Case Definition
Clinical evidence of illness1 occurring when and where transmission is likely with laboratory confirmation of infection by one of the following methods:
- Detection of Jamestown Canyon (JC), Snowshoe Hare (SSH), or other California serogroup viruses (e.g. LaCrosse) viral nucleic acid (e.g., PCR) in an appropriate clinical specimen (e.g. blood, cerebral spinal fluid (CSF)).
- Fourfold or greater rise in virus-specific plaque-reduction neutralization test (PRNT) antibody titres detected in paired sera (acute and convalescent-phase sera ideally collected at least 2 weeks apart).
- Virus-specific IgM antibodies in a CSF sample AND a PRNT antibody titre of ≥ 1:20 in serum.
Clinical evidence of illness1 occurring when and where transmission is likely.
AND
Virus-specific IgM antibodies in serum.
AND
Virus-specific PRNT antibody titres of ≥ 1:20 in a single serum specimen.
1Clinical illness is characterized by a febrile illness of variable severity, which can include neuroinvasive disease such as meningitis and/or encephalitis. Signs and symptoms can include fever, chills, headaches, myalgia, arthralgia, fatigue, nausea, diarrhea, vomiting, abdominal pain, rash, stiff neck, confusion or altered sensorium, visual disorders, altered reflexes, abnormal movements, seizures, and coma.
