What Is It?

Scientifically known as variola, smallpox is among the few contagious bioterror agents. The last naturally occurring case was in Somalia in 1977 and the World Health Organization declared it eradicated in 1980. Symptoms are severe and permanently disfiguring. To pass the disease on to someone else, direct face-to-face contact is required. It falls somewhere between tuberculosis and chickenpox in its level of contagiousness.

Smallpox is lethal in about 30 percent of all cases.

Two other forms of smallpox are historically rare but usually fatal:

Purpura Variolosa, or hemorrhagic-type smallpox, and Flat-type smallpox. These two variations usually develop in 3 percent and 5 percent, respectively, of people infected with variola major. Variola minor, a variation of the smallpox virus, is less severe than the major strain, and kills about 1 percent of those infected.

After the anthrax attacks in the United States in the fall of 2001, the U.S. government ordered production of enough smallpox vaccine to vaccinate the entire U.S. population should it be needed.

How Is It Spread?

Infection is caused by the inhalation of small fluid droplets, called aerosols, or by direct contact with lesions or contaminated objects.

The smallpox virus is difficult to transmit artificially as an aerosol agent and can be easily killed by a number of household disinfectants and sunlight.

What Are the Symptoms of Exposure?

This bioterror agent has an incubation period of seven to 17 days, with the first symptoms usually appearing 12 to 14 days after exposure. The first symptoms a victim will experience include high fever, backache, headache, fatigue and physical collapse. These ailments, as well as extreme physical exhaustion and unable to do much of anything, also reduce the virus's transmission rate.

People become contagious when they have severe aches and pains and exhaustion and find it hard to get out of bed. Contagiousness begins only with the appearance of a rash, generally two or three days after the initial onset of symptoms. This rash will be in the form of pink dots in the mouth and throat and spread to the face and arms, then to the torso and legs. The dots eventually become lesions, filling with pus and becoming painful. Within eight to nine days of getting the rash, scabs will form over the lesions, and will fall off around 14 days after the first symptoms appear. Victims will be contagious until all scabs fall off. Disfiguring scars are the result.

Purpura Variolosa causes severe loss of blood into the skin and internal organs.

Flat-type smallpox causes slow-developing soft lesions that don't rise above the skin's surface.

How Is It Treated?

No definitive treatment exists for smallpox. Vaccination within four days of infection can prevent or mitigate the disease's effects. Containment and targeted vaccination can control and eventually eradicate the disease.

The smallpox vaccine is made up of live vaccinia virus and has the highest rate of adverse side effects of any commonly used vaccine. Estimates in 1960 showed that if the entire U.S. population were given the vaccine, about 1,500 would suffer side effects and 300 would die from them. Now, however, more of the human population is susceptible to complications. People who have HIV/AIDS, or have experienced medical procedures such as chemotherapy or transplant surgery increases the chance they will suffer complications from the vaccine.

Vaccinia immune globulin is a treatment that can lessen severe reactions to the vaccine. The antiviral medication Cidofovir can also treat bad reactions.

The United States has adopted a policy of vaccinating selected health care workers and first responders who would administer smallpox vaccinations in the event of an outbreak. Since the Sept. 11 terrorist attacks, the U.S. government has boosted its stockpile of the vaccines, which have significant side effects, to cover the entire U.S. population in case of an emergency.

Who Has It/Where Can It Be Found?

After 1980, smallpox samples were supposed to be stored at CDC facilities in Atlanta and at a Russian lab called Vector in a town called Koltsovo. But it was later discovered that the then-Soviet Union had produced and tested about 20 tons of weaponized smallpox for use by the Soviet military. The program's smallpox and other biowarfare agents have been unaccounted for. This concerns the international community, since it's possible former Soviet scientists looking to get out of that country could take offers from nations that sponsor terrorism or terrorist groups such as Al Qaeda to hand over the samples or information on where they are.

As of November 2002, intelligence reports show that four nations have in hand unauthorized stockpiles of the virus: Iraq, North Korea, France and Russia.

It is feared that Russia lacks the security to prevent samples of the virus, or the expertise on how to develop it, from being sold on the world market. In fact, according to a 1994 report from the Defense Intelligence Agency, both Iraq and North Korea sought and received smallpox technology from the Russians in the early 1990s.

In December 2002, it was reported that the CIA was investigating an informant's accusation that Iraq obtained a particularly virulent strain of smallpox from a Russian scientist who worked in a smallpox lab at the Research Institute for Viral Preparations in Moscow during Soviet times.

A natural outbreak of smallpox occurred in Iraq in 1971, and again in 1972. It is possible the Iraqis isolated the virus then and kept a sample for themselves for future use. In 1994, U.N. weapons inspectors examining Iraqi medical facilities uncovered an industrial-sized freeze dryer, the type used by microbiologists to extend the life of germ samples. It was labeled in Arabic "smallpox machine." Iraqi officials claimed the freeze dryer was meant for the smallpox vaccine, not the virus.