With the arrival of 70-degree days in the Washington region, ticks have awakened from their chilly spring torpor to quest for the blood of vertebrate hosts. Bug geeks like me should know better than to wander about the forest in search of solitary bees without taking adequate precautions against hungry ticks. As you probably have guessed, I served up a spring dinner for a tiny lone star tick. No doubt this little rascal ascended my leg and found a nice tight spot to dine where my belt encircled my waist. Ticks often embed at joints of arms and legs or where clothing restricts their upward movement. Unfortunately, I did not discover and remove the tiny bloodsucker until almost 36 hours after it had attached, thereby providing maybe just enough time to transfer a nasty parasite from the tick to my bloodstream. Unlike its cousin the blacklegged tick, Ixodes scapularis, the lone star tick does not vector the dreaded Lyme disease. Lucky me. Unfortunately, lone star ticks transmit several illnesses including Southern Tick Associated Rash Illness (STARI) which has been associated with a bacterium Borrelia lonestari. Symptoms of STARI include a rash, fever, fatigue, and pain in muscles and joints. A second disease spread by the lone star tick is ehrlichiosis. Ehrlichia bacteria produces nasty flu-like symptoms including headache, joint ache, fever, fatigue, muscle ache, confusion, and several other disheartening symptoms. Unlucky me.
The Washington-metropolitan region continues its woes with many ticks and the illnesses they spread. In 2016 Maryland and Virginia made the CDC’s list of top 10 states reporting Lyme disease. The blacklegged tick, Ixodes scapularis, is the carrier of Lyme disease in our area while on the west coast the western blacklegged tick, Ixodes pacificus, is the culprit. Lyme disease can be a serious debilitating disease. In the short-term, flu-like symptoms including headache, fever, and fatigue are sometimes accompanied by an unmistakable bulls-eye rash called erythema migrans. An untreated infection becomes more serious when the bacterium moves to joints, the heart, and the nervous system. The microbe behind Lyme disease is a bacterium called Borrelia burgdorferi. However, several different species of Borrelia and other disease agents are transmitted by blacklegged ticks. In 2016, I removed a partially engorged blacklegged tick from the dark side of my leg and discovered it carried the rarer brother of Borrelia burgdorferi a microbe known as Borrelia miyamotoi. This bacterium produces symptoms similar to Lyme disease including fever, chills, headache, fatigue and pain in joints and muscles. Fortunately, a timely treatment with antibiotics spared me this unpleasant misadventure.
The number of Lyme disease cases rises dramatically in May and June, peaks in July and August, and declines in autumn. However, in many parts of the country, ticks are active even on warm days in winter and Lyme disease is a year-round threat. Ticks are prone to drying out and unusually dry winters are thought to put a dent in their populations. A recent study suggests that milder and moister winters in the Northeast may favor survival of blacklegged ticks. Warmer, more humid conditions may also allow these forest-floor dwelling ticks to move higher up on plants where the chances of encountering people and pets may be greater. Changing climate and a variety of other factors including what hosts ticks feed upon are thought to explain why diseases such as Lyme are more common in northern areas of the US.
What drives boom and bust cycles in populations of blacklegged ticks? One fascinating study found that as populations of small mammals like white-footed mice and chipmunks increased, tick populations also increased. These small forest dwelling mammals are favored hosts for newly hatched larval ticks, but more importantly they are rife with Borrelia and serve as an excellent host for the ticks to acquire this infectious bacterium. Greater abundance of small mammals like mice and chipmunks follow years in which oak trees produce bumper crops of acorns in a phenomenon called masting. However, years of acorn bounty are followed by years of acorn scarcity, leaving behind hordes of hungry Lyme infested ticks to seek blood meals from humans and their pets. Yikes! White-tailed deer are frequently implicated with ticks and Lyme disease; however, researchers found deer to be less important contributors to the risk of Lyme disease than populations of small mammals. When it comes to Lyme disease, blame the mighty mouse and the mighty oak more than Bambi.
Small immature stages of ticks called nymphs will molt and become adults after taking a blood meal. Both stages can transmit diseases to humans. The adult lone star tick running on my arm is so named for the white spot on its back.
To reduce the risks of becoming a meal for a tick and the unfortunate recipient of Lyme disease, STARI, ehrlichiosis, or other tick borne illnesses, remember the word “AIR”. This stands for Avoid, Inspect, and Remove.
“A” - Avoid ticks and their bites in the following ways. When taking Fido for a walk, stick to the path, trail, or pavement. You are unlikely to encounter ticks on non-grassy surfaces. If you enter habitats where wildlife and ticks are suspected, such as grassy meadows, boarders of fields and woodlands, and vegetation along the banks of streams, wear long pants and light colored clothing. This will help you spot ticks on your clothes as they move up your body. Be a geek. Tuck your pant legs into your socks. This forces ticks to move up and over your cloths rather than under them where tasty skin awaits. Apply repellents labeled for use in repelling ticks. Some are applied directly to skin, but others can only be applied to clothing. Don’t forget to treat your footwear, socks, and pant legs. Immature ticks called nymphs are a key vector of Lyme disease and these precautions will help prevent nymphs and adults from attaching to your skin. If repellents are used, be sure to read the label, follow directions carefully, and heed precautions particularly those related to children. If your adventures take you into tick territory, consider placing your cloths directly in a clothes dryer rather than a hamper upon returning home. The heat of the dryer will kill hitchhiking ticks that might otherwise escape clothes in the hamper and cause trouble after your return home.
“I” - Inspect yourself, your family, and your pets thoroughly if you have been in tick habitats. Remember to do this when you return from the outdoors and when taking a shower. A thorough inspection may involve enlisting a helper to view those "hard to see" areas around back.
“R” - Remove ticks promptly if you find them. Removal within the first 24 hours can greatly decrease your risk of contracting a disease. If you find a tick attached, firmly grasp the tick as close to your skin as possible using a pair of fine forceps and slowly, steadily pull the tick out. Cleanse the area with antiseptic. The CDC and the Bug Guy do not recommend methods of tick removal such as smearing the tick with petroleum jelly or scorching its rear end with a match. Cases of Lyme disease are the most common in children and seniors so take special care to keep kids of all ages safe when they play outdoors.
What of the lone star tick that enjoyed a partial fill-up from a careless Bug Guy? If you discover a tick that has embedded in your skin and you wish to determine its identity and discover what disease organisms it might harbor, there are several tick testing services that will identify the tick and perform molecular analysis to determine several important disease agents it may be carrying. After removing my tick and sending it off to a laboratory, I had results of my close encounter with a lone star tick within a week. The little rascal was negative for the causal agents of Lyme disease, relapsing fever, anaplasmosis, Rocky Mountain spotted fever, Pacific Coast tick fever, tularemia, and ehrlichiosis. Lucky me. If your tick tests positive for one or more tick borne disease, consult your physician and develop an action plan. Several tick testing services can be found on the internet by simply googling “Tick Testing Services.” They provide step by step directions to prepare your sample for analysis and where to send it.
Around the home, reduce habitat for small mammals that serve as the blood meal for ticks and the source of disease causing bacteria. Remove piles of brush, unstacked wood, and rubbish that serve as a refuge for rodents and other small mammals. Mow and remove unkempt grasses, weeds, and other vegetation at the edge of the lawn. Mulch beds that border the transition zone between lawn and forest edge. By opening up these areas, raptors and other predators may more easily spot and remove small mammals. Design patios and play areas for children away from forest edges where ticks are more likely to be found. If you follow these precautions, you can greatly reduce the risk of encountering ticks and associated illnesses, while still enjoying the great outdoors.
Bug of the Week thanks Abby Isaacs for providing inspiration for this episode. The great articles “Climate, Deer, Rodents, and Acorns as Determinants of Variation in Lyme-Disease Risk” by Richard S Ostfeld, Charles D Canham, Kelly Oggenfuss, Raymond J Winchcombe, and Felicia Keesing, and “Environmental Factors Affecting Survival of Immature Ixodes scapularis and Implications for Geographical Distribution of Lyme Disease: The Climate/Behavior Hypothesis” by Howard S. Ginsberg, Marisa Albert, Lixis Acevedo, Megan C. Dyer, Isis M. Arsnoe, Jean I. Tsao, Thomas N. Mather, and Roger A. LeBrun were used to prepare this article, as were the following websit:
Learn more about this tick encounter at ABC2 (WMAR Baltimore): Tick Season Has Begun