevent a YF epidemic in a region or country at least 80% of the population must have immunity. To accomplish this, the YF vaccine should be incorporated into the childhood immunization programs in order to provide effective protection to the entire population. Gambia, a country in Africa, reported 85% vaccine coverage in 2000. No cases have been reported since 1980, even though the virus remains present in the environment.
Although yellow fever stimulated many changes and opportunities in our American History, it is reassuring to know that an effective vaccine and mosquito control efforts has and can continue to make yellow fever a nightmare of the past. |