Living With Yellow Fever

Yellow Fever is not a disease that many associate with the United States. Today, Yellow Fever is largely confined to tropical areas of Africa and South America. The most recent outbreak is in Sudan. The WHO estimates about 200,000 cases and 30,000 yellow fever deaths every year. For over half a century, a vaccine against yellow fever has been available. Vaccination of people traveling to and from yellow fever areas along with mosquito control and quarantine measures helps keep the virus out of the United States. Travelers to areas with Yellow Fever may be required by those countries to have a Yellow Fever Vaccination, available from public health departments.

Yellow Fever, and the Yellow Fever Mosquito, Aedes aegypti, both are believed to have originated in Africa and brought to the Americas with the slave trade. Yellow Fever in the Americas was present in 1648 when an epidemic was recorded in the Yucatan.

The United States had notable outbreaks of Yellow Fever in the 18th Century including a severe outbreak in Philadelphia in 1793. Bob Arnebeck has an interesting account of the outbreak. Philadelphia of 1793 had a population of about 50,000 and was the seat of government. Washington, DC was under construction at the time. Some were lobbying to keep Philadelphia as the capitol. However, that effort diminished with the 1793 Yellow Fever Outbreak.


In 1793, refugees infected with Yellow Fever arrived in Philadelphia and the fever spread to thousands of people. The death toll was 4000, about 9 percent of the population. This was the first major outbreak of Yellow Fever in the United States and no one knew what caused the disease or how to prevent it. The natural reaction was panic and people fled the city to escape the plague. President George Washington left for Washington, DC to oversee construction of the new capital city. Alexander Hamilton, the first Secretary of Treasury contracted Yellow Fever but survived. Nearby cities such as Baltimore were alarmed that refugees from Philadelphia might spread the disease and posted armed guards to prevent travel from Philadelphia. It would take over a hundred years to understand the transmission of Yellow Fever by mosquitoes and open the door to eliminating large Yellow Fever outbreaks in the United States.

About jjneal

Jonathan Neal is a retired Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
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2 Responses to Living With Yellow Fever

  1. David Rentz says:

    Your posts are very timely.
    Recently I had the opportunity to go to Brazil for a conference and discovered that it was a requirement to get a Yellow Fever vaccination not only to enter Brazil but to return to Australia. Fair enough. but then when I went to the vaccination centre I was told that there are important dangers in receiving the vaccination if you are over 60. You could develop liver and brain problems. Then when they discovered that I was over 70, two centres refused to give it, the other said it was a risk but worth it if I wanted to go. I decided against it. Subsequently I have heard a variety of scenarios for and against.

    With the Olympics and World Cup heading to Rio in the next few years and the fact that older people are the ones that can afford to attend, it makes one wonder how they will cope with this dilemma. And most of the coaches and managers are in the “older” category as well.

    Something to think about.

    • jjneal says:

      The yellow fever vaccine is a live attenuated virus vaccine. All vaccines come with a potential risk, but also a benefit. Some countries will allow “certificates of exception” if a physician will certify that the risk of a vaccine is high and the risk of contracting the disease is low. There is a trend toward yellow fever spreading into urban areas in South America so the risk is somewhat higher today than 20 years ago. However, high rates of vaccination among the population and lower populations of competent mosquito vectors keep the disease low. Still, unvaccinated travelers should avoid areas with high yellow fever incidence, avoid exposure to mosquitos and wear repellents and protective clothing to avoid bites.

      There was a problem in Peru with on lot of a vaccine that was given during a yellow fever outbreak over 10 years ago. Even with the elevated risk, the risk from vaccination was substantially lower than yellow fever vaccination. There are certain conditions where the vaccine is contraindicated, such as people with thyroid issues. The vaccine may not work in AIDS patients. However, as vaccines go the risk of the yellow fever vaccine is very low and the benefit to those traveling in yellow fever areas, very high.

      There is work on a vaccine that does not use live virus and that vaccine may be lower risk.

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