A rapid outbreak of monkeypox is ongoing in non-endemic countries since May 2022. We report the first case of monkeypox in the Republic of Korea. This occurred in a 34-year-old male patient who traveled to Europe in June 2022. On the day of his return to the Republic of Korea (June 21, 2022), the patient presented with a genital lesion. The results of the monkeypox real-time polymerase chain reaction tests were positive in the penile ulcer, oropharyngeal and nasopharyngeal specimens. The patient subsequently developed fever and skin rash after hospital admission. Careful history taking along physical examination should be conducted in the patients who have epidemiologic risk factors for monkeypox. Moreover, appropriate specimens should be obtained from lesions and tested for the monkeypox virus.

Objectives: Monkeypox outbreaks in nonendemic countries have been reported since early May 2022. The first case of monkeypox in the Republic of Korea was confirmed in a patient who traveled to Europe in June 2022, and an attempt was made to isolate and identify the monkeypox virus (MPXV) from the patient’s specimens. Methods: Clinical specimens from the patient were inoculated in Vero E6 cells. The isolated virus was identified as MPXV by the observation of cytopathic effects on Vero E6 cells, transmission electron microscopy, conventional polymerase chain reaction (PCR), and sequencing of PCR products. Results: Cytopathic effects were observed in Vero E6 cells that were inoculated with skin lesion swab eluates. After multiple passages from the primary culture, orthopoxvirus morphology was observed using transmission electron microscopy. In addition, both MPXV-specific (F3L and ATI) and orthopoxvirus-specific genes (A39R, B2R, and HA) were confirmed by conventional PCR and Sanger sequencing. Conclusion These results indicate the successful isolation and identification of MPXV from the first patient in the Republic of Korea. The isolated virus was named MPXV-ROK-P1-2022.

We aimed to characterize the genomes of monkeypox virus isolates from the Far East, providing insights into viral transmission and evolution. Genomic analysis was conducted on 8 isolates obtained from patients with monkeypox virus disease in the Republic of Korea between May 2022 and early 2023. These isolates were classified into Clade IIb. Distinct lineages, including B.1.1, A.2.1, and B.1.3, were observed in 2022 and 2023 isolates, with only the B.1.3 lineage detected in six isolates of 2023. These genetic features were specific to Far East isolates (the Republic of Korea, Japan, and Taiwan), distinguishing them from the diverse lineages found in the Americas, Europe, Africa, and Oceania. In early 2023, the prevalence of the B.1.3 lineage of monkeypox virus identified in six patients with no overseas travel history is considered as an indicator of the potential initiation of local transmission in the Republic of Korea.