Introduction:
Smallpox long reigned as the king of dreaded contagious diseases. It killed more people than any other virus in recorded history -- about 500 million people in the 20th century alone. For about 20 years, smallpox seemed to have vanished, no longer haunting the dreams of most people. Many had never even heard of it. Unfortunately, terrorist’s suicidal viciousness and new biological attacks have brought the threat of smallpox back to the future.

What is it?
Smallpox is one of the classic childhood viral illnesses. The first written descriptions of smallpox are from early China where it was described as a disease from the west. Even before that, smallpox left physical evidence -- it has been found in ancient Egyptian mummies. The disease later spread as part of the great Islamic expansion across North Africa and into Spain. The ill-fated travel of the Crusades then brought it to the rest of Europe where for many generations it caused about 10 percent of all deaths every year.

European explorers then brought it to the American colonies, where epidemics were devastating to colonists – but especially to Native Americans. Smallpox-contaminated blankets may have been given to natives as intentional acts of biological warfare. Later, George Washington believed that British troops intentionally infected colonial forces with smallpox.

Eventually, almost everyone on earth got smallpox. This airborne disease was so contagious that it became a standard feature of life on our planet. Most people recovered, but the overall mortality rate when infected was 1 to 30 percent -- and even higher during some epidemics.

Today we are living in a New World, not unlike the one discovered by the European explorers. We live in a world with little immunity to smallpox, and where people might be inhumane enough to intentionally spread it. Though smallpox would still be wildly contagious -- spreading without discrimination across national borders -- there is hope.

Who gets it?
In 1967, the World Health Organization (WHO) began an intense campaign to eradicate smallpox from the planet through quarantine and vaccination. People all over the world lined up to get the shot on their upper left arm. All known contacts of people with smallpox were vaccinated or revaccinated immediately, and quarantined if they developed a fever within the next 17 days.

The last case of wild smallpox occurred in 1977. The last reported case of non-wild smallpox infection occurred in 1978 when two people contracted the disease after exposure to the virus in a lab.

What are the symptoms?
People with the illness got sick suddenly, with a high fever, headache, and marked fatigue. Nausea, vomiting, abdominal pain, back pain, and muscle pains were also common. A few days later, pox (which looked like “pearls of pus”) appeared – mostly on the face and legs – and the fever fell. The pox usually lasted 10 or 12 days, with the fever often returning. (Red Book 1(591), 2006)

Is it contagious?
Wildly.

How long does it last?
Symptoms usually develop 7 to 17 days after exposure. The illness then usually lasts about 2 weeks.

How is it diagnosed?
Laboratory diagnosis is available.

How is it treated?
In the past, the goal of smallpox treatment was to support people until the disease had past. If smallpox occurs again, other treatments may be tried.

Also, giving the smallpox vaccination within 1-4 days after exposure to smallpox may prevent illness, or at least make it less severe.

While studies are very limited, some antiviral medications such as Cidofovir, may have a role in treating smallpox (Red Book, 1(591) 2006).

How can it be prevented?
On May 14, 1796, Jenner took material from cowpox on the hand of milkmaid Sarah Nelm and inoculated it into the arm of young James Phipps. Jenner then deliberately exposed Phipps to smallpox – and Phipps didn’t get it! With the solid success of using cowpox (the virus is called vaccinia), “vaccination” was born.

The success was so dramatic that 10 years later President Thomas Jefferson predicted that one day people would only know about the dread of smallpox from reading history books. And there was a time that it looked as if Mr. Jefferson had been proven right. Vaccination was so successful that smallpox was considered extinct. The United States stopped routine childhood immunization for smallpox in 1972. Health care workers stopped receiving the vaccine in 1976, and in 1995, the United States halted routine vaccination of US military personnel

Though the likelihood of wild smallpox infection remains exceedingly remote, the recent heightened concern regarding smallpox as a biological weapon has resulted in renewed public awareness of this disease.

Today, if smallpox is intentionally spread, the cornerstones of prevention are quarantine and vaccination.

Interestingly, one Danish pharmaceutical company is working on a newer, safer smallpox vaccine. In November 2008, Bavarian Nordic announced promising results regarding their smallpox vaccine, Imvamune. Imvamune was developed specifically for people with weakened immune systems. So far, early research involving volunteers with HIV infection shows reassuring safety results. Complete data from the trial is expected in the second half of 2009 (www.bavarian-nordic.com/22-08_UK).