ABC Medical Center > Smallpox

What is Smallpox?

21:56 - 4 May , 2021


It is a highly contagious disease caused by a virus from the orthopoxvirus family called Variola, whose infection has a high mortality rate; historically, it is believed to have killed more people than all other infectious diseases combined. 

Although its natural incidence is considered eradicated since 1977, the date on which the last official case of smallpox, as a result of intense vaccination campaigns around the world, there is concern that from keeping samples of the virus, it could be used as a bioterrorism weapon.

There is no cure for smallpox nor specific treatments, so the vaccine is the only option to prevent it, but as it presents a high risk of serious side effects, its use is not justified except in people exposed to the virus.

There are two types of smallpox:


It is the traditional manifestation and it is the most serious. Its fatality rate is greater than 30%. It causes a systemic inflammatory reaction that causes organ failure and leads to death during the first 15 days of occurrence of the condition. Likewise, there is a risk of developing a more virulent variety called malignant or hemorrhagic, with symptoms worsening and bleeding in the skin and mucous membranes. It progresses rapidly, causing death in less than a week. About 10% of those infected with major smallpox can develop the hemorrhagic variety.


It causes the same symptoms as the major, but with less intensity. Its mortality rate is 1%.

The transmission mechanism of the virus can be:

  • By direct contact through body fluids and through the air when coughing, talking, or sneezing. 
  • Through contaminated surfaces and objects. 

Signs and symptoms Smallpox

By having an incubation period of eight to 15 days, the symptoms begin from that period, which includes:

  • Intense migraine
  • Tiredness and weakness.
  • High fever.
  • Muscle pains.
  • Sore back.
  • Nausea and vomiting.

After a few days with these symptoms, reddish skin rashes begin to appear on the face, hands, and arms, to later spread to the chest and transform into pus-filled blisters that remain for approximately 10 days. Then, they form crusts that later peel off on their own, leaving deep scars and injuries, and may even cause blindness. 

Diagnosis and treatment Smallpox

Diagnosis in people exposed to the virus in laboratories or due to a bioterrorist outbreak, requires PCR or polymerase chain reaction tests where copies of the virus DNA are generated from samples of the eruptions or pus thereof. 

Another method of diagnosis is to use an electron microscope in the laboratory to analyze the viral culture made from the samples taken from the skin lesions. 

Being an incurable disease, the treatment seeks to control the symptoms and keep the patient hydrated. In case of developing secondary bacterial infections, antibiotics are prescribed. 

If a smallpox outbreak occurs and you were vaccinated as a child, you will surely require a booster dose, considering that with this second dose, partial or total immunity extends to 20 years. 

In our Pediatric Center, a team of highly trained specialists awaits you 24 hours a day, 365 days a year, ensuring optimal care and results by providing care based on clinical practice guidelines and international protocols.

We have two pediatric intensive care units attended by experts in the management of critically ill pediatric patients and equipped with cutting-edge technology to offer the best treatment options.

Our subspecialists in pediatric emergencies are always ready to provide specialized care when you need it most.

Trust your children’s health to our experts.


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  • healthychildren.org
  • medigraphic.com
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