West Nile Virus and your backyard

Photo: istockphoto.com/Robert Simon
West Nile virus has slowly been on the rise in parts of the U.S. and Canada. Do we need to be worried about mosquitoes and the water features in our garden? Mild symptoms for the average person Most people infected with West Nile Virus either won't get sick at all or will develop mild flu-like symptoms. Seriously ill people should be more cautious since they may experience a severe reaction that starts off with the rapid onset of a severe headache followed by high fever, stiff neck, nausea, difficulty swallowing, vomiting, drowsiness and, confusion. Likewise anyone with a weakened immune system should be careful since they are at risk for developing serious symptoms like meningitis, encephalitis and acute flaccid paralysis. Media hype Public misconceptions, dramatic media coverage and inaccurate reports have many people worried about standing water, especially gardeners who have incorporated pools and fountains into their outdoor designs. Understanding the habits and lifecycle of the mosquito may help not only relax but know where there is a legitimate threat of West Nile. Know thy enemy Mosquito larva live in shallow, still water. They can't breathe underwater and so rely on a small breathing tube on their posterior. In still waters the larva can simply push its tube through the surface. Moving water makes it almost impossible for get their tube through the surface. As a result, larva will drown. Mosquitoes instinctively avoid water with constant movement and the amount of movement required is almost negligible. Any backyard water feature with a fountain, spitter, waterfall or even just a pump to circulate water will not be attractive to mosquitoes. So go ahead and enjoy them -- most are perfectly safe. Water fixes If you have a pond without moving water, it's a simple matter to buy a pump for some kind of slight movement. It's a worthwhile investment anyway, as they'll only enhance the appeal of your pond. Another alternative is to add a few Koi ornamental fish to the pond. Fish feed on mosquito larva as well as the mosquitoes as they lay their eggs. Just don't feed the fish and this should keep them eating naturally. Birdbaths can become fertile breeding ground for mosquitoes so the water should be changed weekly. Hot wet spots Rain barrels are probably the most attractive mosquito breeding grounds typically found in a garden. The water is stagnant and still, there are plenty of rich nutrients for the larva to feed on and there are no natural predators to prey. To prevent an infestation, barrel tops should be covered with a very fine mesh to keep out both debris and, more importantly, mosquitoes. If your barrel doesn't have a lid, it's easy enough to fashion one on your own -- just a long as it's covered. It's hard to overstate how important this is; rain barrels are essentially petrie dishes for West Nile Virus. Any other places where stagnant water accumulates in your yard, such as ditches, wading pools, buckets or containers, should be drained as soon as possible. How is your neighbourhood? The Centers for Disease Control and Prevention (CDC) has a regularly updated West Nile Virus Activity report showing the current U.S. hot spots. During the season (May to October), the Foodborne Waterborne and Zoonotic Infections Division, Centre for Infectious Disease Prevention and Control (CIDPC), produces weekly West Nile Virus MONITOR reports and maps, summarizing West Nile Virus activity in Canada. If your area is reported as being a hot spot for West Nile then be sure to use an effective mosquito repellant and go indoors at dusk. Rest easy Follow the above measures and your can relax, knowing you've protected your family from West Nile Virus. While it's good to be cautious, don't let the threat of the virus stop you from enjoying the water features in your garden. Andrew Hind is a freelance writer specializing in eco-friendly gardening.