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

• Published in: PloS one Vol. 12; no. 7; p. e0181807
• Main Authors: Hofhuis, Agnetha, van de Kassteele, Jan, Sprong, Hein, van den Wijngaard, Cees C., Harms, Margriet G., Fonville, Manoj, Docters van Leeuwen, Arieke, Simões, Mariana, van Pelt, Wilfrid
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 24.07.2017; Public Library of Science (PLoS)
• Subjects: Adult; Age; Aged; Arachnids; Attachment; Biology and Life Sciences; Bites; Bites (Injuries); Borrelia burgdorferi; Borrelia burgdorferi Group - genetics; Borrelia burgdorferi Group - isolation & purification; Borreliosis; Deoxyribonucleic acid; Developmental stages; Disease control; Disease transmission; DNA; DNA, Bacterial - genetics; DNA, Bacterial - isolation & purification; Engorgement; Epidemiology; Humans; Infections; Infectious diseases; Insect bites; Lyme disease; Lyme Disease - diagnosis; Lyme Disease - etiology; Lyme Disease - microbiology; Lyme Disease - transmission; Mathematical models; Medicine and Health Sciences; Middle Aged; Parasites; Parasitic diseases; Pathogens; Patients; Polymerase chain reaction; Prevention; Probability; Prospective Studies; Public health; Risk; Structural equation modeling; Studies; Tick Bites - complications; Ticks; Young Adult; Netherlands
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0181807

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