Smallpox is a very serious illness caused by a virus called the "Variola" virus. Smallpox is a viral disease characterized by a skin rash and a high death rate. Over the centuries smallpox has killed more people than all other infectious diseases combined but worldwide immunization has stopped the spread of smallpox three decades ago. Smallpox gets its name from the pus-filled blisters or pocks that form during the illness. Although the names may sound alike, smallpox is not related to chickenpox, which is a milder disease caused by a different virus. 

There are two forms of smallpox:

• Variola major: It is a serious illness with a death rate of about 30% or more in unvaccinated people
• Variola minor: It is a milder infection with a death rate of less than 1%.

Possible Complications

• Arthritis and bone infections
• Bacterial infections at the skin at the sites of the lesions
• Brain inflammation
• Death
• Eye infections
• Pitted scars from pustules
• Pneumonia
• Severe bleeding

Smallpox is the only disease that has been completely wiped out throughout the world. Smallpox is also potentially one of the most devastating biological weapons ever conceived.

Causes
Smallpox was once found throughout the world, causing illness and death wherever it occurred.

• It spreads through tiny drops of the infected person's saliva when the person coughs, talks, or sneezes.
• Smallpox usually passes from person to person during close, face-to-face contact.
• The virus could also be spread through other body fluids and contaminated clothing or bed linen.
• The virus is acquired from inhalation, The virus starts in the lungs. From there, the virus invades the bloodstream and spreads to the skin, intestines, lungs, kidneys, and brain.
• Smallpox was primarily a disease of children and young adults, with family members often infecting each other.The incubation period for smallpox is approximately 12-14 days.

Signs & Symptoms
Smallpox spreads very easily from person to person. The first symptoms of smallpox usually occur within 10 to 14 days after exposure, with the rash appearing two to four days later. The first symptoms could appear, however, as early as seven days after exposure, or as late as 17 days. Symptoms are flu-like and include high fever, fatigue and headache and backache, followed by a rash with flat red sores.

• Backache
• Delirium
• Diarrhea
• Excessive bleeding
• Fatigue
• High fever
• Malaise
• Raised pink rash -- turns into pus-filled lesions that become crusty on day 8 or 9
  Severe headache
• Vomiting

Diagnosis
Diagnosis of smallpox is made using an electron microscope to identify virus in fluid from the papules, urine, or in the patient's blood prior to the appearance of the papular rash.

• Blood tests will show a low white blood cell count at first, but higher levels of white blood cells are seen later in the disease. Platelet count will be low.
• A DIC panel can be positive if there is excessive bleeding. Antibodies turn positive soon after the infection is complete.
• Sometimes, Special laboratory tests can be used to identify the virus.

Treatments
If the smallpox vaccination is given within 1-4 days of exposure to the disease, it may prevent illness, or at least lessen the degree of illness associated with the disease. There is no proven treatment for smallpox, but research to evaluate new antiviral agents is ongoing. Patients with smallpox can benefit from supportive therapy such as intravenous fluids, medicine to control fever or pain and antibiotics for any secondary bacterial infections that may occur.

• Treatment, once the disease symptoms have started, is limited.
• Sometimes antibiotics are given for secondary infections that may occur.
• Vaccinia immune globulin may help shorten the disease.
• Exposed persons would need to be isolated immediately. The isolation would avoid face-to-face contacts with that person.
• Emergency measures to protect a broader segment of the population would have to be implemented immediately