Diagnosis

Initial diagnosis of smallpox is most likely based on a history and physical examination findings.

• The doctor may take a throat swab to make the diagnosis of smallpox. A sample from a freshly opened pustule may also be useful in diagnosis. For suspected cases of hemorrhagic smallpox, the doctor may sample fluid from a spinal tap (lumbar puncture). Under certain conditions, cytoplasmic inclusion bodies (also known as Guarnieri bodies) may be visible within the cells. This is also evidence of smallpox infection.
  
  
• Technicians isolate the variola virus in labs with only the highest biosafety levels (Biosafety level IV). The CDC in Atlanta and the US Army Medical Research Institute of Infectious Diseases (USAMRIID) at Ft. Detrick, Maryland, are the only laboratories in the US with these capabilities right now.
  
  
• The doctor sends the possible smallpox sample using special means. Viral cultures, polymerase chain reaction (PCR), and/or enzyme-linked immunoabsorbent assay (ELISA) may be undertaken to make a definitive diagnosis once the sample arrives as the lab.
  
  
• Even one case of smallpox is considered an international public health emergency, and public health officials must be notified of a possible case of smallpox immediately.