Diversity of microbial communities identified in exotic ticks imported in USA by migrating songbirds

Birds are capable of carrying ticks and, consequently, tick-transmitted microorganisms over great distances and geographical barriers such as oceans and deserts. Ticks are hosts for several species of spotted fever group rickettsiae (SFGR), which can be transmitted to vertebrates during blood meals. In this study, the prevalence of SFGR was examined in ticks infesting migratory songbirds using PCR. During the 2009 and 2010 spring migration seasons, ~2064 northward-migrating passerine songbirds were examined for ticks at Johnson Bayou, Louisiana. A total of 120 ticks were removed from 38 songbird species for tick species identification and SFGR detection. Ticks were identified, comparing their 12S rDNA gene sequence to homologous sequences in GenBank, as Amblyomma longirostre, Amblyomma nodosum, Amblyomma calcaratum, Amblyomma maculatum, Amblyomma spp. and Haemaphysalis species, all originating from South America. The nucleotide sequence similarity of the PCR products revealed several exotic SFGR. Furthermore, we evaluated the microbial load and bacterial communities associated with exotic ticks by using 454-based metagenomics approach. A total of 112 genera and 142 species belonging to representatives of all bacterial phyla were detected. Our results indicate that exotic tick species arriving attached to migrating songbirds may play an important epidemiological role in importing previously unknown pathogenic bacteria to North America.