Epidemiological investigation and physician awareness regarding the diagnosis and management of Q fever in South Korea, 2011 to 2017

Abstract

Background In South Korea, the number of Q fever cases has rapidly increased since 2015. Therefore, this study aimed to characterize the epidemiological and clinical features of Q fever in South Korea between 2011 and 2017. Methods/Principal findings We analyzed the epidemiological investigations and reviewed the medical records from all hospitals that had reported at least one case of Q fever from 2011 to 2017. We also conducted an online survey to investigate physicians' awareness regarding how to appropriately diagnose and manage Q fever. The nationwide incidence rate of Q fever was annually 0.07 cases per 100,000 persons annually. However, there has been a sharp increase in its incidence, reaching up to 0.19 cases per 100,000 persons in 2017. Q fever sporadically occurred across the country, with the highest incidences in Chungbuk (0.53 cases per 100,000 persons per year) and Chungnam (0.27 cases per 100,000 persons per year) areas. Patients with acute Q fever primarily presented with mild illnesses such as hepatitis (64.5%) and isolated febrile illness (24.0%), whereas those with chronic Q fever were likely to undergo surgery (41.2%) and had a high mortality rate (23.5%). Follow-up for 6 months after acute Q fever was performed by 24.0% of the physician respondents, and only 22.3% of them reported that clinical and serological evaluations were required after acute Q fever diagnosis. Conclusions Q fever is becoming an endemic disease in the midwestern area of South Korea. Given the clinical severity and mortality of chronic Q fever, physicians should be made aware of appropriate diagnosis and management strategies for Q fever. Author summary Human Q fever, zoonosis caused by Coxiella burnetii, presents with diverse clinical manifestations, from self-limited febrile illnesses to endocarditis. It is usually diagnosed using serological tests. Because of the diagnostic challenge and nonspecific symptoms, it has been considered an underrecognized infectious disease, particularly in non-endemic or non-epidemic areas. In South Korea, Q fever was designated as a notifiable disease in 2006, and the number of Q fever cases has increased sharply since 2015. This study shows that Q fever is becoming an endemic disease in the midwestern area of South Korea. In this study, patients with acute Q fever primarily presented with mild illnesses such as hepatitis (64.5%) and isolated febrile illness (24.0%). However, patients with chronic Q fever presented with vascular infection (52.9%) and endocarditis (35.3%); such patients were likely to undergo surgery (41.2%) and had a high mortality rate (23.5%). We also surveyed physicians' awareness regarding how to appropriately diagnose and manage Q fever. This survey showed that more than half of the physicians did not follow-up suspected patients with acute Q fever who had negative serological results at the early stage of illness using a serological test and that follow-ups for identifying chronic Q fever after primary C. burnetii infection were only performed by 24.0% of physicians.