Arthur Conan Doyle (1859-1930): Physician during the typhoid epidemic in the Anglo-Boer War (1899-1902).

When the Anglo-Boer War broke out in October 1899, Arthur Conan Doyle, a retired ophthalmologist, was already famous as the creator of Sherlock Holmes. Motivated by patriotism and adventure, Doyle joined the medical staff of a private field hospital endowed by philanthropist John Langman (1846-1928). Langman Hospital opened in Bloemfontein, South Africa, at the height of that city's typhoid fever epidemic which raged from April to June 1900. There were nearly 5000 cases of typhoid and 1000 deaths but official statistics do not truly reflect the magnitude of the suffering. Doyle argued that the British Army had made a major mistake by not making antityphoid inoculation compulsory. Because of the new vaccine's side effects, 95% of the soldiers refused immunization. Despite his strong opinions, Doyle failed to press the issue of compulsory inoculation when he testified before two Royal Commissions investigating the medical and military management of the war in South Africa. One can only imagine how the army might have benefited from the new idea of prophylactic vaccination in preventive medicine if Doyle had not let these opportunities slip away. As a consequence, antityphoid inoculation was still voluntary when Great Britain entered World War I in August 1914.

"Wonders unconceived": reflections on the birth of medical entomology.

Prior to Patrick Manson's discovery in 1877 that the mosquito Culex fatigans was the intermediate host of filariasis, the association of insects with disease and the nature of disease transmission was almost entirely speculation. Manson's work was incomplete, however, because it showed the manner in which the mosquito acquired the infection from humans, but failed to show the way in which the mosquito passed the infection to humans. That pathogens were transmitted by the bite of an infected female mosquito was later proven experimentally with bird malaria by Manson's protégé, Ronald Ross. In 1898 Ross demonstrated that the infective stage of the malarial parasite was injected into the host when the mosquito released saliva into the wound prior to injesting blood. Insects were suspected as carriers of disease for centuries, yet it was not until the late 1870s that the uncritical acceptance of folk beliefs was supplanted by research-based scientific medicine. Why did it take so long? The answer lies in the fact that early medicine itself was imprecise and could not have pursued the subject with any hope of useful results until the last quarter of the 19th century. A better understanding of the nature of the disease process (germ theory of disease) and improved technology (microscopes and oil-immersion lenses with greater resolving power, and synthetic tissue stains) were indispensable for revealing the nexus between those partners in crime: insects and parasites.

"More fatal than powder and shot": dysentery in the U.S. Army during the Mexican War, 1846-48.

In terms of deaths due to disease, the Mexican War (1846-48) was the deadliest of all American wars. Nearly 13% of the entire U.S. force perished from disease. Of the total 12,535 war deaths, 10,986 (88%) were due to infectious diseases (overwhelmingly dysentery, both bacterial and amoebic); seven men died from disease for every man killed by Mexican musket balls. Camp pollution was the greatest error committed by U.S. troops in the Mexican War. The indifference of line officers and recruits to the need for proper sanitation and military hygiene fueled the dysentery outbreaks, and the poor conditions in military hospitals contributed further to the spread of disease. This defect in military culture undermined the health of the army and led to medical disaster. Disease caused an enormous drain on the U.S. Army's resources, eroded troop morale, and influenced strategy and tactics. As we enter the 21st century, dysentery is still a major public health threat, killing hundreds of thousands of people annually-primarily children in developing countries where personal hygiene is poor and disposal of human and animal wastes is indiscriminate.

Two faces of death: fatalities from disease and combat in America's principal wars, 1775 to present.

Throughout America's first 145 years of war, far more of the country's military personnel perished from infectious diseases than from enemy action. This enduring feature of war was finally reversed in World War II, chiefly as a result of major medical advances in prevention (vaccines) and treatment (antibiotics). Safeguarding the health of a command is indispensable for the success of any campaign. Wars are lost by disease, which causes an enormous drain on the military's resources and affects both strategy and tactics. Disease and combat mortality data from America's principal wars (1775-present) fall into two clearly defined time periods: the Disease Era (1775-1918), during which infectious diseases were the major killer of America's armed forces, and the Trauma Era (1941-present), in which combat-related fatalities predominated. The trend established in World War II continues to the present day. Although there are currently more than 3,400 U.S. military fatalities in Iraq, the disease-death toll is so low that it is exceeded by the number of suicides.

"Winged sponges": houseflies as carriers of typhoid fever in 19th- and early 20th-century military camps.

Typhoid fever was the scourge of 19th- and early 20th-century armies. During the Spanish-American War (1898) and the Anglo-Boer War (1899- 1902), typhoid killed more soldiers than enemy bullets. Walter Reed and his coworkers investigated the cause of the typhoid epidemics in the U.S. Army camps and concluded that, next to human contact, the housefly (Musca domestica) was the most active agent in the spread of the disease. British medical officers in South Africa, facing even worse typhoid epidemics, reached the same conclusion. The experiences of the American and British armies finally convinced the medical profession and public health authorities that these insects conveyed typhoid. The housefly was now seen as a health menace. Military and civilian sanitarians waged fly-eradication campaigns that prevented the housefly's access to breeding places (especially human excrement), and that protected food and drink from contamination. Currently, M. domestica is recognized as the mechanical vector of a wide variety of viral, bacterial, and protozoal pathogens. Fly control is still an important public health measure in the 21st century, especially in developing countries.