Can Larval Tick Bites Cause Lyme Disease?
They are smaller than nymphs.
And they may still transmit infection.
Larval tick bites Lyme disease risk may be higher than previously thought.
According to a study published in Parasites & Vectors, larval ticks—once considered harmless—may be capable of transmitting Borrelia afzelii and Borrelia miyamotoi. These infections can occur from bites that often go unnoticed.
Researchers found that larvae of Ixodes ricinus can transmit these pathogens to vertebrate hosts, challenging the long-held assumption that only nymphs and adult ticks pose a risk.
Larva, nymph, and adult stages of Ixodes ticks. (Credit: CDC)
Why Larval Bites Matter
Larval ticks are extremely small and easily missed. Unlike nymphs, they are often not considered a source of infection.
However, this study suggests that assumption may need to change.
Individuals in the Netherlands are estimated to receive at least 30,000 larval bites annually out of approximately 1.1 million total tick bites.
Clinical implication: even bites that go unnoticed may carry risk.
Changing the Understanding of Lyme Transmission
“Larval transmission of Borrelia miyamotoi has implications for checking for ticks and continuing precautions even after the perceived Lyme risk has decreased,” noted Peter Krause, MD of Yale University.
The authors concluded that these findings challenge the traditional view that larval ticks do not contribute to Lyme disease transmission.
This may change how clinicians and patients think about tick exposure risk.
Clinical Takeaway
Larval tick bites Lyme disease risk should not be ignored—especially in endemic areas.
Tick prevention strategies should continue even when exposure seems minimal or when only very small ticks are present.
Key question: Could unnoticed larval bites explain cases of Lyme disease without a known tick exposure?
For additional discussion, see Larval ticks may be a threat after all.
References:
- van Duijvendijk G, et al. Larvae of Ixodes ricinus transmit Borrelia afzelii and B. miyamotoi. Parasites & Vectors. 2016.
- Krause PJ, et al. Borrelia miyamotoi infection in nature and in humans. Clin Microbiol Infect. 2015.
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
I’m looking for evidance of transmission from other vectors.
And also body fluids.
Your help is appreciated!
There are reports that other vectors harbor pathogens seen in ticks. These researchers have not been able to prove that these pathogens are transmitted via a bite of another vector. I am not familiar with the literature. Again, it is difficult to prove infection even if tests of other fluids are positive e.g PCR research.