Parvatrema duboisi (Digenea: Gymnophallidae) Life Cycle Stages in Manila Clams, Ruditapes philippinarum, from Aphae-do (Island), Shinan-gun, 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.

Morphological and Molecular Confirmation of Parvatrema duboisi Metacercariae in the Manila Clam Ruditapes philippinarum from Gochang-gun, Korea.

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.

Prevalence of Intestinal Protozoans among Schoolchildren in Suburban Areas near Yangon, Myanmar.

Although intestinal protozoans are common etiologies of diarrhea, few studies have been conducted in Myanmar. This study planned to investigate the prevalence of Giardia lamblia, Entamoeba coli, Entamoeba histolytica, and Endolimax nana among schoolchildren and their guardians in suburban areas near Yangon, Myanmar. We performed a cross-sectional survey among schoolchildren and their guardians from 7 primary schools in South Dagon and Hlaing Thar Yar districts, Yangon, Myanmar. Stool samples were observed with a microscope after concentration technique and iodine staining. Total 821 stool samples, including 556 from schoolchildren and 265 from guardians, were examined. The median age was 6 years old for schoolchildren and 36 years old for guardians. A 53.1% of the school children and 14.6 % of the guardians were males. The overall prevalence of each intestinal protozoan species was as follows: 3.4% (28/821) for G. lamblia; 3.5% (29/821) for E. coli; 1.2% (10/821) for E. histoytica, and 3.0% for E. nana. This study showed that intestinal protozoans are common in primary schoolchildren and their guardians in suburban areas near Yangon, Myanmar. Health interventions, such as hand washing education, improvement of sanitation, and establishment of water purification systems are urgently needed in this area.

Molecular Description of Macroorchis spinulosus (Digenea: Nanophyetidae) Based on ITS1 Sequences.

We performed a molecular genetic study on the sequences of 18S ribosomal RNA (ITS1 region) gene in 4-day-old adult worms of Macroorchis spinulosus recovered in mice experimentally infected with metacercariae from crayfish in Jeollanam-do Province, Korea. The metacercariae were round, 180 µm in average diameter, encysted with 2 layers of thick walls, but the stylet on the oral sucker was not clearly seen. The adult flukes were oval shape, and 760-820 µm long and 320-450 µm wide, with anterolateral location of 2 large testes. The phylogenetic tree based on ITS1 sequences of 6 M. spinulosus samples showed their distinguished position from other trematode species in GenBank. The most closely resembled group was Paragonimus spp. which also take crayfish or crabs as the second intermediate host. The present study is the first molecular characterization of M. spinulosus and provided a basis for further phylogenetic studies to compare with other trematode fauna in Korea.

Pygidiopsis cambodiensis n. sp. (Digenea: Heterophyidae) from experimental hamsters infected with metacercariae in mullets from Cambodia.

Pygidiopsis cambodiensis n. sp. is described based on adult flukes recovered from Syrian golden hamsters experimentally infected with metacercariae from mullets (Liza macrolepis) purchased at a local fish market in Phnom Penh, Cambodia. The specimens were examined by light and scanning electron microscopy. Among the 13 species so far assigned to Pygidiopsis, the new species belongs to the summa-type (including Pygidiopsis pelecani, Pygidiopsis phalacrocoracis, Pygidiopsis piclaumoreli, Pygidiopsis plana, and Pygidiopsis summa) which lack circumoral spines and have vitelline follicles extending posteriorly from the level of the ovary some distance into the post-testicular space and the uterus not exceeding the acetabulum anteriorly. The new species differs from the other five species of the summa-type particularly in the morphology of the ventrogenital complex, including the genital sac, gonotyl, and gonotyl spines (= rodlets). The genital sac is well developed, sucker-like, slightly larger than the ventral sucker, muscular, and equipped with two gonotyls on the ventral side of the sac. Gonotyls are protruding pad-like, and the number of rodlets on the left gonotyl is four to five and that on the right gonotyl is 10-11 in two rows. This is the fifth Pygidiopsis species reported in Asia, following P. summa (Japan, Korea, and Vietnam), P. phalacrocorasis (Japan), P. pelecani (China), and Pygidiopsis marivillai (Philippines).

Toxoplasma gondii B1 Gene Detection in Feces of Stray Cats around Seoul, Korea and Genotype Analysis of Two Laboratory-Passaged Isolates.

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.

Heterophyid trematodes recovered from people residing along the Boseong River, South Korea.

We conducted an epidemiological survey to determine the status of heterophyid fluke infections among people residing along the Boseong River, Gokseong-gun, South Korea (= Korea) from October 2011 to February 2012. Fecal specimens were collected from 115 (male 51, female 64) people and examined for intestinal helminth eggs using the Kato-Katz thick smear technique. The eggs of Metagonimus yokogawai together with other Metagonimus spp. were detected in 28 (24.3%) cases. Eleven egg positive people were treated with 10mg/kg praziquantel followed by MgSO4 purging in order to recover the adult flukes. Whole consecutive diarrheic stools were collected individually 4-5 times. Adult flukes recovered were 66,499 specimens (6045.4/positive case) of M. yokogawai, 343 (38.1) of Metagonimus miyatai, 3293 (299.4) of Metagonimus takahashii, 81 (20.3) of Heterophyes nocens, 6 (3.0) of Heterophyopsis continua, and 1 (1.0) of Stictodora fuscata. The results indicated that the surveyed area is a highly endemic area of metagonimiasis (three Metagonimus species) with low-grade mixed infections of 3 other heterophyid flukes. The infected people experienced variable degrees of gastrointestinal discomfort and indigestion. They consumed raw freshwater and brackish water fish, including sweetfish and mullets. It is strongly recommended that people residing in the survey area avoid eating raw fish to prevent M. yokogawai and other heterophyid infections.

Intestinal nematodes from small mammals captured near the demilitarized zone, Gyeonggi province, Republic of Korea.

A total of 1,708 small mammals (1,617 rodents and 91 soricomorphs), including Apodemus agrarius (n = 1,400), Microtus fortis (167), Crocidura lasiura (91), Mus musculus (32), Myodes (= Eothenomys) regulus (9), Micromys minutus (6), and Tscherskia (= Cricetulus) triton (3), were live-trapped at US/Republic of Korea (ROK) military training sites near the demilitarized zone (DMZ) of Paju, Pocheon, and Yeoncheon, Gyeonggi Province from December 2004 to December 2009. Small mammals were examined for their intestinal nematodes by necropsy. A total of 1,617 rodents (100%) and 91 (100%) soricomorphs were infected with at least 1 nematode species, including Nippostrongylus brasiliensis, Heligmosomoides polygyrus, Syphacia obvelata, Heterakis spumosa, Protospirura muris, Capillaria spp., Trichuris muris, Rictularia affinis, and an unidentified species. N. brasiliensis was the most common species infecting small mammals (1,060; 62.1%) followed by H. polygyrus (617; 36.1%), S. obvelata (370; 21.7%), H. spumosa (314; 18.4%), P. muris (123; 7.2%), and Capillaria spp. (59; 3.5%). Low infection rates (0.1-0.8%) were observed for T. muris, R. affinis, and an unidentified species. The number of recovered worms was highest for N. brasiliensis (21,623 worms; mean 20.4 worms/infected specimen) followed by S. obvelata (9,235; 25.0 worms), H. polygyrus (4,122; 6.7 worms), and H. spumosa (1,160; 3.7 worms). A. agrarius demonstrated the highest prevalence for N. brasiliensis (70.9%), followed by M. minutus (50.0%), T. triton (33.3%), M. fortis (28.1%), M. musculus (15.6%), C. lasiura (13.2%), and M. regulus (0%). This is the first report of nematode infections in small mammals captured near the DMZ in ROK.

Diphyllobothrium nihonkaiense: wide egg size variation in 32 molecularly confirmed adult specimens from Korea.

The eggs of Diphyllobothrium nihonkaiense were reported to be smaller than those of the classical Diphyllobothrium latum in general. However, verification using a large number of adult tapeworms is required. We assessed the egg size variation in 32 adult specimens of D. nihonkaiense recovered from Korean patients in 1975-2014. The diagnosis of individual specimens was based on analysis of the mitochondrial cytochrome c oxidase 1 gene sequence. Uterine eggs (n = 10) were obtained from each specimen, and their length and width were measured by micrometry. The results indicated that the egg size of D. nihonkaiense (total number of eggs measured, 320) was widely variable according to individual specimens, 54-76 µm long (mean 64) and 35-58 µm wide (mean 45), with a length-width ratio of 1.32-1.70 (mean 1.46). The worm showing the smallest egg size had a length range of 54-62 µm, whereas the one showing the largest egg size had a length range of 68-76 µm. The two ranges did not overlap, and a similar pattern was observed for the egg width. Mapping of each egg size (n = 320) showed a wide variation in length and width. The widely variable egg size of D. nihonkaiense cannot be used for specific diagnosis of diphyllobothriid tapeworm infections in human patients.

High Prevalence of Enterobius vermicularis Infection among Schoolchildren in Three Townships around Yangon, Myanmar.

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.