The survey on paragonimiasis was made in the communes of An Lac, Dong Quan, Tan Linh, Truc Lau, Khanh Hoa and Khai Trung of the Luc Yen district, Yen Bai province during 2002 - 2003. A total of 1,143 stool samples and 367 sputum samples were examined showing a positive rate of 0.5% (0 - 8%) and 6.8%, respectively. Paragonimus patients were found in three communes of An Lac, Khanh Hoa and Dong Quan. The most of the patients were children (80.8%). The local people were found to have poor hygienic condition with no latrine or under-standard latrine as well as the habit of free defecating. The patients were treated with praziquatel 25mg/kg thrice/day x 2 consecutive days. 92.3% patients were cured with no eggs and clinical symptoms three months after drug administration.
Paragonimiasis ; Epidemiology

This survey was undertaken to determine the recent prevalence of lung fluke, Paragonimus westermani, in the three localities of Wiseong county, Kyungpook Province, Korea and to compare the prevalence among the residents in the same areas between 1924 and 1980. The three localities, Ku-seong, Sam-chun, and Um-ji villages (dong) have been known as the endemic areas of Paragonimus westermani. The surveys were made on the general population. They were examined using intradermal test with Paragonimus westermani antigen, and the diagnosis of paragonimiasis was made depending on the positive intradermal reaction. The sputum examination could not be performed beacause the residents were inaccessible. The prevalence of Paragonimus westermani among the residents in the three communities varied from 1.4 percent to 7.9 per cent, with an average of 4.0 per cent. Whereas, the average reported by Ichinomiya in 1924 was 4.7 percent. There are no significant differences in the sex and age specific rates of infection between 1924 and 1980. With the abundant density of Semisulcospira snails and crayfish in Sam-chun stream and the high rate of infection with Paragonimus westermani among the residents in the village, it is found that Sam-chun village, one of the three localitied in Wiseong county, where Ichinomiya (1924) surveyed, was still the endemic focus of Paragonimus westermani.
parasitology-helminth-trematoda ; Paragonimus westermani ; paragonimiasis ; epidemiology

This study was undertaken to evaluate the status of human paragonimiasis in Kang Hwa Gun, Kyunggi Do, Korea from March 1973 to October 1975 by the use of intradermal screening test with Veronal buffered saline antigen. A total number of 7,352 (male 3,936; female 3,4l6) consisting of 3,447 primary school children, 2,689 middle school students, l,008 high school students of 9 Myuns out of 13 Myuns of this County and 208 residents of all age group in Kilgeong-Ri, Yangdo Myun were examined by the intradermal test with Paragonimus antigen. In order to detect Paragonimus egg, the sputum and the stool examinations were undertaken on the residents in Kilgeong-Ri. The infestation rate of crayfish with Paragonimus metacercaria was also examined in Konneung and Jeongha village in Kilgeong-Ri. The following results were obtained in this survey: As a whole, 16.6 per cent of the examiners showed positive reaction with sexual difference of 16.1% in male and 14.8 per cent in female. In age groups, the highest positive rate showed in middle school age group (17.1 per cent) than primary school (14.0 per cent) and high school age group (11.4 per cent). In regional differences of positive rates, the highest rate (28.4 per cent) showed at Yangdo Myun followed by Kilsang Myun (27.0 per cent), Hwado Myun (25.0 per cent), and Naega Myun(20.8 per cent). In the result of 208 residents Kilgeong-Ri, the positive of 36.1 per cent in male and 20.2 per cent in female. The highest positive rate showed in 10 to 19 age group (41.5 per cent). Among the residents in Kilgeong-Ri, Paragonimus eggs were detected in 11 residents by the sputum and the stool examinations. The infestation rate of crayfsh with Paragonimus metacercariae was 100 per cent (41 out of 41 crayfishes) in Konneung village, and 84.6 per cent (9 out of 13 crayfishes) in Jeongha village, Kilgeong-Ri The fluctuation of the infection rate of crayfish with Paragonimus metacercariae was decreased in Konneung village in 2 years after the treatment with Bilevon against 10 paragonimiasis patients.
parasitology-helminth-trematoda ; epidemiology-paragonimiasis ; Paragonimus westermani ; crayfish-Cambaroides similis

Authors carried out the survey for human paragonimiasis in Ko-Hoong County, Chun-Nam Province, Korea from July to September 1964 by the use of intradermal screening test with Veronal buffered saline antigen. Eight myuns (village) out of 13 myuns of this county were selected for the survey, regarding balanced selection. The number of 2,916 primary school children of high class and 764 residents of all age groups in these areas were examined (total 3,680; male 1,961; female 1,719). The following results were obtained in this survey. As a whole, 20.1 per cent of the examiners showed positive reaction, with sexual difference of 20.9 per cent in male and 19.1 per cent in female. In regional differences of positive rate, the highest rate(50.1 per cent) was showed at Po-Doo myun and lowest rate(3.6 per cent) was showed at Do-Yang myun. In age group, the highest positive rate was showed in 16 to 20 age group (46.7 per cent). In regional comparison of paragonimiasis infectivity of whole nation (province and county), Ko-Hoong County as nearly same as the Hea-Nam County, Chun-Nam Province follows next of Cheju Province, the highest prevalance area of paragonimiasis in Korea, in concentration of prevalence of paragonimiasis.
parasitology-helminth-trematoda ; paragonimiasis ; Paragonimus westermani ; skin test ; epidemiology ; Veronal buffered saline antigen

By performing the county-wide surveys of Paragonimus westermani infection in several areas in the Chilgok county, Kyungpook Province, three endemic foci of Paragonimus westermani were found. The foci found in this survey were Haksan first dong, Haksan second dong, and Settom in Kumhwa village, all in Kasan myun, Chilgok county. In the three communities, the positive rates for the fluke among the residents by the intradermal test with Paragonimus antigen varied from 22.3 per cent to 25.0 per cent; school children from these areas showed infection rates above 50 per cent. The rate in males and females was 23.9 and 23.0 per cent, respectively. This difference was not significant. The presence and number of Semisulcospira snails and Astacus crayfish, the intermediate hosts of Paragonimus westermani in the stream communities and the high infection rates for the fluke in the residents were the supporting factors in determining the foci.
parasitology-helminth-trematoda ; Paragonimus westermani ; paragonimiasis ; epidemiology ; host ; snail ; Semisulcospira snails ; Astacus crayfish

In order to determine the epidemiological pattern of the Paragonimus westermani, the infestation rates of the cercarial and metacercarial larvae of digenetic trematodes in the snail and crayfish host, and the prevalence of Paragonimus westermani among the residents in the vicinity of the stream Namdae, Wyangpi, and Kwang, in the Ulchin county, Kyungpook province were studied from March to October in 1984. The population density of the snails per square meter of the habitats ranged form 5 to 25, with average of 15. Among the seven habitats, one, Ducheon, had snails infested with the cercariae of Paragonimus westermani, and the proportion of infested snails was very low, the average being 0.152 per thousand. Of six hundred and four crayfish examined, 113 or 18.7 per cent harboured the encysted larvae of Paragonimus westermani. A high infestation rate for the metacercariae in the crayfish was found in two habitats; 39.0 per cent in the Ducheon and 21.6 per cent in the Sokwang. The prevalence of Paragonimus westermani among the residents in Ulchin county was relatively high, 25.8 per cent by the Paragonimus intradermal tests and the difference in the rate of infection between males and females was found to be significant(t>2). The results obtained in this study indicate that endemic foci of Paragonimus westermani exist in Ulchin county and the prevalence of this lung fluke among the residents is relatviely high.
parasitology-helminth-trematoda ; Paragonimus westermani ; paragonimiasis ; epidemiology ; intermediate host ; crayfish ; snail ; metacercaria

An ecologic study on Paragonimus in Malaysia was attempted from May to September 1967. Seven streams located in various directions and distances from Kuala Lumpur were surveyed for the study of intermediate hosts, snail and crab. One Malayan village and one aborigine village where infected crabs were found, and two tuberculosis hospitals in K.L. were surveyed for the study of human population. Intradermal tests along with sputum or stool examination to detect human infection by Paragonimus were employed. Wild animals, only a few, were shot in the vicinity of the aborigine village and several domestic cats from the Malayan village were bought. These animals were autopsied and examined for adult Paragonimus. Among five species of crab collected from the study areas, only two species, Potamon jahorenes and Parathelphusa maculata were found to be infected with Paragonimus. P. maculata seemed to be better crab host for the Paragonimus because this species had higher infection rate and metacercarial density than the other in the very same area. Three out of seven streams had infected crabs and the infection rate as well as the infection intensity varied from one stream to another. Only avilable snail in the streams was identified as Brotia costula. The infection rate of the snail was very low, six snails out of 11,898, which is about the same rate reported from other countries. Infected snail, however, had thousands of rediae uncountable containing about twelve microcercocercariae in each redia, sufficient enough to maintain the life cycle of the parasite even with only a few infected snail, the amplifier. This is the first confirmed report on the snail host of Paragonimus from Malaysia where the existence of Paragonimus had been reported in 1923. The first trial to study human population by means of intradermal test, sputum and/or stool examinations in Malaysia showed no evidence of human infection of Paragonimus. The number of animals, wild and domestic, examined for natural infection was too small to draw any statement. These examined animals were all negative for adult Paragonimus. Even though more extensive studies on wild animals and human population may be necessary for the definite conclusion, the facts that infected crabs from jungle stream where human contacts are extreamely rare, and also highly infected crabs from the area where none of humans or domestic animals were infected, strongly suggest the life cycle of Paragonimus in this area may be maintained by wild animal hosts rather than by human host. The morphology of all stages of the parasite, the pattern of penetrating glands, flame cells and excretroy bladder of cercaria, lancet shaped single cuticular spines and 6 branched ovary of adult worm obtained from experimentally infected cat, and the shape of egg including all measurements agree well with the characteristics of Paragonimus westermani.
parasitology-helminth-trematoda ; Paragonimus westermani ; epidemiology-paragonimiasis ; crab ; Potamon jahorenes ; Parathelphusa maculata ; cat

A study on the infection status of intermediate hosts of Paragonimus, snail and crab, was conducted on Che Ju Island for four years to understand ecology of Paragonimus in the area and to evalute the control program by mass chemotherapy The infection rate of the first intermediate host of Paragonimus, snail, showed higher rate in the area where human association was more frequent and had higher human infection rate compared with the area with lower human infection and less contact by people. Larger snails were infected more frequently than smaller ones. After the mass treatment on human population, the infection rate of snail dropped markedly in four years. The infection rate and the intensity of infection of crabs were influenced by many factors:by frequency of human association, by prevalence of paragonimiasis in the population and volume of water flow, dilution effect. The distribution of metacercariae in infected crabs varied by body sites; the most frequently in gill, next in legs, internal organs and thoracic muscle in order. If crabs were examined for existence of metacercariae only gills, about 6% of infected crabs of may be missed as negative. The infection status of the crabs was not different by distance from the actual site of pollution. Also seasonal fluctuation of crab infection was not remakable. The crab infection by size showed time sequence of exposure; smaller crabs had lower infection rate and metacercaria density reaching to the maximum by 3 cm of size. As shown in the snail infection, the crab infection remarkably decreased after the control measure of human paragonimiasis, mass chemotherapy, in four years.
parasitology-helminth-trematoda ; paragonimiasis ; Paragonimus westermani ; metacercaria ; epidemiology ; snail ; crab ; host ; chemotherapy

OBJECTIVE: To investigate the sequences of internal transcribed spacer 2 (ITS2) and cyclooxygenase 1 (COX1) genes of Paragonimus metacercariae in freshwater crabs in Henan Province, identify the species of Paragonimus and evaluate its genetic relationships with Paragonimus isolates from other provinces in China. METHODS: Freshwater crabs were collected from 8 survey sites in Zhengzhou, Luoyang, Pingdingshan, Nanyang and Jiyuan cities of Henan Province from 2016 to 2021, and Paragonimus metacercariae were detected in freshwater crabs. Genomic DNA was extracted from Paragonimus metacercariae, and the ITS2 and COX1 genes were amplified using PCR assay, followed by sequencing of PCR amplification products. The gene sequences were spliced and aligned using the software DNASTAR, and aligned with the sequences of Paragonimus genes in the GenBank. Phylogenetic trees were created using the MEGA6 software with the Neighbor-Joining method based on ITS2 and COX1 gene sequences, with Fasciola hepatica as the outgroup. RESULTS: The detection rates of Paragonimus metacercariae were 6.83% (11/161), 50.82% (31/61), 18.52% (5/26), 8.76% (12/137), 14.29% (9/63), 17.76% (19/105), 18.50% (32/173) and 42.71% (41/96) in freshwater crabs from 8 survey sites in Zhengzhou, Luoyang, Pingdingshan, Nanyang and Jiyuan cities of Henan Province, with a mean detection rate of 19.46% (160/822), and a mean infection intensity of 0.57 metacercariae/g. The amplified ITS2 and COX1 gene fragments of Paragonimus were approximately 500 bp and 450 bp in lengths, respectively. The ITS2 gene sequences of Paragonimus metacercariae from 8 survey sites of Henan Province showed the highest homology (99.8% to 100.0%) with the gene sequence of P. skrjabini (GenBank accession number: MW960209.1), and phylogenetic analysis showed that the Paragonimus in this study was clustered into the same clade with P. skrjabini from Sichuan Province (GenBank accession number: AY618747.1), Guangxi Zhuang Autonomous Region (GenBank accession number: AY618729.1) and Hubei Province (GenBank accession number: AY618751.1), and P. miyazaki from Fujian Province (GenBank accession number: AY618741.1) and Japan (GenBank accession number: AB713405.1). The COX1 gene sequences of Paragonimus metacercariae from 8 survey sites of Henan Province showed the highest homology (90.0% to 100.0%) with the gene sequence of P. skrjabini (GenBank accession number: AY618798.1), and phylogenetic analysis showed that the Paragonimus in this study was clustered into the same clade with all P. skrjabini and clustered into the same sub-clade with P. skrjabini from Hubei Province (GenBank accession numbers: AY618782.1 and AY618764.1). CONCLUSIONS Paragonimus species from freshwater crabs in Henan Province were all characterized as P. skrjabini, and the ITS2 and COX1 gene sequences had the highest homology to those of P. skrjabini from Hubei Province. The results provide insights into study of Paragonimus in Henan Province and China.
Animals ; Paragonimus/genetics* ; Brachyura/genetics* ; Cyclooxygenase 1/genetics* ; Phylogeny ; China/epidemiology* ; Sequence Analysis, DNA ; Paragonimiasis

Paragonimiasis is a food-borne parasitic zoonosis caused by infection with lung flukes of the genus Paragonimus. In Vietnam, research on Paragonimus and paragonimiasis has been conducted in northern and central regions of the country. Using a combination of morphological and molecular methods, 7 Paragonimus species, namely P. heterotremus, P. westermani, P. skrjabini, P. vietnamensis, P. proliferus, P. bangkokenis and P. harinasutai, have been identified in Vietnam. Of these, the first 3, P. heterotremus, P. westermani and P. skrjabini, are known to infect humans in other countries. However, in Vietnam, only P. heterotremus, found in some northern provinces, has been shown to infect humans. Even nowadays, local people in some northern provinces, such as Lai Chau and Yen Bai, are still suffering from P. heterotremus infection. In some provinces of central Vietnam, the prevalence and infection intensity of P. westermani metacercariae in freshwater crabs (the second intermediate hosts) are extremely high, but human cases have not been reported. Likewise, although P. skrjabini was found in Thanh Hoa Province, its pathogenicity to humans in Vietnam still remains uncertain. The results of molecular phylogenetic analyses of Vietnamese Paragonimus species provides new insights on the phylogeny and taxonomy of the genus Paragonimus. Comprehensive molecular epidemiological and geobiological studies on the genus in Vietnam and adjacent countries are needed to clarify the biodiversity and public health significance of the lung flukes.
Animals ; Humans ; Paragonimiasis/*epidemiology ; Paragonimus/classification/genetics/*isolation & purification ; Phylogeny ; Prevalence ; Sequence Analysis, DNA ; Shellfish/parasitology ; Vietnam/epidemiology