Under-diagnosis of vector-borne diseases among individuals suspected of having Scrub Typhus in South Korea

• Published in: PloS one 2023-06, Vol.18 (6), p.e0286631-e0286631
• Main Authors: Won, Eun Jeong, Kim, Seong Hoon, Byeon, Kyeong Hwan, Jeon, Chae-Hyeon, Kang, Seung-Ji, Park, Joo-Heon, Kee, Seung-Jung, Choi, Hyun-Woo
• Format: Article
• Language: English
• Subjects: Anaplasmosis; Antibodies; Asymptomatic; Biology and Life Sciences; Blood; Climatic changes; Complications and side effects; Diagnosis; Disease; Erythema; Fever; Health aspects; Illnesses; Immunofluorescence; Infections; Infectious diseases; Influence; Laboratories; Medical diagnosis; Medicine and Health Sciences; Pathogens; Polymerase chain reaction; Real time; Scrub typhus; Serology; Typhus; Vector-borne diseases; Vectors (Biology)
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0286631

Due to environmental and ecological changes and suitable habitats, the occurrence of vector-borne diseases is increasing. We investigated the seroprevalence of four major vector-borne pathogens in human patients with febrile illness who were clinically suspected of having Scrub Typhus (ST) caused by Orientia tsutsugamushi. A total of 187 samples (182 patient whole blood and sera samples, including 5 follow-up) were collected. Antibodies to Anaplasma phagocytophilum, Ehrlichia chaffeensis, Borrelia burgdorferi, and Bartonella henselae were tested by using indirect immunofluorescence assays. Molecular diagnoses were performed using real-time PCR. Of the 182 cases, 37 (20.3%) cases were designated as confirmed cases of ST, and the remaining 145 (79.7%) cases as other febrile diseases (OFDs). The seroprevalence of A. phagocytophilum, E. chaffeensis, B. burgdorferi, and B. henselae was 51.4% (19/37), 10.8% (4/37), 86.5% (32/37), and 10.8% (4/37) among the ST group, and 42.8% (62/145), 10.4% (19/145), 57.7% (105/145), and 15.9% (29/145) among the OFD group, respectively. There were no significant differences in the seroprevalence between the ST and the OFD groups. Considering the co-occurrence, 89.0% (162/182) had at least one antibody to tick-borne pathogens, 37.0% (60/162) were positive for two pathogens, 17.3% (28/162) for three pathogens, and 6.2% (10/162) for four pathogens. In real-time PCR, O. tsutsugamushi was positive in 16 cases [15 (40.5%) in ST group and 1 (2.2%) in OFD group], and the four other pathogens were negative in all cases except one confirmed as anaplasmosis. In evaluating the five follow-up samples, the appearance of new antibodies or an increase in the pre-existing antibody titers was detected. Our data highlighted that acute febrile illness and manifestations suggestive of a vector-borne infection must be recognized and further considered for coinfections in clinical practice and the laboratory.