Taming mankind's ancient foes: despite inherent dangers and entrenched opposition, a handful of men tracked down the sources of yellow fever and malaria, and devised methods to combat their spread.

Disaster was bearing down on them. Of this Major William Gorgas was certain. It could be a few scant months away, but more likely only weeks. Perhaps they had only days. It was 1904, and Panama was bustling with excitement and activity as work on "The Big Ditch" was about to begin. A canal through the Isthmus of Panama, linking the Atlantic and Pacific oceans, was a colossal undertaking. If successful, it would revolutionize global travel, communication, and commerce. Could the Americans succeed where the earlier French effort, led by Ferdinand de Lesseps, the celebrated builder of the Suez Canal, had failed so miserably?

The eyes of the world were on Panama. The eyes of Major Gorgas were on the arriving steamers that daily disgorged hundreds of new engineers, carpenters, laborers, mechanics, administrators, clerks, photographers, and journalists. Soon there would be tens of thousands. Gorgas, an army surgeon, knew this human wave was flesh food for a ravenous predator that thrived in Panama's tropical environs: Stegomyia fasciata. Similar in many ways to hundreds of other mosquito species, the Stegomyia mosquito had one major difference: it was the carrier of deadly yellow fever.

Over generations, the native population of Panama had built up immunity to the disease. But the new arrivals, many from the U.S. and Europe, were not immune. It was only a matter of time before they became infected. Then, with lightning speed, a full-blown epidemic would break out. Thousands would die. Gorgas could see the calamity approaching. His anxiety was magnified by the knowledge that the looming catastrophe was avoidable. He knew how to fight and win the war against the Stegomyia and its lethal yellow fever parasite. He had proven this in Havana, Cuba. But Major General George W. Davis, the first governor of the Canal Zone, and other members of the seven-man Isthmian Canal Commission did not take seriously Gorgas' "theory" that mosquitoes transmitted yellow fever and malaria. Commissioner John Walker said the notion of mosquito transmission was "balderdash."

Dr. Gorgas gave the commission members a tour of the Canal Zone and explained as explicitly as he could the potential dire consequences of the approaching pestilence and what must be done to avoid a disastrous epidemic. However, Governor Davis and the commissioners were not about to squander money to chase mosquitoes. They budgeted only $50,000 for Gorgas' sanitation department, a small fraction of what he needed for an aggressive campaign against the deadly contagion. Gorgas would not let up. He repeatedly cabled the commissioners, who had returned to the United States. For his efforts, he received only silence--or rebukes. He was reminded by return cable that cables were expensive and that any further communication should be by surface mail.

In November 1904, the first cases of yellow fever appeared. Panic spread quickly and soon a mass exodus was underway. American workers fled Panama in droves, jumping aboard any available ship headed toward the United States. President Theodore Roosevelt, who had witnessed the devastation of yellow fever in Cuba during the Spanish-American War, was not about to allow the disease to derail the canal project. Realizing that Governor Davis and the Canal Commission members were the problem, Roosevelt relieved Davis. Gorgas was named acting governor and given a free hand (and generous funding) to attack the crisis. When the new governor, Charles E. Magoon, arrived, he gave Gorgas full backing. Gorgas would need it because Canal Zone workers and natives resisted his mosquito control program as stubbornly as had the commission.

The Cuba Experience

Perhaps Dr. Gorgas' patient perseverance, in the face of widespread resistance, was bolstered by the fact that he had once been a skeptic himself. During the Spanish-American War (1898), only 968 soldiers died from combat, compared to 5,000 who perished from disease, many of those from yellow fever. During the U.S. occupation of Cuba following the war, conquering the disease became a high priority. U.S. Surgeon General George Miller Sternberg, one of the founders of modern bacteriology, appointed army surgeon Major Walter Reed to head the Yellow Fever Commission. Yellow fever had plagued the southeastern United States for over two hundred years, with epidemics often reaching a fatality rate of 40 percent of those infected. In Cuba, however, the fatality rate reached 85 percent.

The cause of the fever was unknown, though the most common belief was that it was spread by direct person-to-person contact, or by contact with the clothing, bedding, or other personal effects of infected persons. For 19 years, Dr. Carlos Juan Finlay, a Havana physician, had been insisting that the disease was transmitted by mosquito. He had even correctly identified the precise species responsible: Stegomyia fasciata. However, his findings were largely rejected, and he was frequently and scornfully dismissed as "the mosquito man."

Dr. Reed's commission decided to investigate Dr. Finlay's mosquito theory more closely.

Together with Drs. Aristedes Agrimonte, Jesse W. Lazear, and James Carroll, the commission vigorously attacked the problem of causation, heedless of the danger to their own health and lives. Drs. Lazear and Carroll both came down with yellow fever. Dr. Carroll recovered, but Dr. Lazear died after several days of delirium and black vomit--a true martyr to science. Dr. Lazear's notebook provided the key to the dread disease's etiology, showing that it was transmitted to humans by the female Stegomyia.

In October 1900, Major Reed was able to announce to the annual meeting of the American Public Health Association that "the mosquito serves as the intermediate host for the parasite of yellow fever." To say that Reed's claim was not universally accepted would be a gross understatement. But for Reed the task at hand was to devise a Stegomyia eradication program. He entrusted that task to Major William Crawford Gorgas.

Although Dr. Gorgas had serious reservations about Reed's mosquito vector theory, he nevertheless devised a plan to go after the Stegomyia. Unlike many other mosquito species, which will lay their eggs in any standing water, it was discovered that the Stegomyia females would lay their eggs only in clear water very near to humans.

Dr. Gorgas initiated a house-to-house, building-by-building, street-by-street inspection and eradication program that involved fumigation and covering or emptying all water jars, cisterns, rain barrels, buckets, cans--anything that would collect water and provide a place for the Stegomyia to lay their eggs. Follow-up inspections were carried out, and careful records were kept. Under Gorgas' supervision, the systematic eradication program banished yellow fever from Havana in a matter of months. The killer disease, which had taken an average of 500 lives per year for many years, was all but wiped out. It would be 18 years before the disease would claim another life in the city. This was more than enough proof to convince Dr. Gorgas that his earlier skepticism had been misplaced.

When Dr. Gorgas finally was unleashed in Panama, he immediately began applying the sanitation lessons learned in Cuba, with the same astounding results. Yellow fever was quickly brought under control as the Stegomyia and its breeding places were eradicated. However, Gorgas was convinced from the beginning that malaria, not yellow fever, would prove the greatest challenge in Panama. Although not as virulent as yellow fever, malaria was far more prevalent. "If we can control malaria, I feel very little anxiety about other diseases," said Gorgas. "If we do not control malaria our mortality is going to be heavy."

The work of British physician and entomologist Sir Ronald Ross was to prove invaluable to Gorgas' anti-malaria efforts in Panama. Ross had grown up in India, where his father, a British army general, contracted malaria. Like his father, Ross also later contracted malaria. He became convinced that mosquitoes are the vectors that carry the disease to humans. But which species? There were so many. Throughout the 1880s and 1890s, he conducted countless experiments, but nearly despaired of discovering the actual culprit. Perseverance paid off, however, and in 1897, he identified the Anopheles mosquito as the vector, a discovery for which Ross subsequently was awarded the Nobel Prize.

Ross' discovery narrowed down the uncertainty somewhat for Gorgas' team, but still left many questions unanswered. "It was not known how many different species of Anopheles existed," wrote Dr. Joseph Le Prince, one of Gorgas' assistants, "nor was it definitely known which of them were the important malaria carriers." To Le Prince, who had also been Gorgas' right hand at Havana, it was clear that "much investigative or pioneer work" remained to be done. He later wrote:

   We had no means of determining
   how seasonal changes would affect
   propagation, and the available data
   were unreliable. It was generally believed
   at that time that all mosquitoes
   traveled more or less with gentle air
   currents, but there was no positive
   knowledge of habits of flight, and
   the length of flight of Anopheles
   was yet to be determined. It was not
   known if or how topography affected
   the distribution of species, whether
   Anopheles larvae thriving in small
   collections of water held by plants
   were of ... importance, or whether
   certain species were confined to
   fixed geographical limits.

So, while Gorgas' sanitation teams gathered detailed information on Stegomyia concentrations for their campaign against yellow fever, they also began building a comprehensive database on Anopheles concentrations and habits as well. They soon learned that Panama was an Anopheles tropical paradise. The tiny vampire insects were everywhere, and in huge numbers. Unlike the Stegomyia, which only propagated in clean water, Anopheles thrived in any kind of water. Panama's heavy rainfall, dense jungles, tall grasses, and plentiful swampland combined to make Anopheles ubiquitous.

An early survey by Gorgas' teams showed Anopheles breeding grounds in or near ever)' existing settlement and village. In a village of five hundred near the now-famous Culebra Cut, Gorgas found that every child he examined had a greatly enlarged spleen, a sign of chronic malarial infection. Every adult he interviewed told of attacks of chills and fever within the preceding six months. Half of the U.S. Marine detachment encamped near the same village was already infected with malaria.

Strategy for Extermination

Dr. Gorgas mapped out a multi-pronged plan of attack. One of his chief assistants for implementing the plan was John J. Moran, who had worked with him in Cuba and, as a "human guinea pig," had survived infection with yellow fever. Moran and William J. Murphy had successfully carried out Gorgas' Stegomyia eradication program in the Canal Zone, leading a sanitary brigade of 400 men who methodically fumigated buildings and rid the area of the water sources that provided the mosquito breeding grounds.

The Anopheles eradication program was, of necessity, far more extensive, involving:

* Draining all pools and marshes within 200 yards of all villages and 100 yards of all individual houses;

* Constructing graded concrete ditches to replace many muddy ditches that collected stagnant water;

* Cutting and maintaining grass and brush to a height less than one foot within 200 yards of villages and 100 yards of individual houses;

* Oiling of ponds and swamps when drainage was not possible to kill mosquito larvae. When oiling was not sufficient, the brigades spread a larvacide devised by Dr. Le Prince composed of carbolic acid and caustic soda, which proved very effective;

* Medicating construction workers, natives, and tourists with prophylactic doses of quinine;

* Screening residences, as well as commercial and governmental buildings;

* Exterminating adult mosquitoes through fumigation and hiring collectors to gather live specimens that remained in tents and buildings.

The program was a smashing success. Yellow fever was totally eradicated, and the death rate due to malaria plummeted, from a maximum of 16.21 per 1,000 in July 1906 to 2.58 per 1,000 in December 1909.

The conquering of the Stegomyia and Anopheles mosquitoes made possible the construction of the Panama Canal, one of the great engineering marvels of the world. Dr. Gorgas' eradication program also provided health and sanitation authorities worldwide with a detailed textbook for practical control of a dread scourge that has afflicted mankind from time immemorial. Countless millions can thank Gorgas and his medical and scientific comrades--Walter Reed, Joseph Le Prince, Jesse Lazear, Carlos Juan Finlay, Ronald Ross, and many others--who put the welfare of humanity above their own personal safety and heroically persevered in the pursuit of truth despite public scorn, disbelief, and often vicious opposition.

RELATED ARTICLE: Persecuted savior: DDT.

In 1948, Swiss chemist Paul Hermann Muller received the Nobel Prize "for his discovery of the high efficiency of DDT as a contact poison against several arthropods." Muller had discovered the insecticidal properties of DDT (dichloro-diphenyl-trichlorethane), which proved invaluable in fighting epidemic typhus (a disease transmitted by lice) during World War II. However, DDT's greatest public health triumph came with its use to combat malaria. Spraying DDT twice a year on the inside walls of houses in malaria-endemic areas has proven over and over again to cause a dramatic drop in malaria. In fact, DDT use is responsible for the complete eradication of malaria from many countries today. Its low cost, low toxicity, effectiveness, and long-term activity have made DDT, literally, a lifesaver to millions of people.

However, the publication of Rachel Carson's book Silent Spring, in 1962, launched an ongoing crusade against the pesticide by radical environmentalists that has resulted in its ban in the U.S. and much of the rest of the world. The anti-DDT crusade culminated in the UN's POPs (Persistent Organic Pollutants) treaty in 2001, which prohibits agricultural use of DDT. The treaty allows for the continued use of DDT for public health purposes (as in mosquito eradication), but underdeveloped countries that are most in need of the pesticide are under heavy pressure from the World Bank, World Health Organization, and environmental activists to abandon DDT use. As a result, more than a million people (most of them children) die from malaria every year and as many as 300 million suffer from mild to serious malarial infections.

--WILLIAM F. JASPER