| As a part of our study of the effects of diseases on society, |
| of the, uh, social consequences of man's diseases, |
| we should certainly include yellow fever. |
| Now, yellow fever's a deadly disease that's caused by a virus, |
| and it's been the source of many epidemics since at least the eighteenth century |
| in Africa, Europe, and the Americas. |
| In fact, it still kills more than 30,000 people a year worldwide. |
| And there's still no cure for the disease. |
| However, there is a vaccine to immunize us against it. |
| The road to the discovery of that vaccine was a rocky one, I think. |
| It's called 'yellow' fever because one of its symptoms is jaundice - |
| a yellowish colour that the skin takes on, because of liver damage. |
| It's transmitted by mosquitoes, either from man to man - this's called the 'urban' cycle - |
| or from monkey to man - this's called the 'sylvatic' or 'jungle' cycle. |
| The disease probably originated in west Africa, |
| and it was carried from there to the West Indies |
| and the New World in the eighteenth century with the ships of the slave trade. |
| The first big outbreak of yellow fever happened in Cuba in 1762 and 1763, |
| and it killed thousands of American and British colonial troops there. |
| After that, between then and 1900, |
| it killed about ten percent of Cuba's population. |
| The next big epidemic hit in the heart of the United States, |
| in Philadelphia, Pennsylvania, in 1793. |
| It killed five thousand people there, |
| while twenty thousand more fled the city in panic. |
| These included President George Washington, Thomas Jefferson, |
| Alexander Hamilton, Dolly Madison, |
| and most of the federal government officials. |
| Because you might remember that Philadelphia was the capital of the United States then. |
| Washington, DC was still under construction, |
| and it would not be a working seat of government until 1800. |
| About twenty years after the Philadelphia epidemic, |
| another significant yellow fever epidemic hit Haiti. |
| In 1802, Napoleon Bonaparte had sent an expedition of 40,000 soldiers there |
| with the intention of using the island as a base for invading the United States, by way of New Orleans. |
| New Orleans was at that time still in the hands of France. |
| But Napoleon's army - including its commander, who was Napoleon's brother-in-law - |
| was completely decimated by the fever, |
| and his invasion plans were abandoned. |
| Later in the same century, in the 1880s, |
| France was again foiled, and history was again changed, by yellow fever. |
| The French effort to build the Panama Canal ended in failure |
| as a result of the heavy toll on the workers and technicians, from both yellow fever and malaria. |
| These epidemics continued to occur over and over |
| because no one had been able to figure out how the disease was transmitted, |
| how it was carried from person to person. |
| In Philadelphia, Benjamin Rush - who was a signer of the Declaration of Independence |
| and also the chief medical officer for the new government - |
| Doctor Rush relied so heavily on blood-letting as a treatment |
| that he probably killed more people than he cured. |
| The most widespread theory was that yellow fever spread through contaminated water |
| or by direct physical contact with infected people, |
| and some people actually abandoned family members in their panic. |
| The idea that mosquitos were the disease vector, the method of transmission, |
| had been proposed in 1881, by a Cuban scientist named Carlos Finlay, |
| but he hadn't been able to prove this to the satisfaction of other scientists. |
| It wasn't until twenty years later, in 1900, that Carlos Finlay's idea was finally proved. |
| The United States Army had occupied Cuba after the Spanish American War of 1898, |
| and since Cuba was still considered to be the breeding ground for yellow fever in the New World, |
| the US government commissioned a US Army surgeon, Doctor Walter Reed, |
| to solve the problem before its occupation forces also succumbed to this disease. |
| And Doctor Reed's team did soon prove that the mosquitoes were the culprits, |
| at their research center just outside Havana. |
| As a result, yellow fever was quickly eliminated from Cuba, |
| and the US Public Health Service started a mosquito control program |
| that included fumigation, eliminating or treating standing pools and bodies of water, and so forth. |
| In addition, the Panama Canal was completed by the Americans - |
| who then controlled the canal's operation for the next 99 years. |
| And Walter Reed - well, Walter Reed's name should be familiar to many of you. |
| The Walter Reed Army Medical Center in Washington, DC |
| is the well-known hospital where the US President, US congressmen, |
| and US military personnel receive medical treatment. |