Results of a West Nile virus seroprevalence survey, South Oakville, Ontario, 2003

摘要: This report outlines the main results from the West Nile virus (WNv) seroprevalence study undertaken by the McMaster Institute of Environment and Health for the Ontario Ministry of Health and Long Term Care. The primary objective of this study was to estimate the number of people living in south Oakville in the summer of 2002 who were infected by West Nile virus. This estimate was determined by measuring the seroprevalence of West Nile virus (WNv) antibody among study participants. In addition, the study also examined the risk factors associated with infection by WNv in the south Oakville WNv hotspot (forward sortation postal code areas L6L and L6K) by assessing levels of knowledge, beliefs and attitudes about WNv in the community as well as measuring certain behaviours associated with risk reduction for WNv. West Nile virus is a mosquito-borne flavivirus that primarily infects birds, producing a transient high viraemia that allows transmission of the virus back to feeding mosquitoes in an amplifying cycle. Humans can become infected by bites from mosquitoes that bite both birds and us. Factors that determine the prevalence and severity of illness are not well understood. WNv was recently introduced to North America, where it was first detected during an epidemic of encephalitis in the summer of 1999 in Queens, New York. Evidence that WNv had arrived in Canada came in the summer of 2001 when active surveillance of the avian population indicated that several dead crows in southern Ontario tested positive for the virus. No human cases occurred in Ontario until 2002. Ontario had 319 confirmed and 86 probable human cases that …