Definition

     Smallpox is a viral disease characterized by a skin rash and a high death rate.

Cause

     It is caused by a virus.

Symptoms 

     Smallpox has two forms: 1) Variola major -- which is a serious illness with a mortality rate according to the CDC of 30% or more, in unvaccinated people, and 2) Variola minor -- a milder infection with a mortality rate of less than 1%. The incubation period for smallpox is approximately 12-14 days. The symptoms are:

• High fever

• Fatigue

• Severe headache

• Backache

• Malaise

• Rash, raised and pink on the skin, starting centrally and spreading outwards. (First the mucosa of the mouth and throat, then face, forearms, trunk, and legs. Rash turns to pus-filled lesions that become crusty on the eighth or ninth day.)

• Delirium

• Vomiting and diarrhea

• Excessive bleeding

Screening and Diagnostics

• Virus can be seen by electron microscope and by culture.

• Low white blood cell count initially, that increases later in the disease.

• Low platelet count.

• DIC panel can be positive in cases of hemorrhage.

• Antibodies turn positive soon after the infection is complete.

Treatment 

     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. Treatment, once the disease symptoms have started, is limited.

     There is no agent that has been specifically made for treating smallpox. Sometimes antibiotics are given for secondary infections that may occur. Vaccinia immune globulin (antibodies against a disease similar to smallpox) may help shorten the disease.

     If a diagnosis of smallpox were made, exposed persons would need to be isolated immediately. The isolation would include not just the person who contracted the disease, but all other face-to-face contacts with that person.

     These individuals would need the vaccine and need to be monitored. Emergency measures to protect a broader segment of the population would have to be implemented immediately, within the recommended guidelines from the CDC and other federal and local health agencies.

Prognosis

     In the past, this was a major illness with significant mortality as high as 30%.

Complications

• Bacterial infections at the skin at the sites of the lesions

• Pitted scars from pustules

• Arthritis and bone infections

• Pneumonia

• Severe bleeding

• Eye infections

• Brain inflammation (encephalitis)

• Death

Prevention

     Many people were vaccinated for smallpox in the past -- but the vaccination is no longer given because the virus has been eradicated. According to the CDC, the United States has supply of the smallpox vaccine sufficient for the entire population at this time.

     There are some complications associated with the vaccine, should the vaccine need to be given in the future to control an outbreak. Some of these are easily treated rashes, while other potential complications are more serious. The risk of complications is relatively low. (For example, the chance of encephalitis, which could be a fatal complication, is 1 out of 300,000).

     When smallpox was eradicated, the general population was no longer vaccinated because the potential complications and costs began to outweigh the benefits of taking it. The experience of vaccination of both military personnel and civilian health care workers in 2002-2003 suggested that the risk was very low but nonetheless present, and very small numbers of people had unforeseen reactions.

     Smallpox vaccination is not currently being done for members of the general public. As of mid-2003, any further vaccination outside of military personnel is likely to be done, in a closely supervised fashion, in health care workers and emergency responders. There is ongoing review of smallpox vaccination, including the current and newer vaccines.