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Introduction ⬇

Smallpox, an infectious disease caused by the variola virus, was once worldwide in scope; however, vaccination has all but eliminated the virus, with the exception of existence of the variola virus in laboratory reserves. Since 2001, concerns about its use as a biologic weapon have prompted medical and public healthcare professionals to make recommendations for steps to be taken in case of exposure and outbreak. There are two principal forms of smallpox: variola minor and variola major. Smallpox is spread from person to person by means of coughing; direct contact; or contaminated clothing, bedding, or infected bodily fluids. A person sometimes is infectious to others at the onset of fever but is always infectious to others by the time of rash onset until smallpox scabs have completely disappeared. This test is used to determine the presence of the DNA virus responsible for smallpox.

Procedure ⬆ ⬇

  1. Open skin lesions with a blunt instrument (e.g., blunt edge of a scalpel) and collect the vesicular or pustular fluid on a cotton swab.

  2. Remove scabs with a forceps; they can also be used.

  3. Place specimens in a Vacutainer tube; restopper and seal it with adhesive tape.

  4. Place the Vacutainer tube in a durable, watertight container for transport.

  5. Ensure that the laboratory examining the specimens is a biosafety level 4 laboratory.

  6. Confirm smallpox infection by the appearance of brick-shaped virions under the electron microscope.

  7. Definitive laboratory identification requires growth of the virus in cell culture.

  8. Use a cotton swab to obtain specimens from the oral cavity or oropharynx if necessary.

Procedural Alert

  1. Observe airborne precautions (i.e., gloves, gowns, and N95 or equivalent mask should be worn by laboratory personnel). Place patient in a negative pressure room and keep door closed at all times. All laundry and waste should be transported in biohazard bags and autoclaved before being laundered or incinerated.

  2. Specimen collection and examination should be performed by laboratory personnel who have recently been vaccinated.

  3. All surfaces should be cleaned with bleach or quaternary ammonia.

Clinical Implications ⬆ ⬇

  1. Evidence of virions or Guarnieri bodies indicates presence of smallpox infection.

  2. High levels of antibodies indicate infection.

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain the purpose, procedure, and risks of obtaining a specimen. Assess for and document signs and symptoms of infection (chills, high fever, backache, pustules that leave a pockmark).

  2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Isolate (airborne precautions) the individual immediately if the smallpox virus is identified.

  2. Report signs and symptoms.

  3. Smallpox vaccination within 3 days after exposure may prevent or significantly decrease severity of symptoms. After 3 days and up to 7 days after exposure, vaccination offers some protection or may modify infection severity. Adverse effects range from mild and self-limited to severe and life-threatening events.

  4. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Clinical Alert

  1. A confirmed case of smallpox should be reported to local, state, and federal health authorities.

  2. Because there are no antiviral drugs for smallpox, supportive therapy and antibiotic drugs for secondary bacterial infections should be offered to the patient.

  3. Household members should be vaccinated and monitored closely.

Reference Values ⬆

Normal

No Guarnieri bodies isolated in scrapings of skin lesions

Absence of brick-shaped virions (i.e., variola virus) by electron microscopy

Low levels of neutralizing, hemagglutinin-inhibiting, or complement-fixing antibodies