Tick busted at the border! But millions get through.

In December 2013, a live Anatolian brown tick (Rhipicephalus bursa) from Macedonia was found on an untanned hide by US Customs and Border Protection agents in Philadelphia. Ticks are vectors of both bacterial and viral pathogens, such as Lyme disease and Rocky Mountain Spotted Fever. This was only the fourth case of this species entering the U.S. 

Tennessee's state ornithologist Scott Somershoe was catching migrant birds on a coastal island in Georgia and remarked that large numbers of birds were arriving from their wintering grounds in the Caribbean Islands, Central, and South America forests with ticks on them. Given that millions of birds move between continents, I find it surprising that we don't see more cases of ticks establishing themselves in North America. But this amazing migration phenomenon is not new. Birds have been moving between North and South America for millions of years and as far north as Pennsylvania for 20,000 years. 

One fascinating project would be to pull ticks off birds at places where migrant birds first land or pause (stopover sites) and look at the ectoparasite community and the microbiota they harbor. If ticks and their microbiota differ between sites where the same birds live then why aren't birds homogenizing parasite communities?

Ixodes tick