Outline
Introduction
Smallpox was a very contagious and deadly disease that often left people disfigured and had affected humans for thousands of years. It is caused by the variola virus. In 19080, smallpox was officially declared to be eradicated by the World Health Organization (WHO) as a result of a global immunization campaign. The last known case of smallpox was documented in Somalia in 1977. There were two strains of the variola virus; variola minor and variola major. The former was less common and had a mortality rate (death rate) of around 1%. However, the latter was the more common strain and had a mortality rate of 30%. Between 65-80% of survivors are marked with deep pitted scars (also known as pockmarks) that are most prominent on the face. The origin of smallpox is unknown, although the earliest evidence of the disease dates back to the 3rd century BCE in Egytptian mummies. The disease occurred throughout history in outbreaks. There are two theories for the origin of smallpox. Either humans were infected by a variola-like virus from rodents or another variola virus mutated into the one we now know today. Egypt had one of the earliest large concentrations of human population which makes it a likely candidate for the origin of smallpox.
Symptoms
The first symptoms of smallpox usually occur 10 to 14 days after the person has been infected. During the incubation period (the time it takes for symptoms to arrive after being exposed to a carcinogen, chemical, pathogen etc.) of 7 to 19 days, you look and feel healthy and you are unable to transmit the disease to others. Although the incubation period is 7 to 19 days, the average length is 10 to 14 days. Following the incubation period, an onset of flu-like symptoms occurs. The initial symptom stage lasts anywhere between 2 to 4 days. The disease is somewhat contagious during this stage. During this stage of infection, people are usually too sick to do their regular activities. Next, people have early rashes in a stage that lasts about 4 days and it is during this stage that people are the most contagious. The rashes start as small red spots on the tongue and mouth. According to the CDC “These spots change into sores that break open and spread large amounts of the virus into the mouth and throat”. Once the sores in the mouth start breaking down, a rash appears on the skin that starts on the face and continues to spread on the arms and legs and then to the hands and feet. According to the CDC, “It usually spreads to all parts of the body in 24 hours”. “As this rash appears, the fever begins to decline and the person may start to feel better. By the fourth day, the sores fill up with a thick fluid and the fever may begin to rise again until scabs form over the bumps”. The next stage lasts about 10 days and the person is still contagious. The sores become pustules (sharply raised, round and firm to the touch) and after 5 days, the pustules form a crust and scab. In the next stage that lasts for about 6 days, the person is still contagious and the scabs begin to fall off leaving marks on the skin. Four weeks after the rash, all scabs have fallen off and the person is no longer contagious.
Transmission
According to the CDC, “Before the eradication of smallpox, it was mainly spread by direct and prolonged face to face contact between people. Smallpox patients became contagious once the first sores appeared in the mouth and throat. These sores spread the virus when the infected person coughed or sneezed and droplets from their nose and mouth spread to other people. Patients remained contagious until all smallpox scabs fell off. These scabs and fluid found in the patient’s sores also contained the variola virus. The virus was able to spread through these materials or through objects that were contaminated by them. Those who cared for smallpox patients washed their bedding and clothing and had to wear gloves to not get infected”. In very rare cases, smallpox was able to spread through the air in enclosed settings. There was no evidence to suggest that smallpox was transmissible by animals or insects. Therefore, humans were the only possible source of transmission.
Prevention and Treatment
According to the Mayo Clinic, “In the event of an outbreak, people who had smallpox would be kept in isolation in an effort to control the spread of the virus”. Anyone who had contact with someone who developed an infection would need a smallpox vaccine which would prevent or reduce the severity of the disease if given within 4 days of exposure to the virus. Once a person was infected, it was impossible to treat them and you would need to let the disease run its course. There are two vaccines that are currently available. One vaccine uses a live virus that’s related to smallpox but it may cause serious complications while the other vaccine is safe. There are vaccines that protect people from smallpox. Currently, the vaccine is not recommended for the general public as smallpox has been eradicated. If there were to be a smallpox outbreak, health officials would use a smallpox vaccine to contain and control it. Although some antiviral drugs may help treat the disease, there is no treatment for smallpox that has been tested in people who are sick and proven effective. The smallpox vaccine is also known as vaccinia virus vaccine. This is because the vaccine is made from a virus called vaccinia, which is a proxy virus that is similar to smallpox, but less harmful and deadly. There are two licensed vaccines in the United States and one investigational vaccine that may be put into use in case of an emergency. Before contact with the virus, the vaccine can protect you from getting sick. Within 3 days of being exposed to the virus, the vaccine may protect you from getting the disease. If you still get the disease, you might get less sick than someone who hasn’t received the vaccine. Within 4 to 7 days of being exposed to the virus, the vaccine might give you some protection from the disease. If you still get the disease, you might not get as sick as an unvaccinated person would. Once you have developed the smallpox rash, the vaccine will not protect you. In july 2018, the FDA approved tecovirimat for treatment of smallpox. In laboratory tests, it has shown to stop the growth of the virus that causes smallpox and to be effective in treating animals that had diseases similar to smallpox. The drug has not been tested on people who were sick with smallpox although it has been given to healthy people. The results of those tests showed that there were minimal side effects. In addition to the treatment of smallpox, this drug may be able to treat adverse reactions from the smallpox vaccine. Similar to tecovirimat, cidofovir and brincidofovir also stop the growth of the virus that causes smallpox. These drugs are very similar to tecovirimat in terms of testing, side effects and prevention. If you were vaccinated as a child, partial immunity may last up to 10 years and 20 years with revaccination.
Impact on Life Expectancy
Many people have wondered how being infected with smallpox can affect life expectancy. Many people claim that inoculation was one of the first methods that had a positive effect on life expectancy. While some evidence suggests that smallpox deaths declined over the course of the 18th century, it is difficult to say for certain whether inoculation caused said decline. It is hard to prove such claims as life expectancy and quality of life were so low.
Eradication of Smallpox and the Smallpox Eradication Program
It was only with the establishment of the World Health Organization (WHO) in the aftermath of World War II that international quality standards of the production of the smallpox vaccine were introduced. This caused a shift in the fight against smallpox. It was now an international issue. By 1959, the World Health Assembly (governing body of the WHO) passed a resolution to eradicate smallpox globally. However, it was not until 1966 that the WHO provided the Intensified Smallpox Eradication Program with funding to increase efforts of smallpox eradication. By 1966, the number of smallpox infections had been reduced substantially. The last variola major infection was recorded in Bangladesh in October of 1975 and the last variola minor infection occurred in Merka, Somalia on October 26th, 1977. During the following years, WHO researchers searched for remaining smallpox cases in the African continent but were unable to find any. In 1978, a laboratory accident in the United Kingdom occured where a sample of the variola virus was spread through the university laboratory ventilation system which infected two people and killed one. In May 1980, the World Health Assembly officially certified the global elimination of smallpox; the first ever disease humans eradicated. It recommended that countries cease vaccinations and all laboratories destroy their remaining stocks or transfer them to Moscow or Atlanta. These are the only known places which hold samples of the variola virus for research purposes.
Sources
“Smallpox.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 22 Sept. 2020, www.mayoclinic.org/diseases-conditions/smallpox/symptoms-causes/syc-20353027.
“What Is Smallpox?” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 7 June 2016, www.cdc.gov/smallpox/about/index.html.
Ochmann, Sophie, and Max Roser. “Smallpox.” Our World in Data, 28 June 2018, ourworldindata.org/smallpox.