Health authorities in British Columbia have reported the presence of invasive mosquitoes and a virus that can lead to brain inflammation in humans in the Sea-to-Sky region located north of Vancouver. This discovery followed an investigation initiated by a series of childhood encephalitis cases.
Following three pediatric encephalitis infections in August 2024, researchers embarked on a search for the invasive mosquitoes in the area spanning from Squamish to Pemberton. Anya F. Smith, a senior scientist at the B.C. Centre for Disease Control (BCCDC), confirmed the identification of two mosquito species carrying the California serogroup virus. This group of mosquito-borne viruses is known to cause encephalitis and meningitis in humans.
Among the mosquitoes found to be carrying the virus was the northern house mosquito, originally native to Africa, Asia, and Europe. The virus levels detected were relatively low, preventing the team from pinpointing the specific strain of the California serogroup virus present.
Stefan Iwasawa from the BCCDC emphasized the significance of the study in enhancing preparedness for future infections. He highlighted the potential impact of rising temperatures due to climate change, potentially increasing mosquito exposure. Understanding the mosquito species prevalent in British Columbia and the viruses they can transmit is crucial for readiness, prevention, and response efforts against California serogroup virus infections.
Despite 15 documented cases of the virus in British Columbia between 2009 and 2024, no cases were recorded in the Sea-to-Sky corridor in 2025. The health authorities reassured the public that the risk of severe illness from the California serogroup virus in British Columbia remains low.
