PREVENTING LARVAL DEVELOPMENT OF MOSQUITOES TO FIGHT WEST NILE VIRUS
In this year of heavy rain and the proliferation of mosquitoes across Canada, the first cases of West Nile Virus (WNV) have just been confirmed in the country.
WNV is transmitted to humans mainly through the bite of a mosquito carrying the virus. Mosquitoes usually become carriers of the virus by biting an infected bird. WNV mainly infects birds, but sometimes also humans or other animal species, such as horses.
In North America, the first human case of WNV infection was reported in 1999 in the New York State. In Canada, we have been monitoring its evolution since 2002. For 20 years, a minimum of 5 cases have been recorded, with a peak per year of 2,401 cases in 2007. Contaminations are not linear, but we estimate that they are underestimated since many patients remain asymptomatic. These cases are estimated at nearly 80%. The symptoms of the virus are multiple. We notice severe and unusual headaches, high fever, stiff neck, confusion, muscle weakness, gastrointestinal problems, redness on the skin with pimples, and swollen lymph nodes.
While research is still underway to assess the mortality risks linked to the virus, we know that it can be fatal in the short, medium and long term. In 2016, researchers presented their research findings at the American Society of Tropical Medicine and Hygiene (ASTMH) annual conference. In a study group of 4,144 people who contracted this disease in Texas between 2002 and 2012, 286 patients died in the first 3 months, 286 died in the 10 years that followed due to complications linked to the disease.
To effectively fight the proliferation of the virus, the first thing to do is to prevent the larval development of mosquitoes. To do this, we must make basic rules habitual and instinctive: empty and dry old tires, children’s toys, paddling pools, clean gutters regularly, tilt fishing boats and equipment on their side to empty them, change regularly water animals in outdoor dishes and monitor rainwater collection trays and other flowerpots. However, doing this will not be enough to prevent the presence of mosquitoes. For years, many municipalities across Canada have undertaken the deployment of responsible mosquito abatement programs.
In Quebec, Ontario and the Maritimes, G.D.G. Environnement specializes in the integrated management of mosquito nuisance.
QUEBEC HONORABLY DISTINGUISHES ITSELF BY FOCUSING ON A 100% ORGANIC APPROACH.
In Quebec, each program must receive approval from the Ministry of the Environnement, de la Lutte contre les Changements Climatiques, de la Faune et des Parcs. The Wildlife Department also analyzes the possible impacts of treatments and applies, where appropriate, mitigation measures in accordance with the sensitivity of the intervention environments or larval development sites. It is the point of balance between issues associated with public health, human well-being and the protection and conservation of wildlife and the environment. The approach is prudent and ensures that municipal officials can work with organic solutions with peace of mind.
COLLECTIVE PROGRAMS OF NUISANCE INTEGRATED MANAGEMENT.
When we talk about integrated management, we are not simply talking about targeted larviciding treatments but about complete programs, which include the analysis of the territory, its characterization, and the determination of the best applicable solutions to the particular nuisance problems of the targeted sector. All this is enhanced by a communication plan that allows all citizens to understand the ecological program, inviting them to participate by cleaning objects containing water in their backyard to reduce the nuisance coming from artificial breeding sites. Additional control is sometimes prescribed and based on installing urban or peripheral trapping terminals.
TRAPPING POINTS TO IDENTIFY AND ASSESS SPECIES.
The installation of these trapping terminals initially allows us to identify the species present in the territory and detect the pathogens (Vno, EEE, and VSC) that these vectors can transmit. Furthermore, these terminals, when deployed as barriers, can be used to control adult mosquito populations in certain areas. Finally, the analyses are carried out in our laboratory, which is dedicated to species identification and virus detection (RT-PCR). Our facilities are certified by the National Microbiology Laboratory (Viral Zoonoses) of Health Canada.
THE BEST MEANS OF MOSQUITO CONTROL REMAINS TARGETING LARVAL POPULATIONS.
After 40 years of field study, biologists at GDG are unanimous that the best means for mosquito population reduction remains larval control. The collective program is the most logical approach because it targets the problem at the source, considering that the larvae are confined to ponds, which represent a very small percentage of the municipality’s territory. Once adults, the mosquito problem is completely different and no means of control can effectively reduce the nuisance. On this condition, we can reduce the negative effects of mosquito bites and thus limit the transmission of the Nile Virus and other transmitted pathogens.