Q Do turkeys carry the deer tick? While growing up, I remember visiting a turkey farm and we had to check for ticks when we got out. We are concerned now because a large flock of wild turkeys visits our yard several times a day to eat the seed that spills from our bird feeders.

A It's not likely that wild turkeys in this region will lead to an increased abundance of the black-legged (deer) tick, or increased risk of human Lyme disease.

Although black-legged tick larvae (the first stage out of the egg) do feed on ground-inhabiting birds, small mammals are the preferred hosts on which tick populations build. An experimental study in New York found larval ticks released onto turkeys disappeared and presumably died rather than feed and develop. So turkeys might actually reduce the abundance of black-legged ticks.

As to your childhood memory of visiting a turkey farm in Minnesota, it's more likely that the concern was poultry lice or mites. They occasionally occur in chickens and turkeys, especially in winter, but it is rare. Lice are insects, and mites are arachnids (related to spiders). Both poultry lice and mites can crawl onto the skin of people who handle infested birds. People may suffer temporary itching and skin irritation, but these poultry organisms cannot live on the skin of humans.

From Roger Moon, veterinary entomology, University of Minnesota, and Dr. Rob Porter, poultry pathologist, University of Minnesota.

UV life span

Q I purchased a new furnace two years ago, including an air purifier that works with UV lights. The air purifier manual recommends replacing the UV bulbs once a year. Both lights are still working today after two years. Do UV lights lose their effectiveness over time?  Do I really need to change the bulbs annually?

A Probably. It's preventive maintenance. As these lamps operate, they lose 15 to 20 percent (and as much as 50 percent) of their capacity within the first 1,000 to 2,000 hours of burning time. Certainly, a lamp may burn for years without failing, but unless the output is checked, it would be difficult to say whether it is still producing the minimum irradiance it was selected to deliver. New lamps every year will help to ensure that they are producing the intended amount of UV energy -- and the cost of annual replacement is not excessive.

William Bahnfleth, Indoor Environment Center, Penn State, University Park, Pa.

Send your questions to Fixit in care of the Star Tribune, 425 Portland Av. S., Minneapolis, MN 55488, or call 612-673-7032, or e-mail fixit@startribune.com. Sorry, Fixit cannot supply individual replies.