The fever will be quite high; o F and they will be too ill to carry on with normal activities. The viruses will also get into the skin at this time. This phase of the disease is called the prodrome. Meanwhile, the viruses in the skin will cause a skin rash to develop. In ordinary Variola major the rash starts out as irregularly shaped red spots macules. The first spots are usually seen on the face and neck and will then develop on the hands, wrists, forearms, feet, ankles, and lower leg.
These spots will also develop on the chest and abdomen but are much less numerous than those seen on the head, neck and limbs. These macules will all appear within 24 hours. The red spots will all at the same time develop into red bumps papules after about three days. By the fourth day, the all the papules will fill with a thick, opaque fluid and have a depression in the center. These skin lesions are now called pustules.
Their fever will rise again at this time and remain high until scabs form. In time all the pustules will break open and a crust will form over the skin lesions followed by a scab.
On day 14 of the rash the skin lesions will scab over. All the skin lesions will go from macule, to papule, to pustule, to crust, to scab at the same time and it will take about 17 days for this to occur. People with smallpox are infectious to others until all the scabs have fallen off. When t he scabs fall off they leave marks on the skin that eventually become pitted scars.
The skin rash takes about three weeks to complete macule to last scab falling off. People with the hemorrhagic form of Variola major do not develop the same rash as in ordinary Variola major. Following the prodrome the skin on the chest and abdomen will turn a purplish red dusky erythema. The capillaries in the skin will then leak blood into the skin. It will start out as small dots petechiae that will get larger purpura and larger ecchymoses.
Nearly everyone with this form of Variola major will die. The flat form of Variola major was also nearly always fatal. After the prodrome the skin would develop a dusky erythema that would then slowly become papules.
Sometimes the papules would become blisters. The fever in the prodrome does not go away as in ordinary Variola major. The skin lesions do not crust or scab over but rather the skin will peel away in sheets. Usually death occurred during the second week of the illness.
Why is smallpox an attractive BW? Even if the person does not die they are very ill for a couple of weeks. Less than 10 viruses are needed to start an infection. Those viruses are most likely to result in disease when inhaled. Aerosol exposure of less than 15 minutes is sufficient to cause an infection.
Symptoms of infection do not start for days. Person-to-person transmission of this disease is common and many more people would be infected. An aerosol of the organism would be very effective way of infecting many people at one time. The virus is not very hardy. It will only last a couple of hours at high temperatures and high humidity. Yet, even indoors the virus only lasts for about 2 days. Occupying an area contaminated with smallpox would not require decontamination as long as those occupying the area waited until all the virus had become inactivated.
Laboratory Diagnosis. These swabs will then need to be sent to a laboratory that is prepared to handle this very hazardous sample.
The swab can be examined for the presence of virions using an electron microscope, techniques to look for small amounts of Variola DNA polymerase chain reaction; PCR , or by using antibodies specific for the virus to detect it or by growing the virus on live cell cultures.
Naturally occurring smallpox was wiped out worldwide by — the result of an unprecedented global immunization campaign. Samples of smallpox virus have been kept for research purposes. And advances in synthetic biology have made it possible to create smallpox from published amino acid sequences.
This has led to concerns that smallpox could someday be used as a biological warfare agent. No cure or treatment for smallpox exists. A vaccine can prevent smallpox, but the risk of the vaccine's side effects is too high to justify routine vaccination for people at low risk of exposure to the smallpox virus.
These are smallpox lesions on the skin of the trunk. This photograph was taken in Bangladesh in The first symptoms of smallpox usually appear 10 to 14 days after you're infected. During the incubation period of seven to 17 days, you look and feel healthy and can't infect others. Following the incubation period, a sudden onset of flu-like signs and symptoms occurs.
These include:. A few days later, flat, red spots appear first on your face, hands and forearms, and later on your trunk.
Within a day or two, many of these lesions turn into small blisters filled with clear fluid, which then turns into pus. Scabs begin to form eight to nine days later and eventually fall off, leaving deep, pitted scars. Lesions also develop in the mucous membranes of your nose and mouth and quickly turn into sores that break open.
Most people who get smallpox survive. However, a few rare varieties of smallpox are almost always fatal. These more-severe forms most commonly affect pregnant women and people with impaired immune systems. People who recover from smallpox usually have severe scars, especially on the face, arms and legs. Then he repeatedly exposed the boy to the variola virus — and the child did not develop smallpox.
Sometime in the s, the virus used to make the smallpox vaccine switched from cowpox to vaccinia. The smallpox vaccine prevents infection in 95 percent of those who receive it, and is also able to prevent or lessen infection when given within a few days of exposure to variola virus. Since the eradication of smallpox, scientists have developed a newer version of the vaccine that uses attenuated weakened viral strains.
Unlike most other vaccines, the smallpox vaccine does not involve an injection or "shot. A doctor uses the needle to prick the skin usually in the upper arm multiple times in a few seconds. A successful vaccination causes a red and itchy lesion to develop at the vaccine site within three to four days. This lesion turns into a large blister that fills with pus and begins to drain in the first week.
It begins to dry and scab over in the second week and then falls off leaving a small scar in the third week. During this process, the vaccinia virus can be easily transferred to another part of the body or even another person through touch. Touching the vaccination sore and then the eye can lead to a serious infection that can threaten vision. The vaccination sore may also develop into a serious toxic or allergic rash.
Rarely, people develop other significant or even life-threatening reactions to the vaccine, including:. Research suggests these complications kill one or two people out of every million vaccinated for smallpox. But most people who get the smallpox vaccine experience only mild reactions.
These may include:. When sores in the mouth break open, the virus infects the trachea and lungs. But before the virus can spread much farther, it needs to replicate. Research suggests this likely happens in the lymphoid organs, specifically the spleen, bone marrow, and lymph nodes.
After replication, the virus can move into the bloodstream, causing secondary infections of other organs:. Smallpox can also cause eye infections, pneumonia , arthritis, and bone infections. Death from smallpox usually results from high blood pressure, issues with blood coagulation, and cardiovascular collapse.
Some people develop a severe, rare form of smallpox called hemorrhagic smallpox, which causes bleeding, especially of the skin, the mucous membranes throughout the body, and the gastrointestinal tract. Most people diagnosed with smallpox survive, but they can be left deeply scarred or blind.
For people at heightened risk, such as those who are pregnant or immunocompromised, smallpox can be fatal. But the virus can be found inside laboratories for research purposes. There is some concern that these stores could be stolen and used in a bioterrorism attack. While this risk is low, the CDC has an emergency plan in place and continues to develop new vaccines and medications.
While no one has smallpox now, this disease has been a threat to public health for thousands of years. Archaeologists found smallpox-like rashes in three Egyptian mummies from the third century B. But these lesions may have been caused by many other diseases, including those produced by other poxviruses.
Ancient Indian treatises provide the first reliable descriptions of smallpox, though it's unclear how old these medical texts are. Some experts date the treatises to the sixth century B. C, while others claim they go all the way back to the 15th century B. In China, the first reliable description of smallpox was in the fourth century A. Smallpox reached Japan in the sixth century A. North America saw its first cases of smallpox in the 17th century and Australia in the 18th century.
In , the World Health Organization initiated a vaccination program to rid the world of smallpox and launched renewed efforts in with its intensified eradication program. In , a 3-year-old girl from Bangladesh named Rahima Banu was the last person on the planet to naturally acquire variola major; in , a hospital cook in Somalia named Ali Maow Maalin was the last person to have naturally acquired variola minor.
In , a woman named Janet Parker became the last known person to die of smallpox. A medical photographer at the Birmingham University Medical School in England, Parker worked on a floor above a microbiology lab that was researching variola virus. Scientists suspect she contracted the disease by visiting the lab or through airborne virus that traveled through the building's ventilation system. Indeed, there is historical evidence that smallpox was sometimes used intentionally as a biological weapon against Black, Indigenous, and People of Color BIPOC populations.
In , a Spanish ship sailing from Cuba, which was carrying an infected enslaved African, arrived in Mexico. Academics believe this marked the arrival of smallpox in the Americas. The disease began to circulate, and rapidly wiped out an estimated 90 percent of Native Americans. European populations had gained increased immunity to the disease, thanks to repeated exposure, but Native Americans had no immune defense for the virus.
In Australia, the first recorded major smallpox epidemic broke out in Most of the British colonists there had been exposed to smallpox as children and were unaffected, but the disease ravaged the Aboriginal community, killing up to 70 percent of that population. The slave trade also spread smallpox across Africa. In , after exposure to smallpox from Europeans, whole clans of Khoisan people died, making it easier for Europeans to wrest control of their land.
Until , smallpox outbreaks were still common in South America, Africa, and Asia. The variola virus that causes smallpox belongs to the genus Orthopoxvirus. Other viruses in this genus that can cause diseases in humans are monkeypox and cowpox, spread by infected animals. The leading public health institute in the United States, the CDC works to protect citizens from threats like smallpox.
Its website is a go-to resource for information about smallpox, including vaccines and bioterrorism risk. Mayo Clinic. Based in Rochester, Minnesota, Mayo Clinic is a nonprofit dedicated to clinical practice, education, and research. Its website offers an overview of smallpox, including information on symptoms, diagnosis, and treatment. MedlinePlus is part of the U. National Library of Medicine, the world's largest biomedical library. The MedlinePlus homepage for smallpox has a brief introduction to the disease with links to other websites for details on symptoms and prevention.
Another page on the website has a helpful explainer on smallpox. NIAID supports research — basic, preclinical, and clinical — to advance product development for biodefense and emerging infectious diseases, including new vaccines and treatments for smallpox. Founded in , the World Health Organization is a United Nations specialized agency focused on international public health.
Its website delivers extensive information on smallpox, including the methods that resulted in the eradication of the disease and current efforts to prevent outbreaks.
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