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.
Vaccination and Lymph System
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Smallpox is caused by a virus called
Variola major. It is spread: Through the airborne droplets of infected salivaBetween people who have direct contactThrough the handling of contaminated bed linens or clothing
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 usually occur about 12 days after exposure. Hemorrhagic or malignant symptoms usually do not appear until death is near.
Early symptoms include: High feverFatigueSevere headacheBackacheStomach painFatigueSore throatNausea and vomitingDelirium
2 to 3 days later: Rash appears on the mouth, throat, face, and arms, then spreads to the legs and trunkRed, flat lesionsLesions appear at the same timeLesions fill with fluid, then pusCrusts form during the second weekScabs form and fall off after 3-4 weeks
Hemorrhagic symptoms include: High feverFatigueHeadacheBackachePossible stomach painDark red colorationBleeding into the skin and mucus membranes
Malignant symptoms include: High feverFatigueHeadacheBackacheSlowly developing lesions that remain soft and flatSkin looks like reddish-colored crepe rubberLarge amounts of skin may peel, if the person with smallpox survives
You will be asked 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 microscopeTaking a sample (a culture) of saliva and fluid from skin lesionsBlood test to detect antibodies to smallpox
No effective treatment for smallpox currently exists. Doctors can offer supportive care. Steps will be taken to prevent the spread to others.
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.
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 vaccinatedWear a mask, gloves, goggles, and a gownDisinfect clothing, bed linens, and surfaces
People in the hospital will be placed in a special room. In some cases, forced quarantine may be necessary.
Many people were immunized prior to 1972. That protection has likely worn off or decreased. Routine
is not recommended in the United States.
An emergency supply of the vaccine is kept. A vaccination within 4 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.
Breman JG, Henderson DA.
Diagnosis and management of smallpox.
N Engl J Med. 2002;346(17):1300-1308.
Frequently asked questions and anwers on smallpox. World Health Organization website. Available at:
http://www.who.int/csr/disease/smallpox/faq/en. Accessed January 16, 2015.
Henderson DA, Inglesby TV, Bartlett JG, et al. Smallpox as a biological weapon: medical and public health management.
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 January 16, 2015.
Last reviewed February 2016 by David Horn, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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