The number of human WNV Illness cases reported in 2002 has been changed from 405 cases (includes both probable and confirmed) to 394.

The change to 394 accurately reflects the number of human cases in 2002. This number has resulted from a concentrated case–by-case epidemiological review of the data collected the first season of human West Nile Virus in Ontario, and is based on the official Health Canada 2002 case definition of West Nile Virus. The re-assessment has been reviewed together with the Public Health Agency of Canada.

The original webpage and its now outdated information reporting 405 WNV cases is available unchanged for reference.

Human cases of WNV recorded for 2002 must meet the "Probable" or "Confirmed" case definition to be included in the statistics provided below.

WNV human case data are provided to the Public Health Branch by the Central Public Health Laboratory (CPHL). The CPHL notifies, in order, the attending physician, the health unit in which the case resides, and the Public Health Branch.

See definitions of "probable" and "confirmed"

The chart below shows probable and confirmed positive West Nile virus tests on humans in Ontario in 2002.

Note :
Public health unit investigators have reported a total of 19 persons with WNv illness who have died, four of these deaths being directly attributed to WNv illness.

The following are the case definitions for "Probable" and "Confirmed" West Nile virus (WNv) cases used by the Ontario Ministry of Health and Long-Term Care in 2002.

Probable Case
A person who has symptoms and history consistent with WNv illness, and who has laboratory tests demonstrating a four-fold or greater change in haemagglutination inhibition or enzyme-linked immunosorbent assay (ELISA) titres in paired acute and convalescent sera.

Confirmed Case
A person who has symptoms and history consistent with WNv illness, and who has laboratory tests demonstrating;

(a) a four-fold or greater change in haemagglutination inhibition or enzyme-linked immunosorbent assay (ELISA) titres in paired acute and convalescent sera with confirmation by a Plaque Reduction Neutralizing Test (PRNT),

or

(b) isolation of WNv from or demonstration of WNv antigen or genomic sequences in tissue, blood, cerebrospinal fluid, or other body fluid. Detection of WNv genome should be shown by at least two different amplification assays that target distinct regions of the viral RNA,

or

(c) demonstration of IgM antibody to WNv in CSF by IgM-capture ELISA with confirmation by a PRNT.

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