Once widespread in the Western hemisphere (including the Southern U.S.), dengue fever was largely eradicated in the 1960s after the carrier mosquitoes were targeted with the pesticide DDT. The disease slowly rebounded after DDT was banned, and while it generally stays confined to the tropics now, a handful of small, scattered outbreaks have occurred in the U.S. along the Mexican border over the past 30 years, according to the CDC.
Known as "breakbone fever" because of the shattering pain it causes, dengue fever is transmitted by a mosquito found in warm climates, and is not contagious. People often contract dengue fever without realizing they have it, but in some cases it can lead to dengue hemorrhagic fever, a severe form of the illness which causes internal bleeding and can lead to shock and even death.
The CDC and health officials in Florida have confirmed at least 28 cases of the fever in Key West. More than 1,000 other residents -- roughly 5 percent of the local population -- may have been exposed without getting ill, according to a CDC report released last week.
Health officials are worried that the fever may spread northward. "We're concerned that if dengue gains a foothold in Key West, it will travel to other southern cities where the mosquito that transmits dengue is present, like Miami," the chief of the dengue branch at the CDC, Harold Margolis, said in a statement.
Fun Facts: Mosquitoes, Disease & DDT
At least 80 percent of human infectious diseases are arthropod-borne—transmitted by insects, mites, or ticks. They have caused the death of hundreds of millions of people by infecting them with the pathogens that cause typhus, bubonic plague, yellow fever, malaria, dengue fever, sleeping sickness, encephalitis, elephantiasis, leishmaniasis, and yaws.
More than 3,000 species of mosquitoes have been described in scientific journals. Most of them are in tropical areas, where as many as 150 species have been found in a single square mile. The United States contains about 170 species, Canada 70, and Arctic lands less than two dozen. In the Canadian Arctic, researchers who bared their arms, legs, and torsos in an experiment reported as many as 9,000 bites per minute. Unprotected human beings there could lose half of their blood in two hours, and die. Hundreds of cattle and horses have been killed by just such exsanguination, in our southeastern states.
In addition to its effectiveness, DDT is inexpensive. The cost of spraying in 1959 was $205,000, but if substitutes had to be used, malathion would have cost $637,000, and propoxur would have cost $1,762,000 for the same control. A 1.5 oz. whisky jigger full of 70 percent wettable DDT covers 144 square feet of wall surface, killing all mosquitoes that land there during the next six months.
Evidence That DDT Fights Cancer
• Drs. Charles Salinskas and Allan E. Okey reported that DDT in rodent diets inhibited development of induced mammary cancers and leukemia.
• A.E. and E.K. McLean determined that after animals had ingested DDT, the highly toxic aflatoxins they had been fed were not fatal, perhaps because they were converted to non-toxic metabolites by the liver. DDT was also known to induce the formation of hepatic microsomal enzymes which, in turn, inhibited the growth of tumors and cancers.
Dr. Wayland Hayes performed tests for the U.S. Public Health Service, feeding human volunteers up to 35 milligrams of DDT in their food every day for 18 months. (The average human intake of DDT in the United States at that time was about 0.03 mgs per day, or 0.36 mgs per year.) No adverse effects resulted, either at the time of the study, or during the next 10 years.
As a result of such studies, I felt that it was safe for me to ingest DDT. I was delivering addresses to various audiences almost every week. I carried a commercial box of DDT onto the stage, dug out a tablespoon of DDT (about 12 mgs), swallowed it, and washed it down with water before beginning my talk about DDT’s lack of toxicity to vertebrate animals. Esquire magazine, in September 1971, pictured me ingesting a tablespoon of DDT. The text explained that I had “eaten two-hundred times the normal human intake of DDT, to show it’s not as bad as people think.”
At the same time, the pseudo-environmentalists were going wild against DDT. Clifton Curtis of the World Wildlife Fund, for example, wrote that “DDT is so potent that as long as it is used anywhere in the world, nobody is safe”—and provided no data to back up his assertion. Dr. Gilbert L. Ross, of the American Council on Science and Health, characterized Curtis’s remarks as “typical of the dangerous environmental disinformation masquerading as science that has been stirring DDT hysteria ever since the 1960s.” Ross pointed out that “Extensive scientific studies have not found any harm to humans, even during the massive overuse of DDT in agriculture in the 1950s and 60s.” Furthermore, the scientific reports show that there is no indication of DDT use harming people, birds, bird eggshells, or other vertebrate animals.
During the 1960s, the World Health Organization proposed the possible eradication of malaria, worldwide, and malaria control was achieved in areas with a population of 279 million people. Thirty-six formerly malarious countries totally eradicated the disease. The U.S. National Academy of Sciences stated in 1970: To only a few chemicals does man owe as great a debt as to DDT. In little more than two decades DDT has prevented 500 million human deaths, due to malaria, that would otherwise have been inevitable. . . .