Infectious diseases

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.Infectious
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Columbian Exchange

The early history of European and African settlement in the Western Hemisphere provides a depressingly long list of epidemics and pandemics. Many of these occurred on a large geographical scale, sparked by the contact of Native Americans;and infectious diseases[infectious diseases]Native American communities with immigrant men and women who carried deadly pathogens to which the carriers themselves were immune or highly resistant. In turn, these intruders were susceptible to Native American diseases, one example of which may have been Syphilissyphilis. It seems that some infected Spanish explorers contracted that Sexually transmitted diseasessexually transmitted disease (STD) and spread it after their return to Europe. For their part, Native Americans died by the thousands of imported Old World diseases such as Measlesmeasles, mumps, Smallpoxsmallpox, Typhustyphus, and influenza. This biological interaction is sometimes referred to as part of the “Columbian Exchange,” taking its name from the Italian explorer
Christopher Columbus.

Although early immigrants from Europe and Africa tended to share resistance to a wide range of pathogens, later generations, long removed from their homelands and isolated from certain diseases in the New World, tended to lose their natural defenses to the Old World diseases. When new immigrants arrived from the Old World, even from the same cities and regions as the ancestors of second- or third-generation colonists or slaves, their reinfusion of disease-causing pathogens could and often did trigger outbreaks–even epidemics–among the settled immigrants populations. Perhaps ironically, however, this was least likely to occur in large cities such as New York, Boston, and Philadelphia, in which steady streams of new immigrants kept levels of exposure and resistance relatively high among the urban populations.

Some imported diseases, such as mosquito-borne Malariamalaria and Yellow feveryellow fever, were initially and inadvertently inserted into humid coastal environments in the New World that were well suited to the insects by Spanish slavers and their human cargoes. While the African immigrants;infectious diseasesAfrican immigrant populations were generally resistant to the potentially deadly diseases, both Native Americans and Europeans proved to be highly susceptible. The insects became carriers when they sucked the blood of human carriers. In regions where human carriers diminished in number, as along the northern Atlantic coastline (thanks in part to the practice of quarantine), the incidence of the disease dropped off. Fresh arrivals of African or Caribbean slaves along the southern U.S. coasts, however, helped maintain high incidence levels. Even before Walter Reed and other researchers untangled the true nature of yellow fever during the early twentieth century, Americans sought strict limitations on immigrants and even trade from Cuba and other island sources of the disease whose carriers set off recurrent outbreaks.

Epidemics During the Age of Sail

Traditional Western medicine had long associated disease with filth, a lack of basic hygiene, and, by the later eighteenth century, poverty. From the 1820’s, ships from Europe brought trickles and then floods of immigrants from Ireland and central Europe. Many of these people were both poverty-stricken and sick with opportunistic diseases such as Typhustyphus, Influenzainfluenza, and Typhoid fevertyphoid fever. Cramped and unsanitary quarters, lack of clean clothing, and poor nutrition shipboard exacerbated weak constitutions and undermined the healthy. Rightly fearful of the spread of infectious diseases, civic and state authorities in North America maintained quarantines and isolation facilities at major ports for sick or suspect passengers. Although a single case of influenza might be gotten over with no lasting effects, chronic conditions such as STDs and LeprosyHansen’s disease[Hansens disease]Hansen’s disease (leprosy) presented almost no possibilities of cure. Those who suffered from such maladies would be turned away, to find refuge elsewhere. They might then
attempt to enter the country illicitly or simply return to their homelands.

Even due diligence could fail, especially with emerging diseases. CholeraCholera had first broken out of its homeland in eastern India in 1817, but America was spared the ensuing first pandemic. The second pandemic proved less accommodating, and Irish immigrants;infectious diseasesIrish immigrants brought the waterborne disease with them to Canadian and U.S. port cities in 1832. New York City;epidemicsNew York City lost 3,000 residents in July and August, and New OrleansNew Orleans;epidemics suffered 4,340 fatalities during three weeks in October. Eventually spreading to the Frontier;and disease[disease]western frontier, cholera killed an estimated 150,000 people in North America between 1832 and 1849. The year 1866 saw the final epidemic of cholera in the United States, when eastern and Gulf port cities counted 50,000 deaths.

The popular conception of Roman Catholic Irish immigrants as lazy, poor, and disease-ridden was reinforced by the huge numbers of penniless refugees who appeared as the Great Irish Famine;and disease[disease]potato famine (1845-1852) ravaged their homeland. A British government report in 1856 noted that malnutrition and starvation among the Irish were accompanied by many other medical conditions, including infectious diseases: “fever, Scurvyscurvy, diarrhea and Dysenterydysentery, cholera, Influenzainfluenza and ophthalmia.” Despite the availability of vaccines, Smallpoxsmallpox “prevailed epidemically,” and Typhustyphus was nearly endemic in crowded Irish cities. Each year, hundreds of thousands of Irish died and one-quarter million Irish emigrated. Although British port authorities were supposed to screen out emigrants carrying diseases before they departed, this task was often left to American officials. As a result, many emigrants died on ships, earning the passenger vessels the nickname
“Coffin ships”[coffin ships]“coffin ships.” Despite screening and quarantine procedures, many disease carriers still managed to enter the United States, and many of them settled in already overcrowded and unsanitary Ethnic enclaves;and infectious diseases[infectious diseases]ethnic enclaves in American cities, inducing outbreaks as well as increased public health structures and efforts to combat the increasingly complex disease regimes.

Public Health and Anti-Immigrant Sentiment

The fact that a significant percentage of immigrants were Roman Catholic and, to a growing extent, Jewish, as well as poor and suffering from diseases, fed the fears and prejudices of Nativism;and public health[public health]nativist and other anti-immigrant groups. During the last decades of the nineteenth and first decades of the twentieth centuries, groups such as the Immigration Restriction LeagueImmigration Restriction League harnessed the ideas of new medical pseudosciences in their attempts to limit the diversity of immigrants. They blamed the perceived prevalence of certain diseases among eastern and central European immigrants, especially Typhustyphus and Tuberculosistuberculosis (TB), on natural genetic dispositions.

U.S. Health Service officers inspect Japanese immigrants as they arrive on the West Coast of the United States in the early 1920’s.


Tuberculosis was once widely considered to be a genteel or sensitive person’s disease. However, as it spread among the working classes in large U.S. cities, it became associated with poverty, squalor, and ethnic minorities, and sufferers were rounded up for isolation. A major outbreak in 1892 in New York City led to passage of the [a]National Quarantine Act of 1893National Quarantine Act of 1893. San Francisco;plague outbreakSan Francisco’s Plaguebubonic plague outbreak in 1900-1901 was very likely sparked by stowaways aboard a visiting Japanese freighter. However, its first known fatality was a Chinese immigrant who lived in a very poor Chinese neighborhood. Residents of Ethnic enclaves;and infectious diseases[infectious diseases]Chinatown, fearing both mobs and the government, hid subsequent cases of plague until the outbreak could no longer be concealed. Anti-Chinese sentiment then flashed across the city, and there were calls to eradicate the Asian American neighborhood. Cooler heads prevailed, however, and modern antiplague measures kept the number of fatalities to only 122.

The popular linkage of disease and immigrants remained a major factor in U.S. public policy. Along the Mexican immigrants;infectious diseasesU.S.-Mexican border, perfunctory visual inspections for obvious signs of diseases were replaced by mandatory flea-dip baths for large numbers of very poor laborers and immigrants who sought work or refuge from the dislocations of the Mexican RevolutionMexican Revolution after 1917. The worldwide Influenza;pandemicinfluenza pandemic that followed World War I[World War 01];influenza pandemicWorld War I may have killed more than 40 million people, including 675,000 Americans–a fatality rate that was five times the annual average for that disease. Like the war itself, the pandemic underlined the metaphorical shrinkage of the world and the increasing immediacy of threats that included disease. This sentiment resulted in the federal immigration restriction acts of 1921 and 1924.

Modern Health Threats

Twentieth century science and technology complicated ideas about the relationship between immigrants and infectious diseases. Medical researchers have found cures or effective treatments for a wide variety of potentially deadly diseases. While Americans generally have access to these, many are beyond the reach of potential immigrants. At the same time, jet aircraft have made intercontinental travel swift and relatively cheap. Visitors and U.S. travelers abroad, as well as immigrants, can and do enter America as carriers of a wide variety of pathogens.

Those Illegal immigration;and infectious diseases[infectious diseases]who enter a country illicitly, or choose to remain undocumented, often avoid public health screening and surveillance officials who might identify them as carriers and treat their conditions. Instead, such individuals threaten members of the communities in which they settle. By the end of the twentieth century, Tuberculosistuberculosis was making an alarming resurgence across the globe, especially in developing countries in Asia and Africa. The United States has one of the world’s lowest levels of incidence of the disease, but neighboring Mexican immigrants;infectious diseasesMexico’s rate is ten times higher. TB presents a problem that is being echoed by other diseases: the natural evolution of drug-resistant varieties that threaten to make the American pharmaceutical arsenal obsolete.

Sexually Sexually transmitted diseasestransmitted diseases, including Acquired immunodeficiency syndromeHIV/AIDS, can be treated, but immigrant communities are often resistant to public health measures. The worldwide spread of HIV/AIDS means that immigrants from Africa or Haiti are not alone suspect. The incidences of forms of hepatitis, Malariamalaria, dengue fever, and even Leprosyleprosy were on the rise across the United States during the early twenty-first century, with health practitioners often noting the prevalence of the foreign-born among their victims. Since many modern-day immigrants find work in agricultural and food preparation and service sectors, the possibilities are good for spreading diseases beyond local communities. The failure effectively to screen those who cross America’s borders also opens the door for incidences of Bioterrorismbioterrorism, as it raises the potential for other types of terrorism as well.Infectious diseases

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.

Acquired immunodeficiency syndrome

African immigrants

Ellis Island

Eugenics movement


Great Irish Famine

Haitian boat people

Health care

Smuggling of immigrants


Transportation of immigrants

“Undesirable aliens”

World migration patterns