With symptoms including fevers and rashes, scrub typhus is a disease estimated to affect a million people annually, mostly in Asia, and is caused by the bacterium Orientia tsutsugamushi. Transmitted by the bites of mite larvae, known as chiggers, O. tsutsugamushi is an obligate intracellular pathogen, meaning that it must be inside a host cell to survive. Compared to other closely-related bacteria with a similar lifestyle, it has a large genome, featuring many repeated sequences of DNA. These repeats are represented in this diagram: along the genome, pictured as a grey circle, each coloured bar indicates a region of DNA with multiple copies, linked together to show where the repeats are found. Piecing together a genome with so many repeats is challenging, but new sequencing techniques recently enabled more accurate reconstructions of genomes from multiple O. tsutsugamushi strains, providing more detailed insights into an important yet relatively poorly-understood pathogen.
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