The Yellow Fever virus was brought to the Americas in the 17th century mainly through the slave trade. Neither the European explorers nor the Native Americans had any type of immunity to this virus. It was spread throughout the “New World” via local mosquitoes—the most popular way for deadly diseases to infect hosts.
Majorly Devastating Yellow Fever Epidemics in the “New World” include: 1690 in New York, 1699 in Charleston, 1741 in Virginia, 1793 in Philadelphia, 1850 (nationwide), 1873 in Memphis, 1878 in New Orleans, and 1886 in Jacksonville. The most likely way that this disease was brought and spread was through water barrels that came off travelling ships. Port cities, in particular, were hit extremely hard because of this.
Many Yellow Fever outbreaks took such an abundance of victims that digging individual graves became obsolete. In several cities that suffered infestations, certain mass grave mounds or areas were dedicated to the victims. The Yellow Fever Epidemics that plagued early civilizations demonstrated how small and simple public health measures can rapidly prevent and control the outbreak of diseases.
Breakdown and Transmission
Generally, Yellow Fever comes from an arbovirus. This is an extremely large group of pathogens in which there are over 500 that have been recognized. Many of these diseases infect birds and reptiles but humans are almost always an accidental host. Despite this fact, there has been over 100 different types of arbovirus that have infected humans. More specifically, Yellow Fever is a single stranded RNA virus called Flavivirus (Flavus meaning yellow). Flavivirus also causes a variety of other human diseases including: West Nile virus, Japanese Encephalitis, and Dengue Fever.
The virus is able to infect humans through mosquito bites. It can also infect the mosquito’s eggs which can lay dormant until they hatch and are able to infect others. Mosquitoes are this disease’s true reservoir species. The type of mosquito that is responsible for the spread of Yellow Fever is the Aedes aegypti.
The 3 Different Forms of Yellow Fever
Yellow Fever has three different forms in which it is able to infect humans.
Sylvatic Yellow Fever - This form is also known as “jungle yellow fever” and is transferred to humans through either a wild mosquito bite or contact with an infected monkey that has been bitten by the mosquito.
Immediate Yellow Fever – This is the most common type of the disease. Humans become infected when semi-domesticated mosquitoes bite them. This happens mostly with villages that are close to where wild mosquitoes naturally inhabit forest areas.
Urban Yellow Fever – This form of Yellow Fever emerges when mosquitoes migrate from their natural habitat and become domesticated in urban areas.
Yellow Fever can be mild and exhibit flu-like symptoms or can be severe. The incubation period is usually from five to fifteen days and more extreme cases can result in kidney failure, meningitis, jaundice, and hemorrhagic manifestations. The major general symptoms of Yellow Fever are: reddening of the eyes, fever, vomiting, back pain, headache, bleeding, muscle aches, and hepatomegaly. An infected person will not experience any symptoms in between three to six days after infection. After this time period, one enters the acute phase. Usually, the symptoms (fever, headache, muscle aches, sensitivity to light, loss of appetite, dizziness, reddening of eyes) fade and are often gone quickly. Even though the symptoms of Yellow Fever go away, some individuals enter the toxic phase. This is where the disease turns life-threatening. The symptoms can progress into jaundice, abdominal pain, vomiting (sometimes with blood), decreased urination, lowered heart rate, liver and/or kidney failure, and even brain dysfunction.
Unfortunately, a vaccine for yellow fever was not discovered until the 1930’s. Before the vaccine was discovered, general medicinal practices were used in hopes of ridding the infected person of the disease—bloodletting and purging were particularly popular. However, there is no treatment for yellow fever. If a person is not vaccinated, and they enter the toxic phase, the only thing that can be done is to make them comfortable as the disease progresses.
Cover Photo: http://www.bbc.com/news/health-26724645
In Text Photo: http://www.tnhistoryforkids.org/cities/memphis
Reservoir Species: http://medical-dictionary.thefreedictionary.com/reservoir+host
Aedes aegypti: https://www.vectorbase.org/organisms/aedes-aegypti
In Text Photo: https://www.vectorbase.org/organisms/aedes-aegypti
Three Different Forms: http://www.historyofvaccines.org/content/timelines/yellow-fever
Acute and Toxic Phase: http://www.mayoclinic.org/diseases-conditions/yellow-fever/basics/symptoms/con-20032263
Bloodletting and Purging: http://www.bcmj.org/premise/history-bloodletting