Genus Paragonimus Research Articles

Paragonimiasis pulmonar

Paragonimiasis is a food-borne zoonosis caused by a trematode of the genus Paragonimus 1,2. Infestation is rare in Spain, but the influx of people from endemic areas should make us keep this condition in the differential diagnosis of our patients 2,5. We report the case a patient from Ecuador and resident in Spain for 7 years with active pulmonary tuberculosis on arrival in Spain and later diagnosed with of pulmonary paragonimiasis due to persistent haemoptysis. The diagnosis was established by surgical lung specimen showing granulomas containing parasite eggs and the macroscopic view of the fluke within a lung cavity. Initial tuberculosis treatment and current treatment with praziquantel controlled both conditions.

A Paragonimiasis Patient with Allergic Reaction to Praziquantel and Resistance to Triclabendazole: Successful Treatment after Desensitization to Praziquantel

Paragonimiasis is an infectious disease caused by trematodes of the genus Paragonimus. This trematode can be treated successfully with praziquantel in more than 90% of the cases. Although praziquantel is generally well tolerated, anaphylactic reactions to this drug have been reported in a few cases. We report here a 46-year-old Korean female with paragonimiasis, presumed to be due to Paragonimus westermani, who displayed an allergic reaction to praziquantel and resistance to triclabendazole treatment. The patient was successfully treated with praziquantel following a rapid desensitization procedure. Desensitization to praziquantel could be considered when no alternative drugs are available.

Morphological and molecular characterization of Paragonimus westermani in northeastern India

Evidence for the presence of lung flukes of the Paragonimus westermani in India remains scant. In particular, evidence based on morphology of adult worms is lacking. Metacercariae of the genus Paragonimus, recovered from crabs in two regions of northeastern India, were raised to adulthood in laboratory rats. Morphologically, these worms appear to be P. westermani. DNA sequences from the second internal transcribed spacer (ITS2) and a portion of the ribosomal large subunit gene (28S) of the nuclear ribosomal RNA gene repeat, as well as fragments of the mitochondrial cytochrome c oxidase subunit 1 ( cox1) and NADH dehydrogenase subunit 1 ( nad1) genes, all supported this identification. Molecular phylogenetic methods were used for studying the relatedness of these Indian flukes with counterparts from southeast and far-east Asia. Molecular data showed that Indian representatives of the P. westermani complex represent a distinct lineage. It is unclear whether the Indian form can cause disease in humans as some members of the complex do elsewhere.

Food-borne trematode infections of humans in the United States of America

This review examines the literature on imported (allochthonous) and local (autochthonous) cases of food-borne trematode (FBT) infections in the United States of America (USA) from 1890 to 2009. Most of the literature is concerned with imported cases of the opisthorchiids Clonorchis sinensis and Opisthorchis viverrini. These flukes cause serious pathology in the liver and biliary system of humans. Chronic cases may induce liver (hepatocarcinoma) and bile duct (cholangiocarcinoma) cancers in humans. Clonorchiasis and opithorchiasis are preventable diseases that can be avoided by eating properly cooked freshwater fish products. Several species of lung flukes in the genus Paragonimus are local or imported FBT in the USA. The endemic cycle occurs in the USA with various local snails and crustaceans serving as intermediate hosts. Paragonimids are acquired when humans eat raw or improperly cooked freshwater crustaceans containing metacercarial cysts. Infection can cause severe lung disease and the symptoms of paragonimiasis often mimic those of tuberculosis and other non-helminthic diseases. Paragonimiasis can be avoided by not eating raw or improperly cooked shellfish. The liver fluke Fasciola hepatica can be acquired by eating raw or uncooked vegetation. The cycle exists in the USA involving local snails and aquatic vegetation. Although some cases are local, most are imported by travelers or immigrants. Fascioliasis can cause serious liver and biliary diseases in humans and consumption of tainted vegetation should be avoided. Lesser known FBT have been reported in the USA including species of Alaria, echinostomids, heterophyids, troglotrematids, and a self-induced infection of Plagiorchis. Treatment of the FBT mentioned in this review consists of various regimens of praziquantel, except for F. hepatica where the drug of choice is triclabendazole.

Paragonimus westermani Found in the Tip of a Little Finger

Paragonimiasis is the infestation of lung flukes of the trematode genus Paragonimus. Because the symptoms and radiologic findings of paragonimiasis mimic those of tuberculosis, some patients with paragonimiasis are initially treated for tuberculosis. Although Paragonimus may also reach ectopic sites such as the peritoneum or brain, infection in the skin is rare. To our knowledge, paragonimiasis has not been found in the tip of a finger. We report a case of 39-year-old woman who was belatedly diagnosed as having paragonimiasis with a parasitic migration to the tip of the left little finger after initial misdiagnosis of tubercular serositis.

Phylogenetic reconstruction using secondary structures and sequence motifs of ITS2 rDNA of Paragonimus westermani (Kerbert, 1878) Braun, 1899 (Digenea: Paragonimidae) and related species

BackgroundMost phylogenetic studies using current methods have focused on primary DNA sequence information. However, RNA secondary structures are particularly useful in systematics because they include characteristics that give "morphological" information, not found in the primary sequence. In several mountainous regions of Northeastern India, foci of Paragonimus (lung fluke) infection reportedly involve species that are known to prevail in neighbouring countries. The present study was undertaken to demonstrate the sequence analysis of the ribosomal DNA (ITS2) of the infective (metacercarial) stage of the lung fluke collected from the edible crab hosts that are abundant in a mountain stream of the area (Miao, Changlang District in Arunachal Pradesh) and to construct its phylogeny. Using the approach of molecular morphometrics that is based on ITS2 secondary structure homologies, phylogenetic relationships of the various isolates of Paragonimus species that are prevalent in the neighbouring Near-eastern countries have been discussed.ResultsInitially, ten predicted RNA secondary structures were reconstructed and the topology based only on the predicted RNA secondary structure of the ITS2 region resolved most relationships among the species studied. We obtained three similar topologies for seven species of the genus Paragonimus on the basis of traditional primary sequence analysis using MEGA and a Bayesian analysis of the combined data. The latter approach allowed us to include both primary sequence and RNA molecular morphometrics; each data partition was allowed to have a different evolution rate. Paragonimus westermani was found to group with P. siamensis of Thailand; this was best supported by both the molecular morphometrics and combined analyses. P. heterotremus, P. proliferus, P. skrjabini, P. bangkokensis and P. harinasutai formed a separate clade in the molecular phylogenies, and were reciprocally monophyletic with respect to other species. ITS2 sequence motifs allowed an accurate in-silico distinction of lung flukes.ConclusionData indicate that ITS2 motifs (≤ 50 bp in size) can be considered a promising tool for trematode species identification. RNA secondary structure analysis could be a valuable tool for distinguishing new species and completing Paragonimus systematics, more so because ITS2 secondary structure contains more information than the usual primary sequence alignment.

Discovery of Paragonimus westermani in Vietnam and its molecular phylogenetic status in P. westermani complex

Paragonimus westermani is the most well-known species among the genus Paragonimus. It is widely distributed in Asia with considerable genetic diversity to form P. westermani species complex. While P. westermani distributed in Japan, Korea, China, and Taiwan are genetically homogeneous to form the East Asia group, those found in other geographic areas are heterogeneous and would be divided into several groups. Recent discoveries of P. westermani in India and Sri Lanka highlighted new insights on molecular phylogenetic relationship of geographic isolates of this species complex. Since Vietnam is located at the east end of Southeast Asia, the intermediate position between South and East Asia, it is of interest to see whether P. westermani is distributed in this country. Here, we report that P. westermani metacercariae were found in mountainous crabs, Potamiscus sp., collected in Quangtri province in the central Vietnam. Adult worms were successfully obtained by experimental infection in cats. Molecular phylogenetic analyses revealed that P. westermani of Vietnamese isolates have high similarities with those of East Asia group.

Distribución parcial de Paragonimus (Digenea: Troglotrematidae) en Antioquia, por presencia de metacercarias en cangrejos dulciacuícolas

Paragonimosis or lung fluke disease courses with signs similar to those seen in tuberculosis. The causative agent is a parasite of the genus Paragonimus (Digenea: Troglotrematidae). People become infected by ingesting raw or partially cooked crabs containing metacercariae. The first focus of human paragonimosis in Colombia was recorded in the county of Urrao, where two species of crabs infected with Paragonimus were found. In 2005, crabs with Paragonimus' metacercariae were captured near Medellín, western Colombia. This prompted a search for the parasite in other locations through its presence in the crabs. To establish the distribution of Paragonimus in Antioquia, we evaluated the presence of metacercaria in freshwater brachyuran crabs. From 2005 to 2007, crabs were captured in 13 counties of Antioquia. The crabs were relaxed and dissected to determine presence of trematodes and then to make the taxonomic identifications. From 52 crabs captured in 9 counties, 42 (80.8%) were found with Paragonimus metacercariae. The crabs were identified as Pseudothelphusidae in 2 genera--Hypolobocera and Strengeriana--and were assigned to four species. Three of the species were recorded for the first time as hosts of Paragonimus. A Paragonimus' distribution map was constructed for Antioquia; for the first time urban zones were included. Because of the high rate of infection, the handling and consumption of raw and poorly cooked crabs pose risk factors for human infection. Because crabs are affordable and provide means of easy diagnosis, crabs are targeted as primary agents of and diagnostic tools for paragonmosis.

Discovery of Paragonimus proliferus in Northern Vietnam and their molecular phylogenetic status among genus Paragonimus

During an epidemiological survey for Paragonimus and paragonimosis in northern Vietnam, we found extremely large excysted metacercariae (2.50 +/- 0.14 mm in length and 0.72 +/- 0.08 mm in width; mean +/- standard deviation of 20 samples) in mountainous crabs, Potamiscus mieni. Adult worms were successfully obtained by intraperitoneal injection with those large excysted metacercariae in a cat. Morphological and morphometric data of those large excysted metacercariae and the adult worms derived from them are identical to those of Paragonimus proliferus found in Yunnan province, China. However, when second internal transcribed spacer region and cytochrome oxidase subunit 1 gene sequences of those metacercariae and adult worms were compared with those of known Paragonimus spp. deposited in the GenBank, they were almost completely identical to those of Paragonimus hokuoensis metacercariae in China, of which adult worms have never been reported. This is the first record of P. proliferus in Vietnam and the first record from outside of China. Phylogenetic relationship between P. proliferus and P. hokuoensis is discussed.

Morphological and molecular identification of two Paragonimus spp., of which metacercariae concurrently found in a land crab, Potamiscus tannanti, collected in Yenbai Province, Vietnam

Paragonimosis is an important food-borne zoonosis especially in Asian countries. Among Paragonimus species, Paragonimus westermani followed by P. skrjabini complex are the major pathogens for human paragonimosis in Asia. In addition, P. heterotremus is an important pathogen in southern China and the Indochina Peninsula and is the only proven species to cause human paragonimosis in Vietnam. During a recent survey in Yenbai Province in northern Vietnam, we found small and large types of Paragonimus metacercariae often concurrently in mountainous crabs, Potamiscus tannanti. Adult worms from those small and large metacercariae were obtained separately by experimental infection in dogs and cats. Morphological and molecular phylogenetic study based on sequences of ITS2 and a part of CO1 genes were performed for the identification of small and large metacercariae and their adults. The results showed that small metacercariae and their adults are completely identical with P. heterotremus in morphology and molecular genetic profiles. In contrast, large metacercariae and their adults have some morphological similarities with P. skrjabini and P. harinasutai, but are unidentifiable from each other by morphology alone. Molecular phylogenetic tree analyses on ITS2 and CO1 genes revealed that large metacercariae and their adults were grouped in the same clade and different from any known Paragonimus species. Although they share the same ancestor with P. skrjabini complex, their genetic distance was considerably different from two other known subspecies, P. skrjabini skrjabini and P. skrjabini miyazakii. Our results provide a new insight on the phylogeny of the genus Paragonimus.

La paragonimose pleuropulmonaire

Paragonimiasis is a food borne zoonosis due to a trematode belonging to the genus Paragonimus. Although present throughout the world, about 90% of the cases occur in Asia where around 20 million people are infected. The parasitic cycle is complex with two different intermediate hosts. Man is infected by ingesting the raw or undercooked flesh of the second host - a freshwater crab or prawn - or possibly of a paratenic mammal host (wild boar), which contains the infective larval stage metacercariae that reaches the lung which is the main target organ. Epidemiological, pathological, and clinical aspects are reviewed. The main symptoms are protracted cough, and recurrent "benign" hemoptysis. Abnormal pleuro-pulmonary imaging features are constant, but protean and non-specific, leading to frequent confusion with tuberculosis. Diagnosis is easily achieved by ova search in the sputum or pleural fluid, or by serology. Evolution is usually considered benign, although not well known. Finally, praziquantel is the effective first choice treatment. Some paradoxical aspects of this disease are underlined such as: underdiagnosis despite a very simple diagnostic procedure, or opposite tendencies according to location, either extinction or re-emergence.

Multiple lineages of the mitochondrial gene NADH dehydrogenase subunit 1 (ND1) in parasitic helminths: implications for molecular evolutionary studies of facultatively anaerobic eukaryotes.

The task of using partial ND1 sequences to infer a phylogeny for species of the genus Paragonimus (Trematoda: Digenea) was complicated by the discovery of at least two ND1 lineages within individual worms. The divergence of the ND1 lineages is shown by phylogenetic analysis not only to predate the divergence of the three Paragonimus species or species groups investigated but also the divergence of some trematode families. Some sequences are clearly pseudogenes as they contain single base deletions and/or premature termination codons. The presence of both pseudogenes and/or mitochondrial heteroplasmy are invoked to explain the presence of multiple and divergent ND1 lineages in these trematodes, which have two distinct cytochemical types of mitochondria. The implications for phylogenetic studies generally and of parasitic helminths specifically, using ND1 sequence data, are discussed. The ability of these organisms to adapt their metabolic processes to the variable availability of oxygen as an electron acceptor are proposed to explain some of the molecular diversity observed in parasitic helminths and possibly also in other anaerobically adapted eukaryotes.

Paragonimíase pulmonar e pleural: relato de dois casos

A paragonimíase é uma infecção pulmonar crônica causada por um trematóide do gênero Paragonimus, sendo o Paragonimus westermani o que mais infecta o homem. É uma doença endêmica da Ásia Oriental, mas também é vista na América. Relatamos dois casos de paragonimíase, em que um dos pacientes apresentava antecedentes e características clínicas e radiológicas sugestivas da doença, diagnosticada pela presença de ovos do P. westermani no escarro, e o outro, um empiema pós-trauma torácico cujo diagnóstico de paragonimíase foi um achado histopatológico pleural após uma decorticação. Este diagnóstico foi confirmado pela presença de ovos do P. westermani em escarro.

A molecular perspective on the genera Paragonimus Braun, Euparagonimus Chen and Pagumogonimus Chen

The status of the genera Euparagonimus Chen, 1963 and Pagumogonimus Chen, 1963 relative to Paragonimus Braun, 1899 was investigated using DNA sequences from the mitochondrial cytochrome c oxidase subunit I (CO1) gene (partial) and the nuclear ribosomal DNA second internal transcribed spacer (ITS2). In the phylogenetic trees constructed, the genus Pagumogonimus is clearly not monophyletic and therefore not a natural taxon. Indeed, the type species of Pagumogonimus, P. skrjabini from China, is very closely related to Paragonimus miyazakii from Japan. The status of Euparagonimus is less obvious. Euparagonimus cenocopiosus lies distant from other lungflukes included in the analysis. It can be placed as sister to Paragonimus in some analyses and falls within the genus in others. A recently published morphological study placed E. cenocopiosus within the genus Paragonimus and probably this is where it should remain.

A molecular perspective on the genera Paragonimus Braun, Euparagonimus Chen and Pagumogonimus Chen

The status of the genera Euparagonimus Chen, 1963 and Pagumogonimus Chen, 1963 relative to Paragonimus Braun, 1899 was investigated using DNA sequences from the mitochondrial cytochrome c oxidase subunit I (CO1) gene (partial) and the nuclear ribosomal DNA second internal transcribed spacer (ITS2). In the phylogenetic trees constructed, the genus Pagumogonimus is clearly not monophyletic and therefore not a natural taxon. Indeed, the type species of Pagumogonimus,P. skrjabini from China, is very closely related to Paragonimusmiyazakii from Japan. The status of Euparagonimus is less obvious. Euparagonimus cenocopiosus lies distant from other lungflukes included in the analysis. It can be placed as sister to Paragonimus in some analyses and falls within the genus in others. A recently published morphological study placed E. cenocopiosus within the genus Paragonimus and probably this is where it should remain.

Paragonimiasis in southwest Cameroon: isolation of microcercous cercariae from land snails caught in a Paragonimus Africanus endemic zone

More than 25 years after the discovery of the 2 main African Paragonimus species, P. africanus and P. uterobilateralis , the snails' first intermediate hosts, which harbour rediae and cercariae as well as these larval stages, remain yet unknown. In the present study, the authors describe microcercous cercariae and rediae with the characteristics of the genus Paragonimus from land snails of the Achatinidae family caught in a forest zone of Cameroon where P. africanus is endemic. The results corroborate Sachs and Cumberlidge's findings in a P. uterobilateralis focus in Liberia and indicate that for both African Paragonimus species, the first intermediate host should probably be land snails rather than fresh water snails.

Mitochondria in the body wall of life cycle stages of lung flukes of the genus Paragonimus, and mitochondrial cytochrome components of the adult worm

1. 1. Mitochondria in the body wall of various stages in the life cycle of Paragonimus were investigated by means of electron microscopy, and cytochrome components of the adult mitochondria by spectrophotometry at − 196°C. 2. 2. Large numbers of mitochondria were found in the ova of unembryonated eggs, epidermal cells of miracidia, tegument of cercariae, and tegument, subtegumental cells and parenchymal cells of juvenile and adult worms. Mitochondria of the tegument of rediae and metacercariae are comparatively few in number. 3. 3. Well-developed cristae were observed in the mitochondria of epidermal cells of miracidia, tegument of cercariae, and tegument and subtegumental cells of juvenile and adult worms. Mitochondria possess poorly developed short cristae in the ova of unembryonated eggs, tegument of rediae and metacercariae, and parenchymal cells of juvenile and adult worms. 4. 4. Adult mitochondria were found to contain cytochrome b, c 1 c, aa 3 and b-type cytochromes.

Host-parasite relationships between Paragonimus ohirai and various crabs. I. Morphology of the metacercariae parasitic in Sesarma (Holometopus) dehaani and S. (H.) haematocheir.

According to Miyazaki (1974), 25 species belonging to the genus Paragonimus have been found in the world. In Japan, five species of the lung flukes, viz., P. westermani, P. ohirai, P. iloktsuenensis, P. miyazakii and P. sadoensis have been known up to date. P. ohirai metacercariae are found in the liver, and in the body and leg muscles of the brackish water crabs, Sesarma (Holometopus) dehaani, S. (H.) haematocheir, S. (Sesarma) intermedium, Helice tridens tridens and Chasmagnathus convexus.

Studies on metabolism of lung fluke genus Paragonimus. VII. Action of bithionol on glycolytic and oxidative metabolism of adult worms

The present study was carried out in order to obtain information on the mechanism of action of bithionol on Paragonimus westermani (Kerbert 1878). Bithionol stimulated lactic acid production of intact adult worms above the level of the control worms, while it inhibited oxygen consumption of intact adult worms in vitro. Bithionol treatment of adult worms in vivo decreased glycolytic and oxidative metabolism of homogenates of uterine eggs and adult worms. Bithionol inhibited lactic acid formation except when fructose 1, 6-diphosphate (FDP) was used as a substrate in the homogenates of adult worms, and it also inhibited oxygen consumption of homogenates of eggs and adult worms. Bithionol inhibited reduction of methylene blue when succinate was used as a substrate. Bithionol inhibited oxidation of reduced cytochrome c in the 1000 g supernatant of homogenates of adult worms. Bithionol inhibited activity of the succinate oxidation in homogenates of adult worms.

Studies on metabolism of lung flukes of the genus Paragonimus VI. Succinoxidase system in homogenates of eggs, larvae, and adults

The present study was concerned with the succinoxidase system in Paragonimus westermani, Paragonimus ohirai, and Paragonimus miyazakii. Potassium cyanide inhibited the motility of larval and adult forms. Succinate stimulated the reduction of methylene blue by homogenates of embryonated eggs, larvae, and adults, while malonate inhibited the reduction. Reduced cytochrome c was oxidized by the 1,000 g supernatant from homogenates of embryonated eggs, larvae, and adults. The supernatant prepared from unembryonated eggs did not oxidize reduced cytochrome c. Succinate stimulated oxygen consumption by the homogenate of adult worms. Oxygen consumption markedly increased in the homogenate of adults when both succinate and cytochrome c were added as substrate to the reaction mixture, while malonate and cyanide inhibited oxygen consumption.