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What is the history of Smallpox and Monkeypox (Mpox) in America and other countries?

Updated December 09, 2023


Smallpox is believed to have originated in Eastern Africa around 10,000 B.C.  The emergence of the virus has been linked to farming practices which included animal domestication and the establishment of large community settlements.  While descriptions of the disease are notably absent from the Bible, the Talmud, and early Greek and Roman literature, researchers believe that ancient Indian texts compiled prior to the birth of Christ documented the illness.    Merchants from Egypt may have been responsible for the spread of smallpox to India. 

Documents from China dating back to the 4th Century A.D. are considered the first to accurately describe the disease. Additional evidence indicates that the smallpox (variola) virus was initially imported into China in the 3rd Century A.D. It is also believed that the virus was imported to Greece in 430 B.C. during the Peloponnesian War, and into Rome in 170 A.D.  By this time it was known that persons who survived the illness were immune from re-infection, and due to their immunity, they were frequently called upon to care for those afflicted. 

Additional documents indicate that the virus was present in Europe by the 6th Century A.D.  During the 6th, 7th, and 8th Centuries, smallpox spread throughout North Africa and Europe by Arab invaders. 

Smallpox first occurred in England during the 16th Century. Queen Elizabeth I contracted the disease in October 1562 and was left permanently disfigured. During this same period, smallpox spread to South and Central America from West Africa by ships transporting slaves to the Americas. 

Severity of outbreak less lethal through time

Early epidemics of the West African subtype of the smallpox (variola) virus in the Americas were highly lethal; however, subsequent outbreaks were less so.  It is estimated that approximately 3.5 million Aztecs in Mexico died during the 1520-1522 epidemic. Additional outbreaks in Peru and Brazil were also devastating to the Native populations. 

Throughout the 17th and 18th Centuries, smallpox outbreaks and epidemics occurred throughout Great Britain and in many European cities. An estimated 400,000 people died yearly from smallpox and more than one-third of all cases of blindness were caused by the disease.  Most cases of smallpox in Great Britain occurred in children under 10 years of age while in the United States during the same time period, smallpox impacted persons of all ages. A smallpox epidemic in Boston, Massachusetts that occurred between April 1721 and February 1722 resulted in nearly 6,000 cases and 855 deaths among the 10,700 residents. 

Weaponization During War

Smallpox was used as a weapon against Native Americans who were hostile to Great Britain during the French and Indian War (1754-1767). The disease was introduced into this population by Sir Jeffrey Amherst, the British Army Commander in North America, with devastating results. 

During the American Revolutionary War, the Continental Army was plagued by disease. Because soldiers were recruited from all over North America and the arrival of soldiers from England and Germany bringing smallpox to America created the opportunity for greater exposure to smallpox, which was especially devastating due to its high mortality rate of between 10 and 60 percent.

Smallpox inoculation, which differs from and was prior to the interventions known as vaccination, was considered safer than natural disease but the procedure came with the risk of serious side effects including death. However, inoculation, also called variolation, was not hygienic and involved taking pus from a person with active smallpox and injecting it under the skin of a healthy individual. The belief was that this process would induce a mild illness and spare an individual from serious illness or death.  The process was known to spread syphilis and would even start disease outbreaks within the community. Strict quarantine measures were also implemented to control the disease, and historians credit these strategies with reducing mortality rates. 

George Washington, a survivor of smallpox, implemented quarantine measures to prevent the spread of smallpox within the Revolutionary Army. While Washington supported the benefits of smallpox inoculation, in May of 1776 he ordered that active-duty troops were not to be inoculated and violation of the order was met with severe penalties. The order was issued due to the inoculation’s side effects that could incapacitate a large portion of the army from engaging in battle and thereby provide the British with an advantage. By 1777, Washington had instituted a system whereby new recruits were mandated to be inoculated upon enlistment. This system ensured that recruits had fully healed from the inoculation and any side effects while being outfitted and prior to being sent into battle, thereby limited the spread of disease in active duty troops. 

Early Vaccination Often Failed to Prevent Smallpox

In 1798, Edward Jenner reported that exposure to cowpox, a virus believed to be related to smallpox and considered relatively harmless, would protect a person from smallpox. Smallpox vaccination was introduced in the U.S. in 1800 by Boston physician Benjamin Waterhouse and was quickly embraced by many in the medical community. 

Despite vaccination, smallpox cases and outbreaks continued to occur, even among those previously infected with or vaccinated against smallpox. Throughout the 19th Century, medical journals reported on the failure of the vaccine to prevent smallpox. It was during this time that supporters of vaccination reported that while the procedure did not always offer protection from illness, it lessened the severity of the disease. In 1844, when an outbreak of smallpox occurred in the U.K., one-third of the vaccinated individuals who contracted the illness had only mild symptoms, while two-thirds suffered severely from the illness. During this outbreak, approximately eight percent of persons previously vaccinated died. Newspapers frequently reported on smallpox deaths that occurred in persons previously vaccinated.   

Europe experienced an epidemic of smallpox in 1871 and 1872. It was noted during this epidemic that vaccinated individuals were often inflicted with severe illness faster than those who were not vaccinated. Severe smallpox illness and death among vaccinated persons occurred frequently. Globally, highly vaccinated countries were significantly impacted during this pandemic. Yet, despite the failure of smallpox vaccinations to fully prevent illness and death, many countries imposed compulsory vaccination laws. 

Different Forms of Smallpox Identified and Vaccine Improvement

On January 6, 1899, the U.S. Marine-Hospital Service published a report entitled Precis upon the diagnosis and treatment of smallpox under the guidance of the Surgeon-General. In this document, public health officials reported that smallpox was contagious but the microbe had not yet been discovered. Respiratory secretions and scabs from the smallpox lesions were considered infectious and the dried materials could live for months on furniture and clothing. It was also believed that the illness was contagious during the four days prior to rash appearance, however, this was not yet confirmed. While it was reported that the illness could affect anyone, persons of color were considered at higher risk probably on account of their conditions of living in small, crowded rooms, with slight regard for cleanliness. 

Several forms of smallpox were identified and these included true smallpox, confluent smallpox, two forms of hemorrhagic smallpox, and varioloid, a modified form that occurred in previously vaccinated individuals. This document expressed the importance of not mistaking the illness for chickenpox, measles, scarlet fever, typhus fever, syphilis, cerebro-spinal fever, impetigo contagiosa, or glanders. The report also contained quarantine and disinfection guidelines and sulphur dioxide, bichloride of mercury, carbolic acid (phenol), and formaldehyde gas were approved products for disinfection. Vaccination was reported as the most effective way to stop the spread of smallpox provided that the vaccine was pure and obtained from a reputable source and public health officials recommended that glycerinized lymph derived from bovines be used. 

Mass Vaccination Not Effective

According to a published report from 1936, between 1921 and 1930, U.S. smallpox rates were highest among the 26 countries that provided data to the League of Nations. High infection rates, however, were attributed to the better reporting systems in the U.S. in comparison to other countries. By 1936, the most common form of smallpox was a mild form known as Variola Minor, with a fatality rate of 0.2 percent or less. It was also reported that in most countries where smallpox vaccination was required, rates were lower; however, in Australia and New Zealand, where smallpox was rarely seen, fewer than one percent of infants were vaccinated. 

The last reported case of indigenous smallpox in the U.S. was reported in 1934. Importations into the U.S., however, continued to occur until 1949.  When smallpox was eliminated from the United States, variola minor, the mildest form of smallpox, had emerged as the predominant strain in circulation. 

In 1959, the World Health Assembly announced its endorsement of global smallpox eradication and called for vaccination of at least 80 percent of the world’s population. The global eradication program was launched by the World Health Organization (WHO) in 1967 with a plan for complete eradication within 10 years. Smallpox cases declined until 1971 but in 1972, cases increased by 23 percent. Epidemics occurred in Botswana and Bangladesh, two countries previously reported as being free of smallpox.  The last known case of smallpox in South America occurred in Brazil in April of 1971, and Indonesia reported its last case in January of 1972. 

When public health officials realized that mass vaccination campaigns targeting at least 80 percent of the population were not effective, a new plan was initiated. The plan involved the detection and containment of cases through the implementation of a surveillance and reporting system in smallpox endemic countries.  This strategy was the result of observations that smallpox could still be eliminated in regions where vaccination was not widely practiced if health officials tracked down and isolated persons with smallpox and quarantined their contacts. 

The last known case of human to human smallpox transmission occurred in Somalia in October 1977. Two additional cases were reported in Birmingham, England in August and September of 1978, however, health officials believed that they were related to laboratory exposures. 

In May 1980, WHO declared that smallpox had been eradicated globally.

Smallpox as a Bioweapon

There are, however, two known locations where smallpox virus continues to be stored, the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia and a laboratory outside of Moscow, Russia. Despite eradication, some government health officials believe that secret smallpox stores exist and could someday be used for bioterrorism. 

Monkeypox (Mpox)

Monkeypox (Mpox) was first identified in 1958 after two outbreaks occurred among monkey colonies involved in research. The first human case was reported in 1970 in the Democratic Republic of Congo (DRC). Between 1981 and 1986, 37 cases were reported in the DRC. 

A large outbreak of mpox occurred in the same region between February 1996 and February 1997. Seventy-one cases and six deaths were reported in Zaire between February and August 1996. An additional 170 cases were reported between March and May 1997, although WHO officials believed that some cases may have been mistaken for chickenpox. 

An outbreak of mpox associated with exotic animals imported from Ghana occurred in the U.S. in 2003. The initial case occurred in a 3-year-old child who was bitten by an infected prairie dog. Health officials initially believed the case was an isolated incident; however, two weeks later, additional cases were reported. Seventy-two cases were linked to the outbreak, with most cases occurring between May 29 and June 9, 2003. 

In May 2022, health officials in the United Kingdom reported two linked cases of mpox. The reported cases were not associated with travel to monkeypox-endemic areas. By May 19, 2022, 38 cases had been confirmed worldwide, with 26 cases reported in the European region, 9 cases reported in the UK, two cases in Canada, and one in the U.S. 

On July 23, 2022, the World Health Organization (WHO) Director General Tedros Adhanom Ghebreyesus declared the ongoing mpox outbreak of 2022 as a Public Health Emergency of International Concern (PHEIC).  The WHO’s independent advisory panel did not overwhelming support the declaration, with only six members supporting the declaration and nine members opposing and marked the first time a UN health official had unilaterally declared a global pandemic.  WHO ended the mpox emergency on May 10, 2023. 

The illness was declared a public health emergency in the U.S. on August 4, 2022.  This emergency order expired on January 31, 2023. 

In November 2022, WHO renamed monkeypox to mpox due to concerns over racism and the negative impact of names on trade, travel, tourism or animal welfare, and avoid causing offence to any cultural, social, national, regional, professional or ethnic groups. 

As of November 30, 2023, the CDC is reporting 31,277 U.S. cases and 55 deaths associated with the 2022-2023 mpox outbreak. Globally, 92,167 cases of mpox have been reported since 2022. 

IMPORTANT NOTE: NVIC encourages you to become fully informed about smallpox/monkeypox (Mpox) and the smallpox/monkeypox (Mpox) vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself. This information is for educational purposes only and is not intended as medical advice.

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