Objective: To evaluate human papillomavirus (HPV) vaccine effectiveness in a cohort of Korean women infected with HPV. Methods: From 2010 to 2021, Korean women aged 20–60 years who diagnosed HPV-positive atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion were recruited from 6 hospitals. HPV vaccine effectiveness was estimated by observing the differences in pathological and clinical information and experimental results— prevalence, viral load (VL), physical state (PS), and HPV16/18 infection duration—between the vaccinated and unvaccinated groups. Results: HPV16/18 prevalence declined from 18.5% to 11.8% as vaccination rates increased from 14.3% to 60.7% in the 1,757 registered cohort women. DNA analysis from 96 samples collected from the participants, indicated that HPV vaccination reduced HPV16 VL by 6 times and increased E2/E6 ratio for both HPV16 and HPV18 by 1.4 and 5 times, respectively. The HPV16 infection rate—lasting more than 18 months from 31.0% to 21.6%—and the HPV18 infection rate—lasting more than 12 and less than 24 months from 35.5% to 21.1%—were reduced by vaccination. We found VL and the infection duration to be directly proportional.Moreover, HPV vaccination reduced not only the VL to 1/4 in both the persistence and clearance groups but also the persistence rate from 90% (27/30) to 70.6% (12/17) in HPV16. Conclusion HPV vaccination reduced the prevalence and duration of infection and kept the PS in an episomal form for both HPV16 and HPV18. The tendency of persistence VL to be higher than clearance in the unvaccinated group implies that the vaccine’s effect of reducing VL in HPV16 may lower the risk of progression to cervical cancer by shortening the infection duration.

Objective: To evaluate human papillomavirus (HPV) vaccine effectiveness in a cohort of Korean women infected with HPV. Methods: From 2010 to 2021, Korean women aged 20–60 years who diagnosed HPV-positive atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion were recruited from 6 hospitals. HPV vaccine effectiveness was estimated by observing the differences in pathological and clinical information and experimental results— prevalence, viral load (VL), physical state (PS), and HPV16/18 infection duration—between the vaccinated and unvaccinated groups. Results: HPV16/18 prevalence declined from 18.5% to 11.8% as vaccination rates increased from 14.3% to 60.7% in the 1,757 registered cohort women. DNA analysis from 96 samples collected from the participants, indicated that HPV vaccination reduced HPV16 VL by 6 times and increased E2/E6 ratio for both HPV16 and HPV18 by 1.4 and 5 times, respectively. The HPV16 infection rate—lasting more than 18 months from 31.0% to 21.6%—and the HPV18 infection rate—lasting more than 12 and less than 24 months from 35.5% to 21.1%—were reduced by vaccination. We found VL and the infection duration to be directly proportional.Moreover, HPV vaccination reduced not only the VL to 1/4 in both the persistence and clearance groups but also the persistence rate from 90% (27/30) to 70.6% (12/17) in HPV16. Conclusion HPV vaccination reduced the prevalence and duration of infection and kept the PS in an episomal form for both HPV16 and HPV18. The tendency of persistence VL to be higher than clearance in the unvaccinated group implies that the vaccine’s effect of reducing VL in HPV16 may lower the risk of progression to cervical cancer by shortening the infection duration.

Objective: To evaluate human papillomavirus (HPV) vaccine effectiveness in a cohort of Korean women infected with HPV. Methods: From 2010 to 2021, Korean women aged 20–60 years who diagnosed HPV-positive atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion were recruited from 6 hospitals. HPV vaccine effectiveness was estimated by observing the differences in pathological and clinical information and experimental results— prevalence, viral load (VL), physical state (PS), and HPV16/18 infection duration—between the vaccinated and unvaccinated groups. Results: HPV16/18 prevalence declined from 18.5% to 11.8% as vaccination rates increased from 14.3% to 60.7% in the 1,757 registered cohort women. DNA analysis from 96 samples collected from the participants, indicated that HPV vaccination reduced HPV16 VL by 6 times and increased E2/E6 ratio for both HPV16 and HPV18 by 1.4 and 5 times, respectively. The HPV16 infection rate—lasting more than 18 months from 31.0% to 21.6%—and the HPV18 infection rate—lasting more than 12 and less than 24 months from 35.5% to 21.1%—were reduced by vaccination. We found VL and the infection duration to be directly proportional.Moreover, HPV vaccination reduced not only the VL to 1/4 in both the persistence and clearance groups but also the persistence rate from 90% (27/30) to 70.6% (12/17) in HPV16. Conclusion HPV vaccination reduced the prevalence and duration of infection and kept the PS in an episomal form for both HPV16 and HPV18. The tendency of persistence VL to be higher than clearance in the unvaccinated group implies that the vaccine’s effect of reducing VL in HPV16 may lower the risk of progression to cervical cancer by shortening the infection duration.

Human infection with Taenia asiatica or a hybrid between Taenia saginata and T. asiatica has not been reported in Cambodia. We detected for the first time a hybrid form between T. saginata and T. asiatica in Preah Vihear Province, Cambodia. An adult tapeworm specimen, i.e., 75 cm long strobila without scolex, was expelled from a 27-year-old man after praziquantel medication and purging. It was morphologically indistinguishable between T. saginata and T. asiatica. Several proglottids were molecularly analyzed to confirm the tapeworm species. The mitochondrial gene encoding cytochrome c oxidase subunit 1 (cox1) and nuclear genes encoding elongation factor-1α (ef1) and ezrin-radixin-moesin (ERM)-like protein (elp) were sequenced, and a single-allele analysis was performed to confirm the haploid genotype. The results revealed that our sample showed a discrepancy between the mitochondrial and 2 nuclear genes. It possessed homozygous sequences typical of T. saginata at cox1 and ef1 loci. However, it was heterozygous at the elp locus, with 1 allele in T. asiatica (elpA) and 1 in T. saginata (elpC), which indicates that it is a hybrid between T. saginata and T. asiatica. The present results confirmed the presence of a hybrid between T. saginata and T. asiatica in Cambodia and strongly suggest the existence of also ‘pure’ T. asiatica in Cambodia.

A 12-year nationwide survey (2008-2019) was performed to investigate the prevalence of Enterobius vermicularis infection among preschool children in Seoul, 4 large cites (Busan, Incheon, Daegu, and Ulsan), and 9 provinces (grouped into 5 localities) in the Republic of Korea (=Korea). The survey was carried out once a year by 16 regional offices of the Korea Association of Health Promotion. The cello-tape perianal swab method (1 smear per child) was applied to detect eggs of E. vermicularis and other helminths. According to the results, the egg positive rate of E. vermicularis infection in 2008-2009 was 1.8-2.0%, but it decreased gradually to 0.6% in 2019 (P<0.05). The prevalence was significantly higher in boys (0.7-5.0%, mean 1.8%) than in girls (0.5-2.8%, mean 1.3%) (P<0.05). The 2 most southern localities, Jejudo (Province) and Jeolla-do (inclusive of Jeollabuk-do and Jeollanam-do) and a mid-western province, Gyeonggi-do, revealed higher prevalences, whereas Seoul and Gangwon-do showed lower prevalences. The results indicate that a low-grade prevalence of E. vermicularis infection (less than 4%) has been maintained for the recent 12 years among preschool children in Korea. Continuous monitoring of enterobiasis in the child age group is necessary in Korea.

Life cycle stages, including daughter sporocysts, cercariae, and metacercariae, of Parvatrema duboisi (Dollfus, 1923) Bartoli, 1974 (Digenea: Gymnophallidae) have been found in the Manila clam Ruditapes philippinarum from Aphaedo (Island), Shinan-gun, Jeollanam-do, Korea. The daughter sporocysts were elongated sac-like and 307-570 (av. 395) μm long and 101-213 (av. 157) μm wide. Most of the daughter sporocysts contained 15-20 furcocercous cercariae each. The cercariae measured 112-146 (av. 134) μm in total length and 35-46 (av. 40) μm in width, with 69-92 (av. 85) μm long body and 39-54 (av. 49) μm long tail. The metacercariae were 210-250 (av. 231) μm in length and 170-195 (av. 185) μm in width, and characterized by having a large oral sucker, genital pore some distance anterior to the ventral sucker, no ventral pit, and 1 compact or slightly lobed vitellarium, strongly suggesting P. duboisi. The metacercariae were experimentally infected to ICR mice, and adults were recovered at day 7 post-infection. The adult flukes were morphologically similar to the metacercariae except in the presence of up to 20 eggs in the uterus. The daughter sporocysts and metacercariae were molecularly (ITS1-5.8S rDNA-ITS2) analyzed to confirm the species, and the results showed 99.8-99.9% identity with P. duboisi reported from Kyushu, Japan and Gochang, Korea. These results confirmed the presence of various life cycle stages of P. duboisi in the Manila clam, R. philippinarum, playing the role of the first as well as the second intermediate host, on Aphae-do (Island), Shinan-gun, Korea.

Human infection with Taenia asiatica or a hybrid between Taenia saginata and T. asiatica has not been reported in Cambodia. We detected for the first time a hybrid form between T. saginata and T. asiatica in Preah Vihear Province, Cambodia. An adult tapeworm specimen, i.e., 75 cm long strobila without scolex, was expelled from a 27-year-old man after praziquantel medication and purging. It was morphologically indistinguishable between T. saginata and T. asiatica. Several proglottids were molecularly analyzed to confirm the tapeworm species. The mitochondrial gene encoding cytochrome c oxidase subunit 1 (cox1) and nuclear genes encoding elongation factor-1α (ef1) and ezrin-radixin-moesin (ERM)-like protein (elp) were sequenced, and a single-allele analysis was performed to confirm the haploid genotype. The results revealed that our sample showed a discrepancy between the mitochondrial and 2 nuclear genes. It possessed homozygous sequences typical of T. saginata at cox1 and ef1 loci. However, it was heterozygous at the elp locus, with 1 allele in T. asiatica (elpA) and 1 in T. saginata (elpC), which indicates that it is a hybrid between T. saginata and T. asiatica. The present results confirmed the presence of a hybrid between T. saginata and T. asiatica in Cambodia and strongly suggest the existence of also ‘pure’ T. asiatica in Cambodia.

A 12-year nationwide survey (2008-2019) was performed to investigate the prevalence of Enterobius vermicularis infection among preschool children in Seoul, 4 large cites (Busan, Incheon, Daegu, and Ulsan), and 9 provinces (grouped into 5 localities) in the Republic of Korea (=Korea). The survey was carried out once a year by 16 regional offices of the Korea Association of Health Promotion. The cello-tape perianal swab method (1 smear per child) was applied to detect eggs of E. vermicularis and other helminths. According to the results, the egg positive rate of E. vermicularis infection in 2008-2009 was 1.8-2.0%, but it decreased gradually to 0.6% in 2019 (P<0.05). The prevalence was significantly higher in boys (0.7-5.0%, mean 1.8%) than in girls (0.5-2.8%, mean 1.3%) (P<0.05). The 2 most southern localities, Jejudo (Province) and Jeolla-do (inclusive of Jeollabuk-do and Jeollanam-do) and a mid-western province, Gyeonggi-do, revealed higher prevalences, whereas Seoul and Gangwon-do showed lower prevalences. The results indicate that a low-grade prevalence of E. vermicularis infection (less than 4%) has been maintained for the recent 12 years among preschool children in Korea. Continuous monitoring of enterobiasis in the child age group is necessary in Korea.

Taenia saginata infection has seldom been reported in Cambodia. In this study, we performed a survey of intestinal parasites in 1,156 residents of Preah Vihear and Stung Treng Provinces in 2018. The results revealed that 26 (2.4%) cases were positive for Taenia spp. eggs. In order to obtain the strobilae of the tapeworms, 2 patients in Preah Vihear were treated with praziquantel and purged with magnesium salts. The proglottids expelled after the medication were morphologically and molecularly analyzed to determine the species. The main uterine lateral braches in gravid proglottids were >15 in number suggesting that they are either T. saginata or Taenia asiatica. The sequences of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene and 2 nuclear loci, elongation factor-1 alpha (ef1) and ezrin-radixin-moesin-like protein (elp), were identical to the sequences of T. saginata available in GenBank but distant from Taenia solium, T. asiatica, and T. saginata-T. asiatica hybrid. This is the first report of the presence of T. saginata in the northern part of Cambodia bordering Lao PDR based on a molecular confirmation.

Gymnophallid metacercariae found in the Manila clam Ruditapes philippinarum (‘Banjirak’ in Korean) from Gochang-gun, Jeollabuk-do, Korea were morphologically and molecularly confirmed to be Parvatrema duboisi (Dollfus, 1923) Bartoli, 1974. The metacercariae were morphologically characterized by having a large oral sucker, small ventral sucker, genital pore some distance anterior to the ventral sucker, no ventral pit, and 1 compact or slightly lobed vitellarium, which were all compatible with P. duboisi. Some of the metacercariae were experimentally fed to mice, and adult flukes were recovered at day 7 post-infection. The morphology of the adult flukes was basically the same as that of the metacercariae except for the presence of uterine eggs; the uterus was filled with up to 40 eggs. The nucleotide sequences (1,193 bp) from ITS regions (ITS1, 5.8S rDNA, and ITS2) of the metacercariae showed 99.7% identity with P. duboisi and 75.7% identity with Gymnophalloides seoi deposited in GenBank. These results confirmed the presence of P. duboisi metacercariae in the Manila clam R. philippinarum in an estuary region of Gochang-gun, Korea.