It's important to learn about Lyme disease prevention and transmission, especially as the warm weather approaches.
Lyme disease is the most common and fastest-growing tick-borne illness in the United States. Some people associate the geographic location of Lyme disease as specific to the Eastern United States, particularly the woods of New England, but that perception is outdated. Thanks to climate change and other factors, these days Lyme is in every state except Hawaii, and in many countries abroad. There are more than 476,000 Lyme disease cases reported in the U.S. each year. Anyone who participates in outdoor activities should be concerned about tick bites. Let’s walk through different tick species, what percentage of them carry Lyme disease, and what symptoms of Lyme disease you should be on the lookout for.
What Are Ticks?
Ticks are arachnids with eight legs. They can be as tiny as a poppyseed or sesame seed, and you might mistake them for a fleck of dirt or not even notice them at all. There are several different kinds of ticks. Black-legged ticks, also known as deer ticks (Ixodes scapularis in the Eastern U.S. and Ixodes pacificus in the Western U.S.) are the only type of tick that carries Lyme disease. Other types of ticks carry other diseases. (Click here for additional information, including a table of ticks, what they look like, and the diseases they can transmit)
Ticks like most, shady spots. Tick-infested areas include wooded areas, leaf litter, tall grass, beach grass, stone walls, areas planted with pachysandra or other ground covers, and perimeters where the lawn meets the woods. Peak tick season is during the warmer months, April through September, but ticks are active year-round and can survive in below-freezing temperatures.
Ticks have a four-stage life cycle: egg, larva, nymph, and adult ticks. Nymphs and adult ticks transmit Borrelia burgdorferi, the Lyme disease bacterium. During their two-to-three year life cycle, ticks feed on hosts such as white-tailed deer, white-footed mice, shrews, chipmunks, ground feeding birds, and many other small mammals. When they pick up Borrelia burgdorferi from these hosts, ticks become carriers of the Lyme disease pathogen. They can then transmit the bacterium Borrelia burgdorferi to the next host they bite, which could be you. (Click here for more information on the tick life cycle)
Lyme Disease and its Transmission
When a black-legged tick bites a host, it feeds—getting a blood meal—for several days. During this time, it can transmit Borrelia burgdorferi and other pathogens to the host. The transmission doesn’t happen right away. The pathogens have to make their way from the tick’s gut to the salivary glands, and then through the tick’s saliva into your skin. As the tick feeds, it fills with blood, making its body engorged. The more engorged a tick is, the longer it’s been on you and the more likely it’s transmitted the Lyme bacteria or other pathogens. Transmission of Borrelia burgdorferi usually happens between 24-48 hours of an infected tick being attached, but it can happen sooner. (It can also be hard to know exactly how long a tick has been attached to you.) Other pathogens can be transmitted much more quickly; Powassan virus can be transmitted in 15 minutes.
Lyme borreliosis is best treated if it is caught early, so if you have a known tick bite or suspect one, see your healthcare provider right away. You might notice an erythema migrans rash, often called a bullseye, but not all Lyme rashes are shaped like a bullseye and not everyone gets a rash. Other early symptoms of Lyme include flu-like symptoms such as joint pain, fever, fatigue, aches, chills, and swollen lymph nodes. If Lyme is not diagnosed and treated right away, the bacteria can spread to other parts of the body like the nervous system and heart. Symptoms can include severe headache and neck stiffness, Lyme arthritis, muscle aches and joint pains, facial paralysis, heart palpitations or shortness of breath (Lyme carditis), numbness or tingling in the hands and feet, and severe extreme fatigue. At its latest stage, Lyme can cause cognitive impairment including vertigo or dizziness, difficulty sleeping, brain fog, difficulty following conversations, and difficulty processing information.
Current laboratory testing for Lyme disease is faulty because it only looks for antibodies against the Lyme bacteria, not for the bacteria itself. You can easily get a false negative test, so your doctor should make a clinical diagnosis of Lyme based on your symptoms and tick exposure.
"...anywhere from less than 1% to more than 50% of black-legged ticks are infected with Borrelia burgdorferi . Many are infected with other pathogens in addition to or instead of Borrelia burgdorferi ."
What Percentage of Ticks Carry Lyme Disease?
Not all black-legged ticks carry the Lyme disease bacteria. Challenges and limitations exist in estimating tick infection rates, but depending on the geographic location, anywhere from less than 1% to more than 50% of black-legged ticks are infected with Borrelia burgdorferi. Many are infected with other pathogens in addition to or instead of Borrelia burgdorferi.
Other Tick-Borne Diseases
Lyme is not the only disease that black-legged ticks can carry. They also can transmit relapsing fever, Powassan encephalitis, babesiosis, human granulocytic anaplasmosis (HGA), and tick-borne encephalitis. Some of these tick-borne diseases (co-infections) require different treatment than Lyme disease, so it’s important that you be evaluated for other tick-borne diseases, not just Lyme, if you are bitten by a black-legged tick. You can get one of these tick-borne diseases without getting Lyme disease, too. And if you’re bitten by a different type of tick, like a dog tick, you can get other illnesses like Rocky Mountain Spotted Fever. (Click here for more information on common tick-borne diseases)
How to Prevent Lyme Disease
The best method of Lyme disease control is prevention. Whether you live in California, the Upper Midwest, or Maine, you should be Tick AWARE when you go outside. This means:
AVOID high tick traffic areas, like tall grasses and leaf piles.
WEAR protective clothing, like a long-sleeved shirt, long pants, socks, and a hat.
APPLY EPA-approved insect repellent such as DEET or picaridin, properly.
REMOVE clothing when you come inside and put in a hot dryer for 10-15 minutes.
EXAMINE yourself for ticks daily. Feel for bumps paying close attention to the back of knees, groin, armpits, in and behind the ears, belly button, and scalp.
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The above material is provided for information purposes only. The material (a) is not nor should be considered, or used as a substitute for, medical advice, diagnosis, or treatment, nor (b) does it necessarily represent endorsement by or an official position of Global Lyme Alliance, Inc. or any of its directors, officers, advisors or volunteers. Advice on the testing, treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient’s medical history.