Confirmed Case

Clinical illness with laboratory confirmation of infection:

• Isolation of Francisella tularensis in an appropriate clinical specimen OR
• Fourfold or greater change in serum antibody titre to F. tularensis antigen OR
• Detection of F. tularensis nucleic acid by polymerase chain reaction (PCR) or sequence-based analysis

Probable Case

Clinical illness with laboratory evidence:

• Detection of F. tularensis in a clinical specimen by fluorescent assay OR
• >1:128 microagglutination titre or >1:160 tube agglutination in a single serum specimen

Definition of clinical illness

Clinical illness is characterized by several distinct forms, including the following:

• ulceroglandular – cutaneous ulcer with regional lymphadenopathy;
• glandular – regional lymphadenopathy with no ulcer;
• oculoglandular – conjunctivitis with preauricular lymphadenopathy;
• oropharyngeal – stomatitis or pharyngitis, or tonsillitis and cervical lymphadenopathy;
• intestinal – intestinal pain, vomiting, and diarrhea;
• pneumonic – primary pleuropulmonary disease; typhoidal – febrile illness without early localizing signs and symptoms.

Clinical diagnosis is supported by evidence or history of a tick or deerfly bite, exposure to the tissues of a mammalian host of Francisella tularensis, or exposure to potentially contaminated water.