President's Page February 2003

Robert W. Haley, MD

Smallpox
How will we care for the patients?

With US troops going into Iraq and tensions escalating in North Korea—both countries suspected of possessing weaponized smallpox—the likelihood of a smallpox introduction in Dallas is increasing. With virtually no immunity left in our population, an introduction could spread rapidly, causing mass illness and bringing our economy to a halt. Whereas some people believe we can count on state and federal agencies to take control in the pinch, most urge that we prepare to manage our own epidemic in case of a multi-city attack or an all-out war.

Here are some basic facts on which our response should be based. People infected with smallpox generally have a two-day fever, followed by the characteristic rash. They become infectious at the end of this febrile period when the enanthem begins in the oropharynx, possibly predating the skin rash by hours to a day. The rash may be hard to recognize or to differentiate from chickenpox in the first day or two.

Smallpox almost always is transmitted by large droplets from coughing or sneezing over no more than six feet, or by contact with fomites, but a rare smallpox transmitter can broadcast infected droplet nuclei by true airborne spread over long distances, as with tuberculosis. Thus, people are most at risk in face-to-face contacts. In historical outbreaks, half or more of the cases tended to be hospital personnel, and the second largest group was household contacts.

Historically, the mortality rate of the most virulent form of smallpox (variola major) was 30 percent. Presumably many deaths—those that would result from dehydration, pyoderma and pneumonia from bacterial superinfection, respiratory failure, shock, and rare GI bleeding—would be treatable today.

The smallpox vaccine, containing live vaccinia virus (a cousin to smallpox ), prevents the illness if given before exposure or within 4 days after exposure. We have ample doses of the old vaccine, which is effective but complicated by fever, malaise, and a very sore arm in up to 30 percent of vaccinees. More severe complications, such as progressive or generalized vaccinia in immunosuppressed or pregnant subjects, eczema vaccinatum in subjects with a history of chronic skin diseases, occur rarely—approximately 1000 major complications per million first-time vaccinations and 100 per million revaccinations. Approximately one or two deaths per million vaccinations would be expected.

The vaccinia virus also can spread from the vaccination site, and this can produce serious, or fatal, infection in contacts with immunosuppression or skin diseases or in infants younger than 12 months. Vaccinia spread can be prevented by covering the vaccination site with a dressing until the scab falls off; thus, vaccinated hospital personnel may continue working, with daily inspection of the vaccination site and dressing.

Given this background, successful management of smallpox will require quarantine to prevent spread, supportive hospital treatment of the most severe cases to minimize mortality, and aggressive vaccination of hospital personnel and close contacts to prevent secondary spread.

Two thirds of victims can be treated satisfactorily at home or in a minimally equipped quarantine facility, such as a restricted hotel. Family members and home caregivers would have to be vaccinated early and quarantine enforced.

The one third of victims requiring hospital care present a dilemma. Without care many would die, but bringing them into the hospital might expose the hospital’s many immunosuppressed patients to fatal infection. Because the hospital care required by the most severe smallpox infections constitutes a relatively narrow range of hospital services directed at the few causes of death, all the services of a full general hospital are not required.

Consequently, the national CDC recommendation is to designate Specialized Smallpox (Type C) Hospitals with the pre-immunized staff and services needed to manage complicated smallpox cases and thus, keep smallpox patients entirely out of our general hospitals. For this to work, every community must act in advance to designate a graduated series of facilities that could be converted and staffed within 24 hours—one to manage up to, say, 100 patients, another to manage up to 1000 patients, and so on. These could be mothballed hospitals, dialysis centers, motels, or other sites, as long as they have sufficient electricity and other utilities to support the required services. (See www.bt.cdc.gov/agent/smallpox/index.asp for more details.)

Of course, no existing hospital or property owner wants to be named the smallpox hospital, but waiting to select the sites until the first smallpox case shows up would maximize the deaths and economic disruption. Dallas is behind other large cities in designating smallpox hospital sites. An informed medical community must help.

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