Hyperendemicity of Haplorchis taichui Infection among Riparian People in Saravane and Champasak Province,Lao PDR

In this study, we found that Haplorchis taichui, a heterophyid intestinal fluke, is highly prevalent, with heavy worm loads, among riparian people in Saravane and Champasak province, Lao PDR. Fecal specimens were collected from 1,460 people (717 men and 743 women) in 12 riparian (Mekong river) districts and were examined by the Kato-Katz fecal smear technique. The overall helminth egg positive rate was 78.8% and 66.4% in Saravane and Champasak province, respectively. The positive rate for small trematode eggs (STE), which included H. taichui and other heterophyids, Opisthorchis viverrini, and lecithodendriids, was 69.9% and 46.3% in Saravane and Champasak province, respectively. To obtain adult flukes, 30 STE-positive people were treated with 40 mg/kg praziquantel and then purged. Whole diarrheic stools were collected 4-5 times for each person and searched for fluke specimens using a stereomicroscope. Mixed infections with various species of trematodes (H. taichui, Haplorchis pumilio, O. viverrini, Prosthodendrium molenkampi, Centrocestus formosanus, and Echinochasmus japonicus) and a species of cestode (Taenia saginata) were found. However, the worm load was exceptionally high for H. taichui compared with other trematode species, with an average of 21,565 and 12,079 specimens per infected person in Saravane and Champasak province, respectively, followed by H. pumilio (41.9 and 22.5, respectively) and O. viverrini (9.4 and 1.5, respectively). These results show that diverse species of intestinal and liver flukes are prevalent among riparian people in Saravane and Champasak province, Lao PDR, with H. taichui being the exceptionally dominant species.     

Infection Status of Zoonotic Trematode Metacercariae in Fishes from Vientiane Municipality and Champasak Province in Lao PDR

The infection status of fishborne zoonotic trematode (FZT) metacercariae was investigated in fishes from 2 localities of Lao PDR. Total 157 freshwater fishes (17 species) were collected in local markets of Vientiane Municipality and Champasak Province in December 2010 and July 2011, and each fish was examined by the artificial digestion method. Total 6 species of FZT metacercariae, i.e., Opisthorchis viverrini, Haplorchis taichui, Haplorchis yokogawai, Haplorchis pumilio, Centrocestus formosanus, and Procerovum varium, were detected in fishes from Vientiane Municipality. The metacercariae of O. viverrini were detected in 50 (49.5%) out of 101 fishes (6 species), and their average number was 154 per fish infected. The remaining 5 species of heterophyid metacercariae were detected in 36.8%, 65.8%, 9.4%, 23.9%, and 5.1% fishes examined, and their average densities were 12, 1,038, 4, 15, and 13 per infected fish, respectively. In fishes from Champasak Province, 3 species of FZT metacercariae, i.e., O. viverrini, H. taichui, and H. yokogawai, were detected. Only 2 O. viverrini metacercariae were found in only 1 Barbonymus schwanefeldi. The metacercariae of H. taichui and H. yokogawai were detected in 60.0% and 50.0% of fishes examined, and their average densities were 47 and 28 per fish infected. By the present study, it has been confirmed that several species of FZT metacercariae are prevalent in fishes from Vientiane Municipality, with P. varium being a new member of FZT in Lao PDR. In comparison, FZT metacercariae are less prevalent in fishes from Champasak Province.     

First report of human infection with Gynaecotyla squatarolae and first Korean record of Haplorchis pumilio in a patient

Gynaecotyla squatarolae (Digenea: Microphallidae) is a minute intestinal trematode whose natural hosts are aves. We conducted a feces screening survey in a coastal village of Muan-gun, where the residents routinely consume brackish water crabs as a food. Through this survey, a 50-year-old female was found to shed gymnophallid and heterophyid eggs in her stool, and 845 adult flukes were collected from her purged stool. The adult worms were morphologically grouped into three species. A total of 841 worms were Gymnophalloides seoi. Three worms were identified as G. squatarolae, and the last one proven to be Haplorchis pumilio. This is the first worldwide report of G. squatarolae infection in humans, and the first H. pumilio infection in Korean people.     

Haplorchis pumilio and H. taichui in Vietnam discriminated using ITS-2 DNA sequence data from adults and larvae

Samples of Haplorchis taichui and Haplorchis pumilio of different life-stages (cercariae, metacercariae and adults) and from different host species (snail, fish, dog, cat and human) were collected in Nghe An and Nam Dinh Provinces in Vietnam. Samples from Thailand were available for comparison. All adults and metacercariae were initially identified using morphological criteria. Polymerase chain reaction (PCR) assays were developed for discriminating between the species. The complete sequence for the nuclear ribosomal internal transcribed spacer-2 (ITS-2) was obtained from one adult and one metacercaria of H. taichui and three adults and three metacercariae of H. pumilio from Vietnam. Sequences from cercariae from three different snails clustered with those of H. pumilio. Intra-individual variation in the ITS-2 region was detected by sequencing of cloned PCR products. These are the first sequences from Vietnamese Haplorchis spp. to be reported and demonstrate that H. taichui and H. pumilio can be identified unambiguously from any life-stage, including the cercarial stage that is difficult to identify using morphology. Discrepancies in the literature are discussed and examples of apparent misidentification highlighted. The data provide a resource to assist in taxonomic studies on heterophyids, in the design of probes for diagnosis and for field surveys to identify infection in snails.     

Complete Mitochondrial Genome of Haplorchis taichui and Comparative Analysis with Other Trematodes

Mitochondrial genomes have been extensively studied for phylogenetic purposes and to investigate intra- and interspecific genetic variations. In recent years, numerous groups have undertaken sequencing of platyhelminth mitochondrial genomes. Haplorchis taichui (family Heterophyidae) is a trematode that infects humans and animals mainly in Asia, including the Mekong River basin. We sequenced and determined the organization of the complete mitochondrial genome of H. taichui. The mitochondrial genome is 15,130 bp long, containing 12 protein-coding genes, 2 ribosomal RNAs (rRNAs, a small and a large subunit), and 22 transfer RNAs (tRNAs). Like other trematodes, it does not encode the atp8 gene. All genes are transcribed from the same strand. The ATG initiation codon is used for 9 protein-coding genes, and GTG for the remaining 3 (nad1, nad4, and nad5). The mitochondrial genome of H. taichui has a single long non-coding region between trnE and trnG. H. taichui has evolved as being more closely related to Opisthorchiidae than other trematode groups with maximal support in the phylogenetic analysis. Our results could provide a resource for the comparative mitochondrial genome analysis of trematodes, and may yield genetic markers for molecular epidemiological investigations into intestinal flukes.     

Fishborne Trematode Metacercariae in Freshwater Fish from Guangxi Zhuang Autonomous Region, China

A survey was performed to investigate the infection status of fishborne trematode (FBT) metacercariae in freshwater fish from Guangxi Zhuang Autonomous Region, China. A total of 307 freshwater fish of 31 species were collected from 5 administrative regions of Guangxi Zhuang Autonomous Region. They were examined by artificial digestion method from July 2003 to August 2004. No metacercariae were detected in fish from Fusui-xian. In fish from Mashan-xian and a market in Nanning, 3 species of metacercariae, Haplorchis taichui, Haplorchis pumilio, and Centrocestus formosanus, were mainly detected. Metacercariae (8 in number) of Clonorchis sinensis were found in 1 Chanodichthys dabryi purchased from a market in Nanning. In fish from Yangshuo, Metagonimus yokogawai metacercariae were detected from all 18 fish species examined. Total 13 C. sinensis metacercariae were found in 3 out of 10 Hemibarbus maculatus from Yangshuo. All 7 Zacco platypus from Yangshuo were infected with 8-112 Echinochasmus perfoliatus metacercariae. In fish from Binyang-xian, H. pumilo metacercariae were mainly detected in all 5 fish species examined, and only 1 metacercaria of C. sinensis was found in a Hemiculter leucisculus. From the above results, it was confirmed that some species of freshwater fish play a role of second intermediate hosts for FBT in Guangxi Zhuang Autonomous Region, China. In particular, 4 species of intestinal flukes, M. yokogawai, H. taichui, H. pumilio, and C. formosanus, were prevalent in fish hosts, whereas C. sinensis metacercariae were detected only in 3 fish species.     

Foodborne Trematode Metacercariae in Fish from Northern Vietnam and Their Adults Recovered from Experimental Hamsters

The prevalence of foodborne trematode (FBT) metacercariae was investigated in fish from 2 localities of northern Vietnam in 2004-2005. Freshwater fish (9 species) were collected from local markets in Hanoi City (n=76) and Nam Dinh Province (n=79), and were examined for FBT metacercariae using the artificial digestion technique. Adult flukes were obtained from hamsters experimentally infected with the metacercariae at day 8 post-infection. Three (Haplorchis pumilio, Centrocestus formosanus, and Procerovum varium) and 6 (Haplorchis taichui, H. pumilio, C. formosanus, P. varium, Stellantchasmus falcatus, and Heterophyopsis continua) species of FBT metacercariae were detected in the 2 regions, respectively. Overall, among the positive fish species, H. pumilio metacercariae were detected in 104 (80.0%) of 130 fish examined (metacercarial density per infected fish; 64.2). C. formosanus metacercariae were found in 37 (40.2%) of 92 fish (metacercarial density; 14.7). P. varium metacercariae were detected in 19 (63.3%) of 30 fish (Anabas testudineus and Mugil cephalus) (metacercarial density; 247.7). S. falcatus metacercariae were found in all 10 M. cephalus examined (metacercarial density; 84.4). H. continua metacercariae (2 in number) were detected in 1 fish of Coilia lindmani. Morphologic characteristics of the FBT metacercariae and their experimentally obtained adults were described. The results have demonstrated that various FBT species are prevalent in northen parts of Vietnam.     

Larval Gnathostomes and Zoonotic Trematode Metacercariae in Fish from a Local Market in Yangon City,Myanmar

A survey was performed to investigate the infection status of zoonotic helminth larvae in fish from a local market of North Dagon District in Yangon City, Myanmar. A total of 486 fish in 13 species were collected 8 times from December 2015 to December 2019. All fish were transported under ice to a laboratory in Korea and examined for helminth larvae using artificial digestion method. Larval gnathostomes and metacercariae of more than 8 zoonotic trematode species, i.e., Opisthorchis viverrini, Haplorchis taichui, H. pumilio, H. yokogawai, Centrocestus spp., Stellantchasmus falcatus, Pygidiopsis cambodiensis, and Procerovum sp., were detected. Larval gnathostomes were found in 58 (16.0%) out of 362 fish of 6 species, with mean intensity of 2.8 per fish infected. Metacercariae of O. viverrini were detected in 10 (2.9%) out of 349 fish of 5 species, with mean intensity of 16.9 per fish infected. Metacercarial prevalences of 4 intestinal flukes, H. taichui, H. pumilio, H. yokogawai, and Centrocestus spp., were 16.8%, 26.0%, 12.5%, and 15.0% in the positive fish species, respectively, and mean metacercarial intensity was 63.3, 26.8, 86.2, and 8.7 per fish infected. Metacercariae of S. falcatus and P. cambodiensis were detected only from the mullet, Chelon macrolepis. Metacercariae of Procerovum sp. were found in Channa striata and Anabas testudineus. Collectively, it was confirmed that the fish were infected with gnathostome larvae and metacercariae of O. viverrini and intestinal flukes in Yangon City, Myanmar.     

Co-infection with Opisthorchis viverrini and Haplorchis taichui detected by human fecal examination in Chomtong district, Chiang Mai Province, Thailand

Diseases caused by the liver fluke, Opisthorchis viverrini and the minute intestinal fluke, Haplorchis taichui, are clinically important, especially in the Northeast and North regions of Thailand. It is often difficult to distinguish between these trematode species using morphological methods due to the similarity of their eggs and larval stages both in mixed and co-infections. A sensitive, accurate, and specific detection method of these flukes is required for an effective epidemiological control program. This study aimed to determine the prevalence of O. viverrini and H. taichui infections in human feces by using formalin-ether sedimentation and high annealing temperature random amplified polymorphic DNA (HAT-RAPD) PCR methods. Fecal specimens of people living along the Mae Ping River, Chomtong district were examined seasonally for trematode eggs using a compound microscope. Positive cases were analyzed in HAT-RAPD, DNA profiles were compared with adult stages to determine the actual species infected, and specific DNA markers of each fluke were also screened. Our results showed that out of 316 specimens, 62 were positive for fluke eggs which were pre-identified as O. viverrini and H. taichui. In addition, co-infection among these two fluke species was observed from only two specimens. The prevalence of H. taichui infections peaked in the hot-dry (19.62%), gradually decreased in the rainy (18.18%), and cool-dry seasons (14.54%), respectively. O. viverrini was found only in the hot-dry season (6.54%). For molecular studies, 5 arbitrary primers (Operon Technologies, USA) were individually performed in HAT-RAPD-PCR for the generation of polymorphic DNA profiles. The DNA profiles in all 62 positives cases were the same as those of the adult stage which confirmed our identifications. This study demonstrates the mixed infection of O. viverrini and H. taichui and confirms the extended distribution of O. viverrini in Northern Thailand.     

Haplorchis taichui as a Possible Etiologic Agent of Irritable Bowel Syndrome-Like Symptoms

The aim of this study is to clarify the clinical features of Haplorchis taichui infection in humans in Nan Province, Thailand, and to correlate the clinical features with irritable bowel syndrome (IBS)-like symptoms. In this study area, only H. taichui, but neither other minute intestinal flukes nor small liver flukes were endemic. The degree of infection was determined by fecal egg counts and also by collecting adult worms after deworming. The signs and symptoms of individual patients together with their hematological and biochemical laboratory data were gathered to evaluate the relationship between the clinical features and the severity of infection. Special emphasis was made to elucidate the possible similarities of the clinical features of H. taichui infection and IBS-like symptoms. The results showed useful clinical information and the significant (> 50%) proportion of haplorchiasis patients complained of abdominal pain, lassitude, and flatulence, which were the important diagnostic symptoms of IBS. This study has reported a possible link between H. taichui and IBS, and H. taichui might probably play a role in the etiology of these IBS-like symptoms.     

High Prevalence of Haplorchis taichui, Phaneropsolus molenkampi, and Other Helminth Infections among People in Khammouane Province, Lao PDR

The prevalence of liver and intestinal helminth infections, including Opisthorchis, Haplorchis, Phaneropsolus, hookworms, Enterobius, and Taenia, was surveyed in Khammouane province, Lao PDR. Fecal specimens were collected from 1,242 people (590 men and 652 women) in 3 Mekong riverside villages and were examined by the Kato-Katz thick smear technique. The overall helminth egg positive rate was 81.1%. The positive rate for small trematode eggs, including Opisthorchis viverrini, heterophyids, and lecithodendriids, was 81.1% and the positive rate for hookworms was 6.7%. To obtain adult worms, 35 people who were positive for small trematode eggs were treated with 20-30 mg/kg praziquantel and 10-15 mg/kg pyrantel pamoate, and then purged. Diarrheic stools were collected from 33 of these people and searched for helminth parasites using a stereomicroscope. Mixed infections with various helminths (Haplorchis taichui, Haplorchis yokogawai, Prosthodendrium molenkampi, Phaneropsolus bonnei, echinostomes, hookworms, Trichostrongylus spp., Trichuris trichiura, Enterobius vermicularis, and/or Taenia saginata) were found. The total number of helminth specimens collected was 20,907 (approximately 634 per person). The most common species was H. taichui, followed by P. molenkampi, O. viverrini, P. bonnei, E. vermicularis, hookworms, and Trichostrongylus spp. These results show that diverse species of intestinal nematodes, trematodes, and cestodes are infecting humans in Khammouane province, Lao PDR.     

Zoonotic Trematode Metacercariae in Fish from Phnom Penh and Pursat,Cambodia

A survey was performed to investigate the infection status of freshwater fish with zoonotic trematode metacercariae in Phnom Penh and Pursat Province, Cambodia. All collected fish with ice were transferred to our laboratory and examined using the artificial digestion method. In fish from Phnom Penh, 2 kinds of metacercariae (Opisthorchis viverrini and Haplorchis yokogawai) were detected. O. viverrini metacercariae were positive in 37 (50.0%) of 74 fish in 11 species (average no. metacercariae/fish, 18.6). H. yokogawai metacercariae were detected in 23 (57.5%) of 40 fish in 5 species (average no. metacercariae/fish, 21.0). In fish from Pursat Province, 5 kinds of metacercariae (O. viverrini, H. yokogawai, Haplorchis pumilio, Centrocestus formosanus, and Procerovum sp.) were detected; O. viverrini metacercariae (n=3) in 2 fish species (Henicorhynchus lineatus and Puntioplites falcifer), H. yokogawai metacercariae (n=51) in 1 species (P. falcifer), H. pumilio metacercariae (n=476) in 2 species (H. lineatus and Pristolepis fasciata), C. formosanus metacercariae (n=1) in 1 species (H. lineatus), and Procerovum sp. metacercariae (n=63) in 1 species (Anabas testudineus). From the above results, it has been confirmed that various freshwater fish play the role of a second intermediate host for zoonotic trematodes (O. viverrini, H. yokogawai, H. pumilio, C. formosanus, and Procerovum sp.) in Cambodia.     

Fishborne Trematode Metacercariae in Luang Prabang,Khammouane, and Saravane Province,Lao PDR

Fishborne trematode (FBT) metacercariae were investigated in fish from 3 Provinces of Lao PDR. Total 242 freshwater fish of 40 species were collected in local markets of Luang Prabang (59 fish of 16 species), Khammouane (81 fish of 19 species), and Saravane (97 fish of 14 species), and each of them was examined by artificial digestion method. Four species of metacercariae (Opisthorchis viverrini, Haplorchis taichui, Haplorchis yokogawai, and Centrocestus formosanus) were detected. O. viverrini was detected in 35 fish (14.5%), and their density was 252 per infected fish (Luang Prabang, 88 metacercariae in 5 fish; Khammouane, 187 in 6 fish; Saravane, 303 in 24 fish). H. taichui was found in 102 fish (42.1%), and their density was 485 per infected fish (Luang Prabang, 260 metacercariae in 38 fish; Khammouane, 1,084 in 23 fish; Saravane, 359 in 41 fish). H. yokogawai was detected in 92 fish (38.0%), and their density was 222 per infected fish (Luang Prabang, 362 metacercariae in 17 fish; Khammouane, 126 in 20 fish; Saravane, 214 in 55 fish). Metacercariae of C. formosanus were found in 8 fish (3.3%), and their density was 3 per infected fish. In the present study, it has been confirmed that FBT metacercariae, in particular, H. taichui, H. yokogawai, and O. viverrini, are highly prevalent in fish from Luang Prabang, Khammouane, and Saravane Province, Lao PDR.     

Potential Zoonotic Trematodes Recovered in Stray Cats from Kuwait Municipality,Kuwait

Stray cats are a common feature roaming the streets and alleys of Kuwait; they could be a source of parasites, including trematodes, that affect humans. A survey was conducted to identify feline trematodes and throw the light on their public health significance in Kuwait. Out of 240 stray cats trapped from different localities of Kuwait from June 2011 to May 2012, 59 (24.6%) were found to be infected with 14 species of trematodes. The most common were trematodes of the genus Heterophyes, particularly H. heterophyes and H. dispar that were found in respectively 15.8% and 10.8% of the cats examined. Other trematodes recorded, with lower prevalences, were Heterophyes nocens (2.9%), Haplorchis taichui (3.8%), Stictodora sawakinensis (2.1%), Stellantchasmus falcatus (1.6%), Echinochasmus japonicus (1.6%), and Mesostephanus dottrensi (1.3%). Centrocestus cuspidatus, Galactosomum fregatae, Ascocotyle sp., Mesostephanus appendiculatus, Haplorchis yokogawai, and Pygidiopsis genata showed the lowest prevalence (0.4%) and intensity. The majority of the trematodes are recorded for the first time in Kuwait and even in the Gulf region. The study reveals that stray cats are good indicators of fish-borne trematodes in the environment. As all trematodes recovered are zoonotic, their significance to public health should be considred.     

High Prevalence of Haplorchiasis in Nan and Lampang Provinces,Thailand, Proven by Adult Worm Recovery from Suspected Opisthorchiasis Cases

Opisthorchiasis, a risk factor for cholangiocarcinoma in humans, is of public health importance in Thailand. The Annual Surveillance Reports from Nan and Lampang Provinces, Thailand, for the year 2011 showed an opisthorchiasis prevalence of over 70% by recovery of eggs in the feces. This study investigated whether most cases are actually due to minute intestinal flukes (MIF) rather than Opisthorchis viverrini, as the eggs of both can hardly be differentiated by morphology. Fifty and 100 cases from residents in Nan and Lampang, respectively, had stools positive for eggs initially assumed to be those of O. viverrini. Each patient was given praziquantel at 40 mg/kg in a single dose. After 2 hr, 30-45 ml of the purgative magnesium sulfate was given, and stools were collected up to 4 times sequentially. The stools were examined for adult worms by simple sedimentation. It was found that 39 of 50 cases (78.0%) from Nan Province had Haplorchis taichui, with intensities ranging from 5 to 1,250 with an average of 62 worms/case. Taenia saginata (7 cases) and Enterobius vermicularis (1 case) were other helminths recovered as the co-infectants. In Lampang Province, H. taichui was recovered from 69 cases (69.0%). The number of flukes recovered ranged from 1 to 4,277, with an average of 326 worms/case. Four cases had Phaneropsolus bonnei, and 10 T. saginata as the co-infectants. Adult specimens of O. viverrini were not recovered from any stool. Clearly, MIF infection, especially haplorchiasis, is more common in northern Thailand. These findings should encourage the Public Health Office to employ more specific tools than Kato''s method for surveillance of opisthorchiasis in Thailand.     

High prevalence of liver and intestinal fluke infections among residents of Savannakhet Province in Laos

The prevalence of liver and intestinal fluke infections was surveyed on residents of Savannakhet Province, Laos. Fecal specimens were collected from a total of 981 residents in 4 Mekong riverside villages and examined by the Kato-Katz thick smear technique. The results revealed that the overall helminth egg positive rate was 84.2%, and the positive rate for small trematode eggs, including Opisthorchis viverrini, heterophyids, or lecithodendriids, was 67.1%. To obtain adult flukes, 38 small trematode egg positive cases were treated with a 20-30 mg/kg single dose of praziquantel and purged. Diarrheic stools were then collected from 29 people and searched for helminth parasites using stereomicroscopes. Mixed infections with O. viverrini and 6 kinds of intestinal flukes were found, namely, Haplorchis taichui, Haplorchis pumilio, Haplorchis yokogawai, Prosthodendrium molenkampi, Phaneropsolus bonnei, and echinostomes. The total number of flukes collected was 7,693 specimens (av. no. per treated person; 265.3). The most common species was O. viverrini, followed by H. taichui, P. molenkampi, echinostomes, H. pumilio, P. bonnei, and H. yokogawai. The results indicate that foodborne liver and intestinal fluke infections are prevalent among residents of Savannakhet Province, Laos.     

Mixed infections with Opisthorchis viverrini and intestinal flukes in residents of Vientiane Municipality and Saravane Province in Laos

Faecal examinations for helminth eggs were performed on 1869 people from two riverside localities, Vientiane Municipality and Saravane Province, along the Mekong River, Laos. To obtain adult flukes, 42 people positive for small trematode eggs (Opisthorchis viverrini, heterophyid, or lecithodendriid eggs) were treated with a 20-30 mg kg(-1) single dose of praziquantel and purged. Diarrhoeic stools were then collected from 36 people (18 in each area) and searched for helminth parasites using stereomicroscopes. Faecal examinations revealed positive rates for small trematode eggs of 53.3% and 70.8% (average 65.2%) in Vientiane and Saravane Province, respectively. Infections with O. viverrini and six species of intestinal flukes were found, namely, Haplorchis taichui, H. pumilio, H. yokogawai, Centrocestus caninus, Prosthodendrium molenkampi, and Phaneropsolus bonnei. The total number of flukes collected and the proportion of fluke species recovered were markedly different in the two localities; in Vientiane, 1041 O. viverrini (57.8 per person) and 615 others (34.2 per person), whereas in Saravane, 395 O. viverrini (21.9 per person) and 155207 others (8622.6 per person). Five people from Saravane harboured no O. viverrini but numerous heterophyid and/or lecithodendriid flukes. The results indicate that O. viverrini and several species of heterophyid and lecithodendriid flukes are endemic in these two riverside localities, and suggest that the intensity of infection and the relative proportion of fluke species vary by locality along the Mekong River basin.     

Egg Laying Capacity of Haplorchis taichui (Digenea: Heterophyidae) in Humans

Quantitative fecal egg counts represented as the number of eggs per gram of feces (EPG) are generally a reliable parameter to estimate the worm burden of intestinal and hepatic parasitoses. Although Haplorchis taichui (Digenea: Heterophyidae) is one of the most common minute human intestinal flukes, little is known about the relationship between EPG and the actual worm burden in patients or the severity of the disease. In the present study, fecal samples were collected from 25 villagers in northern Thailand before and after praziquantel treatment. The EPG values of each participant were determined by the modified cellophane thick smear method, and adult worms were collected from the whole stool after the treatment. Eggs per day per worm (EPDPW) of H. taichui were estimated 82 from egg counts and expelled worms. The EPG was not well correlated with the worm burden, and a reverse correlation was observed between the EPDPW and the worm burden.     

Human Infections with Liver and Minute Intestinal Flukes in Guangxi, China: Analysis by DNA Sequencing, Ultrasonography, and Immunoaffinity Chromatography

The prevalence of liver and intestinal fluke infections was determined by surveying inhabitants of Hengxuan, Fusui, and Shanglin villages which were known to be endemic for liver flukes in Guangxi, China in May 2010. A total of 718 people were examined for helminth eggs by the Kato-Katz thick smear technique, ultrasonography, immunoaffinity chromatography, and DNA sequencing. The overall egg positive rate was found to be 59.6% (28.0-70.6%) that included mixed infections with liver and intestinal flukes. Cases showing higher than 20,000 eggs per gram of feces (EPG) were detected between 1.3% and 16.2%. Ultrasonographic findings exhibited overall 28.2% (72 of 255 cases) dilatation rate of the intrahepatic bile duct. Clonorchis sinensis infection was detected serologically in 88.3% (38 of 43 cases) among C. sinensis egg positive subjects by the immunoaffinity chromatography using a specific antigen for C. sinensis. For differential diagnosis of the liver and intestinal flukes, more precise PCR and nucleotide sequencing for copro-DNA were performed for 46 egg positive cases. Mixed infections with C. sinensis and Metagonimus yokogawai were detected in 8 of 46 egg positive cases, whereas 29 specimens were positive for Haplorchis taichui. Ultrasonographic findings and immunoaffinity chromatography results showed usefulness, even in a limited way, in figuring out of the liver fluke endemicity.     

A new endemic focus of Heterophyes nocens and other heterophyid infections in a coastal area of Gangjin-gun, Jeollanam-do

To know the prevalence of heterophyid trematodes among inhabitants of a southern coastal village, i.e., Sacho-ri, Gangjin-gun, Jeollanam-do (Province), 82 stool samples were examined on helminth eggs and protozoan cysts using Kato-Katz and formalin-ether sedimentation techniques. Total 33 people (40.2%) were positive for trematodes (Heterophyes nocens 15 people, Pygidiopsis summa 3, Metagonimus sp.; 4, Clonorchis sinensis 7, Gymnophalloides seoi 6) and/or protozoa (Entamoeba coli 3). Among intestinal trematode egg positive cases, 17 were treated with praziquantel and their whole diarrheic stools were collected after purgation. Adult flukes of H. nocens (number of specimens = 1,294), P. summa (386), Stellantchasmus falcatus (5), Stictodora lari (4), and Heterophyopsis continua (1) were collected using a stereomicroscope. To know the source of human H. nocens infections in this village, metacercarial infections in mullets (10) were examined and most H. nocens metacercariae (101/105, 96.2%) were found in the trunk portion. From above results, the surveyed coastal village has been newly known as an endemic focus of human H. nocens infection and consuming raw mullets was the presumable source of human heterophyid infections.