Climate change has led to an increased frequency of which two diseases transmitted by insects and ticks in Québec?
In Québec, several diseases transmitted by insects and ticks, including West Nile virus and Lyme disease, have become more frequent in recent years due to climate change. Climate change affects temperature and increases the frequency of extreme weather events, which has numerous impacts on public health. The incidence of most endemic mosquito-borne diseases in Canada has seen an approximate 10% increase over the last two decades, an increase largely attributed to climate change.
Impact on West Nile Virus (Mosquito-Borne)
West Nile virus is transmitted to humans primarily through the bite of an infected mosquito. Climate change is expected to directly impact the factors that contribute to the spread of WNV and other mosquito-borne diseases in Canada:
• Range Expansion and Abundance: It is anticipated that climate change will affect the geographical range and local abundance of mosquito species capable of transmitting pathogens like WNV. Modified weather patterns and ecological shifts associated with climate change are expected to impact the distribution and incidence of these diseases.
• Longer Transmission Season: Warmer temperatures can lead to a longer season for mosquito activity. One hypothesis is that climate change could amplify virus transmission due to a longer vector-biting season. In Ontario, for example, the main vector for WNV (Culex mosquitoes) is most active in warmer temperatures. WNV cases in Canada typically occur during the mosquito season, from summer through fall.
Impact on Lyme Disease (Tick-Borne)
Lyme disease is an infection transmitted to humans and animals through the bite of an infected blacklegged tick. Climate change creates more favourable conditions for these ticks to survive and expand their territory:
• Warmer Temperatures and Tick Activity: Blacklegged ticks can be active and bite as soon as the temperature reaches 4°C. Warmer winter temperatures, an effect of climate change, are a key reason why it is possible to encounter these ticks in more places.
• Geographic Expansion: The sources note that blacklegged ticks are spreading, in part due to climate change. This allows them to establish populations in new areas, increasing the risk of Lyme disease in regions where it was previously less common. While this specific mechanism is mentioned in a source discussing Ontario, the principle of range expansion due to warmer temperatures is a key factor in the increased frequency of Lyme disease across eastern Canada, including Québec.
In summary, climate change facilitates the increased frequency of both West Nile virus and Lyme disease by creating a more hospitable environment for the mosquitoes and ticks that carry them. This leads to an expansion of their geographic range, a greater abundance of these vectors, and a longer season during which they are active and can transmit disease. As a result, public health authorities recommend taking personal protective measures, such as using insect repellent and wearing appropriate clothing, to avoid bites from both mosquitoes and ticks.
What are the two most important biting arthropods that transmit disease in British Columbia?
Mosquitoes and ticks are the two most important biting arthropods that transmit disease in British Columbia (BC).These two groups of arthropods are considered the most significant in BC and worldwide due to the number and severity of diseases they transmit to humans and animals. Nearly every type of blood-feeding arthropod can carry a disease agent, but mosquitoes and ticks are the leading vectors of human disease.
Mosquito-Borne Diseases in BC
In BC, several mosquito-borne diseases are a public health concern. Mosquitoes become infected by feeding on an infected animal, typically a bird, and then pass the virus to humans through a bite.
Key mosquito-borne diseases relevant to BC include:
• West Nile Virus (WNV): While WNV has not been detected in BC, it is considered the greatest risk of vector-borne disease in the province. The virus is endemic in neighbouring jurisdictions like Alberta and Washington State. In Canada, WNV is the leading cause of domestically acquired mosquito-borne disease. It is transmitted mainly by Culex mosquitoes, which are found in BC.
• Western Equine Encephalitis (WEE): Historically, WEE was the most important mosquito-borne disease in Canada. Transmitted by Culex tarsalis mosquitoes, human cases have occurred in BC, though localized outbreaks have been sporadic.
• St. Louis Encephalitis (SLE): This is a rare disease in BC, but antibodies have been found in birds and small mammals in the province, suggesting the virus has circulated there. Culex pipiens and Culex tarsalis are the main vectors.
• California Serogroup (CSG) Viruses: These viruses, such as Jamestown Canyon and snowshoe hare virus, are known to cause human infection in Canada and are transmitted by mosquitoes. Their incidence is expected to increase with climate change.
Tick-Borne Diseases in BC
Ticks are responsible for more human diseases in North America than any other group of arthropods. They attach to people or animals that brush against vegetation in wooded areas, tall grasses, and even city parks.
Key tick-borne diseases relevant to BC include:
• Lyme Disease: This is an infection caused by the bacterium Borrelia burgdorferi and is transmitted by the bite of an infected blacklegged tick (Ixodes pacificus on the Pacific Coast). These ticks are present throughout southern and interior areas of BC, including Vancouver Island, the Gulf Islands, and the Lower Mainland. While the infection rate in BC ticks is lower than in eastern Canada, dozens of locally acquired human cases have been confirmed.
• Tick-borne Relapsing Fever: Caused by the spirochete Borrelia hermsii, this disease is transmitted by the soft tick Ornithodoros hermsi. Approximately 40 cases have been documented in southern BC, particularly in the West Kootenay and Okanagan Valley regions.
• Rocky Mountain Spotted Fever (RMSF): This is the most common fatal tick-borne disease in North America. In BC, it can be transmitted by the Rocky Mountain wood tick (Dermacentor andersoni).
• Tularemia: Also known as “rabbit fever,” this bacterial infection can be transmitted to humans through tick and fly bites, as well as by handling infected animals like rabbits and rodents.
In summary, mosquitoes and ticks are deemed the most important disease vectors in British Columbia due to the range of pathogens they can transmit, the potential severity of the resulting illnesses, and their established presence in the province’s environment.
What are the three major kinds of mosquito-borne encephalitis found in Canada?
Western equine encephalitis (WEE), eastern equine encephalitis (EEE), and St. Louis encephalitis (SLE).
What is the proper technique for removing an attached tick?
Rocky Mountain spotted fever (RMSF).
Besides bites, what are other, less common ways West Nile Virus can be spread?
Blood transfusions, organ transplantation, transplacental transfer, and breastfeeding.