Minnesota Structural Pest Management Conference/Black-Legged tick/Disease Transmission Issues
MPMA Active & Allied Members,
MPMA President Larry Ruflett suggested MPMA distribute questions and answers that because of time may not have been answered during the presentation. MPMA thanks Jeff Hahn and David Neitzel for providing the below information.
1. Is there a certain spot the tick likes to feed on the body? Blacklegged ticks can end up almost anywhere on a person’s body. However, some areas, especially points of clothing constriction (i.e., behind knees, groin, waistline, and arm pits), are frequent attachment sites. Most blacklegged ticks get on to a person near the ground (nymphs within a few inches, adults within a foot or two) and then crawl upwards.
2. If an infected tick bites you , are you infected? No. The tick also needs to feed long enough to transmit the disease agents. For example, Lyme disease bacteria, need about 1-2 days of tick attachment to be transmitted. For anaplasmosis, it takes ½ -1 day.
3. Does all these diseases generally present with the spreading rash first? No. Lyme disease cases usually experience a rash near the onset of the illness. Many other diseases (e.g., anaplasmosis, babesiosis) present with a fever instead of a rash. We suggest that people consult with their doctor if they’ve been out in the woods, especially from mid-May through mid-July, and experience a fever or rash.
4. EPA is slow to register rodenticides with deer mice listed as a target pest even though they are common. Comment? I’m not too familiar with the registration process, so I don’t have specific comments.
5. How accurate are tests for Lyme disease? The tests are actually not too bad when used on folks with an illness that is clinically compatible with Lyme disease. If you develop an expanding Lyme disease rash, your doctor might diagnose you without testing you. This is perfectly fine. The tests usually look for the antibodies that your body produces to fight the bacteria. If you get tested too soon (right after the tick bite or when symptoms are just beginning), sometimes your body has not yet had a chance to create those antibodies. By about one month after symptoms begin most Lyme disease cases have developed measurable antibodies.
6. Have you been involved with any research in using tick tubes? Not directly. However, many years ago I helped a researcher that was looking at other potential ways to deliver permethrin treated cotton balls as mouse nesting material. None of that worked out. There have been other researchers who have demonstrated substantial declines in tick numbers (at the property or neighborhood level) after these tubes were used. It is expensive to do on a larger scale but certainly is a tick control option for a property owner with woods, mice, and ticks.
8. Do tick repellents work? Should we spray our shoes and parts? Repellents containing DEET or permethrin can effectively repel ticks. Permethrin treatments of clothing (especially shoes and pants- down low where the ticks get on a person) are probably the most effective. Ticks are repelled for weeks and may be killed if they contact a treated surface.
9. Why the name change to blacklegged tick? This happened many years ago when scientists determined that the deer tick (Ixodes dammini) was actually the same thing as the blacklegged tick (I. scapularis). The older name was the blacklegged tick, so that’s the one used now.
10. Deet, permethrin, both safe for pets or what products for lawn treatment? There are permethrin formulations often used on dogs as well as some other active ingredients (e.g., fipronil). Permethrin can be used for treatments in the environment. Treatments should focus on areas where people might come into contact with blacklegged ticks. Since these ticks are most common in wooded habitat, treatments can focus on the lawn/woods edge and edges of trails.
11. Are there any correlations MDH has found between Lyme disease and Guillain Barre? No. Untreated Lyme disease can cause some problems in the nervous system. The most commonly reported problem is a Bell’s palsy manifestation (facial droop). Meningitis and encephalitis are also reported.
12. What is the percentage of ticks that carry diseases? It is not all of them and varies by site and time. However, in most MN blacklegged tick populations, at least 1/3 of adult ticks and 1/5 nymphs are infected with Lyme disease bacteria. With all the other disease agents I discussed, the infection prevalence is lower (generally 1-10%). These numbers are substantial and most people don’t have to get too many ticks on them before they get one that’s infected. Luckily prompt removal of infected ticks can prevent the transmission of disease agents.
13. What percentage of the deer mouse population will test positive for one or more pathogen? White-footed mice commonly test positive for one or more pathogens. Remember, this is where the ticks become infected as they feed on these mice. I don’t have any recent data summarizing the percent infected, but it will be substantial in some areas. You mentioned deer mice in your question and for deer mice living in wooded areas, I suspect they’d also have fairly high infection prevalence. Luckily, you aren’t going to become infected by handling any of these mice.
14. How would you treat a farm for ticks? For blacklegged ticks, I’d concentrate acaricide treatments in and near wooded areas where people might come into contact with blacklegged ticks. Much of the agricultural region within the state is too open and dry for blacklegged ticks to survive (e.g., they won’t be living in corn and bean fields). However, farms with large woodlots could support blacklegged ticks. If someone has 80 acres of woods, I don’t tell them to spray permethrin or other acaricides over the entire area. Instead, evaluate which areas are used by people and treat those.
15.Will Deet keep them off of you? Yes, DEET works fairly well but permethrin is probably better (see repellent question above).
MPMA thanks you for your membership and support.
Mike Fresvik, Minnesota Pest Management Association
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October 16, 2018
Minnesota Pest Management Association Board of Directors Meeting
Crooked Pint, Maplewood, MN