Category A Definition and Examples

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Category A Definition and Examples

A category A infectious substance is in a form that is capable of causing permanent disability or life-threatening or fatal disease in otherwise healthy humans or animals when exposure to it occurs. Exposure would occur if the substance were released from its protective packaging and a human or animal came into contact with it.

Some examples of category A infectious substances are listed below. A more comprehensive list is included as a PDF attachment on this page.

  • Bacillus anthracis (cultures only)
  • Brucella abortus (cultures only)
  • Brucella melitensis (cultures only)
  • Burkholderia mallei (cultures only)
  • Clostridium botulinum (cultures only)
  • Creutzfeldt-Jakob disease (CJD) brain tissue specimens
  • Dengue virus (cultures only)
  • Escherichia coli, verotoxigenic (cultures only)
  • Ebola virus
  • Francisella tularensis (cultures only)
  • Hantaviruses causing hemorrhagic fever with renal syndrome
  • Herpes B virus (cultures only)
  • Human immunodeficiency virus (cultures only)
  • Lassa virus
  • Mycobacterium tuberculosis (cultures only)
  • Poliovirus (cultures only)
  • Rabies and other lyssaviruses (culture only)
  • Shigella dysenteriae type I (cultures only)
  • West Nile virus (cultures only)
  • Yersinia pestis (cultures only)

New and emerging pathogens should also be classified as category A until or unless additional information is received to move them to category B. For example, in 2009, shipments of Influenza A 2009 H1N1 subtype specimens were initially placed into category A until sufficient information allowed them to be moved to category B.

This is not an exhaustive list. Sometimes deciding on the classification of an infectious substance requires professional judgement and involves knowing the medical history or symptoms of the source patient or animal and/or knowing the local epidemiological conditions at the time the patient specimen or culture was obtained.

If there is doubt as to whether or not a substance meets the criteria of category A, it must be treated as a category A substance for shipping.