Case Report: An imported severe case of paediatric scrub typhus with Karp B subgenotype in non-endemic Northern China, Beijing

Scrub typhus, a zoonosis caused by Orientia tsutsugamushi ( O. tsutsugamushi ), remains a significant public health threat in the Asia-Pacific region. This disease is transmitted through the bite of infected trombiculid mite larvae (chiggers) and typically manifests as acute undifferentiated fever during the early stage. Despite the availability of targeted antibiotic therapies, delayed diagnosis frequently leads to severe complications and fatal outcomes. Here, we report a severe imported paediatric case in Beijing, a city in China's temperate zone, involving a 12-year-old girl with a recent travel history to Yunnan Province. The patient presented with fever, characteristic eschar, regional lymphadenopathy, and septic shock, ultimately progressing to multiorgan dysfunction syndrome. Whole-genome metagenomic next-generation sequencing (mNGS) of blood, cerebrospinal fluid (CSF), and sputum samples revealed O. tsutsugamushi with high sequence read counts, whereas blood cultures remained negative for other bacterial pathogens. Subsequent PCR amplification and Sanger sequencing confirmed the mNGS findings. Phylogenetic analysis of the TSA56 gene classified the strain within the Karp cluster. Serological analysis revealed the presence of O. tsutsugamushi -specific IgM and IgG antibodies. This severe paediatric case highlights the importance of considering travel-associated scrub typhus in the differential diagnosis of febrile illnesses in non-endemic regions. This is particularly relevant for patients with a history of insect bites in areas known to be endemic for O. tsutsugamushi .