What is smallpox?

Smallpox is a highly contagious disease caused by the smallpox virus (variola major or variola minor). Smallpox is often life threatening and causes death in around 30% affected individuals. It is transmitted from person to person by direct contact or by inhaling airborne infected particles called droplet nuclei. Contaminated bed linens or clothing can also spread infection.

Naturally occurring smallpox was eliminated worldwide in late 70s though a worldwide immunization campaign. However, the stockpiles of smallpox virus saved for research purposes may be used as a bioterrorism agent. There is no treatment for smallpox. A vaccine can prevent smallpox but is not usually recommended as it may lead to serious complications in some individuals.

What are the symptoms of smallpox?

Symptoms of smallpox appear 2 weeks after acquiring the infection. The symptoms may include the following:

  • Flu-like symptoms
  • Fever
  • Uneasiness and discomfort
  • Headache
  • Fatigue
  • Severe back pain
  • Vomiting and/or diarrhea
  • Appearance of flat, red spots on the face, hands and forearms
  • Spreading of red spots to the trunk
  • Change of spots into small blisters
  • Filling of blisters with clear fluid, which changes into pus
  • Formation of scabs after a week
  • Shedding of scabs and formation of scars
  • Sores in nose and mouth

Once the sores in mouth break open, the virus spreads into the saliva. Variola major strain of smallpox leads to more severe symptoms and is also more dangerous. Variola minor strain also results in similar, however milder, symptoms. Most of the deaths reported by smallpox are caused by the variola major strain.

What causes smallpox infection?

There are two strains of smallpox virus:

  • Variola major or classic smallpox, the more fatal strain
  • Variola minor or alastrim, the less fatal strain

Smallpox is often transmitted through the droplets that are released in air by an infected person while coughing, sneezing, or talking. It can attack 85% of all non-vaccinated people. The infection spreads slowly and mostly among close contacts. The virus attacks the mucous membrane of mouth cavity or nose. Smallpox virus multiplies in lymph nodes and localizes in small blood vessels of the skin and the mouth cavity.

How is smallpox treated?

Most people infected with smallpox survive. However, infection with variola major strain of smallpox can be fatal in about 1 out of 3 cases. Pregnant women and people with weak immune systems are most vulnerable. People with smallpox infection get severe scars on the face, arms and legs. In some cases, smallpox may also cause blindness.

There is no cure available for smallpox. Treatment aims on providing relief from symptoms. Isolation of infected individuals is recommended to prevent spread of the virus.If the infected individuals acquire bacterial infections, antibiotics are then prescribed.

The smallpox vaccine uses a live virus that’s related to smallpox. This virus may cause severe complications in about 1 of 10,000 patients. These complications may include infections or inflammation of the heart or brain. Due to these high risks, vaccination for prevention is not recommended for healthy, unaffected individuals.

However, in infected individuals vaccination is very effective if given in early stages of infection. Vaccination reduces the severity of the symptoms. Smallpox vaccine may be recommended for family members and close personal contacts of infected patients.

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