Acute Q Fever Diagnosed by Metagenomic Next-generation Sequencing and Clinically Compared With Scrub Typhus

Abstract Background: C. burnetti, the causative agent of Q fever, is considered a potential threat as a biological weapon because of highly infectious and pathogenic. There was an outbreak of Q fever in Zhuhai, P.R. China between December, 2018 and March 2019, although Zhuhai was not the endemic area of Q fever. 46 patients can be detected C. burnetti by metagenomic next-generation sequencing (mNGS). There are many similarities between acute Q fever and scrub typhus in clinical manifestations. Methods: We analyze the differences of clinical manifestations and serological between 46 patients with acute Q fever and 100 patients with scrub typhus. The general information of patients including gender, age, basic disease, days from disease onset and clinical manifestations were evaluated. Results: Their mean age of acute Q fever was 43.6±11.8 (ranging from 32 to 55 years old), younger than scrub typhus patients (53.9±12.7, ranging from 41 to 67 years old) (P<0.001). Males are more susceptible to C. burnetti. There were 45 males (97.8%) in acute Q fever patients and 59 males (59.0%) in scrub typhus patients (P<0.001). Compared with scrub typhus, patients with acute Q fever are more prone to present sore throat (P=0.003), abnormal liver function (P<0.001) and elevated levels of procalcitonin (P<0.001). Meanwhile, skin rash (P<0.001), eschar (P<0.001), lymphadenopathy (P<0.001), leukocytosis (P<0.001), thrombocytopenia (P=0.003), eosinophils reducing or disappearing (P=0.002) and pulmonary involvement on chest imaging (P=0.003) were more common in scrub typhus. There was significant difference between the two groups (P<0.001). Days from minocycline treatment to defervescence in acute Q fever (1.82±1.357, ranging from 0.5 to 3.2 days) were shorter than scrub typhus (2.85±2.801, ranging from 0.0 to 5.7 days) (P=0.008). Conclusions: mNGS is helpful to early diagnosis of acute Q fever. Sex, age, serologic test and physical examination are important in the differentiation of acute Q fever from scrub typhus in Zhuhai, China.