Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 Jul 24;12(7):e0181807.
doi: 10.1371/journal.pone.0181807. eCollection 2017.

Predicting the risk of Lyme borreliosis after a tick bite, using a structural equation model

Agnetha Hofhuis  1 , Jan van de Kassteele  2 , Hein Sprong  1 , Cees C van den Wijngaard  1 , Margriet G Harms  1 , Manoj Fonville  1 , Arieke Docters van Leeuwen  1 , Mariana Simões  1 , Wilfrid van Pelt  1
Affiliations

Predicting the risk of Lyme borreliosis after a tick bite, using a structural equation model

Agnetha Hofhuis et al. PLoS One. .

Abstract

Background: Understanding and quantification of the risk of Lyme borreliosis after a tick bite can aid development of prevention strategies against Lyme borreliosis.

Methods: We used 3,525 single tick bite reports from three large prospective studies on the transmission risk of tick-borne pathogens to humans, with 50 reports of Lyme borreliosis during the follow-up period, among 1,973 reports with known outcome. A structural equation model was applied to estimate the risk of Lyme borreliosis after a tick bite, and quantify the influence of: developmental stage of the tick, detection of Borrelia burgdorferi s.l. DNA in the tick by PCR, tick engorgement, patient-estimated duration of tick attachment, and patient age.

Results: The overall risk of developing Lyme borreliosis after a tick bite was 2.6% (95%CI 1.4-5.1). The risk increased with: - Tick engorgement: 1.4% (95%CI 0.7%-2.3%) for low engorgement to 5.5% (95%CI 2.8%-9.2%) for substantially engorged ticks;- Rising patient-estimated tick attachment duration: 2.0% (95%CI 1.3%-2.8%) after <12 hours, to 5.2% (95%CI 3.0%-8.9%) after ≥4 days;- Detection of Borrelia burgdorferi s.l. DNA in ticks: 6.7% (95%CI 3.6%-13.5%), versus 1.4% (95%CI 0.7%-2.9%) when ticks tested negative.The highest observed risk of Lyme borreliosis was 14.4% (95%CI 6.8%-24.6%) after one tick bite of a substantially engorged tick that tested positive for Borrelia burgdorferi s.l. DNA, which corresponds to one new case of Lyme borreliosis per 7 (95%CI 4-15) of such tick bites.

Conclusions: An individual's risk of Lyme borreliosis after a tick bite can be predicted with tick engorgement, patient-estimated duration of tick attachment, and detection of Borrelia burgdorferi s.l. DNA in the tick.

PubMed Disclaimer

Conflict of interest statement

Competing Interests: On behalf of all authors, the corresponding author states that there are no conflicts of interest.

Figures

Fig 1
Fig 1. Variables [blocks] and assumed (causal) relations [arrows a to g] between predictors of Lyme borreliosis after a tick bite in the structural equation model.
Fig 2
Fig 2. Probability of tick engorgement classes as a function of patient-estimated duration of tick attachment, per tick stage (ignoring tick infection with Borrelia burgdorferi s.l. DNA, and age of the participant).
The solid line represents the mean, the dotted lines the 95% credible interval.
Fig 3
Fig 3. Probability of developing Lyme borreliosis after a single tick bite, as a function of patient-estimated duration of tick attachment.
The solid line represents the mean, the dotted lines the 95% credible interval. Also see Table 1 and S3 Table. Upper graph: ignoring all other variables in our model. Lower graph: stratified for tick infection with Borrelia burgdorferi s.l. DNA, tested by PCR. Ignoring tick stage, engorgement, and age of the participant.
See this image and copyright information in PMC

References

    1. Stanek G, Wormser GP, Gray J, Strle F. Lyme borreliosis. Lancet. 2012;379(9814):461–73. doi: 10.1016/S0140-6736(11)60103-7 . - DOI - PubMed
    1. Hubalek Z. Epidemiology of lyme borreliosis. Current problems in dermatology. 2009;37:31–50. doi: 10.1159/000213069 . - DOI - PubMed
    1. Gray JS, Stanek G. Risk assessment in Lyme borreliosis. Zentralblatt fur Bakteriologie: international journal of medical microbiology. 1998;287(3):175–6. . - PubMed
    1. Jaenson TG. The epidemiology of lyme borreliosis. Parasitol Today. 1991;7(2):39–45. . - PubMed
    1. Gray JS, Kahl O, Robertson JN, Daniel M, Estrada-Pena A, Gettinby G, et al. Lyme borreliosis habitat assessment. Zentralblatt fur Bakteriologie: international journal of medical microbiology. 1998;287(3):211–28. . - PubMed