Trematode Paragonimus Research Articles

A clinical review of human disease due to Paragonimus kellicotti in North America.

Human autochthonous infections with the trematode Paragonimus kellicotti are increasingly being reported in North America, but the true prevalence and geographic distribution are unknown. Ingestion of raw crayfish is reported in most human cases, typically in the context of alcohol intoxication. Risk of infection varies depending on what part of the crayfish is ingested as metacercariae of P. kellicotti (>50% mature to adults) localize to the heart and pericardium of the crayfish. Reported human cases have manifested primarily in otherwise healthy young adults presenting with severe eosinophilic pneumonia, pleuritis, systemic symptoms, dermatologic lesions and cerebral involvement. However, it is likely that many infections go unreported due to lack of awareness, mild illness or the absence of rapid commercially available diagnostic tests. Promising advances have been made related to novel diagnostic targets. Conservation of these antigen targets among at least four Paragonimus species could make these antigens viable for diagnostic testing of P. kellicotti specifically as well as other Paragonimus species, but additional studies and funding investments are required. Public and physician awareness may have improved due to targeted education campaigns, but ongoing activities to raise awareness are needed, particularly in areas where cases have not been frequently reported to date.

Paragonimus westermani ichunensis and paragonimosis in the south of the Russian Far East: yesterday, today and tomorrow

Paragonimosis is a severe parasitic disease, which causative agent (on the territory of Russia, trematode Paragonimus westermani ichunensis Chung, Hsu et Kao, 1978) circulates in the south of the Far East. Two forms of paragonimosis are known: pulmonary and muscular (larval) with clinical manifestations like diseases of a different etiology, mimicking the symptoms of malignant tumors, and in cases of late diagnosis and improper treatment, leading to death. Long-term studies of the ecology and biology of the parasite, as well as monitoring the incidence among residents of the southern Far East of Russia made it possible to analyze the situation with paragonimosis in the designated region. Based on the available data, until the mid-1990s, natural sites of disease were found almost everywhere in the river basins inhabited by mollusks of the genus Parajuga and crayfish of the genus Cambaroides as parasite intermediate hosts. During this period, according to official information, the population invasion rate reached 6%. Then, as a result of the mass extinction of freshwater crayfish, the population of P. westermani ichunensis was on the brink of survival, and from that moment on, the number of diagnosed cases of paragonimosis in the inhabitants of the region began to decline, down to zero in recent years. Currently, the population of crayfish Cambaroides is reviving and a case of P. westermani ichunensis infestation of a tiger cub has been recorded, which indicates the population restoration of the parasite itself. This indicates the functioning resumption of the Paragonimus sp. infection centers in the south of the Russian Far East. It is necessary to be prepared for the possibility of an exponential growth in the number of infected animals with such a developmentтof events. Due to the complexity of the disease diagnosing and the lack of certain knowledge about the parasite biology among the majority of medical workers, it is necessary to be ready to low detection rate among the region population.

The Influence of the Trematode Paragonimus cf. westermani on NO- and HIF-1α-Containing Structures in the Brain of the Crab Eriocheir japonica (De Haan, 1835) Decapoda: Varunidae

The influence of the trematode Paragonimus cf. westermani on the NO- and HIF-1α-containing structures in nerve centers of the brain, depending on degree of infection and behavioral responses, has been studied in the crab Eriocheir japonica (De Haan, 1835). The NO-ergic activity in the brain has been found to increase in crabs with a low level of infection and decrease in individuals with a high level of infection. In addition, an increased HIF-1α-immunoreactivity in neurons and hemocytes of the brain has been detected in crabs that show a high level of infection and modified behavior. The involvement of NO and HIF-1α in the induction of brain tolerance and in the pathological states of the brain formed due to parasitic influences is discussed.

Morphological and molecular characterization of the metacercaria of Paragonimus caliensis, as a separate species from P. mexicanus in Costa Rica

The trematode Paragonimus mexicanus is the etiological agent of paragonimiasis, a food-borne zoonotic disease in Latin America. This species, as well as Paragonimus caliensis, have been reported from Costa Rica, but it is not known if the two are synonymous. Two types of Paragonimus metacercariae from freshwater pseudothelphusid crabs from several localities in Costa Rica were recognized by light microscopy. Morphologically, these corresponded to descriptions of P. mexicanus and P. caliensis. Metacercariae of the former species lacked a membrane or cyst and their bodies were yellow in color. Those of P. caliensis were contained in a transparent thin cyst and were pink in color. Morphotypes of metacercariae were determined using scanning electron microscopy (SEM). Based on the number and distribution of papillae in the ventral sucker, three morphotypes were found for P. mexicanus and two for P. caliensis. Analysis of DNA sequences (nuclear ribosomal 28S and ITS2 genes, and partial mitochondrial cox1 gene) confirmed the presence of P. mexicanus and provided the first molecular data for P. caliensis. The two species are phylogenetically distinct from each other and distant from the Asian species. The confirmation of P. caliensis as a separate species from P. mexicanus raises several questions about the ecology, biological diversity, and epidemiology of the genus Paragonimus in Costa Rica.

Parasitosis in wild felids of India: an overview

Being a tropical country, India provides an ideal environment for the development of parasites as well as for vector populations resulting in a high degree of parasitism in animals and humans. But only a few detailed studies and sporadic case reports are available on the prevalence of parasites in captive wild animals, and the knowledge of parasites and parasitic diseases in wild animals is still in its infancy. The family felidae comprises the subfamily felinae and pantherinae, and within those are all large and small cats. Most of the available reports on parasites in felids describe helminthic infections, which caused morbidities and occasional mortalities in the infected animals. The parasites most frequently found include the nematodes Toxocara , Toxascaris, Baylisascaris, Strongyloides, Gnathostoma, Dirofilaria and Galonchus , the trematode Paragonimus and the cestodes Echinococcus and Taenia . Almost all the studies identified the parasitic stages by classical parasitological techniques and only a few new studies confirmed the species using molecular techniques. Amongst the protozoan parasitic infections reported in felids: babesiosis, trypanosomiasis and coccidiosis are most commonly found. Most of the parasite species found in felids are transmissible to humans (zoonosis) and therefore have public health significance. Routine monitoring of the presence of parasites in captive wild felids is imperative for the formulation and implementation of measures to prevent and control parasitic infections and the transmission of these parasites to humans. This review summarizes the available reports and highlights deficient areas, which require further systematic investigation.

Paragonimiasis: An unusual cause of Cor pulmonale; A case report

Paragonimiasis is a parasitic disease caused by the trematode Paragonimus. It follows ingestion of raw or improperly cooked or prickled crab and crayfish. Adult worms can survive for 20 years. A 42-year-old rural dweller was seen at the chest unit with a three month history of cough, chest pain and haemoptysis and a ten week history of bilateral leg swelling. He recalled that his problem dated back to 18 years ago when he first had cough with rusty brown sputum and chest pain. He was treated for pulmonary tuberculosis even though sputum examination did not reveal any AAFB on two occasions. Further enquiries showed that he had enjoyed fishing and hunting for crabs in his adolescent years and ate the young crabs raw. Abnormal findings were mild central cyanosis, pitting leg and scrotal edema jugular venous pulsation was elevated with tender hepatomegaly. Sputum for ova of paragonimiasis which was positive. Packed cell volume was 55%, ESR of 15 mm in the 1st hour. Chest radiograph: patchy opacities, tubular shadowing and prominent pulmonary conus. Echocardiography showed dilated right atrium and ventricle without septal and valvular lesions. Sputum AAFB, A diagnosis of Cor pulmonale due to Paragonimiasis was made and patient treated with Praziquantel. The patient improved markedly and repeated X-ray showed some improvement in the features. Paragonimiasis is an important tropical lung disease. The most frequent symptoms are cough and haemoptysis. The radiological features include cavities, cysts, calcified nodules all of which make differentiation from pulmonary tuberculosis difficult. In endemic areas, patients who complain of cough and haemoptysis should have their sputum examined by an experienced microbiologist for paragonimiasis.

Molecular and biochemical characterization of hemoglobinase, a cysteine proteinase, in Paragonimus westermani

The mammalian trematode Paragonimus westermani is a typical digenetic parasite, which can cause paragonimiasis in humans. Host tissues and blood cells are important sources of nutrients for development, growth and reproduction of P. westermani. In this study, a cDNA clone encoding a 47 kDa hemoglobinase of P. westermani was characterized by sequencing analysis, and its localization was investigated immunohistochemically. The phylogenetic tree prepared based on the hemoglobinase gene showed high homology with hemoglobinases of Fasciola hepatica and Schistosoma spp. Moreover, recombinant P. westermani hemoglobinase degradaded human hemoglobin at acidic pH (from 3.0 to 5.5) and its activity was almost completely inhibited by E-64, a cysteine proteinase inhibitor. Immunohistochemical studies showed that P. westermani hemoglobinase was localized in the epithelium of the adult worm intestine implying that the protein has a specific function. These observations suggest that hemoglobinase may act as a digestive enzyme for acquisition of nutrients from host hemoglobin. Further investigations may provide insights into hemoglobin catabolism in P. westermani.

Pulmonary paragonimiasis in dogs and cats: a review.

ABSTRACTPulmonary paragonimiasis is a parasitic lung disease of dogs and cats caused by the trematode Paragonimus kellicotti. The disease is encountered most frequently in the Southeastern and Midwestern regions of the United States. The radiographic appearance of pulmonary paragonimiasis is that of multiloculated cysts in dogs and interstitial nodules in cats. Spontaneous pneumothorax is common in both species. Recognition of the characteristic pulmonary lesions on thoracic radiographs justifies repeated faecal examinations in order to find Paragonimus ova to confirm the diagnosis. Necropsy findings are diagnostic. Bithionol®and albendo.‐zole have been used for treatment with variable results. Drug availability and approval remain as problems.

Paragonimus Westermanii: A Case Report

Infestation with the trematode Paragonimus westermanii (or lung fluke) is said to be of common occurrence in China, Japan, Formosa, and the Philippines, where it is the cause of “endemic hemoptysis.” In our own experience with approximately 20,000 Chinese hospital admissions, the disease has been observed but once, although we have been well aware of the condition and have made repeated wet-mount sputum examinations in patients with unexplained hemoptysis. The disease is contracted by ingestion of the fresh-water crab or crayfish, which harbors the larval form. The larvae promptly develop and make their way through the intestinal wall into the peritoneal cavity, and thence through the diaphragm, into the lung parenchyma, where they become encysted and produce symptoms. These flukes may be found in other viscera as well, even the brain, but the lung is the site of predilection. Ova are produced in large numbers and coughed up in sputum which is characteristically mucoid and rusty, not unlike that seen in pneumococcus pneumonia. The fluke is described as thick and fleshy, oval in shape, and measuring 8 to 20 mm. in length by 5 to 9 mm. in breadth. In pathologic specimens tumor-like swellings are seen throughout the lung, mostly peripheral and outlined beneath the pleura. The parasites are contained within these nodules. Sections of the lung reveal scattered areas of infiltration, in which are “burrow-like” cavities containing the flukes. These smaller channels may coalesce to form a larger cavity with bronchial communication. Case Report A 28-year-old Chinese soldier was admitted to the hospital on Sept. 22, 1943, because of coughing up blood. During the previous three or four years there had been frequent episodes of hemoptysis, with production of large amounts of blood especially during or after strenuous physical exertion. At times there were sharp pains in both sides of the chest, not noticeably associated with respiration. There had been shortness of breath on exertion and some loss of weight in the preceding two months, during which hemoptysis had been continuous. The patient had not felt feverish nor had there been night sweats. There was no history of bleeding from other orifices. The patient had been in the army one year. Prior to that he had spent his whole life in Szechuan Province. He had never lived on, or even been near, any large body of water and could not remember having eaten crabs, crayfish, or any other shellfish. His mother and grandmother were said to have been chronic blood spitters; his father had died with generalized swelling, and he had two siblings, both of whom were healthy with no history of hemoptysis. The patient was well developed and fairly well nourished. His temperature was 97.8° F., and his blood pressure 108 systolic and 68 diastolic. The mucous membranes were of fairly good color and no icterus was present. Eyes, nose, and throat were normal. There was no enlargement of the peripheral lymph nodes.