Silent travelers: the potential of migratory birds and their ticks to introduce emerging viruses into Switzerland
Switzerland hosts over 400 bird species, many of which are migratory. Through diverse movement patterns, ranging from short distances to almost global migrations, these birds can introduce zoonotic viruses, such as West Nile virus (WNV) or avian influenza virus (AIV), as well as unknown and potentially emerging viruses. Furthermore, they facilitate the global dispersal of infected ectoparasites,…
Switzerland is home to more than 400 bird species, including numerous migratory birds. These birds, with their varied movement patterns, are capable of introducing zoonotic viruses, such as West Nile virus or avian influenza virus, as well as previously unknown and potentially emerging viruses. Moreover, they aid in the worldwide spread of infected ectoparasites, particularly ticks, which could result in novel tick-borne diseases.
Researchers analyzed 42 bird species (39 migratory, 3 resident) from July to December 2023 at the Bolle di Magadino nature reserve and the Piano di Magadino area in the canton Ticino. This region, due to its transitional climate, acts as a crucial resting and breeding site for migratory birds. The researchers collected 496 oropharyngeal-cloacal swabs, 164 blood samples, and 22 associated ticks.
Despite RT-qPCR testing showing no active West Nile virus or avian influenza virus infections, ELISA testing detected Orthoflavivirus antibodies in 15 out of 164 sera, suggesting previous exposure. Metagenomic next-generation sequencing uncovered a viral community encompassing 33 families (29 of which were found in birds). DNA viruses, mainly belonging to the Circoviridae, Genomoviridae, and Parvoviridae families, dominated the virome, but with low diversity.
The RNA virome, on the other hand, was highly diverse and mainly reflected the birds' dietary habits and the local habitat at the nature reserve. The researchers also report the first detection of Bole tick virus 4 (BoTV4) in Switzerland, found in several ticks (Rhipicephalus turanicus) associated with long-distance migrants. This virus, belonging to the newly established Pestiviridae family, is already present in parts of Asia, Africa, and Europe.
This study marks the first active surveillance of the wild bird virome in Switzerland, establishing a framework for the early detection of emerging viruses and highlighting the crucial role of migratory birds in dispersing ticks and novel tick-borne viruses.
Written by urgent.news from bioRxiv's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
