Use of the Monoclonal Antibody Regdanvimab to Treat Patients Hospitalized with COVID-19:Real-World Data during the Delta Variant Predominance

Regdanvimab is the only monoclonal antibody available in Korea that targets severe acute respiratory syndrome coronavirus 2. We retrospectively evaluated the clinical characteristics of 374 adults hospitalized with coronavirus disease 2019 (COVID-19) who were treated with regdanvimab from September through December 2021. In total, 322 (86.1%) patients exhibited risk factors for disease progression. Most patients (91.4%) improved without additional treatment. No patient died or was transferred to intensive care. This study shows that regdanvimab prevented disease progression in high-risk patients with mild to moderate COVID-19 infections during Delta variant predominance.

Four Times of Relapse of Plasmodium vivax Malaria Despite Primaquine Treatment in a Patient with Impaired Cytochrome P450 2D6 Function

Plasmodium vivax exhibits dormant liver-stage parasites, called hypnozoites, which can cause relapse of malaria. The only drug currently used for eliminating hypnozoites is primaquine. The antimalarial properties of primaquine are dependent on the production of oxidized metabolites by the cytochrome P450 isoenzyme 2D6 (CYP2D6). Reduced primaquine metabolism may be related to P. vivax relapses. We describe a case of 4 episodes of recurrence of vivax malaria in a patient with decreased CYP2D6 function. The patient was 52-year-old male with body weight of 52 kg. He received total gastrectomy and splenectomy 7 months before the first episode and was under chemotherapy for the gastric cancer. The first episode occurred in March 2019 and each episode had intervals of 34, 41, and 97 days, respectively. At the first and second episodes, primaquine was administered as 15 mg for 14 days. The primaquine dose was increased with 30 mg for 14 days at the third and fourth episodes. Seven gene sequences of P. vivax were analyzed and revealed totally identical for all the 4 samples. The CYP2D6 genotype was analyzed and intermediate metabolizer phenotype with decreased function was identified.

Survey of Adverse Events After The First Dose of The ChAdOx1 nCoV-19 Vaccine:A Single-Center Experience in Korea

Vaccination is an important strategy for controlling the coronavirus disease 2019 (COVID-19) pandemic. We conducted a web-based cross-sectional survey based on Google Forms to collect data on adverse events (AEs) after the first dose of the ChAdOx1 nCoV-19 vaccine for healthcare workers (HCWs). Among the 1,676 vaccinated HCWs, 59.5% (998/1,676) responded to the survey. In total, 809 (81.1%) respondents reported experiencing AEs. There were no serious AEs, such as anaphylaxis. The most common AE was pain at the injection site (76.2%), followed by fatigue (75.9%), myalgia (74.9%), and fever (58.4%). HCWs in the younger age group experienced significantly more AEs than in the older age group.

Etiology, Characteristics, and Outcomes of Community-Onset Pyomyositis in Korea: A Multicenter Study

Background@#Pyomyositis (PM) is a serious soft tissue infection and despite its clinical importance, previous studies have not been able to fully determine the clinical characteristics and microbial epidemiology of PM in Korea, which we therefore aimed to investigate. @*Materials and Methods@#We retrospectively identified 140 adult patients diagnosed with PM from 13 general hospitals between January 2012 and December 2015. We analyzed the clinical and microbial characteristics of community-onset PM and compared them with communityacquired (CA) and healthcare-associated (HCA) PM. @*Results@#One hundred eleven organisms were isolated from 96 (68.6%) patients with PM.Staphylococcus aureus (38 patients) was the most common pathogen, followed by streptococci (24 patients), and enteric Gram-negative organisms (27 patients). Methicillin-resistant S.aureus (MRSA) was identified in four (2.9%) patients and in-hospital mortality reached 8.6% (12/140). Enterococci isolates were identified in the HCA PM subgroup only The proportion of MRSA isolates was not comparable between CA and HCA PM subgroups. In the 83 patients with PM infected by monomicrobial pathogens, isolates of Gram-negative organisms were more commonly found in HCA PM subgroup than in CA PM subgroup (47.6% [10/21] of patients with HCA PM vs. 20.7% [12/58] of patients with CA PM; P = 0.01). @*Conclusion@#Gram-positive cocci such as S. aureus and streptococci were dominant etiologies in community-onset PM, whereas MRSA appears to an uncommon causative organism of PM in Korea. Enteric Gram-negative organisms should also be considered as major etiologies, especially in HCA PM patient population in Korea.

Survey of Adverse Events After The First Dose of The ChAdOx1 nCoV-19 Vaccine:A Single-Center Experience in Korea

Vaccination is an important strategy for controlling the coronavirus disease 2019 (COVID-19) pandemic. We conducted a web-based cross-sectional survey based on Google Forms to collect data on adverse events (AEs) after the first dose of the ChAdOx1 nCoV-19 vaccine for healthcare workers (HCWs). Among the 1,676 vaccinated HCWs, 59.5% (998/1,676) responded to the survey. In total, 809 (81.1%) respondents reported experiencing AEs. There were no serious AEs, such as anaphylaxis. The most common AE was pain at the injection site (76.2%), followed by fatigue (75.9%), myalgia (74.9%), and fever (58.4%). HCWs in the younger age group experienced significantly more AEs than in the older age group.

Etiology, Characteristics, and Outcomes of Community-Onset Pyomyositis in Korea: A Multicenter Study

Background@#Pyomyositis (PM) is a serious soft tissue infection and despite its clinical importance, previous studies have not been able to fully determine the clinical characteristics and microbial epidemiology of PM in Korea, which we therefore aimed to investigate. @*Materials and Methods@#We retrospectively identified 140 adult patients diagnosed with PM from 13 general hospitals between January 2012 and December 2015. We analyzed the clinical and microbial characteristics of community-onset PM and compared them with communityacquired (CA) and healthcare-associated (HCA) PM. @*Results@#One hundred eleven organisms were isolated from 96 (68.6%) patients with PM.Staphylococcus aureus (38 patients) was the most common pathogen, followed by streptococci (24 patients), and enteric Gram-negative organisms (27 patients). Methicillin-resistant S.aureus (MRSA) was identified in four (2.9%) patients and in-hospital mortality reached 8.6% (12/140). Enterococci isolates were identified in the HCA PM subgroup only The proportion of MRSA isolates was not comparable between CA and HCA PM subgroups. In the 83 patients with PM infected by monomicrobial pathogens, isolates of Gram-negative organisms were more commonly found in HCA PM subgroup than in CA PM subgroup (47.6% [10/21] of patients with HCA PM vs. 20.7% [12/58] of patients with CA PM; P = 0.01). @*Conclusion@#Gram-positive cocci such as S. aureus and streptococci were dominant etiologies in community-onset PM, whereas MRSA appears to an uncommon causative organism of PM in Korea. Enteric Gram-negative organisms should also be considered as major etiologies, especially in HCA PM patient population in Korea.

Comparison of the Seroprevalence of Measles Antibodies among Healthcare Workers in Two Korean Hospitals in 2019

We performed a point seroprevalence survey of measles among healthcare workers (HCWs) at two Korean teaching hospitals in 2019. A total of 2,830 HCWs underwent an antibody test.The overall seropositivity of measles was 93.1%. The seroprevalence of measles was lowest in HCWs aged 20 - 24 years (81.2%), followed by those aged 25 - 29 years (90.1%). The rates of anti-measles IgG positivity were significantly different between the two hospitals (97.0% vs.89.4%, P <0.001). These results suggest that the seropositivity of measles in HCWs may differ depending on the hospital's vaccination policy.

A Nationwide Survey on the Hospital Vaccination Policies in Korea

BACKGROUND: Healthcare personnel (HCP) are at risk of being exposed to or transmitting infections in hospitals, and vaccination against vaccine-preventable diseases (VPDs) is a well-known preventive strategy. Vaccination against influenza, hepatitis B virus, measles-mumps-rubella, varicella, and pertussis is recommended for HCP. However, there is no information on the current status of hospitals' vaccination policies for HCP in Korea.METHODS: We conducted a nationwide survey on hospital vaccination policies and barriers to implementing recommended vaccination programs in 2018. The online survey questionnaire was distributed to 652 hospitals, and 200 of them responded.RESULTS: Of the 200 surveyed hospitals, 151 (75.5%) conducted a pre-employment screening program for at least one VPD, and 196 (98%) had vaccination programs that included at least one vaccine. Influenza vaccine was most commonly included in their programs (97.5%, n = 195), followed by hepatitis B vaccines (69%, n = 138). However, < 25% of the hospitals included other vaccines in their policies (measles-mumps-rubella, 24.5%; varicella, 18.5%; pertussis, 11%). Only 13 hospitals (6.5%) included the five recommended vaccines for HCP in their policies. Influenza vaccination coverage had a mean of 89.9% and was significantly higher in hospitals fully funding the vaccination cost (91.8% vs. 80.4%, P < 0.001). Among hospitals funding influenza vaccines, the coverage was lower in hospitals with ≥ 700 beds (−6.5%, P = 0.003). Hospitals' financial burden was the most important barrier to implementing vaccination polices as recommended (78.6%, 121/154), followed by lack of awareness (21%) or campaign (21%) and lack of leadership (17%).CONCLUSION: Despite the recommendations on vaccination for HCP, the vaccination policies for HCP differ in hospitals and appear to be insufficient to protect HCP and prevent nosocomial transmission. Strong leadership of each hospital to protect HCP and financial support from the government are required to implement appropriate vaccination policies in hospitals.

A Nationwide Survey on the Hospital Vaccination Policies in Korea

BACKGROUND@#Healthcare personnel (HCP) are at risk of being exposed to or transmitting infections in hospitals, and vaccination against vaccine-preventable diseases (VPDs) is a well-known preventive strategy. Vaccination against influenza, hepatitis B virus, measles-mumps-rubella, varicella, and pertussis is recommended for HCP. However, there is no information on the current status of hospitals' vaccination policies for HCP in Korea.@*METHODS@#We conducted a nationwide survey on hospital vaccination policies and barriers to implementing recommended vaccination programs in 2018. The online survey questionnaire was distributed to 652 hospitals, and 200 of them responded.@*RESULTS@#Of the 200 surveyed hospitals, 151 (75.5%) conducted a pre-employment screening program for at least one VPD, and 196 (98%) had vaccination programs that included at least one vaccine. Influenza vaccine was most commonly included in their programs (97.5%, n = 195), followed by hepatitis B vaccines (69%, n = 138). However, < 25% of the hospitals included other vaccines in their policies (measles-mumps-rubella, 24.5%; varicella, 18.5%; pertussis, 11%). Only 13 hospitals (6.5%) included the five recommended vaccines for HCP in their policies. Influenza vaccination coverage had a mean of 89.9% and was significantly higher in hospitals fully funding the vaccination cost (91.8% vs. 80.4%, P < 0.001). Among hospitals funding influenza vaccines, the coverage was lower in hospitals with ≥ 700 beds (−6.5%, P = 0.003). Hospitals' financial burden was the most important barrier to implementing vaccination polices as recommended (78.6%, 121/154), followed by lack of awareness (21%) or campaign (21%) and lack of leadership (17%).@*CONCLUSION@#Despite the recommendations on vaccination for HCP, the vaccination policies for HCP differ in hospitals and appear to be insufficient to protect HCP and prevent nosocomial transmission. Strong leadership of each hospital to protect HCP and financial support from the government are required to implement appropriate vaccination policies in hospitals.

A Nationwide Survey on the Hospital Vaccination Policies in Korea

BACKGROUND@#Healthcare personnel (HCP) are at risk of being exposed to or transmitting infections in hospitals, and vaccination against vaccine-preventable diseases (VPDs) is a well-known preventive strategy. Vaccination against influenza, hepatitis B virus, measles-mumps-rubella, varicella, and pertussis is recommended for HCP. However, there is no information on the current status of hospitals' vaccination policies for HCP in Korea.@*METHODS@#We conducted a nationwide survey on hospital vaccination policies and barriers to implementing recommended vaccination programs in 2018. The online survey questionnaire was distributed to 652 hospitals, and 200 of them responded.@*RESULTS@#Of the 200 surveyed hospitals, 151 (75.5%) conducted a pre-employment screening program for at least one VPD, and 196 (98%) had vaccination programs that included at least one vaccine. Influenza vaccine was most commonly included in their programs (97.5%, n = 195), followed by hepatitis B vaccines (69%, n = 138). However, < 25% of the hospitals included other vaccines in their policies (measles-mumps-rubella, 24.5%; varicella, 18.5%; pertussis, 11%). Only 13 hospitals (6.5%) included the five recommended vaccines for HCP in their policies. Influenza vaccination coverage had a mean of 89.9% and was significantly higher in hospitals fully funding the vaccination cost (91.8% vs. 80.4%, P < 0.001). Among hospitals funding influenza vaccines, the coverage was lower in hospitals with ≥ 700 beds (−6.5%, P = 0.003). Hospitals' financial burden was the most important barrier to implementing vaccination polices as recommended (78.6%, 121/154), followed by lack of awareness (21%) or campaign (21%) and lack of leadership (17%).@*CONCLUSION@#Despite the recommendations on vaccination for HCP, the vaccination policies for HCP differ in hospitals and appear to be insufficient to protect HCP and prevent nosocomial transmission. Strong leadership of each hospital to protect HCP and financial support from the government are required to implement appropriate vaccination policies in hospitals.

Antibiotic Treatment of Vertebral Osteomyelitis caused by Methicillin-Susceptible Staphylococcus aureus: A Focus on the Use of Oral β-lactams

BACKGROUND@#Vertebral osteomyelitis (VO) is a rare but serious condition, and a potentially significant cause of morbidity. Methicillin-susceptible Staphylococcus aureus (MSSA) is the most common microorganism in native VO. Long-term administration of parenteral and oral antibiotics with good bioavailability and bone penetration is required for therapy. Use of oral β-lactams against staphylococcal bone and joint infections in adults is not generally recommended, but some experts recommend oral switching with β-lactams. This study aimed to describe the current status of antibiotic therapy and treatment outcomes of oral switching with β-lactams in patients with MSSA VO, and to assess risk factors for treatment failure.@*MATERIALS AND METHODS@#This retrospective study included adult patients with MSSA VO treated at nine university hospitals in Korea between 2005 and 2014. Treatment failure was defined as infection-related death, microbiological relapse, neurologic deficits, or unplanned surgical procedures. Clinical characteristics and antibiotic therapy in the treatment success and treatment failure groups were compared. Risk factors for treatment failure were identified using the Cox proportional hazards model.@*RESULTS@#A total of 100 patients with MSSA VO were included. All patients were treated, initially or during antibiotic therapy, with one or more parenteral antibiotics. Sixty-nine patients received one or more oral antibiotics. Antibiotic regimens were diverse and durations of parenteral and oral therapy differed, depending on the patient and the hospital. Forty-two patients were treated with parenteral and/or oral β-lactams for a total duration of more than 2 weeks. Compared with patients receiving parenteral β-lactams only, no significant difference in success rates was observed in patients who received oral β-lactams for a relatively long period. Sixteen patients had treatment failure. Old age (adjusted hazard ratio [HR] 5.600, 95% confidence interval [CI] 1.402 – 22.372, P = 0.015) and failure to improve C-reactive protein levels at follow-up (adjusted HR 3.388, 95% CI 1.168 – 9.829, P = 0.025) were independent risk factors for treatment failure.@*CONCLUSION@#In the study hospitals, diverse combinations of antibiotics and differing durations of parenteral and oral therapy were used. Based on the findings of this study, we think that switching to oral β-lactams may be safe in certain adult patients with MSSA VO. Since limited data are available on the efficacy of oral antibiotics for treatment of staphylococcal VO in adults, further evaluation of the role of oral switch therapy with β-lactams is needed.

Non-Mandatory Influenza Vaccination Rates among Healthcare Workers during the 2017–2018 Influenza Season: a Multicenter Study in Korea

PURPOSE: Annual influenza vaccination is the best strategy to prevent healthcare-associated influenza transmission. Influenza vaccination rates among healthcare workers (HCWs) vary by country, region, and year. We investigated the influenza vaccination rates for HCWs during the 2017–2018 influenza season in South Korea, where a non-mandatory vaccination campaign was conducted.METHODS: We retrospectively investigated factors affecting the influenza vaccination rate among HCWs during the 2017–2018 influenza season in three tertiary hospitals in Goyang City, where the non-mandatory influenza vaccination program is conducted.RESULTS: Consequently, 6,994 of 7,180 HCWs (97%) were included, and the overall vaccination rate was 85%. Nurses had the highest rate with 92%, followed by health technicians (88%), physicians (84%), and non-medical HCWs (79%, P<0.001). Vaccination rates differed, depending on the frequency of contact with patients in the non-medical HCWs (frequent contact vs. less-frequent contact; 90% vs. 73%, P<0.001).CONCLUSIONS: The influenza vaccination rate among HCWs during the 2017–2018 influenza season in Korea was 85%, which is among the highest rates compared with previously reported non-mandatory vaccination rates in other countries. The vaccination rate may vary depending on the HCW's occupational characteristics, including the extent of contact with the patient. Therefore, a multifaceted strategy is needed to increase the vaccination rate of HCWs.

Co-Infection of Scrub Typhus and Human Granulocytic Anaplasmosis in Korea, 2006

BACKGROUND: Scrub typhus, severe fever with thrombocytopenia syndrome (SFTS) and human granulocytic anaplasmosis (HGA) are important arthropod-borne infectious diseases in Korea and share a common point that they are transmitted by arthropod bites mostly during outdoor activities and there are considerable overlaps of epidemiologic and clinical features at presentation. We investigated the co-infection of these infections. METHODS: The study subjects were patients with laboratory-confirmed scrub typhus who were enrolled retrospectively in 2006. SFTS virus (SFTSV) infection was confirmed by a reverse transcriptase polymerase chain reaction (PCR) to amplify partial L segment of SFTSV for molecular diagnosis. HGA was confirmed by a nested PCR to amplify 16S rRNA gene of Anaplasma phagocytophilum. Direct sequencing of the positive PCR products was performed. Clinical features of co-infected subjects were described. RESULTS: One-hundred sixty-seven patients with scrub typhus were included in the analysis. Co-infection of A. phagocytophilum was identified in 4.2% of scrub typhus patients (7/167). The route of co-infection was uncertain. The co-infected patients had not different clinical manifestations compared to the patients with scrub typhus only. All the study subjects were negative for SFTSV. CONCLUSION: We found retrospective molecular evidence of the co-infection of scrub typhus and HGA in Korea. HGA may be more prevalent than expected and need to be considered as an important differential diagnosis of febrile patients in Korea.

Appropriate Use of Surgical Antibiotic Prophylaxis

No abstract available.

Late diagnosis of influenza in adult patients during a seasonal outbreak

BACKGROUND/AIMS: Due to advances in diagnostic techniques, clinicians are more frequently performing influenza diagnostic tests and referring to their test results ahead of the administration of neuraminidase inhibitors (NAIs). To investigate the clinical significance of the time from symptom onset to laboratory diagnosis, we reviewed the clinical characteristics of adult patients with influenza who had an early laboratory diagnosis (ED) or a late laboratory diagnosis (LD) at one of four tertiary care centers during a seasonal outbreak of influenza. METHODS: Clinical data were collected from 1,405 adults during the 2013 to 2014 influenza season. A patient was regarded as receiving an ED or LD if he/she received an influenza diagnostic test at 0 to 1 or 4 to 7 days after symptom onset, respectively. Early NAI therapy and late NAI therapy were defined as the administration of NAI ≤ 2 or > 2 days after symptom onset, respectively. RESULTS: Nearly half of the patients (47.0%) received an ED (n = 661), whereas 13.5% (n = 190) received a LD. Patients with a LD had initial symptoms of cough, sputum production, and dyspnea and experienced pneumonia, antibiotic therapy, hospitalization, and admission to the intensive care unit more often than those with an ED. NAI therapy and early NAI therapy were less frequent in patients with a LD than those with an ED. Of the analyzed baseline characteristics, age ≥ 50 years, influenza B infection, and diagnosis using a polymerase chain reaction test were significantly associated with a LD. CONCLUSIONS: LD was associated with inappropriate antiviral therapy and complicated presenting features in adult patients with seasonal influenza. ED of influenza should be emphasized, especially for older adults.

Outpatient treatment in women with acute pyelonephritis after visiting emergency department

No abstract available.

Clinical Guidelines for the Antibiotic Treatment for Community-Acquired Skin and Soft Tissue Infection

Skin and soft tissue infection (SSTI) is common and important infectious disease. This work represents an update to 2012 Korean guideline for SSTI. The present guideline was developed by the adaptation method. This clinical guideline provides recommendations for the diagnosis and management of SSTI, including impetigo/ecthyma, purulent skin and soft tissue infection, erysipelas and cellulitis, necrotizing fasciitis, pyomyositis, clostridial myonecrosis, and human/animal bite. This guideline targets community-acquired skin and soft tissue infection occurring among adult patients aged 16 years and older. Diabetic foot infection, surgery-related infection, and infections in immunocompromised patients were not included in this guideline.

Korean Nosocomial Infections Surveillance System, Intensive Care Unit Module Report: Summary of Data from July 2013 through June 2014 / 병원감염관리

BACKGROUND: In this report, we present the annual data of the intensive care unit (ICU) module of the Korean Nosocomial Infections Surveillance System (KONIS) from July 2013 through June 2014. METHODS: We performed a prospective surveillance of nosocomial urinary tract infections (UTIs), bloodstream infections (BSIs), and pneumonia (PNEU) in 166 ICUs of 94 hospitals using the KONIS. Nosocomial infection (NI) rate was defined as the number of infections per 1,000 patient-days or device-days. RESULTS: A total of 2,843 NIs were found during the study period: 861 UTIs (846 were urinary catheter-associated), 1,173 BSIs (1,021 were central line-associated), and 809 PNEUs (498 were ventilator-associated). The rate of urinary catheter-associated UTIs was 1.21 per 1,000 device-days (95% confidence interval [CI]=1.13-1.29), and the urinary catheter utilization ratio was 0.84 (95% CI=0.839-0.841). The rate of central line-associated BSIs was 2.33 per 1,000 device-days (95% CI=2.20-2.48), and the utilization ratio was 0.53 (95% CI=0.529-0.531). The rate of ventilatorassociated PNEUs (VAPs) was 1.46 per 1,000 device-days (95% CI=1.34-1.60), and the utilization ratio was 0.41 (95% CI=0.409-0.411). In hospitals with more than 900 beds, although the ventilator utilization ratio was highest, the rate of VAPs was lower than in hospitals with 300-699 or 700-899 beds. CONCLUSION: BSIs were the most commonly reported nosocomial infections. Although device utilization ratios had increased, nosocomial infection rates did not differ significantly from those during the previous period (July 2012 through June 2013).

Low Compliance with National Guidelines for Preventing Transmission of Group 1 Nationally Notifiable Infectious Diseases in Korea

PURPOSE: This study was performed to evaluate the compliance with, and adequacy of, the Korean national guidelines which had been recommended until 2011 for isolation of patients with group 1 nationally notifiable infectious diseases (NNIDs), namely cholera, typhoid fever, paratyphoid fever, shigellosis, and enterohemorrhagic Escherichia coli (EHEC) infection. MATERIALS AND METHODS: We evaluated the clinical and microbiological characteristics of confirmed cases of group 1 NNIDs and compliance with the guidelines in 20 Korean hospitals nationwide in 2000-2010. We also compared the Korean guidelines with international guidelines. RESULTS: Among 528 confirmed cases (8 cases of cholera, 232 of typhoid fever, 81 of paratyphoid fever, 175 of shigellosis, and 32 EHEC infections), strict compliance with the Korean guideline was achieved in only 2.6% to 50.0%, depending on the disease. While the Korean guidelines recommend isolation of all patients with group 1 NNIDs, international guidelines recommend selective patient isolation and screening for fecal shedding, depending on the type of disease and patient status. CONCLUSION: Compliance with the previous national guidelines for group 1 NNIDs in Korea was generally very low. Further studies are needed to evaluate whether compliance was improved after implementation of the new guideline in 2012.

Clinical Characteristics of Vivax Malaria and Analysis of Recurred Patients

BACKGROUND: Plasmodium vivax malaria is an acute debilitating illness characterized by recurrent paroxysmal fever and relapses from hypnozoites in the liver. Although a few studies reported clinical characteristics of vivax malaria in civilians after reemergence in the Republic of Korea, only a small group of patients was analyzed. MATERIALS AND METHODS: We retrospectively reviewed the medical records of patients who had been diagnosed with vivax malaria by peripheral blood smear in a university-affiliated hospital located in a malaria-endemic area between January 2005 and December 2009. RESULTS: During the study period, a total of 352 malarial cases from 341 patients were diagnosed. Vivax malaria was most commonly developed in July and August, 24.7% (87/352), and 21.9% (77/352), respectively. The mean (SD) age was 42.5 (14.7) years and the number of male patients was 243 (71.3%). Six patients had a previous history of vivax malaria from 6 months to 10 years before. A total of 337 patients (98.8%) had fever and the mean (SD) body temperature was 38.3 (1.4)degrees C. Common associated symptoms were chills (213/341, 62.5%), headache (115/341, 33.7%), and myalgia (85/341, 24.9%). Laboratory findings included thrombocytopenia (340/341, 99.7%), anemia (97/341, 28.5%), leukopenia (148/341, 43.4%), increase of aspartate transaminase (177/341, 51.9%), and increase of alanine transaminase (187/341, 54.8%). Hypotension (14/341, 4.1%), altered mentality (3/341, 0.9%), azotemia (3/341, 0.9%), spleen infarction (2/341, 0.6%), and spleen rupture (1/341, 0.3%) developed as complications. Chloroquine was administered to all patients and primaquine was administered with mean (SD) 3.39 (0.82) mg/kg to 320 patients. There were 11 recurrent infections during the study period. The median (range) time to recurrent infection was 100 (32-285) days. Platelet counts were higher (86,550 vs. 56,910/mm3) and time to treatment of malaria was shorter (5 vs. 7 days) in relapsed cases compared with first occurrence cases (P=0.046). CONCLUSIONS: The overall recurrence rate of vivax malaria was 3.2% (11/341) in this study. In recurred cases, malaria was diagnosed earlier and thrombocytopenia was less severe. To evaluate the risk factors associated with recurrence and adequate dose of primaquine in Korean patients, further large-scale prospective studies will be needed.