A review of symbiotic and potentially pathogenic bacteria of mites (subclass: acari): implications for pathogen transmission

Abstract

A dataset of bacterial diversity found in mites was extracted from 131 publications (1946-2013). A hundred and fourteen mite species belonging to three taxa (Parasitiformes, Sarcoptiformes and Trombidiformes) were recorded, which were associated with 64 bacteria species (in 44 genera, 28 families and 19 orders). The intracellular symbiont Cardinium was the most prevalent mite-associated bacterium (30 species infected), followed by Orientia (the causative agent of scrub typhus) and Wolbachia (the most prevalent symbiont within the Arthropoda), with 27 and 23 species infected, respectively. Moreover, a number of bacteria of medical importance were also present in mites, such as Rickettsia, Anaplasma, Ehrlichia, Bartonella, Francisella, Coxiella, Borrelia and Staphylococcus. The differences in bacterial infection pattern among mite taxa will be analysed and discussed. T hese data are not only useful to increase awareness of the potential for mites to transmit disease, but deeper understanding of the impact of symbionts on their arthropod hosts may also facilitate the development of intervention tools for vector control. Due to their small size and the limited taxonomic descriptions available, the study of mite-associated bacteria is extremely challenging and few molecular protocols have been published. Therefore, we are beginning to conduct metagenomic studies focusing on the mite-associated bacteriome of “chiggers” (the parasitic larval stage of trombiculid mites), which are important vectors of scrub typhus in South-East Asia. This disease affects 1 million people per year, causing severe fever and potentially fatal complications. Manipulation of the bacteriome may lead to future opportunities to decrease vector competence in chiggers.