Cardinal Signs for Case Detection

The information below covers anthrax, smallpox, botulism and plague.

In a previously healthy person any of the following four clinical presentations requires urgent attention

1. Inhalational (Pulmonary) Anthrax and Plague

-Rapid onset severe sepsis with respiratory failure, not due to a predisposing illness

-Sudden, severe, unexplained febrile illness or febrile death

Note: cardinal sign for anthrax is mediastinal widening on Chest X-Ray (see anthrax Image 1)

2. Cutaneous Anthrax

-Commonly affects hands, forearms, neck and head (see anthrax Images 2-5)

-Cardinal feature is painless swelling of skin

-Originally a small bump which then ulcerates and becomes weepy

-Pronounced swelling (oedema of skin) frequently surrounds the lesion (see anthrax Image 6)

-Ulcer develops a black centre in 2-6 days

For Microbiologists, the unexpected finding of non-motile Gram-positive bacilli in normally sterile fluids or from a wound, requires urgent consideration of the possibility of B. anthracis.

3. Botulism

-Acute onset of bilateral cranial nerve involvement.

-Descending weakness or paralysis which may extend to complete flaccid paralysis, but patient remains alert.

-Fever is unusual, as is loss of sensation.

4. Smallpox

In the event of a deliberate release in the UK population (mostly non-immune), it is extremely unlikely that single, mild cases of feverish, pox-like illness will occur - it is much more likely that clusters of cases of moderate to severe disease would be seen, with:

-An abrupt onset moderate fever (up to 39ºC), with extreme prostration.

-Characteristic vesicular rash most dense on the extremities and face beginning on the third to fourth day of illness. (See smallpox clinical images).

-Skin lesions over one area of body generally at the same stage of development. New and enlarging vesicles coalesce to form soft, flaccid bullae covered by skin, which easily rubs off.

-Less commonly, an erythematous or purpuric rash may appear earlier in illness (associated with a poorer prognosis).

If a patient presents with any of these, expert clinical opinion should be sought urgently. In addition in England, Wales and Northern Ireland the local HPU Consultant in Communicable Disease Control (or their counterpart in Scotland) and the HPA Duty Doctor (020 8200 6868) should also be contacted urgently and given details. In Scotland the Health Protection Scotland (0141 300 1100) should be contacted.

Links to more detailed descriptions and pictures are available from the disease specific page

Also see

Guidance for the Initial Investigation and Management of Outbreaks and Incidents of Unusual Illness

Cardinal Signs and Tips (PDF, 171 KB)
Unusual Illness, including Deliberate or Accidental Releases: Cardinal Signs and Tips for key Biological Agents v2.2 Feb 2011

Suspect Packages

Category A Matrix

Last reviewed: 15 March 2012