How is Lyme disease transmitted?
Medically reviewed by Neka Miller, PhD on April 10, 2021. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
Lyme disease is a surprisingly common disease. Estimates from the CDC suggest that upwards of 476,000 are diagnosed and treated for Lyme disease every year. This number may suggest some discrepancies as this number includes patients who are treated for Lyme disease presumptively. Still, it goes to show the potential danger of Lyme disease and the need to take it seriously.
One of the most important aspects of preventing Lyme disease is understanding where it comes from and how it is even transmitted. Learn more about Lyme disease transmission below and whether you should seek a Lyme disease test for your symptoms.
What is Lyme disease?
Lyme disease is caused by four species of bacteria. Borrelia afzelii and Borrelia garinii are responsible for causing Lyme disease in Asia and Europe, but Lyme disease cases in the United States are caused by Borrelia burgdorferi and Borrelia mayonii. These bacteria are carried on ticks and spread via tick bite.
Learn more about what causes Lyme disease from our recent blog.
Lyme disease can manifest in different ways and in different stages that may overlap. The initial incubation period for the tick-borne disease is three to thirty days. The most common early symptom of Lyme disease is a rash, called erythema migrans. The rash radiates out from the bite and can clear up in the center, creating a characteristic bull’s-eye pattern. The rash can grow up to 12 inches in diameter, but it typically isn’t painful or itchy.
The infection can also lead to general flu-like symptoms, including:
- Fever
- Headache
- Chills
- Body aches
- Swollen lymph nodes
- Neck stiffness
- General fatigue
Left untreated, Lyme disease can progress to other parts of the body. Along with more erythema migrans, this later stage of Lyme disease can spread to the joints, resulting in arthritis with severe joint pain and swelling. This typically affects the knees and other larger joints, but the swelling and pain can shift to different joints.
The infection can also spread to the brain and nerves, leading to severe neurological problems, including:
Temporary facial palsy, characterized by weakening in the facial muscles, which can cause drooping in the face Meningitis, or inflammation in the membranes of your brain and spinal cord Impaired muscle movements General numbness, pain, tingling, or weakness in your extremities
Lyme disease can also lead to some heart issues. You may experience Lyme carditis, or an irregular heartbeat. Some people also experience heart palpitations, which can feel like your heart fluttering, skipping a beat, or pounding out of your chest.
Lyme disease transmission
Lyme disease in the United States is typically caused by the Borrelia burgdorferi bacteria, but it can also come from Borrelia mayonii. The disease is transmitted through the bite of a tick that is infected with the bacteria. The blacklegged tick, also known as the deer tick, is the primary transmitter in the mid-Atlantic, northeastern, and north-central regions of the United States. The western blacklegged tick transmits Lyme disease on the Pacific Coast. While these ticks are found in every state except for Hawaii, Lyme disease is most often reported in the northeastern and Upper Midwestern United States.
Ticks can attach to any part of the body, but they are most often found in hard-to-see folds in the skin and areas like the groin, scalp, and armpits. The infected tick typically must be attached for at least 36 to 48 hours in order for Lyme disease bacteria to pass into the bloodstream. This means that if you find an attached tick that is considerably swollen, it has likely fed enough to transmit the bacteria. This is why removing the tick as soon as possible can greatly reduce the risk of infection.
For most people, Lyme disease is transferred through the bites of immature ticks known as nymphs. Tick nymphs are extremely tiny, measuring less than 2 mm. This is equivalent to the head of a pin or smaller than a poppy seed. This makes them much harder to discover until they have fed for a long period of time. Adult ticks can still transmit the disease, but they are usually big enough to notice and remove before they can transmit the bacteria. Adult ticks are about the size of a sesame seed. Ticks generally prefer the warmer months of spring and summer, and they tend to be less active during the cooler winter months.
Depending on the tick’s life stage, it can take 10 minutes to 2 hours to actually begin feeding. It’s not uncommon for people to come back from a hike, take a shower, and find adult ticks on their clothes or skin that haven’t yet attached.
Can you get Lyme disease through other means?
Simply put, deer ticks are the primary transmitter of Lyme disease. Other tick species are not known to transmit Lyme disease. This includes:
- The Rocky Mountain wood tick
- Lone Star ticks
- The American dog tick
- The brown dog tick
There is no evidence to suggest that the bacteria can be transmitted via food, water, or air or via the bites of mosquitoes, fleas, lice, or flies. Lyme disease cannot be transmitted from person to person, meaning that you cannot get the disease from kissing, hugging, touching, or having sex with someone who has Lyme disease. Some evidence suggests that untreated Lyme disease can lead to infection of the placenta in pregnant women, but passing the disease from mother to fetus is extremely rare.
Dogs, cats, and other household pets can get Lyme disease, but they can’t spread it to you via contact or bites. The main problem here is that pets can bring infected ticks into your home or yard.
Other tick-borne diseases
While not all ticks carry Lyme disease, they can transmit a handful of other diseases that can also have some serious symptoms.
Anaplasmosis and ehrlichiosis
These are two similar illnesses that can come from tick bites. The incubation period is about 14 days, and the symptoms for the two are generally the same, though ehrlichiosis may be more severe. Both mainly cause flu-like symptoms, like fever, muscle ache, headaches, and a general feeling of being unwell. Ehrlichiosis may also cause a rash, confusion, or changes to mental state.
Babesiosis
Babesiosis is caused by microscopic parasites that infect red blood cells. Many people with this infection do not show any noticeable signs or symptoms. Some people develop flu-like symptoms. The parasite can gradually destroy red blood cells, which can lead to hemolytic anemia. Left untreated, the infection can potentially be life-threatening.
Rocky Mountain spotted fever
Rocky Mountain spotted fever is another bacterial infection transmitted by tick bites. Symptoms for the infection can take up to 14 days to appear. Initial symptoms usually resemble that of the flu, but the disease is characterized by a rash that appears three to five days after the initial symptoms appear. This rash appears as numerous small, red dots that first show on the wrists and ankles before spreading farther. The infection can thankfully be cured easily with a round of antibiotics, but without treatment, the disease can cause serious damage to your heart, kidneys, and other organs.
While not every tick will transmit Lyme disease, it’s important to get tested if you do find an attached tick. You can get tested in your doctor’s office or with an at-home Lyme disease test kit from Everlywell. If your results show a positive, we can connect you with a care coordinator to determine next steps to receive a clinical diagnosis and treatment.