Epidemiological and clinical characteristics of scrub typhus in Guizhou Province, China: An outbreak study of scrub typhus

The reported cases of scrub typhus (ST) have continued to escalate, with outbreaks occurring regionally in China. These pose an increasing public health threat at a time when public health has been overwhelmed. During the period from July to August 2022, in Rongjiang County, Guizhou Province, China, 13 out of 21 fever patients were diagnosed with scrub typhus, based on epidemiological investigation and blood test analysis. The major clinical symptoms of these patients showed fever, chills, headache, eschar, fatigue and pneumonia, which were accompanied by a rise in C-reactive protein, neutrophils, alanine transaminase (ALT) and aspartate aminotransferase (AST). Furthermore, nearly half of them exhibited abnormal electrocardiogram activity. Through semi-nested PCR, Sanger sequencing and phylogenetic tree construction, the Karp strain of Orientia tsutsugamushi (O. tsutsugamushi) was confirmed as the pathogen causing ST in Rongjiang County, which shared the same evolutionary branch with O. tsutsugamushi isolated from wild mouse liver or spleen, indicating that the wild mouse plays an important role in transmitting the disease. In contrast to the sporadic cases in the past, our study is the first to disclose an epidemic and the corresponding clinical characteristics of ST in Guizhou province, which is of great significance for the prevention and treatment of regional illnesses. In this study, 13 cases of ST were identified through clinical and laboratory diagnosis in Rongjiang County, which is the first outbreak of the disease in Guizhou province, China. It is worth noting that ST was caused by the Karp strain, which can be transmitted by wild mice, and the infected population generally had a clear history of outdoor activity. In addition to the typical clinical symptoms such as fever, chills and pneumonia, nearly half of patients with ST also exhibited abnormal electrocardiogram activity. In conclusion, our study presents a method to confirm ST through the combination of clinical and laboratory diagnosis, which provides a reference for the development of effective strategies and measures to tackle ST, and has important public health significance.