The Mosquito of High Crimes: The campaign against yellow fever during the American construction of the Panama Canal, 1904-1905

Alexandra H. Freeman, B.A.

George Washington University School of Medicine, Washington, DC, USA

In 1904, the United States embarked on a great enterprise—one of the first major technological projects ever conducted in a tropical climate—to build the Panama Canal. Pivotal to the completion of this project, the US government employed modern technology for mass construction as well as sanitary science for disease control. This article explores how public health officers utilized newfound scientific data of yellow fever transmission to mount an expensive, systematic and effective yellow fever campaign during the first two years of canal construction. Headed by Chief Sanitary Officer, Colonel William C. Gorgas, this campaign was the first of its kind to use a revolutionary approach to disease control based on the mosquito vector theory. This article will examine how scientifically informed sanitation officers successfully eradicated disease in Panama, ultimately allowing for continued construction of the Panama Canal.

Keywords: yellow fever, eradication, tropical medicine, Panama Canal

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“It was this conviction of the stegomyia mosquito of high crimes . . . against the human race which lifted medical science out of the bog of blind, groping experimentation in tropical sanitation to the firm ground of exact knowledge (1).”

Joseph Bishop (1913)


In a colossal attempt to unite the Pacific and Atlantic oceans, the United States (US) government embarked on a great national enterprise to build the Panama Canal in 1904. The completion of the canal in 1914 was a demonstration of large-scale technological achievement. Less grandiose in size but equally impressive in scale was the success in tropical medicine that allowed engineers to create their waterway. Upon arrival to the Isthmus of Panama, American engineers quickly began engaging the power of mass human labor and large machinery. In conjunction with these efforts, sanitary officials initiated a campaign to eradicate the tiny but noxious stegomyia mosquito (now named Aedes aegypti), carrier of yellow fever. Directed by Chief Sanitary Officer, Colonel William C. Gorgas, the US Sanitation Department in Panama employed a revolutionary approach to disease control based on the mosquito vector theory. This newer, more scientifically informed approach allowed Gorgas to mount a systematic, organized campaign from 1904 to 1906 that effectively eradicated yellow fever in Panama. Backed by a country intent on accomplishing a monumental industrial feat, scientifically informed sanitation officials not only eradicated yellow fever but also and perhaps most importantly, eliminated the fear of living in a tropical climate among US canal employees. These developments ultimately allowed for continued construction of the canal.

Investigating the 1904 yellow fever campaign brings together three aspects important to the history of science and medicine. First, it is a testament to early advances in tropical medicine research at the turn of the twentieth century; second, it opens a window into the role of medicine in large civil engineering projects; and third, it illustrates the sanitation and public health measures the US government began to employ in its imperial undertakings. This article examines the role of yellow fever eradication in the building of the Panama Canal. The campaign against yellow fever created a unique geographical location, which precipitated new relationships among imperial politics, scientific research, and preventative health.

US Construction of the Panama Canal

The US was not the first country to attempt canal construction through the shortest landmass between the Atlantic and Pacific Oceans in the Americas. In 1881, France began construction of what they hoped would become the French waterway—the first of its kind. Financed and directed by Ferdinand de Lesseps, the builder of the Suez Canal, the French Company remained on the Isthmus of Panama for eleven years until they abandoned their excavation efforts in 1892 (2). The French made appreciable advances in digging their canal, but their workforce was ravaged by disease, and one third of the total French workforce died of yellow fever (3). While other factors including administrative difficulties contributed to the failure of the French to complete construction, yellow fever was a leading factor (3).

Interested in a tropical imperial project, the US took advantage of the opportunity to finish what the French had left behind. President Roosevelt believed that canal construction was a practical and essential means by which the US could gain global power. A US controlled canal engendered access to both Atlantic and Pacific Oceans, and supremacy at sea would bolster the nation’s military and commercial clout. Therefore, the US government, led by the efforts of President Roosevelt, accepted the formal transfer of Canal property from the French Company in May 1904 (1). The US established and acquired complete sovereignty over the Panama Canal Zone, a territorial area through which the selected canal route passed and established the First Isthmian Canal Commission to control construction efforts (2). Construction began quickly thereafter, as June 1904 marked the official arrival of US officers to Panama (4).

To complete the canal—one of the first major technological projects ever conducted in a tropical climate—the US government combined newfound expertise in engineering and sanitary science. US engineers operated with modern techniques, including the rock drill, steam shovel, and dynamite explosions to carry out excavation work efficiently (5). Correspondingly, the Sanitation Department utilized newly confirmed yellow fever transmission vectors to employ an effective sanitation and public health campaign. Together, advanced mechanical technology and medical innovation gave the Americans a tremendous advantage over the French in completing their construction project.

The Mosquito Vector and Tropical Sanitation

Prior to the confirmation of the mosquito vector theory at the turn of the twentieth century, the filth theory of disease prevailed: it was generally accepted by physicians and the general population that tropical diseases such as malaria and yellow fever were transmitted via miasmas, or particles of poisonous gas. Miasmatic transmission occurred through exposure to environmental conditions of filth, such as marshes and swamps, as well as via contact with the sick, their clothing and other articles (6). It was known, however, that yellow fever could not be transmitted through exposure to the fluids of yellow fever patients, including their black vomit. Within this miasmatic system, public health campaigns focused their efforts on city cleanup, including efforts to drain marshy areas, improve urban filth, and improve sanitary living conditions (7).

Numerous scientific discoveries by army surgeons and physicians in the late nineteenth and early twentieth centuries challenged the filth theory of disease, contributing to the emergence of a new branch of scientific medicine: parasitology. Laveran, a French Army Surgeon in Algeria, discovered in 1880 the presence of a parasite in the blood of a malarial infected person (20). Around the same time, Patrick Manson, an English army surgeon, discovered that the presence of a small worm, the Filaria sanguinis hominis, was introduced to the human body by the bite of a mosquito. Manson’s work, published in 1898 in Tropical Diseases: A Manual for the Diseases of Warm Climates, was the first scientific evidence that an infectious agent could be transmitted to the human host via an arthropod (20). Building on these findings, Sir Ronald Ross, a medical officer of the English Army, discovered the presence of a malaria parasite in anopheles mosquitoes after the mosquito bit a malarial infected human. He then discovered that these mosquitoes could transmit the malarial parasite into a human, by injecting its “fatal saliva” when biting (6). And ultimately, in 1901, Walter Reed, Surgeon in the US Army, announced that the yellow fever parasite was introduced to the human blood by the bite of an infected stegomyia fasciata mosquito (8).

A turning point in the field of parasitology and tropical sanitation occurred during the Spanish-American War. When the US took possession of Cuba in 1898, an outbreak of yellow fever occurred in Havana, resulting in approximately 1,600 cases and 231 fatalities among US officers (1). Yellow fever became the primary concern of American doctors, but the filth theory of disease was accepted among experts while the mosquito vector theory was still debatable. As sanitation plans to clean up the city and improve its general sanitary conditions failed to eradicate yellow fever (7), Walter Reed, US Army Surgeon, and James Carroll began an investigation of sanitary conditions in Cuba with the US Army Yellow Fever Commission (20). Havana in 1900 presented an exceptional place to study yellow fever; the disease had been endemic to the city since 1762 and during that time had been a major cause of death. In 1881, Carlos Finlay, a prominent physician in Havana, had deduced the transmission theory of yellow fever via the stegomyia although he was unable to prove it experimentally (20). Eager to learn more about the disease that was devastating their troops, the American Medical Board in Havana, took Finlay’s mosquito vector hypothesis seriously (20). The Medical Board conducted a number of yellow fever experiments from June 1900 to February 1901 (1). Through these meticulous experiments, Reed and his Medical Board announced their discovery: the yellow fever parasite enters human blood by the bite of an infected female stegomyia fasciata mosquito (8).

Walter Reed and his head sanitary commissioner, William Gorgas, quickly incorporated this new discovery into a groundbreaking campaign: officials shifted their efforts away from ineffective public health measures of city cleanup based upon the filth theory of disease and its miasmatic transmission (7). Gorgas and his team revolutionized the attack on yellow fever by focusing their efforts on fighting infected mosquitoes. Following this paradigm shift, their team successfully eradicated yellow fever from Havana within three months (7).

Although discoveries such as the germ theory of disease and the mosquito vector theory have come to be seen as revolutionary, by challenging strongly established theories, they were not easily or immediately accepted in the social landscape. When canal construction began in 1904, the mosquito vector theory was so new that its role in tropical medicine remained unclear to both public health workers and the American workforce. President Roosevelt, however, recognized the importance of this new scientific discovery in Cuba and appointed the leading expert in tropical sanitation, William Gorgas, to lead sanitation efforts during canal construction. Gorgas became chief sanitary officer of the First Isthmian Canal Commission in April 1904, and sanitary organization of the Canal Zone began in June upon his arrival to the Isthmus (9).

The US government immediately provided Gorgas with the support he needed to consult the Panamanian government and control local sanitary provisions. The US negotiated a treaty with Panama to verify the compliance of the terminal cities located outside of the Canal Zone, Panama City and Colon, to US sanitary efforts. Therefore, Gorgas’ Sanitation Department had jurisdiction over all work related to health in the Canal Zone, including hospitals, quarantine, street cleaning, and garbage collection. But as cases of yellow fever began to plague the isthmus, disease control became the primary focus of Gorgas’ initial work.

Yellow Fever History in Panama and Disease Transmission

To understand and appreciate the impact of yellow fever on the canal project, we must briefly discuss the disease and its history in Panama. As Walter Reed proved in his experiments in Cuba, yellow fever is transmitted by the bite of an infected female stegomyia mosquito. The stegomyia bites a person who recently contracted yellow fever and twelve days later, becomes infected itself (10). When an infected stegomyia bites another victim, this person will contract the disease six days later. Yellow fever quickly reaches its peak, generally lasting for a few days (10). Jaundice and vomiting blood, a sign of internal hemorrhaging, typify severe cases of yellow fever (11). Milder symptoms, including headache, albuminuria, and fever, accompany less severe cases (11).

Many elements affect the presence of yellow fever in a tropical region and its behavior. The size of the native community, population of non-immune foreigners, geographical features, water supply, sewage system, and urban architectural design all influenced whether the disease was endemic or epidemic. (12). Panama specifically endured a long history of several major yellow fever epidemics because of its unique geographical position between North and South America. Similar to the American soldiers’ experience in Havana, while the native population on the Isthmus developed immunity to the deadly disease, the foreign visitor to this tropical land became its victim. Over a 400-year period, outbreaks of yellow fever epidemics followed the arrival of large congregations of non-immune foreigners on the Isthmus. Several major epidemics of yellow fever occurred throughout Panamanian history: the commerce trade of the Inca and Aztec Empires from the 16th to 19th Centuries, the California gold rush in 1849 whereby immigrants traveled to California via the Isthmus, construction of the Panama railroad in 1855, and especially the French building of the Canal in 1881 (8). Similarly, the arrival of Americans in 1904 created ideal conditions for another epidemic. Although malaria, Chagres fever, and other tropical diseases continued to plague Panama in 1904, yellow fever posed the biggest threat to Canal construction because it evoked the most fear among American employees. Malaria, which does not confer immunity, was endemic to Panama by the early 20th Century, and many Panamians suffered from the disease. However, prior to the arrival of the non-immune Americans in 1904, yellow fever was not endemic and far less prevalent because the natives enjoyed immunity to the disease. Many US employees considered malaria to be an accepted aspect of daily life in the tropics despite its much higher prevalence and lower mortality rate compared to yellow fever. Interestingly, during the period of the yellow fever epidemic, twice as many American mortalities occurred from malaria than from yellow fever: the Sanitation Department reported 108 Canal employee deaths from malaria and 47 Canal employee deaths from yellow fever. Gorgas himself became infected with malaria within one month of his arrival to the Isthmus. Even still, yellow fever posed the biggest threat to US canal construction because, with its harsh and unrelenting symptoms, it disrupted daily routines and created a crisis of overwhelming fear among Canal employees.

The Yellow Fever Outbreak

On November 21, 1904, only six months after the Americans first arrived on the Isthmus, an Italian man was admitted to the San Tomas Hospital with a suspected case of yellow fever (12). With only a few scattered cases of yellow fever among non-canal employees during this time, initially there was a lack of concern with the disease. By January 1905, however, the number of cases increased significantly and sentiments changed. Panama Star And Herald, officially recognized the outbreak on January 30, report aboard ship on the US cruiser Boston, anchored in Panama Bay. Although there was only one fatality, the ship’s doctor, and the cruiser continued northward, the story leaked: “Yellow Jack in Panama” (3).

Yellow fever cases began to rise over the following months. The epidemic reached its peak in June 1905 with the greatest number of cases and fatalities on the Isthmus, 62 and 19, respectively (Graph 1). The overwhelming majority of yellow fever cases occurred in the terminal cities of Panama City and Colon (Graph 2). The total number of cases during the epidemic was 246, and the total number of fatalities was 84 (13).

Following the death of several prominent canal officials in April 1905, the isthmus erupted into chaos. An epidemic of fear ensued, catalyzing the flight of nearly three quarters of the US workforce (3). Chief Engineer Wallace resigned his position, and Canal excavation efforts came to a halt. This period in the spring of 1905, which represented a time of turmoil for both construction and workforce morale in response to peak yellow fever cases, became known as the Great Scare (14).

The ideal of American imperialism in relation to race and health played a role in the attitude toward sanitation and disease on the Isthmus during this time. Some American officials believed that a sense of American imperial pride triumphed over the crisis; there were no grave tropical living problems that a “clean, healthy, moral American” could not readily solve (3). This idea of the “moral American” was consistent with the turn-of-the-century notions of Social Darwinism and American nationalist pride. A nurse in Panama City fled home to New York after a year of service on the isthmus. She reported that yellow fever was claiming the lives of all different kinds of people: “Some of the finest young men who have gone to the Isthmus since I have been there have died of it, and they were well set-up, clean boys with good principles” (3). Yellow fever could hit anybody—regardless of color or race or morals—and the lack of social boundaries evoked great fear among the Americans.

Back on American soil, US newspapers played up the notion of Panama as an exotic and mysterious tropical place, printing “alarmist stories” about the surging yellow fever epidemic. The New York Tribune published stories of more than a dozen “dead trains” that made daily visits to the cemetery to accommodate the great numbers of yellow fever fatalities (16). As an imperial undertaking in a tropical region, the building of the Panama Canal was a sensationalist adventure, and as such, reports about Americans living in a mysterious tropical climate lured on curious readers.

On Panamanian soil, however, the Panama Star and Herald served as an informative voice for the yellow fever epidemic and health conditions on the isthmus during the Great Scare. Published in both Spanish and English for Panamanian residents, this publication reported regular yellow-fever statistics including a list of all new cases and obituaries (3). Without the motivation to paint Panama as an exotic and mysterious location, the local newspapers served as a more grounded source to disseminate information among native and non-native residents of Panama (15). The Panama Star and Herald claimed that men with distorted notions of the tropics as a place of laid-back work adorned with “silken hammocks” and “goo-goo eyed senoritas,” returned to the US with “fantastically overdrawn if not radically and essentially untrue” stories of the US newspapers (15).

Despite differences in newspaper depictions of the situation, the Sanitation Department knew that a serious public health concern was at hand: that they needed to act quickly to not only limit disease morbidity but also secure the US workforce in Panama. In a 1907 Journal of the American Medical Association article, Gorgas stated: “we could readily see that if the conditions as they existed in 1905 were to continue, the canal would never be finished” (17).

The Anti-Yellow Fever Campaign

The US government’s supply of manpower, sufficient sanitary equipment, and money coupled with the Sanitation Department’s steady regulation of preventative measures allowed Gorgas to implement his campaign successfully. The arrival of Chief Engineer John Stevens in July 1905 also marked a major turning point for Gorgas: Stevens mandated that sanitation efforts take priority over all US efforts, including excavation work (18). During the first year of construction, Gorgas had been limited to an annual budget of $50,000 for all expenses. In the wake of the yellow fever epidemic, Stevens ordered $90,000 worth of requisitions for wire screening (3), and $50,000 worth of supplies accompanied by a group of sanitation workers (9). In the spring of 1905, backed with these resources, Gorgas found himself in charge of the most expensive, concentrated public health campaign in history (3).

Gorgas’ initial efforts were two-fold: isolate yellow fever patients and attack the infected mosquito via fumigation and screening. To enforce sanitary provisions efficiently, he divided the Canal Zone into 25 sanitary districts, each under the control of one inspector. Sanitation workers carried out house-by-house fumigations and medical inspectors made daily house inspections. The Sanitation Department conducted interviews to identify places of infection, tracking each suspected yellow fever case meticulously. When a possible place of infection was identified, sanitation workers began thorough fumigation, including fumigation of adjacent houses and buildings (12). In addition, suspected yellow fever patients were transported to the hospital. If patients were left in their homes, the windows of their houses were carefully screened with fine-meshed copper gauze (10). At the hospital, nurses isolated patients in yellow fever wards where hospital beds lay under large screened cages (9). Within the hospital system, strict policies allowed for both treatment of yellow fever and prevention of disease transmission. No known cases of transmission occurred on hospital grounds (9). For not a single case to occur in this highly vulnerable locale was a demonstration of the efficiency and success of the Sanitation Department’s general approach to yellow fever eradication.

With yellow fever cases rising in the urban settings, Gorgas decided to expand his fumigation efforts from individual locations to citywide coverage. He ordered a fumigation brigade to operate daily, house-by-house, block by block, until the entire city had been fumigated. Workers fumigated every block each time a reported yellow fever case occurred on that city block (17). The Sanitation Department used a large quantity of fumigation materials, including approximately 200,000 pounds of pyrethrum and 400,000 pounds of sulphur (17). Despite these efforts, large-scale fumigation was insufficient to eradicate all mosquitoes in the area, and Gorgas realized that he needed to mount a simultaneous attack on mosquito breeding places.

In relation to the yellow fever epidemic, the most significant characteristic of the stegomyia’s behavior was its attraction to water for the purpose of breeding. Panama’s nine month rainy season created numerous pools of stagnant fresh water, ideal stegomyia breeding grounds (1). In the remaining three months of the year, water barrels and cisterns in the cities collected rainwater (19). Here, within pools of stagnant water, stegomyia mosquito proliferated. Sanitation officials thus set out to destroy or modify such containers. They made mosquito-proof water barrels by fastening “muslin or sacking” (This can be paraphrased, not quoted) securely over the top of the barrel and creating a one-inch overflow hole six inches below the top. Water then flowed through a metal or wood faucet (12). Eventually, Gorgas replaced the water tanks, barrels, and cisterns with and sewerage systems (12).

This approach shifted the focus from attacking the adult infected mosquito to striking the mosquito’s urban breeding place. Gorgas recalled that “[when] we left Cuba after the disappearance of yellow fever, we were inclined to think that the results had been obtained principally by the destruction of the infected Stegomyia, but further experience at Panama has convinced me that the important element is the destruction of the Stegomyia generally” (17). It was not until Gorgas’ practical experience in Panama that he saw that the essential coupling of fumigating urban dwellings and attacking mosquito breeding places. Due to these rigorous efforts, the last case of yellow fever on the isthmus occurred in December 1905—and even it was not fatal (13). The isthmus enjoyed an environment free from yellow fever during the remaining eight years of construction (9).


Gorgas and the Sanitation Department in Panama organized a systematic anti-yellow fever campaign from 1904 to 1906 that effectively eradicated disease, allowing US employees to live on the isthmus without fear of this tropical disease. The anti-yellow fever campaign was the first of its kind to employ such effective measures on a large scale and to display the benefits of scientific discovery with regard to tropical sanitation (1). Gorgas’ campaign was successful for two reasons: he drew upon the medical advances in disease transmission as well as his experience in Cuba, and a government dedicated to accomplishing its imperial project supported him. Ultimately, these efforts allowed for continued construction efforts among a large, non-immune foreign workforce.

An examination of the anti-yellow fever campaign in Panama provides several insightful lessons in the history of medicine and its relation to scientific development. The eradication of yellow fever allowed for the practical application of a scientific theory. In Cuba and Panama, doctors and scientists theorized and verified that mosquitoes, not infected humans or poisonous miasmas, transmitted yellow fever. This new approach to disease eradication, built upon scientific discovery, became a cornerstone for twentieth century tropical medicine. Gorgas’ sanitation efforts also catalyzed a fusion of imperialism and science: the US government invested in the health of its builders because they realized sanitation was essential to accomplishing the Canal project. As the historian of science and medicine, William Bynum, so succinctly stated: “Because imperial concerns were public, so was tropical medicine” (20). American pride rested on the completion of the canal. Thus, US imperialists saw the eradication of yellow fever as not only a massive campaign public health project but also an expansion of the American political sphere.

In 1914, the voyage of the first steamship through the Panama Canal, the S.S. Ancon, was a display of large-scale engineering success. The completion of this waterway connected two oceans physically, but the story of its construction combined technology, medical science, imperialism, and tropical sanitation in a tremendous step toward globalization.


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2. Mears JE. The Triumph of American Medicine in the Construction of the Panama Canal. Philadelphia: WM. J. Dornan; 1912.

3. McCullough D. The Path Between the Seas. New York: Simon & Schuster; 1997. p. 448-466.

4. Bennett IE. History of the Panama Canal: It’s Construction and Builders. Washington DC: Historical Publishing Company; 1915. p. 127.

5. Pepperman WL. Who Built the Panama Canal? New York: E.P. Dutton & Co.; 1915. p. 35-40.

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7. Shryock RH. The Development of Modern Medicine. Madison: University of Wisconsin Press; 1974. p. 289.

8. Gorgas WC. The Part Doctors Have Taken in the Construction of the Panama Canal. Texas State J of Med. 1913; July.

9. Gorgas WC. Sanitation in Panama. New York: D. Appleton and Co; 1915.

10. Cornish V. The Panama Canal and Its Makers. London: T. Fisher Unwin; 1909. p. 122-128.

11. Ward JS. Yellow Fever in Latin America: A Geographical Study. Liverpool: Centre for Latin-American Studies; 1972. p. 1.

12. Le Prince J and Orenstein AJ. Mosquito Control in Panama: The Eradication of Malaria and Yellow Fever in Cuba and Panama. New York: G.P. Putnam’s Sons; 1916. p. 272-318.

13. Isthmian Canal Commission U.S. Sanitation Department. Report of the Department of Sanitation of Isthmian Canal Commission, 1905. Washington DC; GPO, 1905. p. 5-6.

14. Slosson EE and Richardson G. Life on the Canal Zone. The Independent. 22 March 1906. p. 653

15. Wild Tales From Panama. Panama Star and Herald. 31 July 1905.

16. Fighting Yellow Fever. New York Tribune. 6 July 1905.

17. Gorgas WC. Sanitation in the Canal Zone. JAMA. 1907; 49(1): 6-8.

18. Stevens. The Truth of History. In Bennett IE. History of the Panama Canal. Washington, DC: Historical Publishing Co; 1915. p. 210.

19. Wallace. Building the Foundations. In Bennett IE. History of the Panama Canal. Washington, DC: Historical Publishing Co; 1915. p. 240.

20. Bynum WF. Science and the Practice of medicine in the Nineteenth Century. Cambridge: Cambridge University Press; 1994. p. 151.

Alexandra (Jana) Freeman is a 2nd year medical student at the George Washington University of Medicine and Health Sciences. She attended a post-baccalaureate pre-medical program at Johns Hopkins University after receiving a BA in the history of science and medicine at Yale College in 2005 where she focused her studies on the history of epidemics and tropical medicine during the 19th and 20th centuries. For comments please please contact:


Historia Medicinae Editor,
Aug 17, 2011, 8:58 PM