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Smallpox

Definition

Smallpox is a viral infection. It is contagious and can be deadly. The disease was eliminated worldwide. This was done through global immunization programs. The last known natural occurring human case was in 1977. Governments have studied its use as a germ-warfare weapon. As a weapon, it would be released in the air. Those exposed could develop the disease. They would then pass it to other people.

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Causes

Smallpox is caused by a virus called Variola major. It is spread:

  • Through the airborne droplets of infected saliva
  • Between people who have direct contact
  • Through the handling of contaminated bed linens or clothing

Risk Factors

The main risk factor for contracting smallpox is exposure to the virus in a laboratory or after its release during a biological terrorism attack.

Symptoms

Symptoms usually occur about 12 days after exposure. Hemorrhagic or malignant symptoms usually do not appear until death is near.

Early symptoms include:

  • High fever
  • Fatigue
  • Severe headache
  • Backache
  • Stomach pain
  • Fatigue
  • Sore throat
  • Nausea and vomiting
  • Delirium

Two to three days later:

  • Rash appears on the mouth, throat, face, and arms, then spreads to the legs and trunk
  • Red, flat lesions
  • Lesions appear at the same time
  • Lesions fill with fluid, then pus
  • Crusts form during the second week
  • Scabs form and fall off after 3-4 weeks

Hemorrhagic symptoms include:

  • High fever
  • Fatigue
  • Headache
  • Backache
  • Possible stomach pain
  • Dark red coloration
  • Bleeding into the skin and mucus membranes

Malignant symptoms include:

  • High fever
  • Fatigue
  • Headache
  • Backache
  • Slowly developing lesions that remain soft and flat
  • Skin looks like reddish-colored crepe rubber
  • Large amounts of skin may peel, if the patient survives

Diagnosis

The doctor will ask about your symptoms and medical history. A possible source of exposure will be looked for. A physical exam will be done.

Test may include:

  • Examination of saliva and fluid from skin lesions under a microscope
  • Taking a sample (a culture) of saliva and fluid from skin lesions
  • Blood test to detect antibodies to smallpox

Treatment

No effective treatment for smallpox currently exists. Doctors can offer supportive care. Steps will be taken to prevent spread to others.

Supportive Care

Fluids are given. The skin is kept clean. Medications can help control fever and pain. Antibiotics do not work against viruses. They may be given if other infections develop.

Public Health Measures

Cases are reported to public health officials. A person infected with smallpox should be kept isolated. This will help prevent the spread of infection.

In most cases, family members would provide care at home. Caregivers should:

  • Be vaccinated
  • Wear a mask, gloves, goggles, and a gown
  • Disinfect clothing, bed linens, and surfaces

People in the hospital will be placed in a special room. In some cases, forced quarantine may be necessary.

Prevention

Many people were immunized prior to 1972. That protection has likely worn off or decreased. Routine vaccination is not recommended in the United States.

An emergency supply of the vaccine is kept. A vaccination within four days of exposure may prevent the disease. It can also make symptoms less severe. Anyone in close contact with someone who is infected after the fever has started should receive the vaccine. Medical and emergency personnel also should be given the vaccine.

Two weeks or more could elapse before the first symptoms occur. The success of an attack would depend on the dose that was inhaled. Experts predict most of the released viruses could live in dry, cool air, without sunlight, for up to a day. Each person infected would likely pass the disease to 10 to 20 other people. Those people, in turn, could spread it to others. The fatality rate in naturally occurring smallpox is 30% or higher.

Revision Information

  • Centers for Disease Control and Prevention

    http://www.cdc.gov

  • National Library of Medicine

    http://www.nlm.nih.gov

  • Health Canada

    http://www.hc-sc.gc.ca

  • Public Health Agency of Canada

    http://www.phac-aspc.gc.ca

  • Breman JG, Henderson DA. Diagnosis and management of smallpox. N Engl J Med. 2002;25;346:1300-1308.

  • Dambro MR. Griffith's 5-Minute Clinical Consult. Philadelphia, PA: Lippincott Williams & Wilkins; 2001.

  • Frequently asked questions and anwers on smallpox. World Health Organization website. Available at: http://www.who.int/csr/disease/smallpox/faq/en.

  • Mandell GL, Bennett JE, et al. Principles and Practice of Infectious Diseases. 6th ed. United Kingdom: Churchill Livingstone, Inc; 2004.

  • Smallpox. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Accessed August 27, 2014.

  • Smallpox. University of Minnesota Center for Infectious Disease Research and Policy website. Available at: http://www.cidrap.umn.edu/infectious-disease-topics/smallpox. Updated February 24, 2014. Accessed August 27, 2014.

  • Working Group on Civilian Biodefense. Smallpox as a biological weapon: medical and public health management. JAMA. 1999;281:2127-2137.