Assessing the Contribution of Songbirds to the Movement of Ticks and /Borrelia burgdorferi/ in the Midwestern United States During Fall Migration
The geographic distributions of Ixodes scapularis (black-legged tick) and the bacterium Borrelia
burgdorferi (the causative agent of Lyme disease) are expanding in the USA. To assess the role of migratory
songbirds in the spread of this tick and pathogen, we captured passerines in central Illinois during the fall of
2012. We compared forested sites in regions where I. scapularis populations were either previously or not yet
established. Ticks were removed from birds and blood samples were taken from select avian species. Ticks were
identified by morphology and molecular techniques were used to detect B. burgdorferi and other tick-borne
pathogens in ticks and avian blood samples. Ixodes spp. were detected on 10 of 196 migrants (5.1%), with I.
scapularis larvae found on 2 individuals. Borrelia burgdorferi sensu stricto was detected in the blood of 9 of 29
birds sampled (31%), yet only 1 infected bird was infested by ticks. The ticks were mostly Haemaphysalis
leporispalustris and I. dentatus larvae, and none tested positive for B. burgdorferi. Infestation of birds by Ixodes
spp. differed significantly by region, while B. burgdorferi infection did not. These data suggest that migratory
birds may play a larger role in the dispersal of B. burgdorferi than previously realized.