The history ofNative American disease and epidemics is fundamentally composed of two elements: indigenous diseases and those brought by settlers to theAmericas from theOld World (Africa, Asia, and Europe), which transmitted far beyond the initial points of contact, such as trade networks, warfare, and enslavement.
The contacts duringEuropean colonization of the Americas were blamed as the catalyst for the huge spread of Old World plagues that decimated the indigenous population.[1]
Because Native American populations had not previously been exposed to most of these pathogens, they suffered extremely high mortality rates that severely disrupted Native American societies. This phenomenon is known as thevirgin soil effect.[2]
Although a variety ofinfectious diseases existed in the Americas inpre-Columbian times,[3] the limited size of the populations,smaller number of domesticated animals withzoonotic diseases, and limited interactions between those populations (as compared to areas ofEurasia andAfrica) hampered the transmission of communicable diseases.[3]
Most Old World diseases of known origin can be traced to Africa andAsia and were introduced to Europe over time.Smallpox originated in Africa or Asia,[4]plague in Asia,[5][6]cholera in Asia,[7][8]influenza in Asia,[9][10]malaria in Africa and Asia,[11][12][13]measles from Asianrinderpest,[14][15][16]tuberculosis in Asia,[17][18]yellow fever in Africa,[19]typhoid in Africa,[20]herpes in Africa,[21]zika in Africa.[22] Furthermore, a form of tuberculosis has also been identified in pre-Columbian populations, by bacterialgenome sequences collected from human remains in Peru, and was probably transmitted to humans throughseal hunting.[23]
One notable infectious disease that may be of American origin issyphilis,[3] which originated in the Americas before 1492.[24][25] However, another journal titledHistory of Syphilis recorded that this disease was also originated from Africa.[26]
Another epidemic disease which believed by modern era experts to be indigenous wasCocoliztli epidemics, which suspected being caused by climate change.[27][28]Cocoliztli epidemics usually occurred within two years of a major drought. The epidemic in 1576 occurred after a drought stretching fromVenezuela toCanada.[29] Proponents of this epidemics outbreak suggest the relationship between drought and outbreak which reflected by the increased numbers ofrodents carryingviral hemorrhagic fever during the rains that followed the drought.[30] At least 12 epidemics are attributed tococoliztli, with the largest occurring in 1545, 1576, 1736, and 1813.[31] Sotoet al. have hypothesized that a sizeable hemorrhagic fever outbreak could have contributed to the earliercollapse of the Classic Mayan civilization (AD 750–950).[32] However, most experts believe other factors, including climate change, played a larger role.[33][34]
The only disease which the native Americans historically shown high immunity against wasScarlet fever.[35][36]
The arrival and settlement of Europeans in the Americas resulted in what is known as theColumbian exchange. Europeans also took plants and goods back to the Old World. Potatoes and tomatoes from the Americas became integral to European and Asian cuisines, for instance.[37]
But Europeans also unintentionally brought new infectious diseases, including among others smallpox, bubonic plague, chickenpox, cholera, the common cold, diphtheria, influenza, malaria, measles, scarlet fever, sexually transmitted diseases (with the possible exception ofsyphilis), typhoid, typhus, tuberculosis (although a form of this infection existed in South America prior to contact),[38] and pertussis.[39][40][41] Each of these resulted in sweeping epidemics among Native Americans, who had disability, illness, and a highmortality rate.[41] The Europeans infected with such diseases typically carried them in adormant state, were actively infected butasymptomatic, or had only mild symptoms, because Europe had been subject for centuries to a selective process by these diseases. The explorers and colonists often unknowingly passed the diseases to natives.[37] Historians agreed that when colonists settled for the very first time atJamestown, it was one of the coldest periods for the last 1000 years, while the area ofRoanoke suffered the largest drought of the past 800 years. The shortage of foods led the colonists to came into conflict with the indigenous population. Such conflicts and cold weather contributed much to the spread of diseases; as colder weather helped the parasite cells ofmalaria which carried by those European settler hosts, who further transmitted by local mosquitoes to develop faster. Those malaria spread into Native Americans, causing many deaths among them.[42]
The introduction ofAfrican slaves and the use of commercial trade routes also contributed to the spread of disease.[43][44] Waves of enslaved Africans were brought to replace the dwindling Indigenous populations, solidifying the position of disease intriangular trade.[45][46]
Since there were numerous outbreaks and all were not equally recorded, historical accounts of epidemics are often vague or contradictory in describing how victims were affected. A rash accompanied by a fever might be smallpox, measles, scarlet fever, orvaricella, and many epidemics overlapped with multiple infections striking the same population at once, therefore it is often impossible to know the exact causes of mortality (althoughancient DNA studies can often determine the presence of certain microbes).[47]Smallpox was the disease brought by Europeans that was most destructive to the Native Americans, both in terms ofmorbidity and mortality. The first well-documented smallpox epidemic in the Americas began inHispaniola in late 1518 and soon spread to Mexico.[37]
Native Americans initially believed that illness primarily resulted from being out of balance, in relation to their religious beliefs. Typically, Native Americans held that disease was caused by either a lack of magical protection, the intrusion of an object into the body by means ofsorcery, or the absence of the free soul from the body. Disease was understood to enter the body as a natural occurrence if a person was not protected by spirits, or less commonly as a result of malign human or supernatural intervention.[48] For examples,Cherokee spiritual beliefs attribute disease to revenge imposed by animals for killing them.[49] TheMapuche inAraucanía regarded the epidemic as a magic brought byFrancisco de Villagra to exterminate them because he could not defeat them in theArauco War.[50]
In some cases, disease was seen as a punishment for disregarding tribal traditions or disobeying tribal rituals.[51] Spiritual powers were called on to cure diseases through the practice ofshamanism.[52] Most Native American tribes also used a wide variety ofmedicinal plants and other substances in the treatment of disease.[53]
in Florida, Spanish settlers forced indigenous groups into strictly controlled settlements. Since the early 16th century, these people were exposed to new diseases brought by Europeans, including smallpox, measles and typhus. A mix of involuntarily relocations and European-imposed changes to agriculture and resolution patterns also created ideal conditions for the spread of infectious diseases, leading to catastrophic declines in the number of the population.[54]
The Trail of Tears was the forced relocation of Native American tribes in the 1830s fromEastern Woodlands to the west of theMississippi River.[55] This relocation ordered by the government primarily targeted "the Cherokee, Choctaw, Chickasaw, Creek, and Seminole" nations[55] Approximately 100,000 native Americans were removed from their families and 15,000 died during the removal and journey west.[55] The journey west consisted of 5,045 miles across nine states.[55] Many people lost their lives on this rigorous forced journey. Cholera was one of the reasons for the deaths of Native Americans during the Trail of Tears. Traveling by steamboat was a common way to travel and cholera was present in the waterways used by the steamboats.[56] It is estimated that 5,000 Native Americans died of cholera on this journey to areas west of the Mississippi.[55]
Many Native American tribes suffered high mortality and depopulation, averaging 25–50% of the tribes' members dead from disease. Additionally, some smaller tribes are threatened with extinction after facing a severely destructive spread of disease.[39]
Epidemics ofsmallpox (1518, 1521, 1525, 1558, 1589),typhus (1546),influenza (1558),diphtheria (1614) andmeasles (1618) swept the Americas subsequent to European contact,[57][58] killing between 10 million and 100 million[59] people, up to 95% of theindigenous population of the Americas.[60] Estimates of mortality range from one-quarter to one-half of the population of central Mexico.[61]
One of earliest examples was what followedCortés' invasion ofMexico. Before his arrival, the Mexican population is estimated to have been around 25 to 30 million. Fifty years later, the Mexican population was reduced to 3 million(one source stated lower number with only 1,5 million survivors left[62]), mainly by infectious disease. A 2018 study by Koch, Brierley, Maslin and Lewis concluded that an estimated "55 million indigenous people died following the European conquest of the Americas beginning in 1492."[63] Estimates for the entire number of human lives lost during theCocoliztli epidemics inNew Spain have ranged from 5 to 15 million people,[64] making it one of the most deadly disease outbreaks of all time.[65] By 1700, fewer than 5,000 Native Americans remained in the southeastern coastal region of the United States.[41] Even after the two largest empires of the America continent, theInca and the Aztecs, were devastated by the virus, smallpox continued to spread further In 1561; The epidemic reachedChile by sea, when a ship carrying the new governorFrancisco de Villagra landed atLa Serena. Chile had previously been isolated by theAtacama Desert andAndes Mountains from Peru, but at the end of 1561 and in early 1562, it ravaged the Chilean natives. Modern time estimates by experts put the number that the Chilean natives lost its 20-25 percent of their population. The Spanish historian Marmolejo said that gold mines had to shut down when all their native labors died.[66]
During theInca Civil War, it was estimated that the smallpox which transmitred by the Spaniard underFrancisco Pizarro killed at least 200,000.[67]
In Florida alone, an estimated 700,000 Native Americans lived there in 1520, but by 1700, the number decreased to only around 2,000 people.[41]
Another notable example was the incident of the so-calledThe Great Dying inNew England around the years of 1616-1619, where the epidemics which carried by European settlers including trichinosis, chickenpox, Influenza, HBD/HDV, Typhus, smallpox, plague, and leptospirosis, resulted in a catastrophic demographic collapse which estimated to of up to 95% casualties of the indigenous population.[68][69][70] ThePennacook, an Algonquian confederation in present-day New Hampshire, eastern Massachusetts, and southern Maine, included subgroups like the Naumkeag, Agawam, Wamesit, Nashua, and Souhegan; also afflicted by this so-called "Great Dying", which suspected as leptospirosis from European contact that spread along the Merrimack River.[71][72] Coastal subgroups, Naumkeag and Agawam, faced 80–90% mortality, their populations falling from 1,000–2,000 to ~100–200 and 500–1,500 to ~50–150, respectively.[46][73] Inland subgroups like Wamesit and Nashua saw 50–75% losses, reducing the confederation from 10,000–20,000 to under 2,000 by 1619.[74][75] The disaster disrupted Pennacook society, leaving villages deserted and easing later English colonization.[76] Archaeological evidence shows mass graves and abandoned sites.[77] During this period, outbreaks ofdiphtheria,dysentery and measles were also reported to have broken out within unspecified tribal group of native Americans.[78]
The population ofMohawk people also hit by smallpox epidemics around 1630s; causing their population to decrease by 63%, from 7,740 to 2,830, as they had noimmunity to the new disease.[79] At some point by 1633, smallpox infected the entire tribes and left the Mohawks unable to care for each other or bury their dead.[80]
In summer 1639, a smallpox epidemic struck theHuron natives in theSt. Lawrence andGreat Lakes regions. The disease had reached the Huron tribes through French colonial traders from Québec who remained in the region throughout the winter. When the epidemic was over, the Huron population had been reduced to roughly 9,000 people, about half of what it had been before 1634.[81] TheIroquois people, generally south of the Great Lakes, faced similar losses after encounters with French, Dutch and English colonists.[41]
During the 1770s, smallpox killed at least 30% (tens of thousands) of theNorthwestern Native Americans.[82][83]
Thesmallpox epidemic of 1780–1782 brought devastation and drastic depopulation among thePlains Indians, as the natives in the area contracted the disease from the 'Snake Indians' on theMississippi. From there it spread eastward and northward to theSaskatchewan River. Its first case was found among the fur traders in October 15, 1781.[84] A week later, reports were made to William Walker andWilliam Tomison, who were in charge of the Hudson and CumberlandHudson's Bay Company posts. By February, the disease spread as far as the Basquia Tribe.[85] After reading Tomison's journals, Houston and Houston calculated that, of the Indians who traded at the Hudson and Cumberland houses, 95% died of smallpox.[86] Paul Hackett adds to the mortality numbers suggesting that perhaps up to one-half to three-quarters of theOjibway situated west of the Grand Portage died from the disease. TheCree also suffered a casualty rate of approximately 75% with similar effects found in the Lowland Cree.[87]
By 1832, the federal government of the United States established asmallpox vaccination program for Native Americans.[88]TheCommissioner of Indian Affairs in 1839 reported on the casualties of the1837 Great Plains smallpox epidemic: "No attempt has been made to count the victims, nor is it possible to reckon them in any of these tribes with accuracy; it is believed that if [the number 17,200 for the upper Missouri River Indians] was doubled, the aggregate would not be too large for those who have fallen east of theRocky Mountains."[89]
Some 21st-century climate scientists have suggested that a severe reduction of the indigenous population in the Americas and the accompanying reduction in cultivated lands during the 16th, 17th and 18th centuries may have contributed to a global cooling event known as theLittle Ice Age.[63][90][91][92][93][94]
Theloss of population was so high that it was partially responsible for the myth of the Americas as "virgin wilderness". By the time significantEuropean colonization was underway, native populations had already been reduced by 90%. This resulted in settlements vanishing and cultivated fields being abandoned. Since forests were recovering, the colonists had an impression of a land that was an untamed wilderness.[95]
Disease had both direct and indirect effects on deaths. High mortality meant that there were fewer people to plant crops, hunt game, and otherwise support the group. Loss of cultural knowledge transfer also affected the community as vital agricultural and food-gathering skills were not passed on to survivors. Missing the right time to hunt or plant crops affected the food supply, thus further weakening the community and making it more vulnerable to the next epidemic. Communities under such crisis were often unable to care for people who were disabled, elderly, or young.[41]
The material and societal realities of disability for Native American communities were tangible.[41] Scarlet fever could result in blindness or deafness, and sometimes both.[41] Smallpox epidemics led to blindness anddepigmented scars. Many Native American tribes took pride in their own appearance, and the resulting skin disfigurement of smallpox deeply affected them psychologically. Unable to cope with this condition, tribe members were said to have committedsuicide.[96]
HistorianDavid Stannard asserts that by "focusing almost entirely on disease ... contemporary authors increasingly have created the impression that the eradication of those tens of millions of people was inadvertent—a sad, but both inevitable and 'unintended consequence' of human migration and progress." He says that their destruction "was neither inadvertent nor inevitable", but the result of microbial pestilence and purposeful genocide working in tandem.[97] HistorianAndrés Reséndez says that evidence suggests "among these human factors, slavery has emerged as a major killer" of theindigenous populations of the Caribbean between 1492 and 1550, rather than diseases such as smallpox, influenza and malaria.[98]The second European explanation was a perceived divine approval, in which God removed the Indigenous peoples as part of His "divine plan" to make way for a new Christian civilization.[99] In following centuries, accusations and discussions of biological warfare were common. Well-documented accounts of incidents involving both threats and acts of deliberate infection are very rare.[100][101]
Fur traderJames McDougall was quoted as threatening some local chiefs that he would use his water bottle infected with smallpox if they did not comply with his demands.[102] another fur trader threatenedPawnee Indians that if they didn't agree to certain conditions, he would use a bottle containing smallpox against their people. The ReverendIsaac McCoy was quoted in hisHistory of Baptist Indian Missions as saying that the settlers deliberately spread smallpox among the natives of the southwest, including the Pawnee tribe, which devastating result was made reported to General Clark and the Secretary of War.[102][103] Artist and writerGeorge Catlin observed that Native Americans were also suspicious of vaccination.[104] The Mandan chiefFour Bears even denounced some settlers whom he had previously treated as his own kins, under the accusation of deliberately bringing the disease to his people.[105][106][107]
A single soldier arriving in Mexico in 1520 was carrying smallpox and initiated the devastating plagues that swept through the native populations of the Americas.[108]
According to one source introduction of smallpox among the Aztecs has been attributed to an African slave named Francisco Eguía. However, this has been disputed by the record that from May to September, smallpox already spread slowly toTepeaca andTlaxcala, and to Tenochtitlán by the fall of 1520. At this time, Cortes was returning to conquer the city after his previous defeat in the battle ofNoche Triste.[109]
After its introduction to Mexico, the disease spread across South America, devastating indigenous populations in what are now Colombia, Peru and Chile during the sixteenth century. The disease was slow to spread northward due to the sparse population of the northern Mexico desert region. It was introduced to eastern North America separately by colonists arriving in 1633 toPlymouth, Massachusetts, and local Native American communities were soon struck by the virus. It reached theMohawk nation in 1634,[110] theLake Ontario area in 1636, and the lands of otherIroquois tribes by 1679.[111] Between 1613 and 1690 the Iroquois tribes living in Quebec suffered twenty-four epidemics, almost all of them caused by smallpox.[112] By 1698 the virus had crossed the Mississippi, causing an epidemic that nearly obliterated theQuapaw Indians of Arkansas.[51]
By the mid-eighteenth century the disease was affecting populations severely enough to interrupt trade and negotiations.Thomas Hutchins, in his August 1762 journal entry while at Ohio'sFort Miami, named for theMineamie people, wrote:
The 20th, The above Indians met, and theOuiatanon Chief spoke in behalf of his and theKickaupoo Nations as follows: "Brother, We are very thankful to SirWilliam Johnson for sending you to enquire into the State of the Indians. We assure you we are Rendered very miserable at Present on Account of a Severe Sickness that has seiz'd almost all our People, many of which have died lately, and many more likely to Die..." The 30th, Set out for theLower Shawneese Town and arriv'd 8th of September in the afternoon. I could not have a meeting with theShawneese the 12th, as their People were Sick and Dying every day.[113]
On June 24, 1763, during thesiege of Fort Pitt, as recorded in his journal byfur trader and militia captainWilliam Trent, dignitaries from theDelaware tribe met with British officials at the fort, warned them of "great numbers of Indians" coming to attack the fort, and pleaded with them to leave the fort while there was still time. The commander of the fort, Simeon Ecuyear, refused to abandon the fort. Instead, Ecuyear gave as gifts two blankets, one silk handkerchief and one piece of linen that were believed to have been in contact with smallpox-infected individuals, to the two Delaware emissariesTurtleheart and Mamaltee, allegedly in the hope of spreading the deadly disease to nearby tribes, as attested in Trent's journal.[114][115][101][116][117] The dignitaries were met again later and they seemingly hadn't contracted smallpox.[118] A relatively small outbreak of smallpox had begun spreading earlier that spring, with a hundred dying from it among Native American tribes in the Ohio Valley and Great Lakes area through 1763 and 1764.[118] The effectiveness of thebiological warfare itself remains unknown, and the method used is inefficient compared toairborne transmission.[119][120]
21st-century scientists such as V. Barras and G. Greub have examined such reports. They say that smallpox is spread byrespiratory droplets in personal interaction, not by contact withfomites, such objects as were described by Trent. The results of such attempts to spread the disease through objects are difficult to differentiate from naturally occurring epidemics.[121][122]
Gershom Hicks, who was held captive by the Ohio CountryShawnee and Delaware between May 1763 and April 1764, reported to Captain William Grant of the42nd Regiment that the smallpox has killed 30 or 40Mingoes, and approximately similar with the Delawares and Shawneese.[123]
In 1832 PresidentAndrew Jackson signed Congressional authorization and funding to set up a smallpox vaccination program for Indian tribes. The goal was to eliminate the deadly threat of smallpox to a population with little or no immunity, and at the same time exhibit the benefits of cooperation with the government.[124] In practice there were severe obstacles. The tribal medicine men launched a strong opposition, warning of white trickery and offering an alternative explanation and system of cure. Some taught that the affliction could best be cured by a sweat bath followed by a rapid plunge into cold water.[125][126] Furthermore the vaccines often lost their potency when transported and stored over long distances with primitive storage facilities. It was too little and too late to avoid the great smallpox epidemic of 1837 to 1840 that swept across North America west of the Mississippi, all the way to Canada and Alaska. Deaths have been estimated in the range of 100,000 to 300,000, with entire tribes wiped out. Over 90 percent of theMandans died.[127][128][129]
In the mid to late nineteenth century, at a time of increasing European-American travel and settlement in the West, at least four different epidemics broke out among thePlains Indians tribes from 1837 to 1870.[39] The Indians traded with the white people regardless spread disease to their villages.[130] In the late 19th century, theLakota Indians of the Plains called the disease the "rotting face sickness".[51][130]
The1862 Pacific Northwest smallpox epidemic, which was brought fromSan Francisco toVictoria, devastated theindigenous peoples of the Pacific Northwest Coast, with a death rate of over 50% for the entire coast fromPuget Sound toSoutheast Alaska.[131] In some areas the native population fell by as much as 90%.[132][133] Some historians have described the epidemic as a deliberategenocide because the Colony of Vancouver Island and theColony of British Columbia could have prevented the epidemic but chose not to, and in some ways facilitated it.[134]
Up until the 20th century, the origin of Cholera was unknown. Symptoms of Cholera are known for their fast and advanced nature.[135] Cholera reached theUnited States in 1829 when immigrants came to America searching for new jobs and opportunities.[136] Cholera, because it mostly resulted from poor hygiene and filthy conditions, disproportionately affects lower-income populations living in unsanitary conditions. Native Americans who lived their lives on reservations found themselves drinking water that was contaminated with vibrio cholerae.[137] Poor drinking water and sanitary conditions contributed to the widespread spread of Cholera cases in Native communities.[138]
One of the most notable Cholera epidemics happened in 1832. In May 1832, an immigrant ship withAsiatic Cholera landed inQuebec.[139] Cholera spread quickly from the northern ports of Quebec down to the Hudson and Lower Manhattan.[140] The rapid spread of Cholera from northern ports marked the onset of epidemics in major cities such as New York. The Epidemic of 1832 has been referred to by historians as the plague of the 19th century.[141] America, up until this point, was not very familiar with the effects of widespread diseases. Cholera is known for its ability to quickly spread and flourish in every environment. Because of this Cholera was found in almost every part of the country during this period.
Cholera's impact during the 1832 epidemic was particularly profound on indigenous communities. Cholera spread to Native populations in 1832 through waterways. Cholera was a problem all over but more prevalent in communities situated near water.[142] Native American communities were more prevalent near sources of water because they wanted to have an accessible source of drinking water[142] Unfortunately, Cholera (bacterium cholerae) spread rapidly through these areas. Increasing the community's chances of being infected. Some communities had more severe Cholera outbreaks than others.The Lakota tribe, for instance, had a major Cholera outbreak and demographic devastation due to the disposal of waste in the Great Lakes, a water source they consistently used for drinking.[143] Cholera outbreaks were more devastating primarily because indigenous communities had little forms of water filtration and lacked immunity to water-borne diseases.[144] Due to a lack of immunity to water-borne disease, Native Americans suffered from higher mortality rates.[145] Lack of immunity and exposure to bodies of water contaminated by cholera contributed to higher mortality rates in indigenous communities during the 1832 epidemic.
The deadliest cholera outbreak happened in the 1850s[146] Cholera outbreaks during the 1850s were widespread, but cases were highly concentrated in areas with dense populations. The outbreak lasted from 1852 to 1860. 23,000 deaths were recorded in Britain alone[147] The outbreak in Britain led to immigrants fleeing their homes and immigrating to America. This started the third significant and most deadly spread of cholera in America. This outbreak spread through the Mississippi River. The spread through the Mississippi reached communities in St. Louis to New Orleans.[citation needed] Many Native American communities contracted Cholera when they used the Mississippi River for transportation. Native American death tolls reached record highs during the outbreak in the 1850s. An example of a moment that became a major transmission event for cholera among tribes was the annual Kiowa Sun Dance. Several tribes were in attendance including the Osage, Comanche, Southern Cheyenne, Arapaho, and Apache.[56] Sarah Keyes, a historian who specializes in the 19th century wrote that "The disease was demographically devastating for many Native nations of the plains. For instance, by the end of the 1854 epidemic the Pawnee had lost as much as 25 percent of their population" (Keyes)[56] The Pawnee tribe was not the only tribe that was devastated by Cholera in the 1850s. Cholera was highly transmissible and led to outbreaks among multiple tribes and indigenous communities.[148] The population of many Native American tribes and communities were forever changed after the 1850 pandemic.
It is true that health disparities and cholera still exist today, specifically in Native American communities. Today there have been a reported 1.3 to 2 million cases across the world and 21,000 to 14,300 deaths (WHO)[149] Limited access to clean water and poor healthcare infrastructure contribute to the Cholera cases and deaths we see today. A majority of the people who contract these diseases are from indigenous communities in the United States. Indigenous communities have been more susceptible to diseases like Cholera because of limited access to clean water.[150] Activists and tribal governments have spoken with public health agencies and organizations to address these healthcare disparities. Many activists have organized protests and discussions with government and health officials.Winona LaDuke is an example of one activist who has been trying to promote a sustainable and healthy environment and land for Native Americans on reservations. She has been involved in theWhite Earth Land Recovery Project which tries to address environmental inequities hurting Native American communities today.[151] Even though Cholera pandemics are no longer a concern, unhealthy water conditions on reservations still present many diseases and issues for indigenous communities today.
General:
... the diseases that decimated the Natives were caused by natural contact....
{{cite journal}}: CS1 maint: location (link){{cite journal}}: CS1 maint: DOI inactive as of September 2025 (link)However, in the light of contemporary knowledge, it remains doubtful whether his hopes were fulfilled, given the fact that the transmission of smallpox through this kind of vector is much less efficient than respiratory transmission, and that Native Americans had been in contact with smallpox >200 years before Ecuyer's trickery, notably duringPizarro's conquest of South America in the 16th century. As a whole, the analysis of the various 'pre-micro-biological' attempts at BW illustrate the difficulty of differentiating attempted biological attack from naturally occurring epidemics.
In retrospect, it is difficult to evaluate the tactical success of Captain Ecuyer's biological attack because smallpox may have been transmitted after other contacts with colonists, as had previously happened in New England and the South. Although scabs from smallpox patients are thought to be of low infectivity as a result of binding of the virus in fibrin metric, and transmission by fomites has been considered inefficient compared with respiratory droplet transmission.
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