Tick-Borne Rickettsiosis and Tsutsugamushi Disease Recorded in 313.

Tsutsugamushi disease was first described in China by Hong Ge in 313. In his book Zhouhou Beiji Fang, three eschar-associated febrile diseases were described: Shashidu, Zhongxidu, and Shegongdu. Shashidu was identified as being identical to tsutsugamushi disease in Japan: it occurred in riverside areas, exhibited an eschar, and was transmitted by tiny red "sand lice". The nature of Zhongxidu remains unknown, but we propose that it is another type of Orientia tsutsugamushi infection: it occurred in mountainous areas, an eschar was observed, and the causative vector was not identified. Moreover, Zhongxidu would have predated Shashidu by five centuries; thus, the first documentation of tsutsugamushi disease would date back 2.2 millennia. O. tsutsugamushi infection without eschar has not been identified in ancient Chinese literature and may be included in Shanghan. Several ancient Chinese books describe that Shegongdu occurs following a Shegong bite. Shegong is described as a bug resembling a cockroach or cicada with a crossbow-like structure, possibly the hypostome and unfolded palps of tick, in its mouth. Thus, Shegong refers to an engorged tick and Shegongdu is a tick-borne rickettsiosis. However, due to a lack of entomological knowledge, these findings have not been recognized for the past 1.7 millennia.

Antibiotic Combination Therapy for Severe Scrub Typhus: Is It Necessary?

Scrub typhus can be adequately treated with doxycycline or azithromycin unless it is treated too late. Such cases present as severe scrub typhus, and their treatment remains a challenging problem. In this article, we briefly review the literature on the treatment of scrub typhus and the limitations of the combination of doxycycline and azithromycin. Several options are suggested for further study in the treatment of severe scrub typhus (such as encephalitis, myocarditis, and pneumonia), including dose escalation of doxycycline, the adjuvant use of steroids, the selective use of beta-lactam antibiotics, and the use of tigecycline.

The effect of Epstein-Barr virus viremia on the progression to severe COVID-19.

ABSTRACT: Epstein-Barr virus (EBV) is frequently reactivated by coronavirus 2019 (COVID-19), and a high incidence of EBV viremia has been reported in patients with severe COVID-19. However, the impact of EBV viremia on progression to severe COVID-19 is unclear. Therefore, we conducted a study to evaluate the effect of EBV on COVID-19 progression.We investigated EBV viremia at the time of admission in COVID-19 patients hospitalized between February 1, 2020, and April 11, 2021. A cross-sectional study was performed to compare the severity of COVID-19 according to the presence or absence of EBV viremia. However, since it is difficult to analyze the influence of EBV viremia on COVID-19 progression with cross-sectional studies, a retrospective cohort study, limited to patients with mild COVID-19, was additionally conducted to observe progression to severe COVID-19 according to the presence or absence of EBV viremia.Two hundred sixty-nine COVID-19 patients were tested for EBV viremia. In a cross-sectional study that included patients with both mild and severe COVID-19, the EBV viremia group had more severe pneumonia than the EBV-negative group. However, in the cohort study limited to mild cases (N = 213), EBV viremia was not associated with COVID-19 progression.COVID-19 severity may affect EBV viremia; however, there was no evidence that EBV viremia was a factor in exacerbating pneumonia in patients with mild COVID-19.

Enhancement of triboelectricity based on fully organic composite films with a conducting polymer.

Triboelectric nanogenerators (TENGs) based on ferroelectric organic materials have advantages of high flexibility, biocompatibility, controllable ferroelectric properties, etc. However, this has limited the electrical output performance due to their lower ferroelectric characteristics than those of inorganic ferroelectric materials. A lot of effort has been made to improve the organic ferroelectric characteristics through composites, surface modifications, structures, etc. Herein, we report TENGs made of ferroelectric composite materials consisting of poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The composite was prepared by simply blending PVDF-TrFE and PEDOT:PSS with a weight ratio from 0% to 60%. When the ratio was 20%, the ferroelectric-crystalline phase was enhanced and the highest dielectric constant was observed. Accordingly, the TENGs consisting of 20% composite film and polyimide exhibited the best output performance: the maximum open circuit voltage and short circuit current were ∼15 V and ∼2.3 µA at 1 Hz oscillation, respectively. These results indicate that the ferroelectric characteristics of PVDF-TrFE can be enhanced by adding PEDOT:PSS as a nanofiller.

Buerger's Disease May be a Chronic Rickettsial Infection with Superimposed Thrombosis: Literature Review and Efficacy of Doxycycline in Three Patients.

Buerger's disease (BD) is a chronic inflammatory vasculitis of unknown etiology. The infectious etiology of BD was proposed by Buerger in 1914. Furthermore, there are scattered reports insisting that BD may be related to rickettsial infection, first asserted by Goodman since 1916, followed by Giroud and other French investigators from the 1940s through the 1960s, Nicolau in the 1960s, Bartolo (1980s), and Fazeli (2010s). However, their causal relationship has hardly been accepted because rickettsial infections are known to be acute febrile, vector-borne illnesses, whereas BD is a chronic afebrile illness. In this article we review the relevant literature on the chronic nature of Rickettsia and Orientia infections and on the rickettsial etiology of BD. Excellent initial responses to doxycycline in three patients with BD are briefly described. Based on these findings, we hypothesize that BD patients acquired a rickettsial infection far before the onset of BD. Over years, the infected area expands to become a segment of the infected vessel. Subsequently, thrombus develops on the luminal surface of the infected endothelial cells, which produces the vascular obstructive manifestations of BD. Collectively, it is postulated that BD is a chronic infection with a member of the family Rickettsiaceae with superimposed thrombosis.

Photothermal inactivation of universal viral particles by localized surface plasmon resonance mediated heating filter membrane.

This study introduces localized surface plasmon resonance (L-SPR) mediated heating filter membrane (HFM) for inactivating universal viral particles by using the photothermal effect of plasmonic metal nanoparticles (NPs). Plasmonic metal NPs were coated onto filter membrane via a conventional spray-coating method. The surface temperature of the HFM could be controlled to approximately 40-60 °C at room temperature, owing to the photothermal effect of the gold (Au) NPs coated on them, under irradiation by visible light-emitting diodes. Due to the photothermal effect of the HFMs, the virus titer of H1Npdm09 was reduced by > 99.9%, the full inactivation time being < 10 min, confirming the 50% tissue culture infective dose (TCID50) assay. Crystal violet staining showed that the infectious samples with photothermal inactivation lost their infectivity against Mardin-Darby Canine Kidney cells. Moreover, photothermal inactivation could also be applied to reduce the infectivity of SARS-CoV-2, showing reduction rate of 99%. We used quantitative reverse transcription polymerase chain reaction (qRT-PCR) techniques to confirm the existence of viral genes on the surface of the HFM. The results of the TCID50 assay, crystal violet staining method, and qRT-PCR showed that the effective and immediate reduction in viral infectivity possibly originated from the denaturation or deformation of membrane proteins and components. This study provides a new, simple, and effective method to inactivate viral infectivity, leading to its potential application in various fields of indoor air quality control and medical science.

Altered Influenza Vaccination Coverage and Related Factors in Pregnant Women in Korea from 2007 to 2019.

BACKGROUND: Pregnant women are at a high-risk of influenza infection. We have previously reported a low influenza vaccination coverage rate (4.0%) in Korea during the 2006-2007 influenza season. We conducted follow-up studies in 2011-2012 and 2018-2019 to observe changes in influenza vaccination coverage. METHODS: Women who delivered at Inha University Hospital (Incheon, Korea) in 2011-2012 and 2018-2019 were enrolled in the study. We surveyed the rate of influenza vaccination, perception scores, and related factors through telephonic interviews and compared the results from 2011-2012 and 2018-2019 with those from 2006-2007. RESULTS: The number of survey respondents was 227 in 2006-2007, 152 in 2011-2012, and 171 in 2018-2019. The rate of vaccination coverage increased from 4.0% in 2006-2007 to 42.0% in 2011-2012 and 59.3% in 2018-2019. Perception scores also increased progressively from 3.8 in 2006-2007 to 4.2 in 2011-2012 and 5.1 in 2018-2019. Physician recommendations for influenza vaccination also increased from 4.8% in 2006-2007 to 36.8% in 2011-2012 and 49.7% in 2018-2019. The most common reason for not getting vaccinated was the lack of awareness of influenza vaccination during pregnancy (36.9%). The perception scores and physician recommendation rates were significantly lower for unvaccinated women (3.87 and 8.4%, respectively) than for vaccinated women (5.14 and 69.1%, respectively). CONCLUSION: The influenza vaccination coverage rate in pregnant women has increased significantly since our study in 2006-2007. However, further improvement in the coverage rate is needed. There is a need for active and comprehensive publicity and education regarding this issue among physicians and pregnant women.

Effect of a serum lactate monitoring recommendation policy on patients treated with linezolid.

ABSTRACT: Lactic acidosis is one of the most fatal adverse effects of linezolid, an antibiotic used to treat serious infections caused by antibiotic-resistant bacteria. However, the measures to prevent lactic acidosis have not been well established.We performed a retrospective study to analyze the impact of applying a serum lactate monitoring recommendation policy in patients treated with linezolid.Since September 2011, we have recommended inpatient monitoring of serum lactate levels in patients treated with linezolid at our hospital. Patients were divided into two groups according to whether they were seen during the non-recommendation or recommendation periods. The frequency of serum lactate monitoring, linezolid-induced lactatemia, lactic acidosis, critical illness, and death were compared between the two periods.After September 2011, adherence to the recommendation to monitor serum lactate increased from 6.1% to 60.1%. No difference was observed in the incidence of linezolid-induced lactatemia and lactic acidosis between the two periods. However, there was a significant difference in the incidence of linezolid-induced critical illness between the non-recommendation and recommendation periods (3 vs 0 cases, P = .044).In patients treated with linezolid, serum lactate monitoring led to early detection of lactatemia, thus enabling rapid rescue. We recommend regular monitoring of serum lactate in all patients treated with linezolid.

Fluoroquinolone Can Be an Effective Treatment Option for Acute Pyelonephritis When the Minimum Inhibitory Concentration of Levofloxacin for the Causative Escherichia coli Is ≤16 mg/L.

The purpose of this study was to determine whether the fluoroquinolone (FQ) minimum inhibitory concentration (MIC) for the causative agent Escherichia coli influences the clinical response of FQ treatment at 72 h in patients with community-acquired acute pyelonephritis (CA-APN). We prospectively collected the clinical data of women with CA-APN from 11 university hospitals from March 2010 to February 2012 as well as E. coli isolates from the urine or blood. In total, 78 patients included in this study received FQ during the initial 72 h, and the causative E. coli was detected. The clinical response at 72 h was significantly higher in patients with a levofloxacin MIC ≤ 16 mg/L than in those with an MIC > 16 mg/L (70.4% vs. 28.6%, p = 0.038). No difference was observed in clinical response at 72 h based on ciprofloxacin MIC. To summarize, FQ can be an effective treatment option for CA-APN when levofloxacin MIC against E. coli is ≤16 mg/L.

Current Status and a Perspective of Mosquito-Borne Diseases in the Republic of Korea.

Background: Mosquito-borne diseases in the Republic of Korea have a unique epidemiology due to the rapid improvement in hygiene and economic status, occurrence of four distinct seasons, and separation from North Korea owing to the political situation. Therefore, we aimed to analyze and review the epidemiology of mosquito-borne diseases in Korea. Methods: The incidence and geographical distribution of malaria, Japanese encephalitis (JE), Zika virus infection, chikungunya fever, and dengue fever were investigated using data from the Korean Centers for Disease Control and Prevention. Lymphatic filariasis and West Nile fever, which have rarely been reported in Korea, have also been discussed in this literature review. Results and Conclusions: Malaria disappeared from Korea in 1979, but since its re-emergence in 1993 there has been constant occurrence with local transmission. In Korea, vivax malaria is the only prevailing disease, and the clinically problematic chloroquine resistance has not been reported. The incidence of JE has greatly reduced since the introduction of the national vaccination program for children in 1985. However, the incidence of JE has been increasing recently, especially in adults >40 years of age. Filariasis, which was previously endemic to Jeju Island and the southern coastal area, has not been reported since 2002. Although there are numerous imported cases with increasing overseas travel, there are still no indigenous cases of Zika, chikungunya, and dengue fever reported in Korea. The West Nile virus was isolated from migratory birds, but there has been only one imported human case to date.

Splenic infarction and infectious diseases in Korea.

BACKGROUND: The spleen contains immune cells and exhibits a pattern of infarction different from other organs; as such, splenic infarction (SI) may provide important clues to infection. However, the nature of the relationship between SI and infectious disease(s) is not well understood. Accordingly, this retrospective study investigated the relationship between SI and infection. METHODS: Hospital records of patients with SI, who visited Inha University Hospital (Incheon, Republic of Korea) between January 2008 and December 2018, were reviewed. Patient data regarding clinical presentation, causative pathogens, risk factors, and radiological findings were collected and analyzed. RESULTS: Of 353 patients with SI, 101 with infectious conditions were enrolled in this study, and their data were analyzed to identify associations between SI and infection. Ten patients were diagnosed with infective endocarditis (IE), and 26 exhibited bacteremia without IE. Twenty-seven patients experienced systemic infection due to miscellaneous causes (negative result on conventional automated blood culture), including the following intracellular organisms: parasites (malaria [n = 12], babesiosis [n = 1]); bacteria (scrub typhus [n = 5]); viruses (Epstein-Barr [n = 1], cytomegalovirus [n = 1]); and unidentified pathogen[s] (n = 7). Splenomegaly was more common among patients with miscellaneous systemic infection; infarction involving other organs was rare. Thirty-eight patients had localized infections (e.g., respiratory, intra-abdominal, or skin and soft tissue infection), and most (35 of 38) had other risk factors for SI. CONCLUSIONS: In this study, various infectious conditions were found to be associated with SI, and intracellular organisms were the most common causative pathogens. Further studies are needed to examine other possible etiologies and the underlying pathophysiological mechanisms.

Nutritional status of patients with COVID-19.

The relationship between immunity and nutrition is well known and its role in coronavirus disease 2019 (COVID-19) is also being paid great attention. However, the nutritional status of COVID-19 patients is unknown. Vitamin B1, B6, B12, vitamin D (25-hydroxyvitamin D), folate, selenium, and zinc levels were measured in 50 hospitalized patients with COVID-19. Overall, 76% of the patients were vitamin D deficient and 42% were selenium deficient. No significant increase in the incidence of deficiency was found for vitamins B1, B6, and B12, folate, and zinc in patients with COVID-19. The COVID-19 group showed significantly lower vitamin D values than the healthy control group (150 people, matched by age/sex). Severe vitamin D deficiency (based on a cut-off of ≤10 ng/dl) was found in 24.0% of the patients in the COVID-19 group and 7.3% in the control group. Among 12 patients with respiratory distress, 11 (91.7%) were deficient in at least one nutrient. However, patients without respiratory distress showed a deficiency in 30/38 cases (78.9%; p = 0.425). These results suggest that a deficiency of vitamin D or selenium may decrease the immune defenses against COVID-19 and cause progression to severe disease. However, more precise and large-scale studies are needed.

Chryseobacterium arthrosphaerae ventriculitis: A case report.

INTRODUCTION: Chryseobacterium arthrosphaerae is a gram-negative bacteria, known for its intrinsic multidrug resistance, which can lead to treatment difficulties. PATIENT CONCERNS: A 56-year-old male had an indwelling external ventricular drainage catheter for 6 months and had been frequently treated with antibiotics for nosocomial infections. He showed cerebrospinal fluid pleocytosis and an abrupt fever during hospitalization. DIAGNOSIS: He was diagnosed as a ventriculitis caused by Chryseobacterium arthrosphaerae (C arthrosphaerae). INTERVENTION: Initially, we used ciprofloxacin as the backbone in combination with minocycline (and rifampin). However, fever and pleocytosis persisted, and improvement was slow. We then switched the minocycline and rifampin regiment to trimethoprim/sulfamethoxazole. Following this switch of antibiotics, the patient's pleocytosis rapidly improved, allowing the replacement of his external ventricular drainage catheters. C arthrospharae was no longer growing in cerebrospinal fluid and he was recovered from ventriculitis. OUTCOMES: The patient remains alive without any incidence of C arthrosphaerae recurrence. CONCLUSION: We propose trimethoprim/sulfamethoxazole alone or in combination with ciprofloxacin to be good candidates for the treatment of ventriculitis by C arthrosphaerae.

Erythematous Patch in Tsutsugamushi Disease - An Atypical Form of Eschar.

Tsutsugamushi disease is caused by the bacterium, Orientia tsutsugamushi and transmitted by chigger mites. In addition to the typical dark eschar, various forms of the eschar, including papules and vesicles, develop at chigger bite sites. Macular lesions were reported only in a human inoculation study; the inoculation lesions relapsed as erythematous macules or erythema-based papules concomitant with fever relapse. Herein, we report an erythematous patch as an inoculation lesion in two patients with tsutsugamushi disease, which, additionally, displayed a central small circle of 1 mm in diameter, possibly a chigger bite site, and desquamation around the circle during doxycycline therapy.

Molecular Epidemiology of Ciprofloxacin-Resistant Escherichia coli Isolated from Community-Acquired Urinary Tract Infections in Korea.

BACKGROUND: Escherichia coli is the predominant causative pathogen for community-acquired urinary tract infections (UTIs), and the increase in fluoroquinolone-resistant E. coli is of great concern in Korea. The objectives of this study were to investigate the genotypic characteristics and molecular epidemiology of ciprofloxacin-resistant (CIP-R) E. coli isolated from community-acquired UTIs in Korea. MATERIALS AND METHODS: E. coli samples isolated from the blood or urine were collected from patients with community-acquired acute pyelonephritis aged 15 years and more who were admitted to 12 Korean hospitals from 1st April 2010 to 29th February 2012. Phylogenetic typing, multilocus sequence typing, and molecular characterization of ß-lactamase and plasmid-mediated quinolone resistance determinants were performed for CIP-R E. coli isolates. RESULTS: A total of 569 E. coli isolates were collected, and 122 (21.4%) isolates were CIP-R isolates. The most prevalent sequence type (ST) was ST131 (28.7%, 35/122), followed by ST393 (14.7%, 18/122), ST1193 (13.1%, 16/122), ST38 (9.0%, 11/122), and ST405 (8.2%, 10/122). The antimicrobial resistance rates of ST131 to cefepime (22.9%, 8/35), ST38 to gentamicin (100%, 11/11), and ST405 to cefotaxime (66.7%, 6/9) were significantly higher than the resistance rates of all other STs combined. Notably, 40% (4/10) of ST405 clones produced extended-spectrum ß-lactamases and were co-resistant to trimethoprim/sulfamethoxazole. aac(6')-1b-cr (20%, 7/35) and CTX-M-14 (40%, 4/10) were more frequently observed in ST131 and ST405 compared with other clones, respectively. CONCLUSIONS: Among the CIP-R uropathogenic E. coli isolates in this study, ST131, ST38, and ST405 were specifically associated with antimicrobial resistance.

A case of Henoch-Schönlein purpura associated with scrub typhus.

BACKGROUND: Henoch-Schönlein purpura (HSP) may be caused by several allergens. However, to date, HSP caused by Orientia tsutsugamushi has not been reported. Here, we report an unusual rash with features of HSP caused by Orientia tsutsugamushi. CASE PRESENTATION: A man visited a tertiary hospital with bilateral symmetrical purpura and fever. He presented with an eschar in the left popliteal fossa and proteinuria. He was diagnosed with tsutsugamushi disease by indirect fluorescent antibody and positive polymerase chain reaction tests. Purpura biopsy demonstrated a feature of leukocytoclastic vasculitis and IgA deposition in dermal vessels, indicative of HSP. CONCLUSIONS: When examining patients with unique rashes, such as in this case, we suggest investigating out-door activities and evidence of mite bites. Furthermore, differential diagnosis of tsutsugamushi disease should be considered when necessary.

Antinuclear antibodies in infectious diseases.

Introduction: Antinuclear antibody (ANA) tests are widely used for the diagnosis of autoimmune diseases, but ANAs are also commonly found in patients with various infections. This retrospective study aimed to investigate the relationship between infections and ANA status.Methods: Patients that visited the Department of Infectious Diseases at Inha University Hospital between January 2007 and July 2018 were investigated. We analysed their ANA test results and reviewed rheumatic and infectious diagnoses of patients with positive ANA findings.Results: Of the 9,320 patients during the study period, 1,111 underwent ANA testing and 110 tested positive. Seven of the 110 patients were previously diagnosed with ANA-positive disease, and 21 were diagnosed with autoimmune disease during the present study. Of the remaining 82 patients, 43 were confirmed with infectious disease. The most common pathogen was Mycobacterium tuberculosis (n = 10), followed by Treponema pallidum (n = 5), Orientia tsutsugamushi (n = 5), Escherichia coli (n = 5), Bartonella henselae (n = 3), and human immunodeficiency virus (n = 3). Of the 39 patients without a confirmed pathogen, 7 were seropositive for O. tsutsugamushi, B. henselae, or Rickettsia spp. Patients were observed at an average of 24 weeks in our hospital. One patient developed systemic lupus erythematosus after being diagnosed with Epstein-Barr virus-induced infectious mononucleosis, and another patient developed adult-onset Still's disease after being diagnosed with scrub typhus.Conclusion: This study showed that various relationships exist between infections and rheumatic diseases. In particular, several patients with a positive ANA test result were found to have intracellular infections such as mycobacterial infections, syphilis, or scrub typhus.

Effectiveness of a single dose of the quadrivalent meningococcal conjugate vaccine, MenACWY-CRM, in the Korean Armed Forces.

Conjugate vaccines are widely used to overcome the disadvantages of polysaccharide vaccines in the prevention of meningococcal disease. However, limited studies have examined the clinical effectiveness of single-dose meningococcal quadrivalent conjugate vaccines in adults. We assessed the effectiveness of the meningococcal vaccination program in the Republic of Korea Armed Forces, since 2013. Following vaccination program implementation, meningococcal disease cases decreased from 0.52/100,000 to 0.06/100,000 and the number of deaths declined from four to zero. Two meningococcal cases that developed post-implementation were identified as serotype B and X. The effectiveness of single-dose conjugate vaccination in recruits, expressed as the incidence rate ratio, was 0.88 during a 19-23-month observation period. These results indicate that meningococcal infections can be prevented by single-dose administration of the quadrivalent conjugate vaccine in at-risk groups, such as soldiers, travelers, and students in dormitories. Continuous investigation is needed to determine serogroup change, including B serogroups.

Geographic distribution of Tick-borne encephalitis virus complex.

A comprehensive understanding of the geographic distribution of the tick-borne encephalitis virus (TBEV) complex is necessary due to increasing transboundary movement and cross-reactivity of serological tests. This review was conducted to identify the geographic distribution of the TBEV complex, including TBE virus, Alkhurma haemorrhagic fever virus, Kyasanur forest disease virus, louping-ill virus, Omsk haemorrhagic fever virus, and Powassan virus. Published reports were identified using PubMed, EMBASE, and the Cochrane library. In addition to TBEV complex case-related studies, seroprevalence studies were also retrieved to assess the risk of TBEV complex infection. Among 1406 search results, 314 articles met the inclusion criteria. The following countries, which are known to TBEV epidemic region, had conducted national surveillance studies: Austria, China, Czech, Denmark, Estonia, Finland, Germany, Hungary, Italy, Latvia, Norway, Poland, Romania, Russia, Switzerland, Sweden, Slovenia, and Slovakia. There were also studies/reports on human TBEV infection from Belarus, Bulgaria, Croatia, France, Japan, Kyrgyzstan, Netherland, and Turkey. Seroprevalence studies were found in some areas far from the TBEV belt, specifically Malaysia, Comoros, Djibouti, and Kenya. Kyasanur forest disease virus was reported in southwestern India and Yunnan of China, the Powassan virus in the United States, Canada, and east Siberia, Alkhurma haemorrhagic fever virus in Saudi Arabia and east Egypt, and Louping-ill virus in the United Kingdom, Ireland, and east Siberia. In some areas, the distribution of the TBEV complex overlaps with that of other viruses, and caution is recommended during serologic diagnosis. The geographic distribution of the TBEV complex appears to be wide and overlap of the TBE virus complex with other viruses was observed in some areas. Knowledge of the geographical distribution of the TBEV complex could help avoid cross-reactivity during the serologic diagnosis of these viruses. Surveillance studies can implement effective control measures according to the distribution pattern of these viruses.

The Eschar Size and Early Inoculation Lesion of Tsutsugamushi Disease on Jeju Island, Korea.

BACKGROUND: Tsutsugamushi disease, or scrub typhus, is an acute febrile illness caused by Orientia tsutsugamushi, which is followed by chronic latent infection. People who reside in areas endemic of tsutsugamushi disease may be frequently reinfected with this organism. Volunteers who are experimentally reinfected with O. tsutsugamushi manifest various systemic and local reactions, including the presence of small-sized eschar. The present study recorded the morphology and size of eschars in patients with tsutsugamushi disease on Jeju Island, Korea. MATERIALS AND METHODS: From March 2018 to February 2019, 23 patients manifesting clinical characteristics and epidemiologic features of tsutsugamushi disease on Jeju Island were investigated. For comparison of eschar sizes between the two regions, 12 patients with tsutsugamushi disease in Incheon were similarly examined. RESULTS: Three patients, two on the first day and one on the fourth day of fever, presented with papules of 2 - 5 mm in diameter. Another three patients, one on the second day and two on the fourth day, presented with ruptured vesicles of 5 - 8 mm in diameter. Thirteen patients presented with eschars covered with dark scabs, with a median diameter of 5 (95% confidence interval [CI], 5 - 7.5) × 4 (95% CI, 3 - 5) mm. The medians of the eschar sizes did not differ between the two cities (P = 0.46 by Mann-Whitney U test), but eschars ≥10 mm in diameter were more frequent in Incheon than in Seogwipo-si (4 of 12 vs. 0 of 13 patients, P = 0.04 by Fisher's exact test). One patient presented with multiple eschars, and no eschar was detected in the remaining three patients. Among 11 Jeju Island patients with positive IgG and IgM antibodies, seven patients revealed higher IgG than IgM antibody titers during the acute phase of the illness, i.e., the IgG antibody response, two patients had equal IgG and IgM titers, and two patients presented the IgM antibody response. Life-threatening complications and death were not observed in this study. CONCLUSION: The patients in Seogwipo-si had small-sized eschars and occasionally exhibited non-necrotic lesions. Many patients had serologically reinfected tsutsugamushi disease. Further studies are needed to investigate the association between these findings.