Gardeners At Greater Risk for West Nile Virus

by C. Rae Hozer,  Cumberland County Master Gardener

Tennessee may see a big spike in West Nile Virus (WNV) cases in 2009. In summers with plentiful rainfall and in places where flooding has occurred, mosquito populations sharply increase. When their numbers are higher, the odds of getting a bite from an infected mosquito go up as well. It only takes one mosquito bite to make you sick.

However, those in-the-know can take steps to protect themselves from West Nile illnesses and to rid their property of mosquito breeding places. The Centers for Disease Control and Prevention (CDC) West Nile web page www.CDC.gov/westnile/ is the place to learn how to better “Fight the Bite”. (That logo and the “West Nile Virus Transmission Cycle” graphic appear here with permission of the Centers for Disease Control and Prevention.)

Plateau Gardeners are at higher risk of mosquito-borne infection if 50 or older, outside unprotected at dusk through early morning hours when mosquitoes are most likely to bite, if they don’t drain or treat standing water where mosquitoes can breed and if there are woods, shrubs, dense vegetation and drainage ditches where mosquitoes hide in daytime nearby. 

Usually a bite by a mosquito infected with West Nile Virus (WNV) results in no symptoms or only moderate discomfort from a fever, headaches, body aches, nausea or vomiting. More serious WNV problems involve inflammation of the brain and central nervous system that can cause encephalitis, meningitis or a West Nile polio-like paralysis.

Older people are at higher risk for severe infections or death as a result of WNV infection but young, healthy and active adults working and exercising outdoors may also suffer extreme West Nile illnesses. The first United States WNV cases were reported in New York in 1999. Tennessee Department of Health statistics say 2002 was our states worst year (fifty-six human WNV cases with six deaths). One WNV fatality that year was seventeen years old.

Remember the first line of WNV defense—Avoid mosquito bites. That’s especially important for those working outdoors in late afternoon or early evening and who like to stand, hose nozzle in hand, spraying their plants in the morning. Working when it’s cool is better heat-wise for the gardener in sizzling hot summer weather but that’s also when mosquitoes are out looking for blood. Keep your insect repellent handy and use it before going outside.  

Remember the second WNV defense—Mosquito-proof your home and property. Mosquitoes need water to breed. Mosquito eggs hatch in larval form. Then larvae mature becoming winged adults. The females fly in search of a blood meal so they can lay eggs. The cycle takes just a few days. Mosquitoes lay eggs in any container of standing water. These pests could be breeding in your backyard. Empty rainwater from buckets, wheel barrows, or unused flower pots. Since mosquitoes breed in very shallow water and need only a few days to mature, even puddles in folds on your bar-b-cue grill cover should be drained. Lakes/reservoirs, ponds, marshes—any permanent bodies of still water are potential mosquito breeding spots. Bacillus thuringiensis israeliensis (Bti) is a biologic control that kills mosquito larvae. Mosquito Dunks contain Bti. Dunks are doughnut-shaped and float. Use them in birdbaths and uncovered rain barrels. Gold fish and Koi eat insect larvae. No additional mosquito-control treatment is needed in a water garden or garden pond containing fish.

Plateau Gardening is written by Master Gardeners for those tending home landscapes and gardens in Tennessee’s Upper Cumberland Region. Contact UT Extension Cumberland County, P.O. Box 483, Crossville, TN 38557, (phone 931-484-6743) for quick answers to specific questions, free publications, or to learn about becoming a Master Gardener. Email comments or yard and garden inquiries to Master Gardener Rae, mgardenerrae@frontiernet.net.