Mosquito Control Guide
Yellow Fever
Typically one of the milder arboviral (i.e., spread by arthropod) ailments is yellow fever, a flaviviral condition transmitted by the bites of infected mosquitoes. Unlike malaria or viral encephalitis, yellow fever tends to last only a short while. The disease got its present-day name back in 1739, but it’s been common in the New World since 1702. Back then it was known as “malignant distemper.” Its current name derives from the jaundice, or yellow skin, prevalent in people with serious cases. The disease is common in both rural and urban areas of tropical countries in Africa and South America. To date it has not been reported in Australia or Asia, despite the fact that a species of mosquito that can carry the disease is indigenous to parts of both continents. The virus has been kept away from those areas by adherence to strict quarantine procedures.
As of 21 January 2002, countries reporting cases of yellow fever infection to the World Health Organization (WHO) include the following.
In Africa:
- Angola
- Benin
- Burkina Faso
- Cameroon
- Cote d’Ivoire
- Democratic Republic of Congo
- Gabon
- Gambia
- Ghana
- Guinea
- Liberia
- Nigeria
- Sierra Leone
- Sudan
In South America:
- Bolivia
- Brazil
- Colombia
- Ecuador
- French Guiana
- Peru
- Venezuela
Symptoms
Yellow fever has both an urban cycle, spread by mosquitoes, and a jungle cycle. The jungle cycle is “sylvatic,” which means it’s carried by monkeys. Incubation lasts anywhere from three to sixteen days before symptoms appear. Mild cases result in symptoms similar to those of the common flu. Body aches and fever are especially common. More serious cases lead to higher fevers, together with muscle pain, upset stomach, dehydration, and violent headaches. Possible aftereffects include meningitis, kidney failure, or internal bleeding. The jaundice is caused by hepatitis, another possible complication.
Despite its usual passivity, the disease can break out in sudden violent epidemics that kill as many as half of all victims. In 1853, an epidemic in New Orleans killed some eleven thousand people. Each year about two hundred thousand cases of yellow fever are reported, despite the availability of an effective vaccine. Some thirty thousand of those patients die. All in all, about half a billion people are currently at risk of contracting the disease. The severity of possible epidemic symptoms is illustrated by its alternate title, “black vomit.”
The Cure
As stated above, there is a vaccine for yellow fever, which provides immunity within seven to ten days after injection. A booster shot is required every ten years. The vaccine contains a live, weakened form of the yellow fever virus, which activates the body’s immune system to create an antibody that protects the patient against future infections. It isn’t usually administered in Western countries, other than to people who work in disease laboratories or who plan to travel into areas where the virus is still active. Most infected countries require visitors to carry an International Certificate of Vaccination, which must be issued by a designated vaccination center. The certificate is valid for ten years from the tenth day after yellow fever vaccination.
Since its invention in April of 1932, the yellow fever vaccine has earned its reputation as one of the safest, most effective vaccines ever devised. The virus inside, an attenuated form of strain 17D, is grown in chick embryos. It was first created and tested on the brains of mice by Max Theiler of South Africa, then tested on humans by doctors at Harvard Medical School and the Pasteur Institute in Senegal. The vaccine made its public debut in 1934, when it was used to save terminal patients in French West Africa. Current versions of the vaccine are based on Theiler’s work on strain 17D for the Rockefeller Foundation in Nigeria. Despite his uncanny resemblance to Boris Karloff, Dr. Theiler received the Nobel Prize for medicine in 1951. Heat-stable 17D vaccines have been available worldwide since the early 1980s.
Unfortunately, the vaccine cannot be administered to patients who are allergic to eggs or to any of its ingredients. It may or may not cause any of various temporary side effects, including fever, headache, rash, swollen glands, muscle pain, or weakness. In a small percentage of cases, side effects may include more serious problems, such as anaphylactic shock or encephalitis (inflammation of the brain). The safety of the vaccine has not yet been determined with regard to pregnant women, or for women who are currently breastfeeding infants. It should not be administered at the same time as the cholera vaccine or any whole cell paratyphoid vaccine, as these vaccinations may reduce immune response to yellow fever vaccine.
The Birth of Modern Medicine?
That’s how some analysts characterize Dr. Benjamin Rush’s response to a yellow fever outbreak in Philadelphia in 1798. “In the month of January,” he wrote, “the fevers discovered an uncommon determination to the brain.” The disease continued to spread until August, when it “appeared in nearly every part of the city, and particularly in places where there was the greatest exhalation from foul gutters and common sewers.” Prominent Philadelphians, including the Washingtons and Jefferson, fled the city.
Dr. Rush had already come to the conclusion that a yellow fever outbreak in 1793 was the result of poor hygiene in filthy areas near the docks, and he and several cronies implemented cleaning measures to halt the spread of the disease. Rush’s efforts were successful, and the outbreak was contained. The emperor of Russia, the king of Prussia, and the queen of Etruria later consulted with Rush on prevention of disease in their own countries. As if that weren’t a significant enough résumé headline, Dr. Rush was also a founder of Dickinson College and of the first American anti-slavery society. He made notable contributions to psychiatry and was a signer of the Declaration of Independence.
Matthew Carey, later the official historian of the 1798 epidemic, put out a pamphlet (Account of the Malignant Fever) claiming the disease was smuggled in by Negro revolutionaries from a rebellion in Sainte Domingue, now Haiti. He believed blacks were trying to overthrow the U.S. and that yellow fever was a form of interracial germ warfare. Luckily, few white Philadelphians paid any attention to Carey’s ridiculous ideas, and blacks demonstrated undeniable heroism by caring for sick whites. Many prominent citizens decided these Negros had actually saved the city while affluent whites deserted it, and white Philadelphians financed two new black churches in 1794 as a reward for conspicuous courage. Sadly, the next generation of whites set fire to black neighborhoods, in the first of five major anti-black riots.
For more information on Dr. Rush and the Philadelphia outbreak, read Destroying Angel: Benjamin Rush, Yellow Fever and the Birth of Modern Medicine, an e-book by Bob Arnebeck. It’s available free at Geocities.com/bobarnebeck/fever1793.html.
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