Smallpox: Causes, Symptoms, Diagnosis, Treatment, and Prevention
As part of the same family of viruses that cause monkeypox, smallpox was a deadly and contagious disease that caused a severe rash and blisters on the skin. The virus that caused smallpox was variola, which is related to monkeypox. Millions of people died of smallpox, and many survivors remain blind and scarred for the rest of their lives.
Fortunately, smallpox was eradicated in 1980, thanks to a global vaccination campaign led by the World Health Organization (WHO). In 1977, smallpox was last naturally detected, and in 1978, it was last lab-acquired. There are only two remaining stocks of the variola virus, one in the United States and one in Russia, which are used for research only.
However, there is still a possibility that smallpox could re-emerge, either through a deliberate release of the virus by bioterrorists, or through accidental exposure of laboratory workers or researchers. In light of this, it is essential to understand the causes, symptoms, diagnosis, treatment, and prevention of smallpox.
Causes of Smallpox
Smallpox was caused by the variola virus, which belonged to the orthopoxvirus genus. Variola major and variola minor were the two main types of variola virus. Variola major was more severe and had a higher mortality rate than variola minor. By entering through the respiratory system or the skin, the virus multiplies in lymph nodes and blood, then infects various organs, especially the skin, where it causes characteristic rash and blisters.
The virus was transmitted from person to person through:
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Airborne exposure: When an infected person sneezed or coughed, they released droplets of saliva or mucus that contained the virus. These droplets could be inhaled by another person who was nearby.
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Direct contact: When an infected person touched another person or their skin lesions, they could transfer the virus. The virus could also be spread through kissing or sexual contact.
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Indirect contact: When an infected person shared their belongings, such as clothing, bedding, towels, or utensils, they could contaminate them with the virus. Another person who used these items could get infected.
Smallpox was contagious from the time the first symptoms appeared until the last scabs fell off the skin, which could take up to four weeks. The most infectious period was during the first week of the rash, when the blisters were filled with fluid.
Symptoms of Smallpox
The symptoms of smallpox usually appeared about 10 to 14 days after exposure to the virus. They came in stages and included:
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Prodromal stage: This stage lasts for two to four days and is characterized by flu-like symptoms, such as fever, headache, backache, body aches, vomiting, and malaise.
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Early rash stage: This stage began on the fourth day of the illness and lasted for about four days. It was characterized by the appearance of small, flat, red spots on the tongue and in the mouth. The spots soon turned into sores that broke open and spread the virus through the saliva, then spread to the face, then to the arms, legs, and trunk. The rash was more prevalent on the extremities than on the torso. Usually symmetrical, the spots become raised and firm and then filled with a clear fluid that becomes cloudy and yellowish.
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Stage of pustule rash: This stage began on the eighth day of the illness and lasted for about nine days. The pustules were hard, round and deep blisters that contained pus. They caused the skin to swell and feel tight, and they caused pain and itching. The fever often returned or worsened during this phase.
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A crust stage occurred on day 13 of the illness and lasted approximately six days. Pustules dried and crusted, leaving behind scarring that was usually permanent. The scabs were brown and crusty and gradually fell off, leaving behind depressed and pitted scars. Scratches and picks can cause infections or bleeding if they are scratched or picked.
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Recovery stage: This stage began on the 19th day of the illness and lasted until the last scabs fell off, which could take up to four weeks. As a result, the skin healed and the fever and other symptoms subsided. There is, however, the possibility of complications or long-term effects, such as blindness, arthritis, and infertility, for some people.
Diagnosis of Smallpox
Clinical signs and symptoms, especially the distinctive rash and blisters, were used to diagnose smallpox. Since smallpox has been eradicated, any suspected case would be considered a public health emergency and require laboratory confirmation immediately. These tests might include:
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Antibody test: This test measured the level of antibodies against the variola virus in the blood. A high level of antibodies indicated a current or past infection.
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Polymerase chain reaction (PCR): This test detected the genetic material of the variola virus in a tissue sample from the skin lesions. It was a fast and accurate way to identify the virus.
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Electron microscopy: This test used a powerful microscope to visualize the variola virus in a tissue sample from the skin lesions. It could also distinguish the variola virus from other similar viruses, such as monkeypox or chickenpox.
Treatment of Smallpox
There was no specific treatment or cure for smallpox. The main goal of treatment was to relieve the symptoms and prevent complications, such as dehydration, bacterial infections, or bleeding. The treatment options included:
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Rest and fluids
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Pain relievers and fever reducers, such as acetaminophen
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Antibiotics, to treat secondary bacterial infections
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Antiviral drugs, such as cidofovir or tecovirimat, which were developed after the eradication of smallpox and have shown some effectiveness against the variola virus in laboratory and animal studies
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Smallpox vaccine, which could prevent or reduce the severity of the disease if given within three to four days of exposure to the virus
Prevention of Smallpox
The best way to prevent smallpox was to get vaccinated against the disease. The vaccine was made from a live but weakened virus called vaccinia, which was related to variola but did not cause smallpox. It was given by scratching the skin with a needle dipped in the vaccine solution, leaving a scar that would heal over time. By stimulating the immune system to produce antibodies against smallpox, the vaccine protected against the disease.
The smallpox vaccine was very effective, but it also had some serious side effects, such as:
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Inflammation and infection of the vaccination site
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Allergic reaction or anaphylaxis
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Eczema vaccinatum, a severe skin reaction that could occur in people with eczema or other skin conditions
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Progressive vaccinia, a life-threatening infection that could occur in people with weakened immune systems
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Postvaccinial encephalitis, a rare but serious brain inflammation that could cause seizures, coma, or death
Smallpox vaccines were discontinued in most countries after the disease was eradicated because of these risks, and they are no longer recommended for everyone. Military personnel, health care workers, and laboratory researchers may still receive the vaccine as part of a bioterrorism preparedness plan, in case the variola virus is ever used as a weapon.
Summary
Millions of people died from smallpox, a deadly disease caused by the variola virus that spreads through respiratory droplets or direct contact with a person's skin lesions. It caused a high fever, headache, body aches, and a rash that turned into blisters and scabs, leaving permanent scarring. Smallpox was eradicated in 1980 due to a global vaccination campaign. Smallpox is only kept in two secure laboratories for research purposes. It is no longer given to the general public, but it may be used in the event of bioterrorism.
