Narrator: In the summer of 1693, Admiral Joseph Wheeler's fleet arrived in Boston from the West Indies with a cargo of rum and sugar. Within weeks, men and women scattered across the city began to show symptoms of a strange illness: Jaundice. High fever. Black vomit. Yellow Fever had come to America. For the next two hundred years, the disease would strike city after city with frightening regularity, and no apparent cause.

Jim Writer, Author: There are some severe epidemics that take place. Late 1700s, Philadelphia looses 10% of its population. As we move into the 1800s, the disease moves south, away from the northeastern seaboards to the southern states. There are some devastating epidemics that strike along the Gulf Coast, especially in New Orleans.

Narrator: Hot and humid, bustling with trade from the Caribbean -- where the fever was present year round -- New Orleans was especially vulnerable to Yellow Fever. Summer epidemics would claim hundreds, even thousands of lives.

Dr. John R. Pierce, U.S. Army Medical Corps: There was no way to protect yourself from it. Even though they knew that it would come in the summer, sometimes it didn't come. There were some summers where there was very little yellow fever. And then another summer it would come and it would be a scourge of biblical proportions.

Narrator: On July 24, 1878, The New Orleans Picayune confirmed fourteen cases and seven deaths in the crowded tenements of the first district. Soon, cases of yellow fever were reported in the better sections of town. Panic gripped the city.

Jim Writer, Author: There was no way to predict who was going to be next or how it was going to spread. The way it moved through a community from house to house, skipping houses, skipping neighborhoods, coming back and getting neighborhoods later on; attacking rich and poor, in some way that makes no sense, that's sort of random. The way it attacked and what it did to its victims just horrified people.

Dr. Paul Jurgensen, Specialist in Infectious Diseases:

People develop a headache, they develop fever, they develop a back pain. They hurt all over and ache all over. And these symptoms usually last for about 48 to 72 hours. And it's just like having the flu. And then the virus attacks the liver. And when the liver is destroyed, proteins, which are very necessary for proper blood coagulation, are also destroyed.

John Tone, Historian: You would bleed from your eyes, from your nose, from your mouth, one of the worst aspects of the disease in its final stages was that you're bleeding internally into your stomach, and then that blood is digested and you end up vomiting it out, and its sort of like wet coffee grounds. It's not a quiet death -- you are struggling, you're frantic. Doctors would have to strap their patients down while they watched them die.

Narrator: New Orleans physicians struggled to treat and understand an illness that seemed to defy all explanation. They prescribed bloodlettings, carbolic acid, massive doses of quinine. To ward off the illness, citizens covered themselves in mustard plaster; shut windows to keep the fever out; burned tar in the belief that the smoke would disturb the "miasma" -- the noxious emissions that for centuries had been thought to carry disease. The city became a smoke-filled hell, pierced by the anguished sounds of the dying, and the acrid smell of putrefying blood. Those who could, fled -- in the tens of thousands.

Jim Writer, Author: People are running in fear. Those who remain are struggling to survive. There may be no food coming in, there is no goods going out. All commerce grinds to a halt.

Dr. Margaret Humphreys, Medical Historian: With everything shut up and closed, New Orleans quickly became a ghost town. The whole fabric of life is disrupted in ways that other diseases didn't do.

Narrator: For decades, yellow fever had been a Southern scourge, its ravages confined below the Mason-Dixon line. But now, steamboats and railroads unite the country north to south, east to west. Yellow Jack, as the disease was known, could travel far, and travel fast.

Jim Writer, Author: 1878 is the turning point in the history of yellow fever: people are more mobile than they were in the pre-Civil War period. Yellow fever has new opportunities for moving away from the port where it's introduced and it does. It takes those opportunities. It rides the rails out to Mobile, up to Memphis, over to Chattanooga.

Narrator: To Kentucky, Indiana, Illinois. Even into Ohio it went, aboard trains crowded with refugees heading North.

Dr. Margaret Humphreys, Medical Historian: Towns where those people might go to didn't want them to come. So, people burned bridges, they tore up train tracks -- anything to keep the epidemic out.

Narrator: Some states set up official quarantines, but in many towns citizens took matters into their own hands.

Dr. Margaret Humphreys, Medical Historian: Armed men would meet the trains and either force them to go on or turn back. And they called that "shotgun quarantines." One man with a shotgun is going to keep a train either moving or at least keep people from getting off of it.

Narrator: But there was no stopping Yellow Jack. The epidemic spread to eleven states and 200 communities. One hundred twenty thousand people became infected. "The King of Terrors continues to snatch victims with fearful rapidity," wrote a Memphis resident. "One by one, those who remain in the city and are liable to the monster malady are taken down."

By the time it ended, with the arrival of the first frost, the Great Mississippi Valley Epidemic had taken 20,000 lives. Economic losses were estimated in the hundreds of millions. The City of Memphis was forced to declare bankruptcy. As news spread, the magnitude of the tragedy registered in every corner of the nation, from San Francisco to New York.

Dr. Margaret Humphreys, Medical Historian: Suddenly what had been a southern problem was now a national problem, in terms of finance, in terms of just spread of disease and the feeling is the south cannot take care of this problem themselves. Either they won't because they're stupid or they're inept or they're too poor and the federal government really needs to step in here because now the South's problems are everybody's problem.

Narrator: The federal government took decisive action. Congress established the National Board of Health, with authority to intervene in a public health emergency. The Board would also help Southern States put in place sanitary improvements and administer a quarantine system designed to keep yellow fever from entering the United States. But neither sanitation nor quarantine would prove to be enough. What was needed were answers to some crucial questions about yellow fever, and how it spread.

At his laboratory in his home in Old Havana, Dr. Carlos Finlay had been studying yellow fever for quite some time. The son of a Scottish father and a French mother, Finlay had left Cuba as a young man to study in Europe, then at Jefferson Medical College in Philadelphia. He returned to Cuba in 1864, where he settled down. In 1872, he began to investigate yellow fever, a disease that year after year swept through his native country. He looked at changes in temperature, altitude, even the alkalinity of the atmosphere. Then, young Dr. Finlay made a scientific breakthrough.

John Tone, Historian: He had read that some diseases could be spread through an intermediate host. There's a particular disease of wheat that has to first incubate in another plant before it can be spread. So he deduced that what was necessary to spread it was an agent that would take it from a sick person to a healthy person.

Narrator: In 1879 an American scientist handed Finlay his next clue. Microscopic slides of tissues from yellow fever victims.

John Tone, Historian: He left Finlay with some photographs that clearly indicated to Finlay that yellow fever must be spread somehow through lesions in the blood vessels. That it must be a biting insect that accesses those blood vessels. That's how he first came upon the idea that it was a mosquito.

Narrator: With nearly a thousand species of mosquitoes, Finlay searched painstakingly for the one that transmitted the disease.

John Tone, Historian: What he did was he figured out where that mosquito was present and he mapped that against where cases of yellow fever occurred. And since they mapped perfectly to each other he deduced that yellow fever was spread by this particular mosquito. The aedes egypti mosquito.

Narrator: It was a remarkable idea -- perhaps too remarkable for its time.

Dr. Margaret Humphreys, Medical Historian: In the 1880s, the germs that cause the most familiar diseases were just being identified. And these germs got into the body in fairly obvious ways. Cholera you swallow it, tuberculosis or diphtheria is inhaled. But the idea that another way that germs could get into the body was through an insect was not out there.

Narrator: In August 1881, at an international scientific conference in Havana, Carlos Finlay unveiled his mosquito theory, outlining three conditions necessary for the transmission of yellow fever.

John Tone, Historian: Number one, the presence of a person with yellow fever. Number two, a person apt to contract yellow fever. And number three, an agent that can transmit yellow fever from a sick person to a healthy person. And he tells them that, in light of all this, all the focus on quarantines and all the other measures that they were proposing to take to control yellow fever would be useless and what they really needed to focus on was the intermediate agent.

Narrator: At the end of Finlay's presentation, there were no questions, no rebuttals. "No one spoke against my theory," Finlay later recalled, "but I would have preferred it to the silence. That conspiracy of silence, and silence ..."

Jim Writer, Author: Finlay is so far out on the edge, so far ahead of his time; there's no way the medical community is going to take him seriously. He becomes the mosquito man, the crazy Cuban doctor who's got this wild theory about insects carrying disease.

Narrator: For the next twenty years, Finlay worked tirelessly to win scientific acceptance for his theory: conducting experiments with mosquitoes on a hundred volunteers, he focused on transmission while others searched for a cause.

John Tone, Historian: Scientists all over the world are drawing blood from yellow fever patients, they're culturing the blood, they're trying to identify the bacterium that causes yellow fever. Finlay wasn't doing that. He was concentrating on the mosquitoes.

Jim Writer, Author: What Finlay needs to do is to show that he can consistently move yellow fever from person to person using the mosquito as a vector. That there is no other explanation for that person's case of yellow fever. And in general he can't do that. He can get a case here and there -- sporadic cases -- but he still is missing conclusive proof.

John Tone, Historian: Because he is working in Havana, which is an endemic center of yellow fever, people would say, "well, maybe your patients caught yellow fever not from the mosquito bite but from something else in the atmosphere." He could never really adequately answer those objections.

Narrator: Finlay's theory languished. In 1898, the United States declared war on Spain. Forty thousand American troops landed on the island of Cuba, a Spanish colony.

Jim Writer, Author: Cuba has been suspected for decades as being a source of the yellow fever that comes into the United States. It's an endemic disease in Cuba, it's always there, and that raises all sorts of fears. There's fears about soldiers becoming infected in Cuba, there's fears about soldiers returning from Cuba and bringing yellow fever with them - really opens up a whole new pathway for yellow fever to infect the United States.

Narrator: In only three months, the American army defeated Spain and occupied Cuba. Fewer than 400 American soldiers were lost to Spanish bullets, but more than 2000 came down with Yellow Jack. An African American regimen, the 24th infantry, lost a third of its men to the disease. Two years in to the occupation, a yellow fever epidemic raged across the island. The lives of 15,000 American troops were at risk.

John Tone, Historian: Because they didn't understand the role of the mosquito, what they would do is that someone would catch yellow fever, they'd be put in a hospital next to someone who had malaria, next to someone else who had typhus. Meanwhile there are mosquitoes buzzing around them, biting one, biting the other, spreading disease back and forth.

Dr. John R. Pierce, U.S. Army Medical Corps: We thought that it was transmitted by fomites. A fomite was any inanimate object that could transmit an illness. And so there was felt to be something on the clothes, on the furniture, the sheets that the sick people slept on. There was felt to be something in those materials that could transmit the disease

Narrator: In July 1900, an outbreak of yellow fever was reported at a U.S. camp just west of Havana. American troops now faced the same danger as other armies who had ventured into the region.

John Tone, Historian: Yellow fever had been the enemy of colonial powers in the Caribbean for a long time. It had destroyed an army that Napoleon sent to Haiti in 1802, and in the 1890's it had devastated Spanish armies in Cuba. Americans were well aware of all of this. So they were very fearful that their armies in Cuba not suffer the same way.

Narrator:

The officer in charge of protecting the health of U.S. troops was Surgeon General George Sternberg, a leading bacteriologist. Like many scientists, Sternberg had spent years the searching for the yellow fever germ. Now he appointed an ambitious army doctor to lead a commission to Havana to try to find it. Major Walter Reed was the youngest man ever to be granted a medical degree by the University of Virginia. After two decades of service in the American West, he was not one to shy away from a challenge.

Jim Writer, Author: Reed is a frontier doctor basically. Most of his career has been spent out on the frontier: Indian country in Arizona, in Kansas, in Nebraska. He takes a class in bacteriology, Johns Hopkins, and it begins to transform him, brings him into contact with the new science of medicine. He moves from this frontier doctor, working in small Army posts, and now becomes a scientist.

Dr. John R. Pierce, U.S. Army Medical Corps: He was highly motivated. He worked most of his life with idea that there was going to be an opportunity for him to make a big difference.

Narrator: Reed chose a trusted friend, James Carroll, as his assistant. To head the laboratory at Havana's Columbia Barracks he named a young American bacteriologist, Jesse Lazear.

The Yellow Fever Board's first task was to disprove an Italian scientist's claim that he had found the elusive yellow fever germ.

Dr. Margaret Humphreys, Medical Historian: There had been a lot of research, a lot of people trumpeting their discovery and then someone else has to come along and prove that that was wrong and this had happened a lot. The problem was that, and they didn't realize it. Yellow fever is caused by a virus. It's a particle that cannot be seen through the kinds of microscopes they had in 1900.

Narrator: Jesse Lazear chafed at what he saw as his colleague's focus on petty scientific disputes. "Reed and Carroll have notions that I don't agree with," he wrote, "and are not inclined to do as much as I would like to see done." Left on his own, Lazear believed he could discover the real cause of yellow fever.

Jim Writer, Author: I just picture Lazear as being a real go-getter. He knows he's smart, he's got the training, he's got the education. And he's got an opportunity now to make a name for himself in the world of medical research.

Narrator: Lazear had arrived in Cuba with his son, Houston, and his wife Mabel, who carried their second child. Camera in hand, the young couple enjoyed the historic sites of Havana. A contract surgeon, Dr. Lazear had left behind a position as head of the laboratories at Johns Hopkins University, where he had been working on malaria, only recently proved to be carried by an intermediate host.

Dr. Margaret Humphreys, Medical Historian: Malaria and yellow fever are both diseases that occurred in certain patterns that matched when the mosquito was active. It's worse in more tropical areas, so it made sense that this disease, yellow fever, could be like malaria, spread by a mosquito.

Narrator: On May 23, Lazear struck out on his own. He went to Quemados, a Havana suburb and the starting point of the 1900 epidemic, and brought back four mosquitoes captured in an infected person's room. He dissected the insects, and looked in vain for the yellow fever germ. Then, in July, Lazear, Reed, and the rest of the Board paid a visit to Old Havana, to the home of Dr. Finlay.

John Tone, Historian: In a sense Finlay was the last option. They had tried everything, they had tried sanitation, they had cleaned Havana, they had disproved various candidates for yellow fever but they hadn't actually found the agent. With so many troops falling sick, and yellow fever being a threat to the American occupation, they finally proved willing to listen to Finlay.

Narrator: As he handed his aedes egypti eggs to the yellow fever board, Carlos Finlay had every reason to be pleased.

Jim Writer, Author: Finally somebody is taking him seriously. Finally somebody is going to test out his theory, take his mosquitoes and give it a shot.

Narrator: On August 2, Walter Reed left for Washington. Although deeply skeptical of Finlay's theory, Reed had instructed his staff to begin conducting mosquito experiments.

Dr. John R. Pierce, U.S. Army Medical Corps: They agreed at that point in time that as they began their mosquito experiments, they would experiment on themselves, that they would be the first guinea pigs to take the mosquito bites to see if they could transmit yellow fever.

Narrator: Convinced that mosquitoes were harmless, Reed expected little to happen in his absence. He could not have been more mistaken. Jesse Lazear took over Finlay's mosquitoes. Meticulously following Finlay's techniques, each day, Lazear would take his "birds," as he called them, to Las Animas -- the U.S. Army Yellow fever ward. There, he would have them "load," feed on the blood of infected patients. Then he would have the "loaded" mosquitoes bite healthy volunteers. After nine inoculations, two on himself, Lazear had failed to produce a single case of yellow fever. Discouraged, he was ready to give up.

Then, on August 27, Lazear noted that one of his birds had failed to load. Concerned that the mosquito might die without a blood meal, he asked his colleague James Carroll if he would allow it to feed. Two days later Carroll fell ill. He appeared jaundiced. His temperature rose to 103 degrees. He was diagnosed with yellow fever.

Dr. John R. Pierce, U.S. Army Medical Corps: Lazear takes it upon himself to go find another volunteer. The young soldier named William Dean is bitten by the same mosquito that has made Carroll ill. Dean a few days later gets sick and so he progresses to what is an obvious case of yellow fever.

Narrator: "Dear Mabel," Lazear wrote his wife, who had returned to the United States to give birth. "I rather think I'm on the track of the real germ. But nothing must be said as yet. I have not mentioned it to a soul."

Jim Writer, Author: He's the physician who inoculates Carroll, which is the first case that the team probably transmits from a mosquito to a person. He's the person who inoculates William Dean, who is definitely the first case of the Army team who transmits yellow fever to/from the mosquito. If he can prove that the mosquito transmits yellow fever, the potential for a Nobel Prize may not be out of line.

Narrator: The morning of September 18, Jesse Lazear did not report to work. The next day he was taken by ambulance to the Columbia Barracks Hospital. Lazear explained that he had been bitten by a stray mosquito while "loading" at Las Animas. But a page from his laboratory book later revealed that he had knowingly subjected himself to the bite of an infected mosquito.

Jim Writer, Author: When Lazear exposes himself to yellow fever he probably doesn't think that his risk of dying is all that great. He's infected two other people: Carroll, James Carroll, and William Dean. And they've become ill but they are both recovering. Lazear probably believes that he too can produce a case of yellow fever in himself and that he too can recover and carry on his work.

Narrator: News of Lazear's illness reached Walter Reed in Pennsylvania. A career military man, Reed now realized that he had left his men in harm's way. "I have been so ashamed of myself for being here, in a safe country," he wrote, "while my associates have been coming down with Yellow Jack. Still I feel that Lazear will pull through ..." Lazear progressed to an advanced case of yellow fever. In the delirium of his final hours, a friend reported, he was tormented by thoughts of his wife and son, and the daughter he would never meet.

Dr. John R. Pierce, U.S. Army Medical Corps: When she got the telegram 'Dr. Lazear died this evening' she was in horrible shock because she didn't even know he was sick. Didn't know that he had yellow fever, she just got a telegram that he had died.

Narrator: "He was a splendid, brave fellow and I lament his loss more than words can tell," wrote a devastated Reed. "But his death was not in vain. His name will live in the history of those who have benefited humanity."

When he had left for Washington six weeks before Lazear's death, Reed had doubted Finlay's mosquito theory. Now, as he returned to Cuba, on October 4, he was firmly converted to the belief that the mosquito was indeed the transmitter of yellow fever.

Jim Writer, Author: Reed has got to be comfortable, before he tells the world that in fact he has an indisputable case of experimentally transmitted yellow fever where the mosquito was the agent of the disease.

Narrator: Known to be cautious and meticulous, Reed now worked furiously. He poured over Lazear's lab books, and noted a twelve-day interval between the time of loading and the day the mosquito transmitted yellow fever to Carroll. Sixteen days in the case of Dean. This observation fit with a theory developed by doctor in Mississippi that there was a lapse of two weeks between the first appearance of yellow fever and the appearance of a second case.

Dr. John R. Pierce, U.S. Army Medical Corps: The light bulb probably just went off and said "hey this is it, you've got to have this period in the mosquito. I'm not sure what takes place in the mosquito, but it must take place in the mosquito and it must take at least 12 days for it to happen." So I think that was kind of an epiphany type thing.

Narrator: During that twelve-day interval, the virus ingested with a blood meal matures in the mosquito's digestive track, making its way to the salivary glands to be transmitted when the mosquito bites again. This was the missing piece -- the one that had eluded Carlos Finlay. Less than three weeks after returning to Cuba, on October 23, Reed made his case for the mosquito theory at a gathering of the American Public Health Association.

Dr. John R. Pierce, U.S. Army Medical Corps: It basically had two cases: it had Carroll's case and it had Dean's case. Lazear had died but they had no evidence that he had experimented upon himself at that point in time. He and Sternberg wanted to get this published as soon as they could because they knew there were other people working in the field and they wanted to get credit for the Army board and for the men involved.

Narrator: While some observers were impressed, the Washington Post called the mosquito theory "silly and nonsensical." Faced with skepticism, Reed realized that he needed incontrovertible proof. He obtained permission to pay $100 in gold to American soldiers and Spanish immigrants to serve as volunteers, $100 more if they became ill.

Though all volunteers were required to sign consent forms, the human experiments triggered a wave of criticism. The Spanish Council in Cuba issued a formal complaint to the American authorities. Reed was undeterred.

On November 20, 1900, at an isolated spot in Havana, Walter Reed opened a specially designed experimental station. He called it "Camp Lazear."

Jim Writer, Author: He designs a camp that accounts for just about everything that he can think of that might interfere or put any doubt into his results. It has to be precise scientific method, there can be no sloppiness at all in what he does.

Narrator: He placed his volunteers in two separate cabins, which he called Building One and Building Two.

Dr. Margaret Humphreys, Medical Historian: They put one set of volunteers in a cabin that was screened and the cabin was loaded up with all sorts of nasty things from yellow fever patients -- blankets they'd vomited on, just all sorts of ... you know, diarrhea on the things -- and they had to sleep on these beds, and these pillows that were soaked from yellow fever victims, many of whom had died.

Jim Writer, Author: The other building that Reed sets up is Building Two; it's called the infected mosquito building. Same size as the infected clothing building, but it's divided into two chambers with a screen between the two chambers. In one side of the building is a volunteer. Infected mosquitoes are let loose into the building and they bite the volunteer.

John Tone, Historian: The people who were exposed to mosquitoes, they caught yellow fever. The people in the fomite cabin, of course, never did catch yellow fever. It was an elegant and clever experiment and it convinced the scientific world that it wasn't some particle of yellow fever contagion in the blood or in skin tissue or something like that. That it had to be transmitted by a mosquito. He convinces the scientific world when Finley couldn't.

Narrator: Reed invited Carlos Finlay to Camp Lazear to witness the success of his experiment. "I supposed old Dr. Finlay will be delighted beyond bounds," Reed wrote, "as he will see his theory at last fully vindicated." It had been twenty years since Finlay had postulated that getting rid of yellow fever meant controlling the mosquito. Now, Major William Gorgas, chief sanitary officer, ordered U.S. Army troops onto every street, and into every home in Cuba's capital, putting Finlay's theory to the test.

Dr. Margaret Humphreys, Medical Historian: As soon as he heard about a case of yellow fever the patient was put in a screened room so that the mosquitoes couldn't get in or out. And they did things to eradicate any mosquitoes that were in that room.

Jim Writer, Author: Teams move out across the city fumigating homes and buildings, tracking down places where mosquitoes breed, eliminating standing water.

Narrator: The campaign was a resounding success. In 1900, there had been 300 yellow fever deaths in Havana. The next year, following the mosquito eradication campaign, there was only one.

Dr. John R. Pierce, U.S. Army Medical Corps: Despite what had had happened in Cuba, despite the fact that yellow fever had gone away from Havana effectively within months, not years, but months, people still didn't accept the theory that insects could carry disease.

Narrator: Back in Washington, Walter Reed spent much of his time trying to convince health officials that controlling mosquitoes was the key to controlling yellow fever.

Dr. Margaret Humphreys, Medical Historian: Reed was particularly frustrated with some of the leaders of Southern Public Health and the State Board of Health of Louisiana. He wrote a letter to one of his friends and said maybe we should arrange for a few of them to be bitten by some loaded stegomaya, the name that they had for the aegis egypti mosquito, to get them out of the way.

Narrator: But Reed's influence in the yellow fever debate would come to an unexpected end. In 1902, Walter Reed died from complications of appendicitis. The nation's champion of the mosquito theory was gone. New Orleans, 1905: the city once known as "The Necropolis of the South" had been relatively free of yellow fever for more than two decades. Proud officials attributed the success to a wall of quarantine stations, especially designed to keep the disease at bay.

John Tone, Historian: When a ship came in, they would make sure that no one aboard that ship had yellow fever. Then they would go aboard the ship, they would fumigate it, they would wash it. They would use everything from vinegar to smoke to try to cleanse the ship, to sanitize it.

Dr. Margaret Humphreys, Medical Historian: They filled the hulls of ships with sulfurous acid gas. They took all the bedding and clothing and hung it up in giant autoclaves, I mean, they were these giant ovens, and toasted the clothing up to 250 degrees Fahrenheit. It was a very impressive-looking apparatus and very active service. The whole system seemed to work for twenty years, so now they're supposed to just shut these things down? It did not seem prudent.

Narrator: The head of the New Orleans Health Board, Dr. Quitman Kohnke, disagreed. A firm believer in the mosquito theory, he urged his colleagues to put in place a program of mosquito control.

Dr. Margaret Humphreys, Medical Historian: Kohnke said, "this is what we need to be doing, we need laws about screening cisterns," and all the rest of it. He didn't get very far. And people somewhat laughed at him, they drew cartoons of this guy, St. George of the dragon fighting off a huge mosquito.

Narrator:

In the spring of 1905, a smuggler's ship with a cargo of bananas bridged New Orleans quarantine wall and quietly made its way through the backwaters of the Mississippi. On June 12, two suspicious deaths were reported near the waterfront. Yellow fever once again threatened New Orleans, and once again the city was unprepared. Without effective mosquito controls in place, millions of aedes egypti bred undisturbed, most dangerously in the 70,000 backyard cisterns where families stored their water.

On June 22, New Orleans authorities declared an emergency. By then, one hundred people had come down with the disease. Twenty had died. Kohnke decided there was no more time to waste. "Even if you are not positive that the mosquito is the only source of the transmission of yellow fever," he told New Orleans' physicians," give your city the benefit of the doubt in this important and vital matter." Under Kohnke's direction, New Orleans organized as if for war. "Science has discovered the cause and has learned to exterminate it," heralded the New Orleans Picayune. The mosquito control techniques that the U.S. Army had used so effectively in Havana were now applied to the Crescent City. House by house, block by block, workmen screened cisterns to prevent mosquitoes from laying eggs. To suffocate the larvae, all standing water was treated with kerosene. Saturdays and Sundays were declared fumigation days. On a single day, residents burned an estimated three hundred tons of sulphur -- giving the mosquito, as The Picayune put it, "a dose of real brimstone." Citizens were urged to sleep under nets and help with the oiling and screening of cisterns. Fines of up to $25 or thirty days in prison were issued to those who failed to comply.

It was a race against the mosquito, but years of inaction had given the aedes egypti a head start. Barely a month after the beginning of the epidemic, six hundred yellow fever cases were reported.

Dr. Margaret Humphreys, Medical Historian: The epidemic is spreading and the city doesn't have enough money to fight the epidemic so what they do is call in the federal government. There's a lot of resentment to federal power but also recognition that that's the only way we're going to get this disease under control.

Narrator: "We regard this as the first crucial test in America of the mosquito theory," proclaimed federal authorities, "and it must be perfect to be efficient."

Jim Writer, Author: They have a mission. Destroy the mosquito. There's no ifs, ands or buts. If you don't cooperate, they'll do it for you.

Narrator: Whenever a new case of fever was reported, a squad went immediately to screen the patient's room and fumigate the house. They were instructed to behave unemotionally and get their work done. "It was like watching a huge machine, well oiled and efficacious," one reporter wrote.

Still, the epidemic seemed to be getting out of control. On August 12, 100 people became ill. Years before, the numbers of sick would have risen exponentially: thousands would have died by the first frosts. But this time, the mosquito control measures that so many had doubted made all the difference.

In September, the number of victims began to decline. A month later, the epidemic was all but over. The final tally for the city of New Orleans was 452 deaths -- a fraction of the toll exacted by epidemics in the past.

Dr. Margaret Humphreys, Medical Historian: It really was a triumph for science in an era where the expert is increasingly being called upon to guide government action.

Narrator: It would go down in history as America's most successful public health campaign -- and the last ever waged against yellow fever in the United States. The brilliance of Carlos Finlay, the dedication of Walter Reed, and the sacrifice of Jesse Lazear spared the United States the suffering and fear that once made Yellow Jack the nation's most dreaded epidemic. Though a cure for yellow fever has not been found, nor the virus eradicated, in the United States, there has not been a yellow fever epidemic for more than one hundred years.