• Parasites, Hosts and Diseases
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• v.34 no.1
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• pp.15-20
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• 1996

Cysts of Entamoebn histoIMtica are still found from humans in Korea, but notall of the cysts are known as pathogenic. The non-pathogenic strain is regarded as a differenL species, E. nispnr. In this study, Korean isolates of conventional E. histolvticn were subjected for the differentiation by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis. Human stools were screened by routine microscopic examination, and cyst or trophozoite positive stools were inoculated into Robinson media. The cultivated trophozoites were prepared for DNA extraction, and the DNAs were used for PCR with common primers of Pl gene. The PCR products were divested with 3 restriction enzymes and RFLP was observed. Also anti-sense primers containing the cleavage site of each restriction eWe were designed for differentiation only by PCR. The PCR products of Korean isolates 59,512, YS-6, and YS-27 were spliced by Taq I and Xmnl but not byAccl, and the isolates S1, S3, S11, S15, S16, S17, S20, YS- l7, and YS-44 were spliced by Acc I but not by Taq I and Xmn I. These RFLP pattern correlated well with PCR products by the species specific primers. The findings confirm that the Korean isolates 59,512, YS-6, and YS-27 are E. histolwtico and others are E. dispar. In Korea, most of the asymptomatic cyst carriers are infected by E. dispar, not by E. histolytica. Key words: Entcmoebc histolytica, Entcmoebn dispar Korean isolates, polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP)

• Parasites, Hosts and Diseases
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• v.51 no.2
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• pp.231-236
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• 2013

The present study was conducted to investigate the clinical outcomes of Entamoeba histolytica infection in symptomatic and asymptomatic Orang Asli (aborigine) communities in Malaysia. Examination was performed on 500 stool samples obtained from Orang Asli communities in 3 different states using formalin-ether concentration, trichrome staining, and single-round PCR techniques. Out of 500 stool samples, single infection of E. histolytica, Entamoeba dispar, and Entamoeba moshkovskii was identified in 3.2%, 13.4%, and 1%, respectively. In addition, 10 samples had mixed infections with E. histolytica and E. dispar. Six samples containing E. dispar were also positive for E. moshkovskii, and only 2 samples had E. histolytica in association with E. dispar and E. moshkovskii. Seventeen E. histolytica-positive samples were from symptomatic subjects, whereas the remaining 11 samples came from asymptomatic subjects. These findings suggest a predominant distribution of pathogenic potential of E. histolytica strains in this community. Therefore, further studies on genotyping of E. histolytica is required, to find out association between E. histolytica genotype and the outcome of the infection.

• Parasites, Hosts and Diseases
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• v.51 no.5
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• pp.519-524
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• 2013

This study investigated the effect of breast-feeding in protection against protozoan infection in infants with persistent diarrhea. Infants were classified into 2 groups; 161 breast-fed infants and the same number of non-breast-fed infants. Microscopic examinations of stool were done for detection of parasites and measuring the intensity of infection. Moreover, serum levels of IgE and TNF-${\alpha}$ were measured by ELISA. Cryptosporidium spp., Entamoeba histolytica/Entamoeba dispar, Giardia lamblia, and Blastocystis sp. were demonstrated in infants with persistent diarrhea. The percentage of protozoan infections was significantly lower in breast-fed infants than that in the non-breast-fed infants. The levels of IgE and TNF-${\alpha}$ were significantly lower in the breast-fed group than in the non-breast-fed group. There were significant positive associations between the serum levels of IgE and TNF-${\alpha}$ and the intensity of parasite infection in the breast-fed group. It is suggested that breast-feeding has an attenuating effect on the rate and intensity of parasite infection.

• Parasites, Hosts and Diseases
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• v.56 no.1
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• pp.33-39
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• 2018

Intestinal parasitic infections remain a major public health problem in many parts of Thailand, particularly in rural areas. This study aimed to determine the prevalence of intestinal parasitic infections and associated risk factors among the people living in Huai Sai sub-district, Bang Khla district, Chachoengsao Province, central Thailand. A cross-sectional survey was carried out from June 2017 to August 2017 which included a total of 224 participants. Stool samples were examined using a simple direct smear and formalin ethyl acetate concentration technique. Association between risk factors and intestinal parasitic infections was assessed using multivariate logistic regression analysis. The overall prevalence of intestinal parasitic infections was 16.1%. Soil-transmitted helminth infections (14.3%) were more common than protozoan infections (1.8%). The most common intestinal parasites were hookworms (6.7%) followed by Strongyloides stercoralis, (5.0%), Ascaris lumbricoides (1.3%) and Trichuris trichiura (1.3%). Entamoeba histolytica/dispar (1.0%), Giardia intestinalis (0.4%), and Blastocystis hominis (0.4%) were the protozoans identified. A high prevalence of infections was found in male participants of ${\geq}40years$ who raised dogs in the households and did not wear boots while working fields. Multivariate analysis showed a significant association of intestinal parasitic infections with gender with the adjusted odds ratio (OR) of 2.4 and 95% confidence interval (CI) of 1.1-5.2 (P=0.020). The results showed a high prevalence of soil-transmitted helminth infections among adults in rural communities which were particularly apparent regarding the skin-penetrating species of nematodes. A greater focus on intervention is required by improving sanitation and personal hygiene to prevent the spread of intestinal parasitic infections.

• Parasites, Hosts and Diseases
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• v.34 no.4
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• pp.247-254
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• 1996

Differentiation of invasive strains of Entamoebn histolytica according to their pathogenicity has been a topic of long debate, but now the pathogenic species only is regarded as E. histolytica while the non-pathogenic species is E. dispar. The present study applied immunoblot to differentiale infections of the two species among microscopically- detected cyst-passers in Korea. The crude extract of 5. histolyticn separated in 5-20% gradient gels, revealed many fractions of 94. 81. 71, 50. 44, 38.5. 37.5, 29, 19. and 18 kDa when the cysteine proteinase inhibitor. E64, was supplemented. The serum IgG antibody of 3 proven E. histolytirc cases reacted loth the antigenic fractions of 117. 110. 99.68,66,60.54.52, 46. and 45 kDa. Sera of PCR confirmed 3 cases of E. disper reacted only to the 117 kDa fraction or the E. histolytica crude extract which was regarded as non specific. To the antitigen of monoxenic E. dispar. sera or E. dispar and E. histolytica cases showed the same immunoblot reactions. The serum IgG antibody reacted with several antigenic fractions of both E. histolytica and E. dispar. but IgM and IgE antibodies showed no reaction to either antigen. Sera of 24 symptomless amebic cyst-passers were screened with the E. histolytica alltigen; two were found to be infected by E. histolytica and 22 were by E. dispar. The present findings suggest that in Korea most of asymptomatic cyst passers of E. histolytica are carriers of E. dispar. Immunoblot using E. histolytica antigen is a good technique for the differentiation of E. histolytica and E. dispar infections.

• Journal of Microbiology
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• v.41 no.2
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• pp.148-151
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• 2003

Waterborne parasite infections are considered a reemerging threat. Most studies on the epidemiology of human cryptosporidiosis, giardiasis, and amebiasis have been carried out in developed countries, and there is little data on the occurrence of these infections in other areas. The objective of this study was to investigate the presence of waterborne parasites such as Cryptosporidium parvum, Giardia lamblia and Entamoeba histolytica in various water samples in Ankara, turkey. A total of 85 samples were examined, 43 from the municipal water supply, 34 from wells, 6 from the Ankara River, and 2 from two untreated dams; by conventional microscopy, immunologically and by polymerase chain reaction (PCR). Oocysts of C. parvum and cysts of G. lamblia were detected by using an indirect fluorescence (antigen) assay, whereas an enzyme linked immunosorbent assay was used to detect the cysts of E. histolytica and E. dispar. In addition, PCR was used for E. histolytica, E. dispar, C. parvum and G. lamblia detection. G. lamblia was found in 2 of the 34 well water samples, and parasites were found in 3 of the 6 Ankara River samples. The 1$\^$st/ contained E. histolytica cysts and Strongyloides stercoralis larvae. the 2$\^$nd/ E. histolytica cysts, and Trichuris trichiura eggs, and the 3$\^$rd/ C. parvum oocysts only. No parasite was observed in the municipal water samples and untreated dam water samples. These results extend our knowledge on waterborne parasites, such occurrence information on waterborne pathogens assists the management and treatment of municipal water.

• Parasites, Hosts and Diseases
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• v.52 no.2
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• pp.215-220
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• 2014

We analyzed 320 clinical samples of parasitic infections submitted to the Department of Environmental Biology and Medical Parasitology, Hanyang University from January 2004 to June 2011. They consisted of 211 nematode infections, 64 trematode or cestode infections, 32 protozoan infections, and 13 infections with arthropods. The nematode infections included 67 cases of trichuriasis, 62 of anisakiasis (Anisakis sp. and Pseudoterranova decipiens), 40 of enterobiasis, and 24 of ascariasis, as well as other infections including strongyloidiasis, thelaziasis, loiasis, and hookworm infecions. Among the cestode or trematode infections, we observed 27 cases of diphyllobothriasis, 14 of sparganosis, 9 of clonorchiasis, and 5 of paragonimiasis together with a few cases of taeniasis saginata, cysticercosis cellulosae, hymenolepiasis, and echinostomiasis. The protozoan infections included 14 cases of malaria, 4 of cryptosporidiosis, and 3 of trichomoniasis, in addition to infections with Entamoeba histolytica, Entamoeba dispar, Entamoeba coli, Endolimax nana, Giardia lamblia, and Toxoplasma gondii. Among the arthropods, we detected 6 cases of Ixodes sp., 5 of Phthirus pubis, 1 of Sarcoptes scabiei, and 1 of fly larva. The results revealed that trichuriasis, anisakiasis, enterobiasis, and diphyllobothriasis were the most frequently found parasitosis among the clinical samples.

• Parasites, Hosts and Diseases
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• v.35 no.3
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• pp.203-210
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• 1997

The difrrrenlial display reverse transcription polymerase chain reaction (DDRT-PCR) aniilysis roils performed to identify the pathogellir strain specific amplicons. mRNAs were purified from the trophozoites of the pathogenif strain YS-27 and the non-pathogenic strain S 16. respectively. Three kinds of rirsl stranded rDNAs were reverse transcribed from the mRNAs by one base anchored oligo-dT 11M (M: A. C, or G) primers. Each cDNA lemplatr was used for DDRT-PCK analysis. A total of 144 pathogenic strain specific amplicons was observed in DDRT-PCR analysis using primer combinations of the 11 arbitrary primers and the 3 one base anchored oli해-dT11M primers. Of these 31 amplit'tons were verified as the amplirons amplified only from the mRNAs of the pathogenic strain by DNA slots biol llybridizatioil. Furthel cklaracleization of the 31 pathogenic strain sprcifil amplicons by DNA slot blot hybridlnation analysis using biotin labeled Probes or the PCR amplified DNA of rysteine proteinase genes revealed that 21 of them were amplliried from the maNAs of the cysteine proteinase genes. Four randomly selected amplirons out of the rest 10 amplirons were used fur screening of cDNA library followed by immunoscreening and all of them were turned outs to be amplified from the mRNA.

• Parasites, Hosts and Diseases
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• v.55 no.5
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• pp.523-532
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• 2017

A field survey studying intestinal parasites in humans and microbial pathogen contamination at environment was performed in a Laotian rural village to identify potential risks for disease outbreaks. A parasitological investigation was conducted in Ban Lak Sip village, Luang Prabang, Lao PDR involving fecal samples from 305 inhabitants as well as water samples taken from 3 sites of the local stream. Water analysis indicated the presence of several enteric pathogens, i.e., Aeromonas spp., Vibrio spp., E. coli H7, E. coli O157: H7, verocytotoxin-producing E. coli (VTEC), Shigella spp., and enteric adenovirus. The level of microbial pathogens contamination was associated with human activity, with greater levels of contamination found at the downstream site compared to the site at the village and upstream, respectively. Regarding intestinal parasites, the prevalence of helminth and protozoan infections were 68.9% and 27.2%, respectively. Eight helminth taxa were identified in fecal samples, i.e., 2 tapeworm species (Taenia sp. and Hymenolepis diminuta), 1 trematode (Opisthorchis sp.), and 5 nematodes (Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, trichostrongylids, and hookworms). Six species of intestinal protists were identified, i.e., Blastocystis hominis, Cyclospora spp., Endolimax nana, Entamoeba histolytica/E. dispar, Entamoeba coli, and Giardia lamblia. Questionnaires and interviews were also conducted to determine risk factors of infection. These analyses together with a prevailing infection level suggested that most of villagers were exposed to parasites in a similar degree due to limited socio-economic differences and sharing of similar practices. Limited access to effective public health facilities is also a significant contributing factor.