Abstract:

Objective To understand the clinical manifestation of scrub typhus, and explore the early clinical indications for severe scrub typhus. Methods Clinical data, chest CT imaging and laboratory findings were collected from patients diagnosed with scrub typhus from January 2017 to December 2021 in the Kunming Third People's Hospital. Then the cases were divided into non-severe scrub typhus (non-severe group) and severe scrub typhus (severe group). Logistic regression model was used to analyze the clinical manifestation of severe scrub typhus in early stage. Results In total, 181 patients with scrub typhus were included in this study, in whom 104 cases (57.5%) were included in the non-severe group, and 77 (42.5%) in the severe group. All patients developed skin eschar, commonly occurring at the trunk, which accounted for 47.5% (86/181) of all cases. Fever was generally seen in all patients. Other clinical manifestations consisted of headache, cough, abdominal pain, muscle aches, and dyspnea. Chest CT imaging revealed pleural effusion in 49.7% (90/181) of the patients. The incidence of pleural effusion was 67.5% (52/77) in the severe group and 36.5% (38/104) in the non-severe group (χ²=17.001, P<0.05). In laboratory tests, blood neutrophil count, level of aspartate aminotransferase, C-reactive protein, procalcitonin, lactate dehydrogenase, D-dimer and interleukin-6 levels were significantly higher in the severe group than in the non-severe group (Z=2.858, -3.870, -5.937, -6.546, -4.153, -4.802, -5.119, respectively, all P<0.05), and peripheral blood platelet count was significantly lower in the severe group than in the non-severe group (Z=-5.039, P<0.05). The regression analysis showed that elevated levels of aspartate aminotransferase, procalcitonin, interleukin-6 and the presence of pleural effusion were early clinical indicative of severe scrub typhus. The area under receiver operating characteristic curve (ROC) was 0.839, which had a sensitivity of 62.3% and a specificity of 96.2%. Conclusion Patients with fever and skin eschar shall be considered potential scrub typhus, and elevated levels of aspartate aminotransferase, procalcitonin and interleukin-6 as well as pleural effusion demonstrated by CT imaging can be early indicative of severe scrub typhus, and worthy of high attention. Patients with tendency to severe condition should be timely diagnosed and treated in order to reduce the mortality.

Key words: Scrub typhus, Rickettsia, Clinical features, Severe cases, Early diagnosis