Co-infection of bacteria and protozoan parasites in Ixodes ricinus nymphs collected in the Alsace region, France.

Fifty nymphal Ixodes ricinus ticks collected in Alsace, France, identified by morphological criteria and using MALDI-TOF MS, were tested by PCR to detect tick-associated bacteria and protozoan parasites. Seventy percent (35/50) of ticks contained at least one microorganism; 26% (9/35) contained two or more species. Several human pathogens were identified including Borrelia burgdorferi s.s. (4%), Borrelia afzelii (2%), Borrelia garinii (2%), Borrelia valaisiana (4%), Borrelia miyamotoi (2%), Rickettsia helvetica (6%) and "Babesia venatorum" (2%). Bartonella spp. (10%) and a Wolbachia spp. (8%) were also detected. The most common co-infections involved Anaplasmataceae with Borrelia spp. (4%), Anaplasmataceae with Bartonella spp. (6%) and Anaplasmataceae with Rickettsia spp. (6%). Co-infection involving three different groups of bacteria was seen between bacteria of the family Anaplasmataceae, Borrelia spp. and Bartonella spp. (2%). Results highlight the panel of infectious agents carried by Ixodes ricinus. Co-infection suggests the possibility of transmission of more than one pathogen to human and animals during tick blood feeding.