May 15, 2020
Black-Legged Tick Nymph - The Unseen Lyme Culprit
Lyme disease is the number one reported vector-borne disease in the United States and the state of Pennsylvania leads the nation in the most reported cases.
By Jason Goetz, Franklin County Mosquito and Tick-Borne Disease Control Specialist
All information for this article was taken from the Centers for Disease Control and the Environmental Protection Agency.
Lyme disease is the number one reported vector-borne disease in the United States and the state of Pennsylvania leads the nation in the most reported cases of this disease. The Black-legged tick, sometimes referred to as the deer tick (Ixodes scapularis), is the vector that transmits Lyme disease to humans. This is why it is so important to understand this species of tick, its life stages and habits, how to prevent tick bites, what to do if you are bitten by a tick, and symptoms of Lyme disease.
Black-legged tick adults and nymphs compared to a dime.
Black-Legged Tick Life Cycle
While understanding the adult Black-legged tick is important, understanding its nymphal stage is equally, if not more important. Ticks are part of the arachnid family and have four life stages (eggs, larvae, nymph, and adult), which typically takes about two years to complete. After emerging from eggs, tick larvae seek out a host to obtain a blood meal. Ticks must take a blood meal in order to molt into their next life stage. Black-legged tick larvae are very small--roughly the size of a pepper flake. The good news about larvae is that they do not transmit Lyme disease at this stage. A Black-legged larva will commonly take its first blood meal from a small rodent such as the white-footed mouse, which is the natural reservoir of a bacterium called Borrelia burgdorferi, the causative agent of Lyme disease). It is at this point that the ticks become infected and carry this bacterium.
After the blood meal as a larva, the tick molts into a nymph. At the nymphal stage, Black-legged ticks are about the size of a poppy seed and are brown in color. Because of their small size, most people do not even realize they have been bitten. This is important to note because according to the CDC, the tick has to be attached for 36 to 48 hours (in most cases) in order for the pathogen to be successfully passed to humans. Since most people do not even know they are being bitten by a nymph, they are not able to remove it quickly and the nymph completes a full blood meal. Centers for Disease Control compiled data that showed confirmed Lyme disease cases in humans start spiking in May and declines in August, with June and July having the highest number of cases. Unlike the adult ticks which are most active from March until May and October through December, nymphal ticks are most active from May until August. This time frame correlates with the months in which human cases are at their highest and also the months where people are most likely to be outdoors. With all of this documentation we can see why the Black-legged tick nymph is the unseen culprit of Lyme disease. So how do we protect ourselves from something we can barely see?
Black-legged Tick Habitat
Before we address what you can do to protect yourself from tick bites, we must understand Black-legged tick habitat. First, think about other preventative products we use, items like sunscreen. We use sunscreen whenever we know that we will be outside during certain times of the year, when we can receive harmful UV rays from the sun. We do not wear sunscreen in our home or in the evening hours because the threat of UV rays is not present. Tick repellent should be used in exactly the same way. We only need to use it when we are entering areas where ticks may be present. The question is: what is an area in which we could encounter a Black-legged tick? We often associate ticks with tall grass and meadows, but the Black-legged tick’s habitat is different. While you may still encounter this tick in tall grass, the more common habitat is in the woods and at the forest edge where grass and woods meet. Black-legged ticks thrive in the woods and areas in and around the forest containing leaf litter, shrubs, and tall or short grasses. Walking through forests or woodlots are prime locations for these ticks. Recognizing the habitat and knowing when you are entering it is the first defense against tick bites.
Prime habitat for both nymph and adult Black-legged ticks.
Repellents and Black-legged Tick Prevention
Now that we know where these ticks dwell, we must know what precautions to take when entering these areas. There are many tick repellent products that are on the market. Regarding these products, it is important to read and follow the instructions on the label, not only for your personal protection, but also to maximize effectiveness. These products can be found in the outdoors section at most retailers and should be approved by the Environmental Protection Agency (EPA) and Center of Disease Control (CDC).
Insect repellents containing DEET are effective at repelling ticks. DEET should be applied each time before entering tick habitat. Like sunscreen, the higher percentage of DEET concentration, the longer time period the product will last. It is important to note that DEET does not kill ticks, it just repels them. DEET products used as directed should not be harmful to use on the skin and clothes, but know DEET can damage synthetic clothing containing plastics.
Another option is products containing 0.5% permethrin. The most common product that contains this active ingredient is Sawyer which is used to treat clothes, but should not be sprayed on skin. Clothes should be placed on an outside line, sprayed, and allowed to dry. The product works when the permethrin makes a strong bond with the fibers in the clothing which can last up to 6 weeks or 6 washings. The permethrin not only deters the tick from climbing on you, but it also kills the tick if one were to grab onto your clothes as you walk by.
The CDC also has recommendations of products containing: Picardian, IR3535, Oil of Lemon Eucalyptus, paramenthane-diol, or 2-undecanone.
In addition to the repellents, there is a certain way we should dress when entering tick habitat. The preferred attire consists of a long sleeve shirt and pants that are light in color. Wearing light colored clothing allows for easier detection of the tick. By having clothing covering as much of the skin as possible, ticks have a smaller selection of areas in which to bite. It is also a good idea to tuck your clothing in wherever possible (shirt into pants, pants into socks). By eliminating gaps in the clothing, you can further mitigate the chance of a tick coming in contact with your skin.
After returning from tick habitat there are additional steps you can take to further prevent a bite. Remove your clothes immediately after returning home and place them in the dryer for 10 minutes on high heat. This step will kill any ticks that may be on your clothes. Take a shower as soon as possible and check your body, paying particular attention to areas in and around the hair, ears, armpits, inside the belly button, around the waist, groin area, and back of knees.
Black-legged Tick Bites and Symptoms of Lyme Disease
If you know you are being bit by a deer tick, remove it as soon as possible. The less time a tick is attached to you, the lower the chances that the bacteria that causes Lyme disease will be transferred. Use fine point tweezers and grab the tick as close to its head as possible. With a steady motion, pull the tick away from the skin and cleanse the area with rubbing alcohol or soap and water.
The most common symptom of Lyme disease is the bullseye rash around the tick bite, yet the rash only occurs in 70% of patients. Other symptoms include fatigue, chills, fever, headache, muscle and joint pain, and swollen lymph nodes. It is recommended that if any of these symptoms develop after a tick bite to contact your medical provider.
Deer Ticks Around Your Home
Many people are curious about ticks around their home and property. It is important to remember that deer ticks need a certain habitat in order to survive. If your house is near a wooded area, harbors leaf litter, shrubs, and taller grasses, there is a possibility that ticks may be on your property. Well-manicured lawns most likely will not harbor any ticks. If you are concerned about ticks at your home and property, you can drag a white piece of felt or sheet along your yard, flower beds, and vegetation to see if there is a population. Ticks will grab onto the sheet as you drag it over thinking it is a host they can extract a blood meal from. Visit the CDC website for more information on keeping your property tick free. https://www.cdc.gov/ticks/
If you are going to enter tick habitat this year it is important to remember the necessary precautions to take in order to prevent bites. Remember Black-legged tick nymphs are very hard to see so a tick check after returning home may not always be adequate. For more information regarding ticks and tick-borne disease visit the Centers for Disease Control’s website at www.cdc.gov, the Environmental Protection Agency’s website at www.epa.gov, or contact Franklin County Planning Department at (717)-264-4125.
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