Smallpox
Smallpox is a contagious and often fatal infection caused by the variola (ver-e-O-luh) virus.
What Is Smallpox?
What do Queen Mary II of England, King Louis XV of France, and Czar Peter II of Russia have in common? Other than being royalty, they all died from smallpox, one of the deadliest diseases in history. This devastating illness first surfaced thousands of years ago, and many believe smallpox killed more people than all other diseases combined before it was wiped out in the late 1970s. The variola (from the Latin word "svarus," meaning "spotted") virus causes two types of smallpox: variola major and variola minor. Variola major (the type discussed in this entry) is extremely serious and can be fatal in up to 30 percent of cases. The milder variola minor is fatal in less than 1 percent of patients.
How Common Is the Disease?
Thanks to the vaccine developed by Edward Jenner in 1796 and the intensified immunization program begun in 1967 by the World Health Organization (WHO), smallpox is no longer found in the world; the last naturally occurring case was reported in Somalia in Africa in 1977. Before this successful eradication program, the illness affected millions of people of all ages every year. Those who survived the severe period of infection often were left scarred or blinded.
Is It Contagious?
Smallpox is so contagious that just one infected person can launch an epidemic. As soon as the first symptoms of the disease appear, an infected person can spread the virus by coughing, sneezing, or even talking. These actions expel tiny virus-packed drops of moisture into the air. When a healthy person breathes in these drops, the virus finds a new home. Less often, touching patients' sores or even just their bed linens or clothes can spread the infection. Smallpox is typically most contagious during the first week of illness. Outbreaks of the disease in a community tended to occur at two- to three-week intervals.
What Are the Signs and Symptoms of Smallpox?
Once the virus enters the body, it quickly reproduces and takes over healthy cells. An infected person usually is not even aware of the viral intruders for at least a week. Then the first wave of smallpox symptoms appears, often resembling those of a cold or the flu: fever, extreme tiredness, headache, backache, and, occasionally, nausea (NAW-zee-uh) and vomiting. These symptoms can last up to a week. About two to three days after the onset of symptoms, a rash of red blisters or lesions appears suddenly on the face, arms, and palms. Within a few days, the lesions fill with fluid and pus and spread to other parts of the body, including the inside of the nose and mouth. The sores can expand and break open, causing pain. Eventually, scabs form and later fall off. During its early stages, smallpox can be confused with chicken pox, which is caused by a different virus (varicella zoster, var-uh-SEH-luh ZOS-ter). Chicken pox produces a much milder rash that usually develops on the body and is less prominent on the face, arms, and hands.
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