Tick-Borne Coinfections Are the Norm, Not the Exception

Tick-borne coinfections are common in Lyme disease and may influence both symptoms and treatment. Lyme disease was first identified in 1975 in children and adolescents in Connecticut who presented with recurrent joint swelling and pain, initially diagnosed as juvenile rheumatoid arthritis.

“The typical patient has had 3 recurrences, but 16 patients have had none,” noted Dr. Alan Steere, a postdoctoral Fellow in Rheumatology at Yale University. [1] “During remission some patients remembered short periods of joint pain, sometimes lasting only hours, without swelling.”

Pain also occurred in the ankle, wrist, temporomandibular joint, shoulder, hip and elbow. Other symptoms included malaise, fatigue, headaches, myalgia, periorbital edema, and swelling of the hands or feet. Out of 12 subjects, 7 suffered from profound fatigue and hyperesthesias, sometimes persisting for months after the arthritis resolved. [1]

Expanding Understanding of Lyme Disease Symptoms

About 25 years ago, chronic manifestations of Lyme disease began to emerge. Twenty-seven patients with a history of Lyme disease presented with mild encephalopathy and axonal polyneuropathy beginning 1 month to 14 years after onset. [2]

Symptoms included memory loss, mood changes, sleep disturbances, fatigue (74%), headache (48%), arthritis (37%), and hearing loss (15%). [2]

Tick-Borne Coinfections in Lyme Disease

While Lyme disease remains the most recognized tick-borne illness, ticks frequently carry multiple infectious agents. :contentReference[oaicite:0]{index=0}

Researchers from Columbia University, Tufts Medical Center, and Yale School of Medicine found:

1. 40% of Lyme disease patients have concurrent Babesiosis
2. 13% have concurrent human granulocytic anaplasmosis (HGA)
3. Two-thirds of Babesiosis patients also have Lyme disease
4. One-third of Babesiosis patients have concurrent HGA [3]

In endemic areas of the United States, up to 28% of Ixodes scapularis ticks carry multiple pathogens. In Europe, coinfection rates reach 13% in I. ricinus ticks and 7% in I. persulcatus. [3]

Coinfections in Ticks: The Rule Rather Than the Exception

Moutailler and colleagues reported that nearly 50% of ticks in the French Ardennes were coinfected, with some carrying up to five pathogens. [4]

Common organisms included Bartonella henselae, Rickettsia species, Borrelia miyamotoi, and Babesia species. [4]

The role of ticks in transmitting some organisms, such as Bartonella henselae, remains debated. [5]

Ticks also carry symbionts—organisms that may influence pathogen behavior. Some, like B. miyamotoi, were initially considered harmless but are now recognized as human pathogens. [6]

When symbionts are included, nearly all ticks carry at least one microorganism, with some harboring up to eight. [4]

Why Identifying Tick-Borne Coinfections Matters

Clinicians often do not routinely test for coinfections when Lyme disease is suspected. One study found that only 17% of nearly 3 million specimens were tested for non-Lyme tick-borne diseases. [7]

However, coinfections can increase disease severity and prolong symptoms. Patients with multiple infections often experience more complex and persistent illness. [8]

Treatment decisions are also affected. Antibiotics used for Lyme disease may not be effective against parasitic or viral infections. For example, doxycycline does not treat Babesia, which requires therapies such as atovaquone combined with azithromycin. [8]

Recognizing tick-borne coinfections is essential for accurate diagnosis, appropriate treatment, and improved patient outcomes.

References:

1. Steere AC, Malawista SE, Snydman DR et al. Lyme arthritis. Arthritis Rheum, 20(1), 7-17 (1977).
2. Logigian EL, Kaplan RF, Steere AC. Chronic neurologic Lyme disease. N Engl J Med, 323(21), 1438-1444 (1990).
3. Diuk-Wasser MA, Vannier E, Krause PJ. Coinfection by Ixodes pathogens. Trends Parasitol, (2015).
4. Moutailler S et al. Coinfection of ticks. PLoS Negl Trop Dis, (2016).
5. Telford SR, Wormser GP. Bartonella transmission debate. Emerg Infect Dis, (2010).
6. Telford SR et al. Borrelia miyamotoi disease. Clin Lab Med, (2015).
7. Connally NP et al. Testing practices. Ticks Tick Borne Dis, (2016).
8. Krause PJ et al. Concurrent Lyme and babesiosis. JAMA, (1996).

Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention