West Nile Virus: A Pesty Subject

Maybe nothing causes more dismay to a person on the brink of sleep than the persistant, zzzzzzzz of a mosquito near their ear. Every camper, hiker, and sunset watcher has something in common – hatred for public enemy number one, the mosquito.

Mosquitos are responsible for malaria, dengue, many forms of encephalitis, as well as passing the Zika virus and the West Nile virus onto humans.

Mosquito borne illnesses cause close to one million deaths annually and affect almost 700 million people globally.

With climate change a reality, West Nile Virus (WNV) has become endemic in North America. Mosquitoes thrive in the weather conditions Ontario and the rest of North America is experiencing.

Continued rain and rising water levels along with pools of stagnant water provide a perfect cradle for mosquito larvae to breed.

Outside workers who work in areas when mosquitos are present are at risk of being bitten from the potentially virus carrying pest including, farmers, foresters, landscapers, groundskeepers and gardeners. Also at risk are painters, roofers, pavers, construction workers, labourers, mechanics, entomologists and other field workers who conduct surveillance and other research activities outdoors.IMG_1008

It’s not only outside workers that are at risk. When performing diagnostics for the West Nile Virus, medical or laboratory workers may also be at risk of infection if they are accidently stuck while testing for the virus or sustain a cut while handling infected tissue.

Organizations and employers that have workers who may be at risk of being bitten must develop and maintain a program that will minimize the risk to workers from contracting WNV. Ministry of Labour Inspectors are informed of WNV and proactively inspect sectors where workers may be exposed to the Virus. That includes golf courses, parks, farms, recreational facilities and other workplaces where mosquitoes are present or water can collect and become a breeding ground for the rapacious pest.

Because mosquitos need a standing body of water for larvae to develop into mature insects, stagnant pools that can found in troughs, ditches, rain barrels, ponds, and tires, must be emptied at least every 4-5 days, or treated with larvicides to reduce the mosquito population.

A WNV Policy and Program to protect workers must include measures and procedures, and workers must be trained in the employer’s steps to protect them.

For outside workers at low risk, a program that informs workers of the risks in addition to insect repellant provided by the employer might suffice. For others, a more comprehensive program is in order.

In Ontario, any WNV program should run during the time that mosquitoes are most likely to be active – usually from July to September and from dusk to dawn. But, as hikers and outside workers know all too well, mosquitoes are also active in the woods, fields or meadows at any time of day if there is sufficient foliage. Covering all parts of the body is a partial solution. In hot humid weather, it could cause another problem – heat stress. Therefore a workplace program must take into consideration all likely outcomes of their decision.

If you are a worker, or employ workers who might be at risk of being bitten by a mosquito, ensure you have performed an assessment of the risk then develop or review your WNV Policy and Program. If you have a Joint Health and Safety Committee, it would be wise to involve them in the process from the beginning.

Date your policy, and have the highest level person in the organization sign off. Ensure all workers are informed of the policy and program and are trained in the steps being taken to protect them from West Nile Virus.

As always, more information can be found on the Centre for Disease Control Website as well as the Ontario Ministry of Labour.

Contact Gloria Bergen if you want assistance with any health and safety policy or program.