February 1, 2002 (Ira Pilgrim)

Yellow Fever

All Cubans (who were on the spot and ought to know) are agreed that those American soldiers who volunteered for the fate of guinea-pigs were brave beyond imagining.

Paul de Kruif, 1926

In the summer of 1793 there was an epidemic of yellow fever in Philadelphia. It is described in excruciating detail in J.H. Powell's 1949 book Bring Out Your Dead. About four or five thousand people died. How many were killed by the disease and how many were killed by the doctors can never be known. Modern medical books peg the mortality rate from yellow fever at about 20%.

The most renowned physician of the time was Dr. Benjamin Rush. Besides being a doctor, he was a political activist and a signer of the Declaration of Independence. He even wrote a book on mental illness. Rush was a firm believer that yellow fever was spread by filth and he encouraged people to burn bedding and things that had been in contact with yellow fever patients. He had the same treatment for everything: bleeding and purging. Large amounts of blood were removed from sick people. His purging was accomplished with a very strong laxative, calomel (mercurous chloride). That laxative was still used by the army in World War II. It was called "compounds cathartic" and was nicknamed by the medics as blasting powder. Mercury is now considered to be a poison and is no longer used for anything. Rush's fellow British-trained physicians did likewise. The French-trained physicians did nothing except try to keep the patient comfortable and allowed Le Bon Dieu (God) to do the healing.

There is no question that, in the matter of yellow fever, Dr. Benjamin Rush was 100% wrong. His remedies didn't help a single one of his patients. We don't know how many he killed, but it must have been a considerable number. When, in 1797, he left medicine to become the Treasurer of the US Mint, it was a blessing for his patients. I have no idea what it did for the treasury. Unfortunately, most doctors at the time treated people the same way, with bleeding and purges for every disease. It has been speculated that George Washington was done in by his doctors.

It was in 1900, during the Spanish American War that the definitive work on yellow fever was done. During that war, 365 soldiers were killed in battle. Five times as many died of yellow fever and botulism (from improperly canned food). The army assigned Medical Corps Major Walter Reed to find out what caused yellow fever and how to prevent it. He and his colleagues, James Carroll, Jesse Lazear and Aristedes Agramonte took on the job. It soon became obvious that the disease didn't spread like a bacterial disease would have. The nurses who took care of yellow fever patients didn't get it. Dr. Carlos Finlay of Havana said that the disease was caused by mosquitoes and he had even characterized and raised the mosquito responsible. Reed and his coworkers decided to test Finlay's theory. They then set a standard of medical ethics that has never been equaled. Before they would ask for volunteers to risk their lives, they tested it on themselves. Carroll got the disease and survived; Lazear got the disease and died. The Cuban Aristedes Agramonte had had yellow fever and was immune, so he couldn't be used. They then asked for volunteers to test Finlay's theory that it was a mosquito that carried yellow fever. It is quite a story, but you'll have to read about it yourself in Paul de Kruif's wonderful book Microbe Hunters.

They proved that yellow fever was caused by a virus and that it was spread by a specific species of mosquito(Stegomyia). All that had to be done to wipe out yellow fever was to get rid of the mosquitoes. The army did this by the very simple expedient of pouring a small amount of oil on all of the rain barrels where the mosquitoes bred. That wiped out yellow fever in Cuba and opened the way to the building of the Panama Canal in Central America.

Why am I writing about yellow fever? It is to point out the stark difference between well intentioned ignorance and understanding. Ignorance can be a killer in the hands of people with the best intentions, while knowledge can enable people to prevent or treat disease. Until that knowledge is obtained, it is often better to do nothing. Even today, the ancient medical principle "First do no harm," is sometimes ignored.

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