The American Plague: The Untold Story of Yellow Fever, the Epidemic that Shaped Our History - Molly Caldwell Crosby (2006)

Part III. Cuba, 1900

Chapter 16. Did the Mosquito Do It?

When the epidemic in Quemados ended, and Reed had sailed for the U.S., the doctors of the Yellow Fever Board found themselves without subjects to research. They decided to move their studies to Las Animas Hospital, literally “the Souls Hospital,” in Havana, where there existed a large number of yellow fever patients, but also Agramonte’s fully equipped laboratory. The doctors settled into a quiet pattern: Agramonte performed autopsies on the yellow fever cadavers in Havana, Carroll continued his work with tissue samples in his lab at Camp Columbia, and Lazear nurtured his mosquitoes.

To Dr. Carlos Finlay’s delight, the Yellow Fever Board had paid him a visit to request samples of mosquito eggs. Finlay was now sixty-five years old, and he had been arguing his case for mosquitoes for twenty years. He took them into his library and pulled a few eggs from the glass edge of a bowl half full of water. Lazear listened intently as Finlay described the life cycle of this particular type of striped house mosquito, its peculiar aptitude for dwellings and fresh-water cisterns, its tendency to stay in a localized area rather than traveling great lengths, the female’s persistence in biting at all times of the day, its genius for adapting from its native forests to human habitats. Aedes aegypti was also a low flyer, drawn to the human scents of carbon dioxide and lactic acid that were heavier than the air and sank downward toward the exposed flesh of ankles and legs. Then, Finlay gave several dried eggs of that particular mosquito species to Lazear to raise for his own studies.

In addition to the stages of the mosquito’s development, there were anatomical details to track. Given Lazear’s methodical nature, the care of the “birds” was perfectly suited for him. As the eggs hatched, Lazear carefully labeled the glass tubes and shipped a few more of the mosquitoes to Dr. Leland Howard, an entomologist with the Department of Agriculture in the U.S. Sure enough, the samples proved to be the striped house mosquito so common in North America. As that generation of insects died, Lazear nurtured the eggs of the next. The most essential factor in rearing a batch of mosquitoes and producing new eggs is a fresh blood supply. The pregnant females need blood in order to lay eggs; and once hatched, the new generation relies on blood meals to thrive.

Las Animas Hospital housed an ample source of yellow fever patients. Lazear carried his fledgling mosquitoes in glass tubes plugged with cotton to the yellow fever ward. He removed the cotton and turned the tube upside down against a man’s arm or abdomen until the mosquito zigzagged its way downward, legs arched, and struck.

Though each of the members of the Yellow Fever Board had volunteered to self-infect, it turned out to be more complicated than that: Reed’s work in the U.S. had detained him longer than planned as he prepared his typhoid report, Cuban-born Agramonte was thought to be immune, and Carroll spent most of his time working at Camp Columbia. Only Lazear, who frequented Havana, was left to test the mosquito theory.

On August 11, Jesse Lazear took one of his carefully labeled yellow fever mosquitoes, flipped the tube upside down and waited as the insect landed and bit his forearm. When the mosquito seemed to have had her fill, Lazear tapped the glass, and she flew upward again. He marked it in his logbook. Contract surgeon Alva Sherman Pinto also volunteered to be bitten. Neither resulted in a case of yellow fever, though the mosquitoes had fed on infected patients and should have been carrying the virus in their wiry, winged bodies. Lazear’s notebook lists a number of other volunteers from Las Animas Hospital, none of whom developed yellow fever. The board became discouraged, especially Lazear, who was ready to “throw up the sponge.”

Then, the prey turned on the predator.

On August 23, Lazear sat down and wrote to his wife, who was now in the hospital on bed rest as she awaited the birth of their baby. In his letter, Lazear expressed his frustration with the fact that both Reed and Carroll seemed so preoccupied with the Sanarelli controversy: “Reed and Carroll have been at that for a long time and they have notions as to what we should do that I don’t agree with. They are not inclined to attempt as much as I would like to see done . . . I would rather try to find the germ without bothering about Sanarelli.”

In letters to both his mother and his wife, Lazear never mentions the experiments he conducted on himself. It may be that he did not want to worry them; two days later, he received word that his wife, Mabel, gave birth to a daughter named Margaret. He wrote to his mother, “The distance seems very great at a time like this.”

On August 27, Lazear finished his work at the lab at Las Animas Hospital in Havana and collected his glass tubes of mosquitoes to take with him to Camp Columbia. It was getting close to noon, the rooms of Las Animas grew stale, and the sun beat down against the tile floor. If he didn’t hurry, the afternoon rain would set in during their ride back to camp. Lazear didn’t want to take the time to return his glass-caged insects to Agramonte’s lab at the military hospital, so he carefully packed up the test tubes in a carrying case to take with him. Cuban doctors watched with curious amusement as Lazear came and went, his arms full of caged mosquitoes, just as Finlay had done twenty years before. As he left the hospital, Lazear noticed that the mosquitoes seemed to be thriving—all but one that is. Lazear made a note that morning that one of the females, who had bitten a new yellow fever patient twelve days before, had refused to feed.

Lunch ended at the mess hall at Camp Columbia, though the afternoon breeze still carried the smell of food and coffee. Most of the men were heading to their bunks to nap through the rainy part of the day, but Lazear returned to the lab to check on the dying mosquito. Carroll was seated at his microscope. Light poured through windows and cracks of the wooden walls leaving a pattern of lines and squares throughout the lab like a giant white web. Lazear tapped the glass tube and watched the listless female mosquito. He complained to Carroll that she had refused to feed that morning and would likely die by the next day. Carroll rolled up his sleeve and volunteered his arm. Without much thought, Lazear held the glass tube against Carroll’s pale skin and waited for the lethargic insect to light on his arm. But the mosquito remained still, clinging to the glass wall. Exasperated, Lazear let go. Carroll took hold of the test tube and patiently held it in place until the mosquito fluttered downward onto his arm and inserted her proboscis like a needle easing into flesh.

At that point, the board had all but given up its hopes of the mosquito as the transmitter of yellow fever. Half a dozen volunteers had fed infected mosquitoes, including Lazear on a number of occasions. Not a single case of yellow fever had developed. Carroll had been skeptical from the start, and by then, believed that the mosquito theory was useless. James Carroll was just feeding one of Lazear’s pet mosquitoes to keep it alive; he never expected to get ill.

Two days later, Carroll, Lazear and Agramonte worked in the one-story Las Animas Hospital in Havana. Lazear’s sickly mosquito was robust and healthy again thanks to her blood meal from Carroll. Lazear went about his usual, careful routine of feeding his mosquitoes on the infected patients in the yellow fever ward, plugging the test tubes with cotton and making marks in his leather logbook. Instead of taking the train along the Marianao railroad that afternoon, the three doctors left the hospital by Doherty wagon. When they came to the fork in the road, Agramonte hopped down and headed toward the military hospital on foot; Carroll and Lazear continued the ride along the sun-washed road to Camp Columbia. Carroll seemed quiet and distracted.

The next day, on August 30, Carroll and a few of the officers swam in the bright water off the coast of Cuba; sea bathing had become a favorite pastime. The water, as warm as the air, created a strange, seamless sensation as one stepped from the beach into the sea. As Carroll glided through the water, looking toward the shore where the wide leaves of palms flapped in the breeze, he felt an unusual chill. He eased toward the shallow water and waded ashore. The sun had given him a piercing headache as if every ray of light drove a nail into his skull. One of the contract surgeons took one look at the ashen-colored man staggering out of the sea and said, “yellow fever.” “Don’t be a damned fool—I have no such thing,” Carroll grumbled.

News that Carroll showed symptoms reached Lazear at the camp. He was panic-stricken; his experiment may have produced the first case of yellow fever, but it had infected his colleague. Lazear used the camp telephone to call Agramonte in Havana, worry and fear shaking his voice. He explained that he himself had been bitten just two weeks before without falling ill. Flustered, he added that Carroll had held the tube himself when the mosquito fed. Though he said the words out loud and searched for excuses, his voice grew thin.

When Agramonte arrived at Camp Columbia the next morning, he found Carroll twisted over the microscope searching his own blood for the oblong shape of the malarial parasite. Carroll peered through the lens and tried to sound casual as he told him he caught a cold at the beach; but his bloodshot eyes and his pallid skin, beaded with perspiration, shocked Agramonte.

Carroll remained stubborn, finally having to be ordered to the hospital where his illness spiraled, and he soon became delirious. His temperature rose to 105 degrees, and his heart swelled under the pressure. James Carroll was forty-six years old, and yellow fever proved far more deadly in those over the age of forty.

Lena Warner was called in to nurse him. Warner, who as a child had the fever during the 1878 epidemic, knew exactly what Carroll was feeling. Weak and ill, he tried to tell her that he had been bitten by a mosquito before contracting the fever, but up to that point, it was still an unbelievable theory. His desperate attemptsto tell her what had happened were dismissed as fever-induced ravings, and Warner made notes on Carroll’s chart that he was delirious. She did, however, agree to Carroll’s pleas to go by the board’s laboratory on her rounds and drop a small bit of banana into the glass test tubes. Then, he gave very specific directions for replacing the cotton in the top of the tube to prevent the mosquito from escaping. Above all else, the insect was not to get out of its glass cage.

In the lab, Lazear and Agramonte continued to search smears of Carroll’s blood for parasites, or any substantial clue to the illness. Rain began to fall and would continue to deluge Cuba in the following days as a tropical storm settled over the mountains of Cuba gathering its dark energy. Lazear flipped through the pages of his notebook to the day that the mosquito had fed on Carroll’s arm. Since then, Carroll had visited the yellow fever wards at both Las Animas and Military Hospital No. 1, as well as an autopsy room that was so filthy Carroll refused to work until it was thoroughly disinfected. He had been exposed to yellow fever on several occasions, as he had every day over the last two months. As a case study, he was a decidedly poor one. The only way to prove that it was in fact the mosquito was to try the experiment again.

As Lazear stood in the lab with a test tube in each hand trying to coax a mosquito from one glass house to the other, a soldier walked by the doorway and saluted him. His hands full of test tubes and a stubborn insect, Lazear cheerfully answered, “Good morning,” instead of returning the salute. The soldier, curious and encouraged by Lazear’s approachable manner, stepped into the room.

“You still fooling with mosquitoes, Doctor?”

“Yes,” Lazear said, balancing the tubes, end to end, “will you take a bite?”

“Sure, I ain’t scared of ’em.” The soldier, like most others, found the work of the Yellow Fever Commission fairly amusing. The mosquito theory, just the thought that these tiny insects as frail and inconsequential as lint with wings could transmit illness, seemed ludicrous.

The soldier had never lived in the tropics before and had not left the base for two months; he was the ideal candidate. Agramonte came into the lab and scribbled the name onto a piece of paper: William E. Dean. He would also be known as patient XY. Several days later, Dean became the second known case of experimental yellow fever.

The moon had been brush-marked with clouds all night, and by early morning, as Dean’s fever climbed, red light rose like embers off the ocean water. The tropical storm that had been shelling the island with rain all week was making its way out of Cuba and heading toward the Gulf of Mexico with much more energy and intensity than it had previously shown. It would claim 8,000 lives in Galveston, Texas, during that September weekend in 1900.

Warner continued to nurse Carroll, relying on many of the same techniques used over twenty years before in Memphis—the patient was kept very quiet, no food or solids could be given, only small sips of water or lemonade. Cold saline enemas were administered. Though acetylsalicylic acid, or aspirin, had just been created at Germany’s Bayer company, the loose powder was not yet in general use for fevers.

In the medical chart, Warner recorded his temperature and pulse every three hours and sent urine samples to the lab twice a day. Carroll’s health continued to decline, and his wife received a daily telegram reporting the condition of her husband. His fever hovered around 104 degrees, his skin reddened by the heat; but for visitors, the most disturbing part was watching his body writhe and lurch in the bed.

Reed was finally notified by telegram as to what was happening in Cuba during his absence. He immediately wrote to Kean: “I cannot begin to describe my mental distress and depression over this most unfortunate turn of affairs. We had all determined to experiment on ourselves and I should have taken the same dose had I been there.”

After a week of delirium and high fever, Carroll’s temperature seemed to subside though his eyes remained saffron yellow. His wife received a telegram that day: Carroll out of danger. He had shown none of the telltale black vomiting, and the doctors felt confident that he would eventually recover. When Reed heard the news, he telegrammed Carroll.

September 7, 1900 
1:15 P.M.

My Dear Carroll:

Hip! Hip! Hurrah! God be praised for the news from Cuba today— “Carroll much improved—Prognosis very good!” I shall simply go out and get boiling drunk!

Really I can never recall such a sense of relief in all my life, as the news of your recovery gives me! Further, too, would you believe it? The Typhoid Report is on its way to the Upper Office. Well, I’m damned if I don’t get drunk twice!

God bless you, my boy.



Come home as soon as you can and see your wife and babies.

Reed sealed the letter, but before he sent it, he flipped the envelope over and scrawled in his large, curled handwriting, onto the back: “Did the Mosquito DO IT?”

With Carroll on the mend, and Dean recovering from his case of yellow fever, the board decided to stop any further experiments. As Agramonte, whose immunity could not be guaranteed, described it, “We felt that we had been called upon to accomplish such work as did not justify our taking risks which then seemed really unnecessary.” Besides, with one colleague down and Reed still in the U.S., the Yellow Fever Board couldn’t afford to lose another member now that they had their first real break in solving a disease that had plagued people for centuries.

One member of the board did not heed the warning.

Lazear wrote to his wife, Mabel, from the Columbia Barracks on September 8, “I rather think I am on the track of the real germ, but nothing must be said as yet . . . I have not mentioned it to a soul.”

The events that followed and the resulting tragedy would be debated for the next five decades.