Epidemiology and clinical characteristics of scrub typhus based on 680 unexplained fever patients in Hainan / 中国热带医学

ABSTRACT

@#Abstract Objective　To analyze the epidemiological characteristics of scrub typhus in 680 patients with unexplained fever in Hainan Island and provide guidance for local scrub typhus prevention and control. Methods　Blood samples from patients with clinically diagnosed unexplained fever in the First Affiliated Hospital of Hainan Medical University, Second Affiliated Hospital of Hainan Medical University, Haikou Municipal People's Hospital and Central South University Xiangya Medical College Affiliated Hospital, People's Hospital of Qiongzhong Li Miao Autonomous County were collected between 2018 and 2021, then samples were tested for Orientia tsutsugamushi specific IgM, IgG antibodies and Orientia tsutsugamushi 56kD-specific antigen genes using colloidal gold immunochromatography and PCR methods. The clinical and epidemiological information of the samples were also collected. Epidemiological analysis was carried out on the obtained sample information and test results. Results　A total of 680 samples from patients with clinically unknown fever were collected. The positive rates of scrub typhus IgM antibody, IgG antibody, PCR were 23.97% (163/680), 36.62% (249/680), 20.88% (142/680), respectively, and eschar or rash was observed in 12.06% (82/680) of all patients. According to the diagnostic criteria, 223 patients were finally diagnosed with scrub typhus. Among them, there were 111 males (49.78%) and 109 females (48.88%); the average age was (53.14±15.12) years old, and the 40-<60 years old was the main incidence group (98 cases, accounting for 43.95%). The ethnicity of the patient with scrub typhus was mainly Han ethnicity (136 cases, accounting for 60.99%). Farmers were the main morbidity group (93 cases, 41.70%). The patient with scrub typhus distributed throughout the island except for Sanya and Wuzhishan, with Haikou and Qiongzhong show the highest number of cases. The number of cases in autumn was the highest (114 cases, 51.12%). The clinical manifestations of infected patients were mainly non-specific symptoms and signs, 36.77% of patients developed skin-specific ulcers or eschars, which were mainly distributed in the shoulder and neck, armpits, elbow fossa, chest and abdomen, back, buttocks, groin, scrotum and other joints and skin folds of the upper and lower limbs. Conclusions　Hainan Island is the foci of scrub typhus and the epidemic time has obvious seasonality. Its prevention should focus on rural areas in autumn, and its clinical features are mainly high fever and eschar or ulceration.