Tick infestation risk and Borrelia burgdorferi s.l. infection-induced increase in host-finding efficacy of female Ixodes ricinus under natural conditions.
An investigation of the risk of human tick infestation, together with the prevalence of Borrelia burgdorferi s.l. infection, was conducted in a sylvatic habitat in western Germany to provide data needed for future risk-benefit evaluations of acaricides used for clothing impregnation. Additionally, data were collected on behavioural changes in Borrelia burgdorferi s.l.-infected adult female I. ricinus ticks and the possible impact of such changes on host-finding efficacy. The risk of I. ricinus-infestation was determined by collecting from the protective clothing of volunteers and by dragging in known tick-infested sites in the Kühkopf Mountain area, Koblenz, Germany, from June through October 2006. The overall tick infestation rate per person per hour was 7.4+/-5.5, with the following sex- and stage-specific differences: males 0.32+/-0.37, females 1.1+/-1.2, nymphs 3.6+/-4.4, larvae 2.4+/-3.5. Concurrent dragging revealed an average 19.4+/-16.2 times higher infestation rate as well as a markedly lower infection rate with borreliae in adult I. ricinus ticks when compared to ticks collected from exposed human volunteers. Although the difference in infection rates was statistically significant (P<0.023) only in adult female ticks, our data indicate that B. burgdorferi s.l. infection may increase host-finding efficacy in adult I. ricinus. The overall exposure risk was 1.0 B. burgdorferi s.l.-infected ticks per person per hour of exposure, or 0.25 ticks per 100 m walking distance in the study area.
Faulde
Michael K
MK
Department of Medical Entomology/Zoology, Central Institute of the Federal Armed Forces Medical Service, P.O. Box 7340, 56065 Koblenz, Germany. MichaelFaulde@bundeswehr.org
Robbins
Richard G
RG
D000818:Animals; D025065:Borrelia burgdorferi / Q000302:isolation & purification* / Q000472:pathogenicity; D003020:Clothing; D005260:Female; D005858:Germany; D006790:Host-Parasite Interactions; D018884:Ixodes / Q000382:microbiology* / Q000472:pathogenicity* / Q000502:physiology; D008193:Lyme Disease / Q000453:epidemiology*; D008297:Male; D012307:Risk Factors; D012621:Seasons; D013984:Tick Infestations / Q000453:epidemiology*