Types
There are two types of smallpox – variola major and variola minor. Variola major is the most common and most severe (a more severe rash and higher fever). This type is further broken down into four subtypes – ordinary (the most common, consisting of 90% of the cases. pustules could form intermittently over the body, or even be so numerous that not one clean patch of skin would be left), hemorrhagic (Very rare and very severe. The virus causes blood vessels to seep from all parts of the body, even within the eyes. Unable to move or speak, patients with hemorrhagic pox often are aware of what is happening to them almost to the point of death. ), modified (develops in those that have been previously vaccinated – usually mild), and flat (the pustules never raise up, but are discolorations in the skin that cause it to slough off). Hemorrhagic and flat are usually fatal. Overall, variola has 30% death rate. Variola minor, is much less common and less severe. It only carries a 1% death rate. No one knows exactly how the variola virus ultimately kills someone, but scientists do know that fatality is based on how much of the virus a person is infected with and how strong someone's immune system is.

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Transmission
Smallpox is very infectious, in its airborne, aerosolized form, but for it to be spread from person to person, a direct and prolonged face to face contact has to occur. At distances of greater than ten feet, the aerosol begins to break down by the effects of both oxygen, and UV rays from the sun. The virus can also be spread through direct contact with infected body fluids or objects that have been contaminated with infected body fluids. People are the most contagious at the time of onset of the rash, and this lasts until the last smallpox scab falls off. Some cases have also shown to be contagious at the onset of the fever, which occurs before the rash. Humans are the only natural host for the variola virus, and it never been known to be transmitted by insects or animals.

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Smallpox Life Cycle
Rash Evaluation Questionaire (CDC)

Incubation Period
(Duration: 7 to 17 days)Average 12 – 14 days
-Not contagious
- People do not have any symptoms and may feel fine.

Initial Symptoms (Prodrome)
(Duration: 2 to 4 days)
-Sometimes contagious*
-The first symptoms of smallpox include fever (101-104 degrees Fahrenheit), malaise, head and body aches, and sometimes vomiting.
- People are usually too sick to carry on everyday activities.

Early Rash
(Duration: about 4 days)
-Most contagious

Rash Distribution
-A rash emerges first as small red spots on the tongue and in the mouth.
- These spots develop into sores that break open and spread large amounts of the virus into the mouth and throat. At this time, the person becomes most contagious.
-The skin rash appears as the sores in the mouth break down, usually spreading to all parts of the body within 24 hours.
-As the rash develops the fever drops and people start to feel better.
-By the third day of the rash, the rash becomes raised bumps.
-By the fourth day, the bumps fill with a thick, opaque fluid and often have a depression in the center that looks like a bellybutton. (This is a major distinguishing characteristic of smallpox.)
-The fever returns with the onset of the raised bumps, and remains until scabs form over the bumps.

Pustular Rash
(Duration: about 5 days)
-Contagious
-The bumps become pustules—sharply raised, usually round and firm to the touch as if there is a small round object under the skin. People often say the bumps feel like BB pellets embedded in the skin.

Pustules and Scabs
(Duration: about 5 days)
-Contagious
-The pustules begin to form a crusty scab.
-Most of the sores usually have scabbed over after the second week.

Resolving Scabs
(Duration: about 6 days)
-Contagious
-As the scabs begin to fall off, they are replaced by pitted scars. .
-The person remains contagious until all of the scabs have fallen off. This takes about three weeks after the rash appears.

Scabs resolved
-Not contagious
-Scabs have fallen off. Person is no longer contagious.

* Smallpox may be contagious during the prodrome phase, but is most infectious during the first 7 to 10 days following rash onset.

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Vaccination
The smallpox vaccination is a live vaccinia virus, closely related to the variola virus. Although the vaccine has a proven track record, supplies of the vaccine are very limited presently. In 1998, there were 90 million declared doses of the smallpox vaccine around the world. The potency of these doses is unknown, and various countries were attemting to determine whether new vaccines needed to be generated. In 1999, countries started testing the potency of their vaccines. Currently, a division of the World Health Organization in the Netherlands tests specimens every 5 years. Properly stored, smallpox vaccines have been shown to last 18 years without losing their potency. The vaccination usually provides individuals with immunity for about ten years. If a person does experience symptoms, they are usually less severe. Even when the vaccine becomes less effective in people who are losing immunity, they are still less likely to transmit the virus. Those who are revaccinated after the first vaccination wears off usually hold their immunity longer than those receiving the vaccine for the first time.

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Vaccine Side Effects
Normal side effects upon receiving the smallpox vaccine include a sore arm and mild achiness. In the past, 1,000 people out of 1,000,000 people experienced complications over the expected ones. Although these reactions were severe, they were not life threatening. These complications include an allergic reaction at the injection site, and spread to other parts of the body. Between 14 and 52 people out of every 1 million people vaccinated experienced life-threatening side effects, and 1 to 2 out of 1 million die. Careful, strict screening is the key to avoiding many of the instances of side effects for this vaccine.

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Vaccine Contraindications
Vaccination is contraindicated for certain groups. These include pregnant women, women who are breastfeeding, children younger than 12 months of age, persons with immune disorders or experiencing therapeutically-induced immunosuppression (people who have had an organ transplant, those receiving cancer treatment), persons with HIV infection, have a heart condition with or without symptoms, including conditions such as previous heart attack, angina, congestive heart failure, and cardiomyopathy (heart muscle becomes inflamed and doesn’t work as well as it should), stroke or transient ischemic attack (a “mini-stroke” that produces stroke-like symptoms but not lasting damage), chest pain or shortness of breath with activity (such as walking up stairs), or other heart conditions being treated by a doctor, high blood pressure diagnosed by a doctor; high blood cholesterol diagnosed by a doctor; diabetes or high blood sugar diagnosed by a doctor; a first degree relative (for example, mother, father, brother or sister) with a heart condition before the age of 50; and/or, currently a cigarette smoker. and persons with a history of eczema.

If the threat of smallpox becomes so great that administration outweighs not receiving the vaccination, a smllpox immune globulin can be given along with the vaccination, if available. A safer vaccinia-based vaccine, produced in cell culture, is expected to become available shortly. There is also interest in developing monoclonal anti-variola antibody for passive immunization of exposed and infected individuals, which could also be administered to persons infected with HIV.

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Receiving the Vaccination
The smallpox vaccine is usually given in the upper arm by a two pronged needle that is dipped into the vaccine solution. The skin is then picked two or three times. This will usually leave a few drops of blood and be sore. If the immunization is successful, a small, red, itchy bump will form where the vaccination was given within three to four days. The bump will then turn into a pus filled blister that will eventually drain during the end of the first week. In the second week, the blister will dry up, and form a scab. In the third week, the scab will fall off and form a scar (To view the progression of a vaccine site, click here.). People will be protected from the disease in as little as three days after receiving the vaccine.

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Treatment and Containment
There is no specific treatment for smallpox beyond treating the symptoms of the illness. The main concern is to stop the spread of the virus before the possibility of an epidemic occurs. Fortunately, during the time when the illness is the most contagious, people are usually so sick that they confined to their beds, leaving their caregivers as the main concern. People are not contagious before the symptoms of the disease manifest. People are urged to receive the vaccination immediately after a known exposure. Receiving this vaccination up to 4 days after exposure and before the rash has been proven to decrease the severity of the infection protect against an outbreak. People that show signs of smallpox need to be isolated immediately. If hospitals do not have isolation facilities, people should be quarentined to their homes. Those that come into contact with the individual(s) need to be vaccinated. Through thorough and efficient diagnosis and containment of the first cases of the disease, an outbreak can be quickly brought under control. Also, if there is evidence a widespread outbreak, people are encouraged to avoid large crowds.

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Sources: CDC (Center for Disease Control and Prevention), Yale School of Management,
World Health Organization (WHO), PBS (Public Broadcasting Service), and the New America Foundation