Smallpox: A Disease of the Past?
Smallpox: A Disease of the Past?
Smallpox infection was often more severe in pregnant women than in non-pregnant women or in men, regardless of vaccination status. Women with smallpox infection during pregnancy have higher rates of abortions, stillbirths, and preterm deliveries than women without the disease. Pregnant women have high incidences of hemorrhagic-type and flat-type smallpox, which are associated with extremely high fatality rates. Although smallpox was eradicated in the late 1970s, current international concern exists regarding the potential use of smallpox virus as an agent for bioterrorism. This manuscript reviews clinical aspects of smallpox, smallpox immunization, and outcomes in pregnant women.
Smallpox, which is caused by the variola virus, was a devastating human disease for more than 3000 years. Smallpox spread throughout the world, and by the end of the 18th century, it was endemic everywhere except in remote, sparsely populated areas.
Smallpox is the first infectious disease in which an effective method of prevention was identified and applied. The practice of deliberately inoculating an individual with variola virus was called "inoculation" or "variolation." The practice appears to have begun as a secret procedure about 1000 AD in China, where the mode of inoculation was by intranasal insufflation of dried smallpox scab material. Variolation also occurred by inoculation of pustule fluid or scab material into the skin. Variolation was practiced first in Africa, India, and China and then later in Europe and North America during the 18th century. This practice often resulted in a milder infection than "naturally acquired" smallpox; however, it was also noted to cause severe disease in some patients.
During the 18th Century, Edward Jenner observed that persons infected with cowpox did not contract smallpox. Jenner demonstrated that inoculating a person's skin with material from a human pustular lesion caused by the cowpox virus provided complete resistance to smallpox virus. This new method, called vaccine (named from vacca [cow]), quickly gained popularity and was used all over the world by the early 19th century. By the early 1950s, many industrialized countries had eliminated endemic smallpox by using liquid vaccine. The World Health Organization (WHO) Smallpox Eradication Program was an intense plan to eradicate smallpox from the globe. Prior to this program, smallpox threatened 60% of the world's population, killed every fourth victim, scarred or blinded most survivors, and eluded any form of treatment. Through this campaign, smallpox was finally pushed back to the horn of Africa and then to a single last natural case, which occurred in Somalia in 1977. A fatal laboratory-acquired case did occur in the United Kingdom in 1978. The global eradication of smallpox was certified in December 1979 and subsequently endorsed by the World Health Assembly in 1980.
Although smallpox infection has been eradicated, the variola virus is not extinct. There are known isolates of variola virus maintained at the Centers for Disease Control and Prevention (CDC) in the United States and the State Research Center of Virology and Biotechnology in Novosibirsk, Russia. However, it is unknown if undeclared stocks of the virus still exist today in a form that is accessible to either rogue governments or terrorists.
Smallpox, which occurs only in humans, is classified as either variola minor or variola major. Variola minor has an overall fatality rate of 1% or less, whereas variola major has a fatality rate of 5% to30%. Case fatality rates of variola major vary, depending on vaccination status and the clinical presentation of the disease. The more severe forms of infection with variola major (i.e., flat-type and hemorrhagic-type) have case fatality rates of approximately96% to 100%.
The variola virus is a single, linear, double-stranded DNA virus that replicates in the cell's cytoplasm. Variola is a member of the Orthopoxvirus family, which includes cowpox, monkeypox, vaccinia, ectromelia, and others. Vaccinia is the agent used in the human vaccine that stimulates resistance to smallpox. All Orthopoxvirus species provide cross-protection in experimental animals and cross-react extensively with all types of serologic tests.
Currently, there is heightened international concern regarding the potential use of smallpox virus as an agent for bioterrorism. Because smallpox results in serious complications of pregnancy, it is imperative that those in women's health know about this disease.
Smallpox infection was often more severe in pregnant women than in non-pregnant women or in men, regardless of vaccination status. Women with smallpox infection during pregnancy have higher rates of abortions, stillbirths, and preterm deliveries than women without the disease. Pregnant women have high incidences of hemorrhagic-type and flat-type smallpox, which are associated with extremely high fatality rates. Although smallpox was eradicated in the late 1970s, current international concern exists regarding the potential use of smallpox virus as an agent for bioterrorism. This manuscript reviews clinical aspects of smallpox, smallpox immunization, and outcomes in pregnant women.
Smallpox, which is caused by the variola virus, was a devastating human disease for more than 3000 years. Smallpox spread throughout the world, and by the end of the 18th century, it was endemic everywhere except in remote, sparsely populated areas.
Smallpox is the first infectious disease in which an effective method of prevention was identified and applied. The practice of deliberately inoculating an individual with variola virus was called "inoculation" or "variolation." The practice appears to have begun as a secret procedure about 1000 AD in China, where the mode of inoculation was by intranasal insufflation of dried smallpox scab material. Variolation also occurred by inoculation of pustule fluid or scab material into the skin. Variolation was practiced first in Africa, India, and China and then later in Europe and North America during the 18th century. This practice often resulted in a milder infection than "naturally acquired" smallpox; however, it was also noted to cause severe disease in some patients.
During the 18th Century, Edward Jenner observed that persons infected with cowpox did not contract smallpox. Jenner demonstrated that inoculating a person's skin with material from a human pustular lesion caused by the cowpox virus provided complete resistance to smallpox virus. This new method, called vaccine (named from vacca [cow]), quickly gained popularity and was used all over the world by the early 19th century. By the early 1950s, many industrialized countries had eliminated endemic smallpox by using liquid vaccine. The World Health Organization (WHO) Smallpox Eradication Program was an intense plan to eradicate smallpox from the globe. Prior to this program, smallpox threatened 60% of the world's population, killed every fourth victim, scarred or blinded most survivors, and eluded any form of treatment. Through this campaign, smallpox was finally pushed back to the horn of Africa and then to a single last natural case, which occurred in Somalia in 1977. A fatal laboratory-acquired case did occur in the United Kingdom in 1978. The global eradication of smallpox was certified in December 1979 and subsequently endorsed by the World Health Assembly in 1980.
Although smallpox infection has been eradicated, the variola virus is not extinct. There are known isolates of variola virus maintained at the Centers for Disease Control and Prevention (CDC) in the United States and the State Research Center of Virology and Biotechnology in Novosibirsk, Russia. However, it is unknown if undeclared stocks of the virus still exist today in a form that is accessible to either rogue governments or terrorists.
Smallpox, which occurs only in humans, is classified as either variola minor or variola major. Variola minor has an overall fatality rate of 1% or less, whereas variola major has a fatality rate of 5% to30%. Case fatality rates of variola major vary, depending on vaccination status and the clinical presentation of the disease. The more severe forms of infection with variola major (i.e., flat-type and hemorrhagic-type) have case fatality rates of approximately96% to 100%.
The variola virus is a single, linear, double-stranded DNA virus that replicates in the cell's cytoplasm. Variola is a member of the Orthopoxvirus family, which includes cowpox, monkeypox, vaccinia, ectromelia, and others. Vaccinia is the agent used in the human vaccine that stimulates resistance to smallpox. All Orthopoxvirus species provide cross-protection in experimental animals and cross-react extensively with all types of serologic tests.
Currently, there is heightened international concern regarding the potential use of smallpox virus as an agent for bioterrorism. Because smallpox results in serious complications of pregnancy, it is imperative that those in women's health know about this disease.
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