Comparative genomics and transcriptomics of 4 Paragonimus species provide insights into lung fluke parasitism and pathogenesis

BACKGROUND

Paragonimus spp. (lung flukes) are among the most injurious foodborne helminths, infecting ∼23 million people and subjecting ∼292 million to infection risk. Paragonimiasis is acquired from infected undercooked crustaceans and primarily affects the lungs but often causes lesions elsewhere including the brain. The disease is easily mistaken for tuberculosis owing to similar pulmonary symptoms, and accordingly, diagnostics are in demand.

RESULTS

We assembled, annotated, and compared draft genomes of 4 prevalent and distinct Paragonimus species: Paragonimus miyazakii, Paragonimus westermani, Paragonimus kellicotti, and Paragonimus heterotremus. Genomes ranged from 697 to 923 Mb, included 12,072-12,853 genes, and were 71.6-90.1% complete according to BUSCO. Orthologous group analysis spanning 21 species (lung, liver, and blood flukes, additional platyhelminths, and hosts) provided insights into lung fluke biology. We identified 256 lung fluke-specific and conserved orthologous groups with consistent transcriptional adult-stage Paragonimus expression profiles and enriched for iron acquisition, immune modulation, and other parasite functions. Previously identified Paragonimus diagnostic antigens were matched to genes, providing an opportunity to optimize and ensure pan-Paragonimus reactivity for diagnostic assays.

CONCLUSIONS

This report provides advances in molecular understanding of Paragonimus and underpins future studies into the biology, evolution, and pathogenesis of Paragonimus and related foodborne flukes. We anticipate that these novel genomic and transcriptomic resources will be invaluable for future lung fluke research.

Paragonimiasis: Neglected, Re-Emerging or Expanding Frontiers. Lessons from a Case Presenting in Jos, Plateau State

BACKGROUND AND OBJECTIVES

Paragonimiasis is endemic in Eastern Nigeria. An upsurge was recorded after the Nigeria/Biafra war as protein lack in Biafra forced people to eat fresh water crabs. Its protean manifestations create confusion with several diseases. Elimination was assumed after a while and suspicion index fell. The interest in reporting this case follows its presentation outside the traditional endemic zone.

RESULTS

The patient, though living in Eastern Nigeria and manifesting several pointers of Paragonimiasis, was treated as tuberculosis despite negative sputum AFB; without improving. He then presented up-country in Jos where history led to suspicion and confirmation of Paragonimiasis. By this time he had severe cor-pulmonale and died despite treatment.

CONCLUSION

In this current economic downturn in Nigeria which may drive people to cheaper protein sources, a high index of suspicion should be raised for paragonimiasis when a patient presents with chronic cough productive of AFB-negative sputum and haemoptysis.

Paragonimiasis

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus. Humans usually become infected by eating freshwater crabs or crayfish containing encysted metacercariae of these worms. However, an alternative route of infection exists: ingestion of raw meat from a mammalian paratenic host. Adult worms normally occur in pairs in cysts in the lungs from which they void their eggs via air passages. The pulmonary form is typical in cases of human infection due to P. westermani, P. heterotremus, and a few other species (Table 5.1). Worms may occupy other sites in the body, notably the brain, but lung flukes have made their presence felt in almost every organ. Ectopic paragonimiasis is particularly common when infection is due to members of the P. skrjabini complex (Table 5.1). Human paragonimiasis occurs primarily in the tropics and subtropics of Asia, Africa, and the Americas, with different species being responsible in different areas (Table 5.1).

Significance of Serology by Multi-Antigen ELISA for Tissue Helminthiases in Korea

It is clinically important to differentiate tissue-invading helminthiasis. The purpose of this study was to assess the specific immunoglobulin G (IgG) antibody positive rates for clonorchiasis, paragonimiasis, cysticercosis, and sparganosis 4 helminthiases from 1996 to 2006 using multi-antigen enzyme-linked immunosorbent assay (ELISA) in Korea. Results of 6,017 samples, which were referred to our institute for serodiagnosis, were analyzed. The subjects with positive serum IgG antibodies were 1,502 (25.0%) for any of the 4 helminthiases. The overall positive numbers for clonorchiasis, paragonimiasis, cysticercosis, and sparganosis were 728 (12.1%), 166 (2.8%), 729 (12.1%), and 263 (4.4%), respectively. The positive serologic reaction to multi-antigens was determined in 309 (20.6%) of the 1,502 total seropositive subjects. Those with multi-antigen positivity were regarded as positive for the antigen of strongest reaction but cross-reaction to others with weak positive reaction. Annual seropositive rates for those 4 tissue helminthiases ranged from 12.1% to 35.7%. The highest rate was observed in age from 60 to 69 years old and prevalence of men (27.4%; 1,030/3,763) was significantly higher than of women (19.1%; 332/1,741). Hospital records of 165 ELISA positive patients were reviewed to confirm correlation with their clinical diagnosis. Paragonimiasis was highly correlated as 81.8% (9/11), cysticercosis 29.9% (20/67), clonorchiasis 29.0% (20/69), and sparganosis 11.1% (2/18). In conclusion, the multi-antigen ELISA using 4 helminth antigens is useful to differentiate suspected tissue-invading helminthiases, especially ELISA diagnosis of paragonimiasis is reliable. The seropositivity is still high among suspected patients in Korea.

Paragonimus kellicotti Presenting With Hemoptysis and a Left Upper Lobe Mass

A 46-year-old man presented to the thoracic surgery clinic with a 6-month history of cough and hemoptysis refractory to treatment. Examination of specimens from repeated biopsies was nondiagnostic, so the patient underwent video-assisted thoracoscopic left upper lobe wedge resection. Pathologic examination revealed Paragonimus organisms, and the patient was prescribed praziquantel, with resolution of his symptoms. Although Paragonimus infections are common in Asia, they are rare in the United States despite P kellicotti being endemic. Clinicians should have a high index of suspicion for patients presenting with unusual lung symptoms in endemic areas to avoid prolonged evaluations with potentially unnecessary diagnostic modalities.

Coinfection of Pulmonary Paragonimiasis and Pulmonary Tuberculosis in Thailand

The authors report a case of coinfection of pulmonary paragonimiasis and pulmonary tuberculosis which is an uncommon coinfection. The patient presented with a one-week history of nonmassive hemoptysis about 1 month after completion of treatment for smear-negative pulmonary tuberculosis (sputum polymerase chain reaction positive for Mycobacterium tuberculosis). She lived in Nakhon Nayok province and reported taking raw crabs from time to time. The complete blood count revealed eosinophilia and her chest radiograph showed patchy infiltration at right lower lung field. Computed tomography scan of the chest revealed consolidation with internal air bubbles at anterobasal segment of right lower lobe. The diagnosis of pulmonary paragonimiasis was confirmed by detecting eggs of the genus Paragonimus in her wet-mount sputum. She was treated with oral praziquantel for 3 consecutive days with improvement. To our knowledge, although coinfection of pulmonary paragonimiasis and pulmonary tuberculosis is rare, it should be considered as the differential diagnosis in patients who live in the endemic area presenting with hemoptysis and eosinophilia.

Pleural fluid characteristics of pleuropulmonary paragonimiasis masquerading as pleural tuberculosis

BACKGROUND/AIMS

Pleuropulmonary paragonimiasis produces no specific symptoms or radiologic findings, allowing for the possibility of misdiagnosis. We evaluated the specific clinical and pleural fluid features of pleuropulmonary paragonimiasis masquerading as pleural tuberculosis.

METHODS

We retrospectively analyzed the clinical and radiologic characteristics of 20 patients diagnosed with pleuropulmonary paragonimiasis between 2001 and 2011.

RESULTS

In total, 17 patients presented with respiratory symptoms, including dyspnea (30%), hemoptysis (20%), cough (20%), and pleuritic chest pain (15%). Chest radiographs revealed intrapulmonary parenchymal lesions, including air-space consolidation (30%), nodular opacities (20%), cystic lesions (15%), ground-glass opacities (10%), and pneumothorax (5%). A pleural fluid examination revealed eosinophilia, low glucose levels, and high lactate dehydrogenase (LDH) levels in 87%, 76%, and 88% of the patients, respectively. These traits helped to distinguish pleuropulmonary paragonimiasis from other pleural diseases such as parapneumonic effusion, malignancy, and pleural tuberculosis.

CONCLUSIONS

Pleuropulmonary paragonimiasis is often initially misdiagnosed as other pleural diseases. Therefore, it is important to establish the correct diagnosis. In patients with unexplained pleural effusion living in paragonimiasis-endemic areas, pleural fluid obtained by thoracentesis should be examined to distinguish pleuropulmonary paragonimiasis. When marked eosinophilia, high LDH levels, and low glucose levels are identified in pleural fluid, physicians could consider a diagnosis of pleuropulmonary paragonimiasis.

Preparation of colloidal gold immunochromatographic strip for detection of Paragonimiasis skrjabini

Background

Paragonimiasis is a food-borne trematodiasis, a serious public health issue and a neglected tropical disease. Paragonimus skrjabini is a unique species found in China. Unlike paragonimiasis westermani, it is nearly impossible to make a definitive diagnosis for paragonimiasis skrjabini by finding eggs in sputum or feces. Immunodiagnosis is the best choice to detect paragonimiasis skrjabini. There is an urgent need to develop a novel, rapid and simple immunoassay for large-scale screening patients in endemic areas.

Methodology/Principal Findings

To develop a rapid, simple immunodiagnostic assay for paragonimiasis, rabbit anti-human IgG was conjugated to colloidal gold particles and used to detect antibodies in the sera of paragonimiasis patients. The synthesis and identification of colloidal gold particles and antibody-colloidal gold conjugates were performed. The size of colloidal gold particles was examined using a transmission electron microscope (TEM). The average diameter of colloidal gold particles was 17.46 nm with a range of 14.32–21.80 nm according to the TEM images. The formation of antibody-colloidal gold conjugates was monitored by UV/Vis spectroscopy. Excretory-secretory (ES) antigen of Paragonimus skrjabini was coated on nitrocellulose membrane as the capture line. Recombinant Staphylococcus protein A was used to prepare the control line. This rapid gold immunochromatographic strip was assembled in regular sequence through different accessories sticked on PVC board. The relative sensitivity and specificity of the strip was 94.4% (51/54) and 94.1% (32/34) respectively using ELISA as the standard method. Its stability and reproducibility were quite excellent after storage of the strip at 4°C for 6 months.

Conclusions/Significance

Immunochromatographic strip prepared in this study can be used in a rapid one-step immunochromatographic assay, which is instantaneous and convenient.

[Geographic distribution and gene sequencing of Paragonimus westermani in some areas of Guangdong Province]

OBJECTIVE

To investigate the current distribution of Paragonimus westermani in Guangdong Province.

METHOD

Snails and crabs collected from mountain streams in regional survey sites were dissected to detect cercarial and metacercarial infections of P. westermani. Domestic cats and dogs artificially infected with the collected metacercariae were also dissected to detect adult worms of P. westermani. The COI and ITS2 gene sequences of those adult worms were compared with those of known Paragonimus specimen deposited in the GenBank.

RESULTS

All of the first intermediate hosts in five survey sites of Liangkou, Nankun, Mountain, Dadong, Muxi, Guowu, were identified as Semisulcospira libertina, whose cercariae infection rates were 0.33%, 0.15%, 0.058%, 0.10%, and 0.05%, respectively; the second intermediate hosts in above five sites were all identified as Sinopotamon denticulatum, whose metacercariae infection rates were 100%, 100%, 38.09%, 55.36%, and 65.26%, respectively. The numbers of metacercariae in the five sites were 79.4, 105.66, 9.16, 16.18, and 15.6 per positive crab, respectively, and 11.12, 7.87, 0.58, 0.69, and 0.85 per gram of crab, respectively. All the metacercariae were identical to those of P. westermani. Adult worms and eggs of P. westermani were found in both reservoir hosts of domestic cats and dogs infected artificially. By comparing the COI genes of five representative samples from each survey site with that of Paragonimus #AF219379.21, AF540958.1 from GenBank, we found out the homology to be 99%, 99%, 99%, 98%, and 99%, respectively. In addition, a comparison of the ITS2 gene sequences between the above five samples and Paragonimus #DQ836243.1, DQ351845.1, AB354217.1 from GenBank revealed 98%, 99%, 98%, 98%, and 98% gene homology, respectively.

CONCLUSION

Two ultra-high and three high endemic areas of P. westermani are discovered in Guangdong Province. No obvious differences were found among the types of P. westermani in the above five endemic areas.

The return of an old worm: cerebral paragonimiasis presenting with intracerebral hemorrhage

Paragonimiasis is caused by ingesting crustaceans, which are the intermediate hosts of Paragonimus. The involvement of the brain was a common presentation in Korea decades ago, but it becomes much less frequent in domestic medical practices. We observed a rare case of cerebral paragonimiasis manifesting with intracerebral hemorrhage. A 10-yr-old girl presented with sudden-onset dysarthria, right facial palsy and clumsiness of the right hand. Brain imaging showed acute intracerebral hemorrhage in the left frontal area. An occult vascular malformation or small arteriovenous malformation compressed by the hematoma was initially suspected. The lesion progressed for over 2 months until a delayed surgery was undertaken. Pathologic examination was consistent with cerebral paragonimiasis. After chemotherapy with praziquantel, the patient was monitored without neurological deficits or seizure attacks for 6 months. This case alerts practicing clinicians to the domestic transmission of a forgotten parasitic disease due to environmental changes.

Paragonimus & paragonimiasis in India

Ever since the discovery of the first indigenous case in 1981, paragonimiasis has gained recognition as a significant food borne parasitic zoonosis in India. The data available on the occurrence of paragonimiasis, until today, may be just the tip of an iceberg as the study areas covered were restricted to Northeast Indian States. Nevertheless, the results of research on paragonimiasis in India have revealed valuable information in epidemiology, life cycle, pathobiology and speciation of Indian Paragonimus. Potamiscus manipurensis, Alcomon superciliosum and Maydelliathelphusa lugubris were identified as the crab hosts of Paragonimus. Paragonimus miyazakii manipurinus n. sub sp., P. hueit'ungensis, P. skrjabini, P. heterotremus, P. compactus, and P. westermani have been described from India. P. heterotremus was found as the causative agent of human paragonimiasis. Ingestion of undercooked crabs and raw crab extract was the major mode of infection. Pulmonary paragonimiasis was the commonest clinical manifestation while pleural effusion and subcutaneous nodules were the common extra-pulmonary forms. Clinico-radiological features of pulmonary paragonimiasis simulated pulmonary tuberculosis. Intradermal test, ELISA and Dot-immunogold filtration assay (DIGFA) were used for diagnosis and epidemiological survey of paragonimiasis. Phylogenitically, Indian Paragonimus species, although nested within the respective clade were distantly related to others within the clade.

Paragonimus kellicotti flukes in Missouri, USA

Paragonimiasis is an infection caused by lung flukes of the genus Paragonimus. In Asia, P. westermani infections are relatively common because of dietary practices. However, in North America, cases of paragonimiasis, which are caused by P. kellicotti flukes, are rare. Only 7 autochthonous cases of paragonimiasis were reported during 1968-2008. In 2009, we reported 3 new case-patients with paragonimiasis who had been seen at our medical center over an 18-month period. Six additional case-patients were identified in St. Louis, Missouri, USA, and treated at Washington University-affiliated health centers in 2009-2010. We report detailed descriptions of these case-patients, which includes unusual clinical manifestations. We also describe public health interventions that were undertaken to inform the general public and physicians about the disease and its mode of transmission.

Experimental infection with Paragonimus heterotremus metacercariae in laboratory animals in Manipur, India

This study was aimed to find out the host-parasite relationship between Paragonimus heterotremus isolated as metacercariae from mountain crabs, Indochinamon manipurensis, in Manipur, India and laboratory animals such as puppies, albino rats, Swiss mice, guinea pigs, and rabbits, as experimental animals. The animals were fed with the metacercariae. Infected animals were sacrificed 35 to 430 days after feeding to recover worms, which were used to determine the developmental stages. Adult worms (n = 14) were recovered from 3 puppies > or = 70 days after feeding and immature worms (n = 25) were recovered from 2 other puppies 35 or 43 days after infection. The infection rate in puppies was 100%. Juvenile worms were recovered from 3 of 13 rats: 1 of 11 rats whose viscera and cavities were examined and both of two rats whose muscles were examined. Rats were not a suitable animal model for pulmonary infection with P. heterotremus. Mice, guinea pigs, and rabbits were also found to be insusceptible to pulmonary infection with P. heterotremus.

Can pleuropulmonary paragonimiasis be cured by only the 1st set of chemotherapy? Treatment outcome and clinical features of recently developed pleuropulmonary paragonimiasis

PURPOSE

Most patients with pleuropulmonary paragonimiasis can be cured by the initial single set of Praziquantel (PZQ) treatment. However, several cases have been reported to have unsatisfactory responses to the initial PZQ treatment. The objective of this study was to evaluate the clinical findings of patients with pleuropulmonary paragonimiasis who needed additional PZQ treatment after the 1st set chemotherapy.

PATIENTS AND METHODS

Thirty-two patients who were diagnosed with pleuropulmonary paragonimiasis at our institution between 2003 and 2008 were retrospectively reviewed.

RESULTS

All patients were treated initially with PZQ for 3 days (1st set chemotherapy). Twenty-four patients (75.0%) showed improvement in respiratory symptoms and pulmonary involvements. However, eight patients (25.0%) suffered from relapsed respiratory symptoms and pleural effusion. For these patients, an additional 2nd set PZQ treatment resulted in the resolution of the symptoms and pulmonary involvements. The characteristics of patients who needed multi-set treatments were as follows; longer duration of respiratory symptoms (single vs multi-set treatment group; 6.67 ± 8.08 vs 17.86 ± 11.84 weeks, p=0.009), higher IgG titer (optical density, O.D.) for Pargonimus westermani (ELISA O.D. for PW, 0.54 ± 0.19 vs 0.88 ± 0.16 O.D., p=0.001) and higher frequency of multiple pulmonary lesions (% of patients with multiple lesions; 16.7% vs 50.0%, p=0.059).

CONCLUSION

The patients who had a longer duration of respiratory symptoms, higher ELISA titer for PW and/or multiple pulmonary lesions needed an additional PZQ treatment after the 1st set of chemotherapy. Close follow-up after the initial treatment is necessary especially for such patients.

Different chest radiographic findings of pulmonary paragonimiasis in two endemic countries

We compared the chest radiographic findings of patients with pulmonary paragonimiasis in the Lao People's Democratic Republic (PDR) with a report from Korea. The clinical and radiological characteristics of 50 confirmed Laotian pleuropulmonary paragonimiasis patients were studied between March 2003 and June 2007. In 49 patients, the chest radiographs showed abnormal findings (98%). Pulmonary parenchymal abnormalities were found in all 49 patients, whereas pleural effusion was only found in 11 patients (22%). The three most common intraparenchymal findings were multiple small cysts (90%), irregular linear densities (68%), and nodular opacities (40%). The numbers of patients who had these three findings were significantly different from the Korean report (P < 0.001). In conclusion, radiographic findings of pulmonary paragonimiasis may vary among countries.

[Paragonimus westermani infection confirmed by the detection of Paragonimus ova in the sputum with bilateral pleural effusion]

A 28-year-old man had a 1-year history of hemoptysis. Consequently, he underwent a medical examination. A right pleural effusion, left hydropneumothorax, and multiple pulmonary nodular shadows were found on chest radiography. During a detailed interview, he reported that the hemoptysis began after eating "kejang" (a raw crab preparation) with a friend a year previously. His peripheral blood eosinophil count and serum IgE level were elevated. In addition, ova were detected in the sputum and bilateral pleural effusion. Morphological examination of the ova and immunoserological examination led to the diagnosis of Paragonimus westermani infection. The pleural effusion could be partially drained, and his symptoms and radiographic results showed improvement after treatment with Praziquantel administered at a dose of 75 mg/(kg x day) for 3 days. After one month, he and his friend ate seasoned raw crabs, Paragonimus was diagnosed in his friend. This case suggests that on encountering a paragonimus infection, everyone who ate food prepared in the same kitchen should be contacted because of possible infection with paragonimus.

[Epidemiological investigation on the intermediate hosts of Paragonimus in Ninghai County of Zhejiang Province]

Freshwater crabs and snails were collected from Ninghai County in Zhejiang Province, and examined respectively for Paragonimus metacercariae and cercariae. Among 97 freshwater crabs found, the prevalence was 11.3% (11/97) with a mean intensity of 1 metacercariae per crab. It was 10.2% (5/49) and 20.2% (4/20) in the groups weighted 5-15 g and 15-25 g respectively, with an average intensity of 1, and no metacercariae were found in weight group of 25-35 g. Two positive crabs were found from 20 crabs with a low weight (< 5 g). Male to female crabs ratio was 2.5:1, and there was no significant difference in prevalence between males [12.7%(7/55)] and females [9.1% (2/22)]. No cercariae or metacercariae were found in 200 snails (Semisulcospira libertino).

North American paragonimiasis (Caused by Paragonimus kellicotti) in the context of global paragonimiasis

Paragonimus species are highly evolved parasites with a complex life cycle that involves at least three different hosts, i.e., snails, crustaceans, and mammals. The adult forms of Paragonimus species reside and mate in the lungs of a variety of permissive mammalian hosts, including humans. Although human paragonimiasis is uncommonly encountered in North America, both autochthonous and imported disease may be encountered. Paragonimus kellicotti, the species endemic to North America, is a well-known pathogen in wild and domestic animals. Five patients with North American paragonimiasis have been reported in the recent medical literature. The biologic, clinical, radiologic, and laboratory features of paragonimiasis are reviewed, with emphasis on North American paragonimiasis whenever possible.

[A new focus of human paragonimosis discovered in Côte d'Ivoire (West Africa): the case of the Lauzoua Island]

Fifteen cases of human paragonimosis were detected in Ivory Coast from 1974 to 1999. Since no further cases have been reported, an epidemiological survey was carried out in local health centers. The purpose of this paper is to described a new focus of paragonimosis discovered on Lauzoua Island. Clinical and parasitological examinations were performed on 17 patients presenting chronic cough, haemoptysis and/or epilepsy. Stools belonging to cats, dogs and pigs as well as river crustaceans were also examined to identify parasite eggs and metacercariae respectively. Paragonimus eggs were found in stools and/or sputum of five patients. Measurements of these eggs after fixation in formalin allowed division into three groups. Stools from cats, dogs and pigs were negative. Small Paragonimus metacercariae (mean: 277 to 323 microm) were found in three Callinectes marginatus crabs (out of 15 caught near the island). No metacercariae were found in local prawns. The presence of these three Paragonimus egg groups as well as of infected crabs near the island will require further study to identify the species and determine the prevalence of each in human infection.

[Epidemiological survey on paragonimiasis in Ningbo City, Zhejiang Province]

Serum samples were collected from 2643 suspected cases of paragonimiasis in 2000-2007 from the outpatient departments of the city hospitals and surrounding areas, and the infection rate in the inhabitants, the first and second intermediate hosts, and animal reservoir hosts were investigated in the historical endemic areas. Serum samples were detected and 417 were found antibody positive (15.8%). Among residents in the historical endemic areas, the seropositive rate was 3.1% (46/1462), 2.8% (18/649) and 3.2% (26/813) in males and females respectively (CHI2 = 0.1833, P > 0.05). The infection rate in first intermediate host (snails), second intermediate host (crabs) and animal reservoir hosts was 0.05% (9/ 19,368), 31.1% (15,627/ 50,313) and 11.9% (52/438) respectively. Evidently, natural nidi for Paragonimus spp. still exist in Ningbo City.

[Paragonimus skrjabini infection in animal reservoir hosts and questionnairing in residents at a village of Hubei Province]

Freshwater crabs (Sinopotamon denticulatum) were examined for metacercariae. Cats and dogs were also examined for Paragonimus infection. Questionnairing was carried out on health knowledge and behaviors among local residents in a village of Baokang County, Hubei Province. Results showed that the infection rate of Paragonimus skrjabini metacercariae in Sinopotamon denticulatum was 20.5% (46/214), with 15.6% (20/128) in a mining area and 30.2% (26/86) for the non-mining area respectively (chi2 = 6.5, P < 0.05). The prevalence in cats and dogs was 25.0% (6/24) and 17.6% (6/34) respectively (chi2 = 0.46, P > 0.05). Questionnairing showed that dogs and cats were with the habit of foraging and defecating at streams and children had the habits of eating raw or under-cooked crabs. The natural and ecological environments are in favor of the life cycle of P. skrjabini.

Pulmonary paragonimiasis with coincidental malignant mesothelioma

A 72-year-old man patient was referred to our institution for evaluation and treatment of right pleural effusion. Eosinophilic pleural effusion and peripheral eosinophilia were identified during the course of hospitalization. Pulmonary paragonimiasis was confirmed by the presence of paragonimus-specific IgG antibodies for Paragonimus (P.) westermani and P. miyazakii in his serum. Although Praziquantel, a highly effective agent for the treatment of lung flukes was repeatedly administered, the pleural effusion did not subside and the patient's condition gradually deteriorated until his death due to circulatory insufficiency. Postmortem examination revealed malignant mesothelioma of the sarcomatous type encasing the right lung and heart. Cardiac involvement accompanied with old and recent-onset myocardial ischemic changes resulted in death of this patient. Here, we report a very rare case of malignant mesothelioma with a concomitant infection of parasitic lung fluke.

[Establishment and application of circulating antigen detection in Paragonimus westermani infection]

Circulating antigen and antibody were detected by CAg-dot-ELISA & CAb-ELISA respectively on the clinically confirmed patients of paragonimiasis, people in paragonimus endemic area, cases with early infection of P. westermani, and cases with other parasitic infections. Circulating antigen was detected in 29 out of 70 cases with paragonimiasis with a sensitivity of 41.5%. The rate of cross reaction in cases with clonorchiasis sinensis and schistosomiasis was 25% (5/20) and 20% (4/20), respectively, and it was negative in 60 cases with other parasitic infections and healthy subjects, with an overall specificity of 93.6%. Specific antibody was detected in 67 of 70 cases with paragonimiasis with a sensitivity of 95.7%. The cross reaction rate in cases of clonorchiasis sinensis and schistosomiasis was 25% (5/20) and 20% (4/20), but negative in 60 cases with other parasitic infections and healthy subjects, with a specificity of 92.1%. 220 persons from paragonimus endemic area were all negative in antigen detection and 7 (3.2%) showed antibody positive. Dot-ELISA for circulating antigen detection may be helpful in diagnosing early infection of P. westermani.

Description of a new lung fluke species, Paragonimus vietnamensis sp. nov. (Trematoda, Paragonimidae), found in northern Vietnam

Based on morphology of metacercariae and adult worms together with molecular data from our previous study, we describe herein a new lung fluke species named Paragonimus vietnamensis sp. nov. Metacercariae of this new species is round and extremely large in size (nearly 800 mum in diameter) having a fragile outer cyst of variable thickness and a thin fragile inner cyst. There are little or no space between metacercaria and the inner cyst wall. These and other morphological features of metacercariae of P. vietnamensis sp. nov. are not completely identical with but have some similarities with those of P. microrchis, P. proliferus, or P. menglaensis. On the other hand, adult worms obtained by experimental infection of these large metacercariae are oval in shape, having a ventral sucker slightly larger than the oral one, and having singly arranged relatively short cuticular spines. These morphological features of adult worms are partly similar to but not identical with those of P. microrchis, P. skrjabini, P. yunnanenis, P. xiangshanensis, or P. harinasutai. Taken these morphological data and our previous molecular phylogenetic analyses of ITS2 and CO1 sequences of metacercariae and adult worms together, P. vietnamensis sp. nov. is different from any other known Paragonimus spp.

Paragonimiasis and its intermediate hosts in a transmission focus in Lao People's Democratic Republic

Human cases of paragonimiasis have been reported in Lao People's Democratic Republic from several provinces, however, detailed descriptions of a focus of transmission including parasites species and intermediate hosts are lacking. Field investigations were carried out between February and July 2004 in three neighboring villages of the province of Vientiane. Persons with chronic cough (more than three weeks) were identified during a door-to-door survey and three sputum samples were examined for Paragonimus spp. and tuberculosis on two consecutive days. Potential intermediate snail and crustacean hosts were sampled among the populations' water-contact sites and examined for metacercarial infections or cercarial shedding. Four dogs were infected with metacercaria and the species of the subsequently retrieved adult parasites were identified. 12.7% (15 cases) of all chronic cough patients (0.6% of the total population) suffered from paragonimiasis. Samples of five species of freshwater snails, two species of crabs and one species of prawn were collected from the Nam Sêt River. None of the snails were infected. Metacercariae of P. harinasutai, P. bangkokensis and P. heterotremus were found in Potamon lipkei crabs while an infection with P. westermani was observed in a Chulathelphusa brandti crab. No paragonimid metacercaria was found in the Macrobrachium dienbienphuense prawns Dang and Nguyen 1972. This study demonstrates the importance of Paragonimus spp. as an etiological agent in patients with chronic cough and suggests that similar transmission might be widespread in Lao People's Democratic Republic. We document herein the transmission of several Paragonimus species indicating that paragonimiasis is an active zoonosis in Lao People's Democratic Republic.

[Dot immuno-gold filtration assay in the diagnosis of suspected paragonimiasis and evaluation of chemotherapeutic effect]

OBJECTIVE

To evaluate the usefulness of dot immuno-gold filtration assay(DIGFA) for the diagnosis of Paragonimus infection.

METHODS

During 2003 to 2006, 72 cases suspected of paragonimiasis in Zhejiang Province were examined with DIGFA for rapid detection of specific antibodies against Paragonimus (Pw-DIGFA). The diagnosis was primarily established with the presence of antibodies, experience of ingesting raw freshwater crabs or crayfishes and clinical presentations. The cases were treated with praziquantel and followed-up at 3 and/or 6 months post-treatment. Antibody level in patients (pre- and post-treatment) were detected in parallel and analyzed comparatively by Pw-DIGFA and ELISA.

RESULTS

The result of detection by Pw-DIGFA was in agreement with that of ELISA. 28 of 72 cases were antibody positive and 44 cases were negative. Among the 28 positives, 26 cases had a history of eating raw freshwater crab or crayfishes and the other 2 cases drank freshwater from brook before. 21 cases showed paragonimiasis-related clinical symptoms such as low-grade fever, cough, or changes in image examination, while the other 7 cases showed only eosinophilia in peripheral blood (15%-70%). The mean absorbance values (A450) of positive sera, negative sera and normal sera tested by ELISA were 1.7361, 0.2973 and 0.2657 respectively. There was significant difference between the positive cases and the negative cases (t=12.047, P<0.01) and no significant difference between the negative cases and normal controls (t=1.919, P>0.05). At 3 month post-treatment, serum antibody in 5 cases whose clinical symptoms and physical signs relieved or disappeared decreased 2-5 titers and that of one case who relapsed with new signs increased by one titer. In Pw-DIGFA, the dot color of 5 cured cases showed a little weaker than that of pre-treatment and the relapsed case displayed similar response. At 6 month post-treatment, 7 sera of clinically cured cases showed significantly weaker response than that of pre-treatment. The antibodies of those sera dropped 3-6 titers.

CONCLUSION

Pw-DIGFA is of supplementary value for clinical diagnosis of paragonimiasis. Antibody detection by pre- and post-treatment using Pw-DIGFA shows potential for the evaluation of therapeutic effect.

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.

Paragonimus westermani: Biochemical and immunological characterizations of paramyosin

Paramyosin of the helminth parasite is a muscle protein that plays multifunctional roles in host-parasite relationships. In this study, we have cloned a gene encoding Paragonimus westermani paramyosin (PwPmy) and characterized biochemical and immunological properties of the recombinant protein. The recombinant PwPmy (rPwPmy) was shown to bind both human immunoglobulin G (IgG) and collagen. The protein was constitutively expressed in various developmental stages of the parasite and its expression level increased progressively as the parasite matured. Immunohistological analysis revealed that PwPmy was mainly localized in subtegumental muscle, tegument and cells surrounding the oral sucker, intestine, and ovary of the parasite. Sera from patients with paragonimiasis showed antibody reactivity against rPwPmy, and IgG1 and IgG4 were predominant. Immunization of mice with rPwPmy also induced high IgG responses. Biochemical and immunological characterization of PwPmy may provide valuable information for the further study to develop a vaccine or a chemotherapeutic agent for paragonimiasis.

Paragonimus heterotremus Chen and Hsia (1964), in Vietnam: a molecular identification and relationships of isolates from different hosts and geographical origins

Paragonimus heterotremus Chen and Hsia (1964), and paragonimiasis caused by this species is a newly detected disease in Vietnam. Twelve samples of Paragonimus (Platyhelminthes: Trematoda: Digenea: Paragonimidae) from different life-stages (eggs, miracidia, metacercariae, adults from natural and experimental hosts) and host species (crab, dog, cat and human) were collected in different geographical locations in Vietnam. DNA sequences were obtained from each for partial mitochondrial cytochrome c oxidase subunit 1 (cox1) (387 bp) and the entire second ribosomal internal transcribed spacer (ITS-2) (361 bp). The ITS-2 sequences were identical among all specimens, including those previously reported in GenBank. For cox1, there were sequence differences between specimens from Vietnam (four provinces, different locations) and those from Guangxi (China) and Saraburi (Thailand). Phylogenetic trees inferred from cox1 and ITS-2 sequences using sequence data for 15 P. heterotremus and for other Paragonimus spp. revealed that all P. heterotremus originating from Vietnam, Thailand and China form a distinct group. This information also confirms the identity of the Vietnamese specimens as P. heterotremus.

A new record of Paragonimus other than P. westermani in southern Thailand

Field surveys of Paragonimus in Surat Thani Province, southern Thailand, revealed a new record of a lung fluke species other than P. westermani. The metacercariae were obtained from the crab, Ranguna smalleyi. The cysts of the metacercariae were spherical in shape and the larval body in the cysts contained pinkish granules. Fully mature adult worms were obtained from experimental infections with a rat and a ferret. The adult worms from the two host animals resembled each other, except for size, and had the anatomical characteristics of P. bangkokensis, ie the cuticular spines were arranged mainly in groups, the ovaries were highly branched, while the testes were more simply divided. Chromosomal preparations of the testes showed a haploid number of 11. As no sequence data of P. bangkokensis has been deposited in the GenBank/EMBL/DDBJ nucleotide database, the ITS2 region was sequenced using the metacercariae as starting material. A similarity search of P. bangkokensis ITS2 sequence using the BLAST program revealed that there was only one base difference between this population and P. harinasutai occurring in central Thailand. The result may suggest a close relationship between P. bangkokensis and P. harinasutai. This is the first description of Paragonimus species other than P. westermani occurring in southern Thailand.

Possible discovery of Chinese lung fluke, Paragonimus skrjabini in Manipur, India

To obtain more information about Paragonimus species prevalent in Manipur, India, hundreds of freshwater crabs, Potamiscus manipurensis, were captured from mountain streams in the Motbung Mountains in Senapati District, from December 1997 to January 1998. Crab extracts were prepared by digestion, differential filtration, and sedimentation. The filtered sediments were critically examined under a stereomicroscope. Isolated Paragonimus metacercariae were used for morphological study and animal experimentation. Forty-seven metacercariae were fed orally to a 3-month-old male puppy of local breed; at autopsy 155 days after inoculation, 12 adult worms were recovered; 2 were free in the thoracic cavity and 5 pairs were in lung cysts. Two adult worms were flattened and fixed in 70% ethanol and the remaining worms were put directly into 70% ethanol and preserved until July 2005. The former 2 worms were stained with borax carmine for morphological study at Sikkim Manipal Institute of Medical Sciences, Sikkim, India. Two adult worms in the latter group were sent to the National Institute of Infectious Diseases, Tokyo, Japan, for morphological identification and DNA sequencing. The morphological features of the borax carmine-stained worms were characteristic of P. skrjabini, although no genetic material for PCR amplification and sequencing could be extracted from the worm.

Triclabendazole for the treatment of fascioliasis and paragonimiasis

Fascioliasis and paragonimiasis, which are caused by liver flukes (Fasciola) and lung flukes (Paragonimus), are emerging public health problems. Several hundred millions of people are at risk of the two diseases that cause considerable morbidity and delay socio-economic development. Triclabendazole, a benzimidazole derivative, has been routinely used since 1983 in veterinary medicine to control infections with Fasciola spp. in domestic herbivorous animals. In 1986, a veterinary formulation of triclabendazole was first administered to two human patients with fascioliasis. Clinical data obtained thus far suggest that triclabendazole is the most efficacious and best tolerated drug for the treatment of fascioliasis. Moreover, the drug holds promise as a useful therapeutic alternative to praziquantel in the treatment of paragonimiasis. This review of triclabendazole includes an overview of the pharmacodynamics and pharmacokinetics, toxicology and efficacy against the major food-borne trematodes in laboratory animals. Data from case reports and clinical trials in humans infected with Fasciola spp. and Paragonimus spp. are summarised and the current state of triclabendazole regarding treatment of human fascioliasis and paragonimiasis is described. Efforts to facilitate broader registration of this drug should go hand-in-hand with research and development on novel drugs against food-borne trematodiasis, better access to improved sanitation, sound health education and the development of new technologies for assuring food safety.

Detection of Paragonimus heterotremus eggs in experimentally infected cats by a polymerase chain reaction-based method

A polymerase chain reaction (PCR) procedure for the detection of Paragonimus heterotremus eggs in stool samples was developed and compared with Stoll's egg count method. The primers were designed on the basis of a previously constructed pPH-13-specific DNA probe, which produced an approximate 0.5-kb amplified product. This PCR method could detect as few as 5 eggs in 0.6 g of artificially inoculated feces of a healthy control cat or as little as 1 x 10(-4) ng of P. heterotremus genomic DNA. The assay had 100% sensitivity in all infected cats. The method did not yield an approximate 0.5-kb product with DNA from other parasites such as Gnathostoma spinigerum, Trichinella spiralis, Fasciola gigantica, Echinostoma malayanum, Opisthorchis viverrini, Dirofilaria immitis, and Taenia saginata; exceptions were Paragonimus siamensis and Paragonimus westermani. In addition, no genomic DNA from Escherichia coli, Burkholderia pseudomallei, Acinetobacter anitratus, Mycobacterium tuberculosis, Staphylococcus aureus, beta-Streptococcus grA, and Proteus mirabilis or from the vertebrate and invertebrate hosts of P. heterotremus was amplified in the PCR assay. This assay has great potential for application in clinical epidemiological studies.

Molecular discrimination between individual metacercariae of Paragonimus heterotremus and P. westermani occurring in Thailand

To accurately discriminate between individual metacercariae of Paragonimus heterotremus and P. westermani occurring in Thailand, polymerase chain reaction (PCR)-based molecular methods were established and subjected to an evaluation. We first amplified and sequenced the second internal transcribed spacer (ITS2) region of the nuclear ribosomal DNA of the two species. Based on their nucleotide differences, P. heterotremus and P. westermani were unequivocally discriminated from each other. These nucleotide differences were further utilized to select the ApaL1 endonuclease site for PCR-restriction fragment length polymorphism (PCR-RFLP) analyses and to design species-specific primers for multiplex PCR reactions. Both PCR-RFLP and multiplex PCR methods allowed a more rapid and labor-effective species discrimination. Furthermore, the multiplex PCR method enabled the most efficient discrimination because species identification involved a single round of PCR in a single tube. In Thailand, P. heterotremus is the only species affecting humans. Thus, the methods established in the present study can be used as reliable tools to identify the lung fluke metacercariae that cause human disease.

Pleuropulmonary Paragonimiasis mimicking Pulmonary Tuberculosis - A Report of Three Cases

Paragonimiasis is an important cause of pulmonary disease worldwide. Infection in humans mainly occurs by ingestion of raw or undercooked freshwater crabs or crayfish. The disease is well known in endemic regions of Asian countries, where culturally based methods of food preparation foster human transmission. Three patients with clinical and radiological features compatible with pulmonary tuberculosis had been treated for tuberculosis without remedy despite an inability to demonstrate acid fast bacilli in sputum smears. All patients had history of ingestion of raw crabs and crayfish. The confirmed diagnosis of pleuropulmonary paragonimiasis was made based on the demonstration of Paragonimus eggs in the sputum, and high absolute eosinophilia in their peripheral blood and pleural fluid. All the patients had been treated with praziquantel successfully.

Expression and cross-species reactivity of fatty acid-binding protein of Clonorchis sinensis

Clonorchis sinensis is a Chinese liver fluke that chronically resides in the biliary tract. The fatty acid-binding protein (FABP) is known to play an important role in the intracellular transport of long-chain fatty acids that are obtained by the fluke from the host. Although FABP has stimulated considerable interest as a vaccine target candidate, the nature of FABP from C. sinensis (CsFABP) remains unclear. In this paper, we describe the cloning and expression of recombinant FABP and immune cross-reaction by Western blot analysis. Sequence analysis revealed that the CsFABP cDNA contained a single open reading frame (ORF) coding for 134 amino acids with an estimated molecular mass of a 15.2 kDa. The DNA sequence of CsFABP cDNA showed significant homology to schistosome cytosolic FABPs, with a 49% amino acid sequence identity and 89% similarity to Schistosoma japonicum. This DNA also showed a high sequence similarity at the amino acid level to S. mansoni (Sm14; 83%) and Fasciola hepatica (80%). The CsFABP cDNA was cloned into expression vector pET28a, expressed in Escherichia coli and the recombinant protein purified by affinity chromatography. The recombinant CsFABP was cross-reacted with sera obtained from patients with fascioliasis and paragonimiasis. These results suggest that CsFABP may be useful as a vaccine for clonorchiasis.

Caspase-3-mediated apoptosis of human eosinophils by the tissue-invading helminth Paragonimus westermani

BACKGROUND

Eosinophils are important cells in host immunity to infections by parasitic worms. Tissue-invasive helminthic parasites have been known to induce apoptosis of immune cells for their successful establishment in vivo. We have previously found that high doses of excretory-secreted products (ESP) secreted by lung fluke Paragonimus westermani newly excysted metacercariae (PwNEM), which cause pulmonary or extrapulmonary paragonimiasis in human beings, accelerate eosinophil cell death. However, little is known about the mechanism of eosinophil apoptosis induced by the Paragonimus-derived products.

OBJECTIVE

We examined involvement of caspase 3 activation in eosinophil cell death induced by ESP produced by PwNEM.

METHODS

Eosinophils were isolated from the peripheral blood of healthy donors by CD16-negative immunomagnetic selection. We examined the inhibitory effect of pan-caspase inhibitor on ESP-triggered phosphatidylserine (PS) externalization on the outer surface of eosinophils and intracellular activation of caspase 3 in cell lysates treated with the ESP.

RESULTS

When ESP secreted by PwNEM were incubated for up to 3 h with eosinophils, they increased surface exposure of PS on eosinophils in a time- and dose-dependent manner. This proapoptotic effect of the ESP on eosinophils was significantly inhibited by pretreatment of cells with pan-caspase inhibitor z-VAD-fmk, and was completely abolished by heat inactivation of ESP at 56 degrees C. The activated forms of caspase 3 were also clearly detected in eosinophils incubated with ESP. Moreover, ESP potently inhibited prolonged survival of eosinophils induced by cytokines such as IL-5, IL-3, and GM-CSF.

CONCLUSION

These results suggest that ESP secreted by PwNEM contain biological active factors causing caspase-3-mediated apoptosis of human eosinophils, thereby enabling the larvae to evade and to subvert the tackle by eosinophils during the early phase of the infection.

Gene sequencing for identification of Paragonimus eggs from a human case

OBJECTIVE

To identify the etiologic agent from a paragonimiasis patient using molecular techniques.

METHODS

The complete nuclear ribosomal DNA second internal transcribed spacer (ITS2) gene sequence of eggs in sputum from a paragonimiasis patient was obtained by directly auto-sequencing its PCR product. ITS2 genes from eggs of Paragonimus westermani and Pagumogonimus skrjabini (both from animal hosts) were also sequenced for comparison. In addition, morphological comparisons were made with the eggs of the two species.

RESULTS

The ITS2 gene from the human case was 100% identical with the sequence from the eggs of P. westermani from an experimentally infected dog but only 92% identical with the sequence from the eggs of P. skrjabini. Morphologically, the eggs from the human case more resembled those from P. westermani infected dog.

CONCLUSION

The patient was diagnosed to be suffered from paragonimiasis westermani by gene sequence analysis.

Identities of two Paragonimus species from Sri Lanka inferred from molecular sequences

Metacercariae of Paragonimus spp. were obtained from field-collected freshwater crabs in Sri Lanka. Genomic DNA was extracted from single metacercariae. Two gene regions (partial mitochondrial cytochrome c oxidase subunit 1 (CO1) and the second internal transcribed spacer of the nuclear ribosomal gene repeat (ITS2)) were amplified using the polymerase chain reaction. Two differing sequences were obtained for each of these gene regions. Phylogenetic analyses placed the type 1 sequences as sister to a clade containing P. westermani and P. siamensis whereas the type 2 sequences were close to published sequences of P. siamensis from Thailand. The possible taxonomic status of these two types are discussed. This is the first report of molecular data about Paragonimus from Sri Lanka.

MORPHOLOGICAL DESCRIPTION AND LIFE CYCLE OF PARAGONIMUS SP. (TREMATODA: TROGLOTREMATIDAE): CAUSAL AGENT OF HUMAN PARAGONIMIASIS IN COLOMBIA

The first morphological description is made of all stages of the life cycle of a Paragonimus species infecting humans in Colombia. Larval stages were obtained both in vitro and from field collections. Adult Paragonimus spp. are described. The aquatic snail Aroapyrgus sp. serves as an intermediate host of this species, both naturally and experimentally, yielding rediae and cercariae. Crabs (Hypolobocera bouvieri monticola and H. emberarum) were found to be the natural second intermediate hosts, and individuals of another crab species (Strengeria sp.) were also infected in the laboratory.

Comparison of two single-day regimens of triclabendazole for the treatment of human pulmonary paragonimiasis

A well-tolerated single-day treatment regimen is required for the community-based treatment of pulmonary paragonimiasis. To identify an optimal single-day treatment regimen, an open clinical trial was performed to compare the efficacy of 2 single-day regimens of triclabendazole. From 1991 to 1993, a total of 154 Ecuadorian patients were allocated to receive either a single dose or 2 doses of 10 mg/kg triclabendazole. Treatment with both regimens was associated with a rapid parasitological response (determined by clearance of Paragonimus eggs from sputum), resolution of most clinical symptoms and radiological signs, and only mild adverse effects. At 3 months after treatment, the cure rate (clearance of eggs from sputum) was 90.9% in the 2-dose group and 84.4% in the single-dose group. Re-treatment with a second 2-dose regimen was curative in all remaining patients by 1 year of follow-up. Our findings show that both single-day treatment regimens of triclabendazole were highly effective in the treatment of pulmonary paragonimiasis and suggest that patients should be re-examined at 3 months to determine the need for repeat treatment.

Paragonimiasis of the breast. Report of a case diagnosed by fine needle aspiration

BACKGROUND

Paragonimiasis infestation is endemic mostly to Asia, Africa and South and Central America and commonly found in the lung. It is extremely rare in soft tissue.

CASE

A case of paragonimiasis occurred in a 66-year-old woman who presented with a left, painful, 2-cm-diameter breast mass and had a history of eating uncooked freshwater crabs. On mammography, an ill-defined, round, isodense mass was detected without calcification. Hemorrhagic material was aspirated by fine needle aspiration (FNA) of the breast mass, which contained many parasitic eggs. They were about 90 microns long, ovoid, yellowish brown, transparent and thick shelled, with a flattened operculum at 1 end. The breast mass was completely excised. Many collapsed eggs of Paragonimus infiltrated the lobules and fibroadipose tissue, with accompanying abscess formation. To confirm the diagnosis, serologic testing for paragonimiasis was performed; it was positive for Paragonimus antibody.

CONCLUSION

Paragonimiasis very rarely presents as a breast mass and can be diagnosed by FNA.

Occurrence of the lung fluke, Paragonimus heterotremus in Manipur, India

OBJECTIVES

To determine the natural crustacean host, the Paragonimus species, and to investigate the potential host-parasite relationship between Manipur Paragonimus and some of the laboratory animals.

METHODS

The laboratory animals such as puppies, albino rats and Swiss mice were infected orally with metacercariae isolated from the fresh water crabs, Potamiscus manipurensis. The fecal specimens of the experimentally infected animals were examined microscopically for Paragonimus eggs at regular intervals. The animals were autopsied on days 35 to approximately 328 after infection and the isolated worms were flattened between glass slides and fixed in 70% alcohol. The worms were stained with carmine and mounted with Canada balsam for morphological studies. The eggs were collected in 5% formol saline solution for microscopy. The flukes were classified into 4 developmental stages.

RESULTS

A total of 11 worms, 5 mature, 5 immature and 1 pre-adult were recovered. The morphological features of the metacercariae, worms and eggs were similar to those of Paragonimus heterotremus.

CONCLUSION

Manipur is one of the rare areas in the world where Paragonimus heterotremus is prevalent and the puppies are ideal experimental animal host. This species may be one of the important causes of paragonimiasis in animals and humans in Manipur.

[Paragonimiasis westermani caused by ingestion of Chinese freshwater crabs]

We encountered three cases of paragonimiasis westermani caused by ingestion of Chinese freshwater crabs. All patients are Chinese living in Japan who had a history of eating raw Shanghai crabs at the Chinese restaurant owned by one of them. A few months later they complained of cough, chest pain and dyspnea. On examination, their peripheral blood showed a remarkable increase in eosinophils. Chest radiographs revealed the presence of pleural effusion in all cases, and of pneumothorax in one. Pleural fluid obtained from two cases showed an increased number of eosinophils, an elevated LDH, and a decreased glucose level. Paragonimus westermani was determined in a positive serum antibody test. The patients were treated with praziquantel for 3 days at a daily dosage of 75 mg/kg and their symptoms were relieved, but one case needed additional treatment with praziquantel for 3 days at a daily dosage of 50 mg/kg because of sustained pleural effusion and a persistently high antibody titer. Most cases of paragonimiasis found in Japan have been sporadic and individual, but three cases occurring close to each other in both distance and time have recently been reported. Such multiple infections are likely to increase because of the gourmet food boom and the internationalization of eating habits. Paragonimiasis must be kept in mind in the differential diagnosis of cases of pleural effusion with eosinophilia. We would therefore like to emphasize the importance of the detection of parasite-specific antibodies and of careful history-taking from patients.