Infectious diseases

Infectious diseases: Columbian Exchange

Infectious diseases: Epidemics During the Age of Sail

Infectious diseases: Public Health and Anti-Immigrant Sentiment

Infectious diseases: Modern Health Threats

Definition: Communicable human diseases caused by pathogenic microorganisms

Significance: During North America’s colonial era, immigrants from Europe and Africa imported many contagious diseases that wreaked havoc on not only Native American populations but also nonimmunized colonists. Successive waves of disease-carrying immigrants during the nineteenth century set off epidemics ranging from cholera to plague, despite ever more effective public health measures, and encountered effective anti-immigrant sentiment and action. During the early twenty-first century, visitors as well as immigrants posed threats to U.S. public health as carriers of new diseases and new strains of old diseases.

Every person and every community lives in an environment filled with bacteria, viruses, fungi, and parasites, many of which carry pathogens potentially lethal to humans. People who live for many years in the same area and with the same neighbors develop effective immune system defenses against the commonly occurring pathogens. Sometimes they pass their immunity along to subsequent generations genetically. When a new pathogen is inserted into a community by changes in the environment or the intrusion of new people, the effects may be devastating, as existing members of the community may have limited or no developed biological defenses. Unlike noninfectious diseases such as diabetes or cancer, an infectious disease can be passed among members of a community by the actions of carriers of pathogens. These carriers might include tainted foods or water; insects, parasites, and their droppings; and infected people. During the centuries before germ theory made modern medicine an effective counter to most infectious diseases, there was little understanding of pathogens and carriers, and little that any human community could do to defend against them.

Joseph P. Byrne

Further Reading

• Apostolopoulos, Yiorgos, and Sevil Sönmez, eds. Population Mobility and Infectious Disease. New York: Springer, 2007. Collection of analytical articles on the variety of forms of population movement and the roles they have played in the spread of disease in the early twenty-first century. 
• Duffy, John. Epidemics in Colonial America. Baton Rouge: Louisiana State University Press, 1953. Older book that remains the standard text on the causes, courses, and effects of epidemic disease in Britain’s North American colonies. 
• Grob, Gerald N. The Deadly Truth: A History of Disease in America. Cambridge, Mass.: Harvard University Press, 2002. Broad overview that goes beyond imported disease and effects of disease on immigrants to chronic and occupational problems from the colonial era to the end of the twentieth century. 
• Markel, Howard. Quarantine! East European Jewish Immigrants and the New York Epidemics of 1892. Baltimore: Johns Hopkins University Press, 1997. Study of the role of Jewish immigrants in the outbreaks of cholera and typhus, the ethnically based initial responses, and the role of the events in the passage of the 1893 screening and quarantine act. 
• _______. When Germs Travel: Six Major Epidemics That Have Invaded America Since 1900 and the Fears They Have Unleashed. New York: Pantheon Books, 2004. Chronicle of the historical outbreaks of tuberculosis, plague, typhus, cholera, HIV/AIDS, and trachoma in a very readable set of analytical narratives. 
• Shah, Nayan. Contagious Divides: Epidemics and Race in San Francisco’s Chinatown. Berkeley: University of California Press, 2001. Study of San Francisco’s large Chinese community that emphasizes the city’s bubonic plague outbreaks and the roles of and influences on popular attitudes toward Asian immigrants. 

See also: Acquired immunodeficiency syndrome; African immigrants; Ellis Island; Eugenics movement; Globalization; Great Irish Famine; Haitian boat people; Health care; Smuggling of immigrants; Sweatshops; Transportation of immigrants; “Undesirable aliens”; World migration patterns.