Yellow Fever and Its Nobel Prize-Winning Vaccine
Yellow fever has a long history, with its first recorded epidemic in the Yucatan Peninsula in 1648, although scientists suspect that it has been around since the 1,000s. Its history has not always been pleasant, but scientific advances less than a century ago produced the yellow fever vaccine, a highly effective form of protection. Let’s take a look at the history of yellow fever, and what you can do to protect yourself from this disease when travelling.
Yellow Fever and Its Nobel Prize-Winning Vaccine
Yellow fever has a long history, with its first recorded epidemic in the Yucatan Peninsula in 1648, although scientists suspect that it has been around since the 1,000s. Its history has not always been pleasant, but scientific advances less than a century ago produced the yellow fever vaccine, a highly effective form of protection. Let’s take a look at the history of yellow fever, and what you can do to protect yourself from this disease when travelling.
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The History of Yellow Fever
For centuries, yellow fever has been one of the most feared diseases because of how lethal it is and how, for a long time, very little was understood about it.
Let’s go back in time to understand this better. Your village in the 1700s gets its first case of yellow fever, and slowly one person after another falls victim to it. No one knows if it is passed through touch, air, or other means. Many people would do all they could to protect themselves without knowing what would work, and for many they still contracted the disease. It was a scary time, which explains why it is such a feared disease.
Thankfully, we now know more about the disease than our ancestors. For example, by the 19th century, scientists knew that yellow fever was not transmitted through person-to-person contact. However, the most popular theory at this time was that yellow fever was related to atmospheric miasmata, or air pollution. This theory likely developed because the disease flourished in urban settings.
A Mode of Transmission
The end of the 19th century brought a war between the US and Spain, where the US invaded Cuba. However, this war saw immense losses, with 13 soldiers dying of yellow fever for every one soldier dying in battle. These massive losses spurred an investigation into the cause of yellow fever, where it was discovered that yellow fever is primarily transmitted through the Aedes aegypti mosquitoes.
Eliminating Urban Cases
In 1915 a Yellow Fever Commission was established to eliminate breeding places for the Aedes aegypti mosquito in the areas where transmission often occurred. In many cases, it was highly effective, yet the disease remained in other sites. In the 1930s it was found that the yellow fever virus originated from monkeys: they were bit by mosquitos who then bit humans, passing along the virus. The virus could then spread further especially in large urban areas with a concentrated population.
Viral Advances
In 1927 Adrian Stokes isolated the virus responsible for yellow fever from a 28-year-old sick man in Ghana who was able to provide his blood as a sample. The isolated virus was named the Asibi strain in recognition of the man it was retrieved from. This isolation stood as the basis for the yellow fever vaccine still used to this day.
The Yellow Fever Vaccine
In 1937, Mex Theiler created a vaccine for yellow fever that effectively eliminated urban forms of the disease. However, epidemics in jungle locations still occurred in the tropical belts of Africa and the Americas.
The yellow fever vaccine stems from Theiler’s development of the 17D strain of attenuated viruses. The 17D strain was achieved by passaging the viral strain isolated by Adrian Stokes more than 200 times in cell cultures. Testing on this strain revealed that the virus had been weakened but could still induce a protective immune response in both monkeys and humans.
Max Theiler received a Nobel Prize in Physiology or Medicine in 1951 for his discovery of a vaccine against yellow fever. As of this point, it is also the only Nobel Prize awarded for a virus vaccine (although the recent work on the COVID-19 vaccine may soon join these ranks).
Theiler had been nominated for a Nobel prize many times before winning in 1951. In 1937 he was nominated for his work on yellow fever in mice. His next nomination came in 1948 with the yellow fever vaccine development as the core reason. In fact, this nomination came from Albert Sabin, a man who later went on to develop the polio vaccine.
Despite the impressive examples of his work, the committee passed on awarding the Nobel prize to Theiler in both 1937 and 1948. However, in 1951 Theiler finally won the Nobel Prize due to a last-minute nomination from the committee’s chairman.
How Does Yellow Fever Spread?
Yellow fever is a mosquito-borne disease that occurs in sub-Saharan Africa and South America. While transmission can occur throughout the year, it may peak during the rainy season.
The mosquito which transmits yellow fever, is mainly Aedes aegypti. The mosquito is active both day and night, most commonly at dusk and dawn.
Symptoms of Yellow Fever
Most people with yellow fever have mild or no symptoms and recover completely.
However, some people may develop symptoms that appear within 3-6 days of the bite and can include:
- fever
- chills
- headache
- muscle aches
- backache
After a brief remission, 10-20% of those who get yellow fever develop a severe form of the illness that can cause high fever, internal bleeding, shock, organ failure, and thereby yellow skin and eyes. The mortality rate of severe cases is 30-60%.
Treatment
There is no treatment specific for yellow fever. Instead, treatment focuses on relieving symptoms, providing fluids, and lowering a fever.
How To Protect Yourself from Yellow Fever
Because yellow fever is a potentially lethal disease, it is important to protect yourself when traveling to areas of risk.
Vaccinate
The yellow fever vaccine offers very high protection from yellow fever. Because of the long-term protection it provides, it is recommended for anyone older than nine months who are traveling to a yellow fever endemic area. Additionally, some of these locations may require proof of vaccination against yellow fever before entering.
Most individuals are protected around 10 days after the first vaccination. Side effects of the vaccination are typically mild and they may include muscle aches, headaches, and low-grade fevers. On rare occasions, someone may develop a severe reaction to the vaccine that can be life-threatening. This is why it is used with caution on those who are immunocompromised, pregnant, or elderly.
Keep Away Mosquitoes
In addition to the vaccine, it is also recommended to protect yourself from mosquito bites. This can include using mosquito netting when sleeping, wearing long pants and shirts, and using mosquito repellant spray on any exposed skin.
Be Vigilant Against Yellow Fever
While yellow fever is no longer the epidemic it once was, it can still cause a severe infection if you do not properly protect yourself from it. The yellow fever vaccine is one of the best forms of protection, and proof that if at first you don’t succeed in getting the Nobel prize, try, try again.
References
- Health risks – HealthyTravel.ch. (2022). Retrieved 17 June 2022, from https://www.healthytravel.ch/health-risks/
- Staples, J. (2008). Yellow Fever: 100 Years of Discovery. JAMA, 300(8), 960. doi: 10.1001/jama.300.8.960
- Frierson J. G. (2010). The yellow fever vaccine: a history. The Yale journal of biology and medicine, 83(2), 77–85.
- Norrby, E. (2007). Yellow fever and Max Theiler: the only Nobel Prize for a virus vaccine. Journal Of Experimental Medicine, 204(12), 2779-2784. doi: 10.1084/jem.20072290