Tick Bite Risk at Outdoor Events: Study Findings

Outdoor events may increase exposure to ticks, particularly in endemic areas. A study of long-distance mountain racers in Scotland highlights the frequency of tick bites during multi-day outdoor activities.

This raises an important question: how common are tick bites during outdoor events? Findings suggest that exposure may be higher than expected, especially when participants travel through dense vegetation.

The event consisted of two days of mountain racing through tick-infested terrain. Teams navigated the course while carrying equipment for overnight camping, according to Hall from the University of Salford.

Participants were provided with tick-removal kits and asked to collect ticks found on their bodies for analysis.

Tick Exposure During the Event

Participants submitted more ticks than expected. All 564 ticks collected were identified as Ixodes ricinus.

On day 1, 8.5% of participants reported tick bites, increasing to 13.8% on day 2. Larval tick bites were also reported in a subset of participants.

One nymph tested positive for Borrelia miyamotoi, a pathogen known to infect humans.

Pathogens Identified in Ticks

The ticks carried several Borrelia species commonly found in Europe, including B. afzelii, B. burgdorferi sensu stricto, B. garinii, B. valaisiana, and B. miyamotoi.

The study did not assess the presence of coinfections, which may underestimate the range of pathogens present.

Interpreting the Risk

Although none of the participants developed a tick-borne illness, the authors suggested that prompt removal of ticks may have reduced the risk of transmission.

These findings suggest that tick exposure during outdoor events may be more common than anticipated, though the likelihood of infection remains uncertain.

Implications for Outdoor Activities

The authors demonstrated that human participation in outdoor events can provide useful data on tick exposure, complementing traditional surveillance methods.

Factors such as off-trail movement and clothing choices may influence exposure risk.

This study illustrates a broader principle: individuals participating in outdoor activities may encounter ticks more frequently than expected, particularly in endemic regions.

Participants and organizers may benefit from awareness of tick bite prevention, review of Lyme disease symptoms, and consideration of coinfections when symptoms arise.

References

1. Hall JL et al. Use of mass-participation outdoor events to assess human exposure to tickborne pathogens. Emerg Infect Dis. 2017.
2. Robertson JN et al. Tick bite risk at a recreational site. Eur J Epidemiol. 2000.
3. Faulde MK et al. Tick exposure in military training. Ticks Tick Borne Dis. 2014.
4. De Keukeleire M et al. Tick exposure in scouts. Ticks Tick Borne Dis. 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