Ticks and Tick-Borne Zoonotic Pathogens from Wild Birds in Northwestern Coastal Spain

Simple Summary Ticks are parasites that, by feeding on blood, can transmit diseases to people and animals, being a cause for concern for health authorities. Their ability to move is limited, but not that of animals they parasitize, especially migratory birds that travel great distances every year. For this reason, it is important to know the percentage of birds that are parasitized by ticks in different countries that are on their migratory routes, the observed species of birds and ticks and whether they carry disease-causing organisms. That has been the objective of our study, which has taken advantage of the regular work of bird ringers over 2 years in both estuaries and forested areas. The results obtained from the examination of almost 1700 birds show a low percentage (2.5%) of birds parasitized by ticks and only one disease-causing organism in a bird's tick. Despite this, the information is relevant showing that the percentage of birds with ticks is higher in forest areas than in estuaries. This study also allows us to complete the information obtained in previous studies carried out in domestic and wild animals in a region that accounts for most of the Lyme disease hospitalizations in Spain.Abstract Migratory and local birds may disperse ticks and their associated pathogens. The aim of this study was to provide information regarding ticks infesting birds in Asturias, a region that accounts for most of the Lyme disease hospitalizations in Spain. From September 2021 to April 2023, trained and experienced bird-banders collected ticks from birds in two estuary and four forest locations. A total of 1698 birds (52 species, 38 genera, and 26 families) were captured. A total of 51 ticks (28 larvae, 20 nymphs, and 3 females) were collected from 43 birds, belonging to three species: Ixodes ricinus (31), Ixodes frontalis (18), and Haemaphysalis concinna (1). The average prevalence of tick infestation was 2.5% and the average tick burden was 1.2 ticks per infested host. The bird species Turdus merula, Parus major, Luscinia svecica, and Anthus pratensis were among the most infested. Anaplasma phagocytophilum was detected in one I. ricinus nymph collected from Phylloscopus collybita. We have not detected Borrelia burgdorferi s.l., Rickettsia spp., Coxiella burnetii, or piroplasmids in any of the 51 analyzed ticks. These results suggest low infestation rate in migratory/estuary birds and a higher rate in forest/sedentary ones. Despite this, the detection of pathogens, although with low prevalence, can pose a risk to public health.