CO-INFECTION OF TICKS: THE RULE RATHER THAN THE EXCEPTION

Claire Valiente Moro ,Elise Vaumourin ,Lorraine Michelet ,Florence Hélène Tran ,Elodie Devillers , Jean-François Cosson ,Patrick Gasqui ,Van Tran Van ,Patrick Mavingui ,Gwenaël Vourc’h ,Muriel Vayssier-Taussat Published: March 17, 2016  DOI: 10.1371/journal.pntd.0004539  http://journals.plos.org/plosntds/article?id=10.1371%2Fjournal.pntd.0004539 Abstract Introduction Ticks are the most common arthropod vectors of both human and animal diseases in Europe, and the Ixodes ricinus tick species is able to transmit a large number of bacteria, viruses and parasites. Ticks may also be co-infected with several pathogens, with a subsequent high likelihood of co-transmission to humans or animals. However few data exist regarding co-infection prevalences, and these studies only focus on certain well-known pathogens. In addition to pathogens, ticks also carry symbionts that may play important roles in tick biology, and could interfere with pathogen maintenance and transmission. In this study we evaluated the prevalence of 38 pathogens and four symbionts and their co-infection levels as well as possible interactions between pathogens, or between pathogens and symbionts. Methodology/principal findings A total of 267 Ixodes ricinus female specimens were collected in the French Ardennes and analyzed by high-throughput real-time PCR for the presence of 37 pathogens (bacteria and parasites), by rRT-PCR to detect the presence of Tick-Borne encephalitis virus (TBEV) and by nested PCR to detect four symbionts. Possible multipartite interactions between pathogens, or between pathogens and symbionts were statistically evaluated. Among the infected ticks, 45% were co-infected, and carried up to five different pathogens. When adding symbiont prevalences, all ticks were infected by at least one microorganism, and up to eight microorganisms were identified in the same tick. When considering possible interactions between pathogens, the results suggested a strong association...