Anisakiasis in humans in South Korea has been considered to be caused exclusively by the larvae of Anisakis simplex sensu stricto and Pseudoterranova decipiens. Recently, however, DNA sequencing of larvae from 15 of 16 anisakiasis patients confirmed the cause to be Anisakis pegreffii infection. Molecular analysis should be performed for all extracted larvae.

Toxoplasma gondii infection induces alteration of the host cell cycle and cell proliferation. These changes are not only seen in directly invaded host cells but also in neighboring cells. We tried to identify whether this alteration can be mediated by exosomes secreted by T. gondii-infected host cells. L6 cells, a rat myoblast cell line, and RH strain of T. gondii were selected for this study. L6 cells were infected with or without T. gondii to isolate exosomes. The cellular growth patterns were identified by cell counting with trypan blue under confocal microscopy, and cell cycle changes were investigated by flow cytometry. L6 cells infected with T. gondii showed decreased proliferation compared to uninfected L6 cells and revealed a tendency to stay at S or G2/M cell phase. The treatment of exosomes isolated from T. gondii-infected cells showed attenuation of cell proliferation and slight enhancement of S phase in L6 cells. The cell cycle alteration was not as obvious as reduction of the cell proliferation by the exosome treatment. These changes were transient and disappeared at 48 hr after the exosome treatment. Microarray analysis and web-based tools indicated that various exosomal miRNAs were crucial for the regulation of target genes related to cell proliferation. Collectively, our study demonstrated that the exosomes originating from T. gondii could change the host cell proliferation and alter the host cell cycle.

The increasing prevalence of Toxoplasma gondii infection in the human population in the Republic of Korea (= Korea) is due to various reasons such as an increase in meat consumption. However, the importance of cats in transmitting T. gondii infection through oocysts to humans has seldom been assessed. A total of 300 fecal samples of stray cats captured around Seoul from June to August 2013 were examined for T. gondii B1 gene (indicating the presence of oocysts) using nested-PCR. Fourteen (4.7%) of 300 cats examined were positive for B1 gene. Female cats (7.5%) showed a higher prevalence than male cats (1.4%). Cats younger than 3 months (5.5%) showed a higher prevalence than cats (1.5%) older than 3 months. For laboratory passage of the positive samples, the fecal suspension (0.2 ml) of B1 gene positive cats was orally inoculated into experimental mice. Brain tissues of the mice were obtained after 40 days and examined for the presence of tissue cysts. Two isolates were successfully passaged (designated KNIH-1 and KNIH-2) and were molecularly analyzed using the SAG5D and SAG5E gene sequences. The SAG5D and SAG5E gene sequences showed high homologies with the ME49 strain (less virulent strain). The results indicated the importance of stray cats in transmitting T. gondii to humans in Korea, as revealed by detection of B1 gene in fecal samples. T. gondii isolates from cats were successfully passaged in the laboratory for the first time in Korea.

Echinostoma flukes armed with 37 collar spines on their head collar are called as 37-collar-spined Echinostoma spp. (group) or ‘Echinostoma revolutum group’. At least 56 nominal species have been described in this group. However, many of them were morphologically close to and difficult to distinguish from the other, thus synonymized with the others. However, some of the synonymies were disagreed by other researchers, and taxonomic debates have been continued. Fortunately, recent development of molecular techniques, in particular, sequencing of the mitochondrial (nad1 and cox1) and nuclear genes (ITS region; ITS1-5.8S-ITS2), has enabled us to obtain highly useful data on phylogenetic relationships of these 37-collar-spined Echinostoma spp. Thus, 16 different species are currently acknowledged to be valid worldwide, which include E. revolutum, E. bolschewense, E. caproni, E. cinetorchis, E. deserticum, E. lindoense, E. luisreyi, E. mekongi, E. miyagawai, E. nasincovae, E. novaezealandense, E. paraensei, E. paraulum, E. robustum, E. trivolvis, and Echinostoma sp. IG of Georgieva et al., 2013. The validity of the other 10 species is retained until further evaluation, including molecular analyses; E. acuticauda, E. barbosai, E. chloephagae, E. echinatum, E. jurini, E. nudicaudatum, E. parvocirrus, E. pinnicaudatum, E. ralli, and E. rodriguesi. In this review, the history of discovery and taxonomic debates on these 26 valid or validity-retained species are briefly reviewed.

Adult echinostomes having 37 collar spines collected from the intestine of Pitalah ducks in Aceh Province, Indonesia in 2018 were morphologically and molecularly determined to be Echinostoma miyagawai Ishii, 1932 (Digenea: Echinostomatidae). Among 20 ducks examined, 7 (35.0%) were found to be infected with this echinostome, and the number of flukes collected was 48 in total with average 6.9 (1-17) worms per duck. The adult flukes were 7.2 (6.1-8.5) mm in length and 1.2 (1.0-1.4) mm in width (pre-ovarian or testicular level) and characterized by having a head collar armed with 37 collar spines (dorsal spines arranged in 2 alternating rows), including 5 end group spines, and variable morphology of the testes, irregularly or deeply lobed (3-5 lobes) at times with horizontal extension. The eggs within the worm uterus were 93 (79-105) µm long and 62 (56-70) µm wide. These morphological features were consistent with both E. miyagawai and Echinostoma robustum, for which synonymy to each other has been raised. Sequencing of 2 mitochondrial genes, cox1 and nad1, revealed high homology with E. miyagawai (98.6-100% for cox1 and 99.0-99.8% for nad1) and also with E. robustum (99.3-99.8% for nad1) deposited in GenBank. We accepted the synonymy between the 2 species and diagnosed our flukes as E. miyagawai (syn. E. robustum) with redescription of its morphology. Further studies are required to determine the biological characteristics of E. miyagawai in Aceh Province, Indonesia, including the intermediate host and larval stage information.

In order to determine the status of Enterobius vermicularis infection among schoolchildren in suburban areas of Myanmar, 761 primary schoolchildren in 3 different townships around Yangon City were subjected to a survey using cello-tape anal swabs. The subjected schoolchildren were 383 boys and 378 girls who were 5-7 years of age. Only 1 anal swab was obtained from each child. The overall egg positive rate of E. vermicularis was 47.2% (359 positives), and sex difference was not remarkable (48.6% in boys and 45.8% in girls). However, the positive rate was the highest in South Dagon (54.6%) followed by Hlaing Thayar (43.8%) and North Dagon (34.8%). This difference was highly correlated with the living standards of the people in each township. Nucleotide sequence of the 5S rDNA from the eggs on the cello-tape (2 children) revealed 99.7% identity with that of E. vermicularis reported in GenBank. The results indicated that E. vermicularis infection is highly prevalent among primary schoolchildren around Yangon, Myanmar.

Fascioliasis is a zoonotic infection caused by Fasciola hepatica or Fasciola gigantica. We report an 87-year-old Korean male patient with postprandial abdominal pain and discomfort due to F. hepatica infection who was diagnosed and managed by endoscopic retrograde cholangiopancreatography (ERCP) with extraction of 2 worms. At his first visit to the hospital, a gallbladder stone was suspected. CT and magnetic retrograde cholangiopancreatography (MRCP) showed an intraductal mass in the common bile duct (CBD) without proximal duct dilatation. Based on radiological findings, the presumed diagnosis was intraductal cholangiocarcinoma. However, in ERCP which was performed for biliary decompression and tissue diagnosis, movable materials were detected in the CBD. Using a basket, 2 living leaf-like parasites were removed. The worms were morphologically compatible with F. hepatica. To rule out the possibility of the worms to be another morphologically close species, in particular F. gigantica, 1 specimen was processed for genetic analysis of its ITS-1 region. The results showed that the present worms were genetically identical (100%) with F. hepatica but different from F. gigantica.

Toxoplasma gondii is an intracellular protozoan that can modulate the environment of the infected host. An unfavorable environment modulated by T. gondii in the brain includes tumor microenvironment. Literature has suggested that T. gondii infection is associated with development of brain tumors. However, in Korea, epidemiological data regarding this correlation have been scarce. In this study, in order to investigate the relationship between T. gondii infection and brain tumor development, we investigated the seroprevalence of T. gondii among 93 confirmed brain tumor patients (various histological types, including meningioma and astrocytoma) in Korea using ELISA. The results revealed that T. gondii seropositivity among brain tumor patients (18.3%) was significantly (P<0.05) higher compared with that of healthy controls (8.6%). The seropositivity of brain tumor patients showed a significant age-tendency, i.e., higher in younger age group, compared with age-matched healthy controls (P<0.05). In conclusion, this study supports the close relationship between T. gondii infection and incidence of brain tumors.