Lyme disease is one of the most frequent tick-borne diseases worldwide, it can be multi-systemic and insidious, in particular when it shows a chronic course. In recent years co-infections represent an emerging issue in Lyme disease spectrum because in addition to Borrelia burgdorferi sl many other potential pathogens may be transmitted by hard ticks Ixodes species. The main co-infections found in Lyme disease described in this review are represented by Anaplasma phagocytophilum, Babesia species, Bartonella species, Rickettsiae species and tick-borne encephalitis virus. For each single co-infecting micro-organism, clinical features, diagnostic issues and therapeutical approaches are discussed. Co-infections represent an emerging problem because they might exacerbate Lyme disease clinical features, they can also mimic Lyme borreliosis sharing common manifestations, and eventually they can change the course of the disease itself. The presence of one or more co-infecting agent during the course of Lyme disease may represent an issue especially in endemic areas for tick-borne diseases and in people occupationally exposed. The aim of this review is to summarize the more important co-infections in patients with Lyme disease and to discuss their importance in the disease process.
