Lyme Disease and Tick Coinfections: What to Watch for This Spring

By Sukrut Dwivedi, DO, FACP, FIDSA

A single tick bite during peak spring season can transmit multiple infections at once, and recognizing the signs early can make all the difference in your recovery. While most people have heard of Lyme disease, fewer realize that the same tiny tick can carry several disease-causing organisms—bacteria, parasites, even viruses—all delivered in one bite. For patients across New Jersey, where tick populations thrive in wooded parks and suburban yards, understanding these coinfections is essential for protecting your health this spring.

What Is a Tick Coinfection, and How Is It Different From Lyme Disease?

A tick coinfection occurs when a single tick transmits Lyme disease plus one or more additional pathogens in the same bite. Lyme disease itself is caused by the bacteria Borrelia burgdorferi, which blacklegged ticks (also called deer ticks) pick up from infected mice and other small mammals. But these same ticks often harbor other disease-causing organisms—different bacteria, parasites, or viruses—that can be transmitted alongside the Lyme bacteria.

The critical difference is that coinfections involve distinct pathogens, each with its own set of symptoms and treatment requirements. While Lyme disease typically causes a characteristic bull’s-eye rash, fever, and joint pain, coinfections can produce overlapping symptoms that may not respond to standard Lyme treatment alone. For example, the parasites that cause babesiosis invade red blood cells, leading to anemia and symptoms that doxycycline—the first-line antibiotic for Lyme—cannot address.

Coinfections are not rare complications. They are increasingly recognized in tick-endemic areas like New Jersey, where multiple disease-carrying organisms circulate in local wildlife populations. Understanding that a tick bite can deliver more than one illness helps explain why some patients develop symptoms that don’t fit the typical Lyme pattern or why they don’t improve as expected with initial treatment.

What Coinfections Can a Single Tick Bite Cause?

Several coinfections can accompany Lyme disease in a single tick bite. Below is a quick-reference guide to help you identify which infection might be causing your symptoms. Use this as a starting point for conversation with your healthcare provider—not as a self-diagnosis tool.

A 2019 study published in the CDC’s Emerging Infectious Diseases journal examined early Lyme disease cases in New York and found coinfections in approximately 12 to 18 percent of patients. Babesia and Anaplasma were the most frequently detected coinfections, underscoring that these are not isolated occurrences but a recognized part of the tick-borne disease landscape in our region.

How Do You Know If You Have a Coinfection and Not Just Lyme?

Use this quick checklist if you’ve had a tick bite and are developing symptoms:

What typical Lyme disease looks like (for comparison):

• Bull’s-eye rash (though not everyone gets this)
• Low-grade fever and mild flu-like symptoms
• Joint pain that develops gradually over days to weeks
• Symptoms begin 3 to 30 days after tick bite
• Generally improves with doxycycline within a few days

Bottom line: If your symptoms are more severe than expected, develop very quickly, include high fever or severe chills, or don’t improve with standard Lyme treatment, contact your healthcare provider right away. These signs suggest possible coinfection and may require different testing and treatment.

How Are Tick Coinfections Diagnosed?

Your doctor starts by asking about your symptoms, recent outdoor activities, and whether you remember a tick bite. A physical exam checks for fever, rash, and other signs of infection.

Here’s what testing typically involves:

For Lyme disease: Blood tests look for antibodies your body makes in response to the infection. However, these tests can be negative in the first few days after a tick bite because your immune system needs time to respond.

For babesiosis: A blood sample is examined under a microscope to look for parasites inside your red blood cells. DNA tests (called PCR tests) can also detect the parasite, and antibody tests help confirm the diagnosis later on.

For anaplasmosis and ehrlichiosis: DNA tests on your blood can identify the bacteria quickly during active illness. Your doctor may also check antibody levels in two blood samples taken a few weeks apart to confirm infection. Complete blood counts showing low white blood cells and low platelets can provide important clues, especially for anaplasmosis.

For less common infections like Borrelia miyamotoi and Powassan virus: Specialized tests are needed that aren’t part of routine Lyme testing. Your doctor will order these if your symptoms suggest one of these infections.

An infectious disease specialist knows which tests to order based on your symptoms and can interpret results accurately. For patients across New Jersey where tick exposure is common, seeing a specialist ensures coinfections don’t get missed.

How Are Coinfections Treated Differently From Lyme Alone?

The good news is that most tick-borne infections can be treated with oral antibiotics. However, the specific treatment depends on which infection (or infections) you have.

For Lyme disease alone: Your doctor will typically prescribe a course of oral antibiotics. Treatment duration varies by syndrome and coinfection, typically ranging from 7 to 21 days, with some disseminated Lyme manifestations treated for up to 28 days. Most patients start feeling better within a few days of beginning treatment.

When anaplasmosis coinfection is present: If you have both Lyme disease and anaplasmosis, a 10 to 14 day course of doxycycline treats both infections concurrently without necessarily extending treatment beyond a standard Lyme course. This is one advantage of doxycycline—it effectively addresses multiple tick-borne bacterial infections simultaneously.

For babesiosis specifically: You’ll need a different combination of medications because the parasite that causes this infection doesn’t respond to the standard Lyme antibiotics. Treatment typically lasts 7 to 10 days, though some patients need longer courses.

What this means for you:

• Treatment duration is determined by the specific pathogen or combination of pathogens you have
• You may need to take more than one medication at the same time if babesiosis is present
• Your doctor will monitor you more closely to make sure the treatment is working
• Patients with weakened immune systems often need extended treatment and more frequent follow-ups

An infectious disease specialist can determine the right treatment plan based on your specific situation, adjust your medications if needed, and monitor your progress through follow-up visits and lab tests. Early, targeted treatment significantly reduces your risk of complications and helps you recover faster.

What Can You Do This Spring to Prevent Tick Bites and Coinfection?

Prevention is your best defense against tick-borne diseases. Here are the most effective steps you can take:

Peak season in New Jersey: For patients across Princeton, Hamilton, Florham Park, Freehold, and Old Bridge, tick exposure is highest in May and June. Even suburban yards with leaf litter, wood piles, or tall grass can harbor ticks.

When Should You See an Infectious Disease Specialist?

Why see a specialist? An infectious disease specialist can coordinate comprehensive testing, adjust treatment for coinfections, and monitor for complications. For patients across New Jersey, early specialist involvement prevents prolonged illness and ensures you receive the right diagnosis and treatment plan.

Frequently Asked Questions

Can you get Lyme disease and a coinfection from the same tick bite?
Yes. A single blacklegged tick can carry and transmit multiple pathogens at once, including the bacteria that cause Lyme disease along with parasites like Babesia or bacteria like Anaplasma. Studies show that coinfections occur in approximately 12 to 18 percent of early Lyme disease cases in endemic areas. Because ehrlichiosis is transmitted by a different tick species (the lone star tick), coinfection with Lyme disease is uncommon.

How long after a tick bite do coinfection symptoms usually start?
The timeline varies by infection. Lyme disease symptoms typically appear 3 to 30 days after a bite, but coinfections like anaplasmosis can cause symptoms within just a few days. Babesiosis may have a longer incubation period, sometimes taking one to four weeks before symptoms develop. Rapid onset of high fever or severe symptoms suggests coinfection.

Does doxycycline treat all tick coinfections?
No. Doxycycline effectively treats Lyme disease, anaplasmosis, and ehrlichiosis, which is why it is often the first-line antibiotic when coinfection is suspected. However, it does not treat babesiosis, which requires a combination of atovaquone and azithromycin. Accurate diagnosis is essential to ensure the right treatment.

Are tick coinfections more dangerous than Lyme disease alone?
Coinfections can be more severe, especially in immunocompromised individuals, elderly patients, or those without a spleen. Babesiosis can cause life-threatening anemia, and Powassan virus can lead to permanent neurological damage. Early recognition and appropriate treatment reduce these risks significantly.

If you have questions about tick bites, concerning symptoms, or need guidance on tick-borne disease prevention, contact the infectious disease specialists at ID Care. Their team provides comprehensive evaluation and treatment for tick-borne diseases, helping patients across New Jersey get the expert care they need this spring.