Hypolobocera guayaquilensis (Decapoda: Pseudothelphusidae): A New Crab Intermediate Host of Paragonimus mexicanus in Manabí Province, Ecuador

To determine that Paragonimus sp. is actively transmitted in a tropical area of the Pacific region of Ecuador where human cases of pulmonary paragonimiasis have recently been documented, a total of 75 freshwater crabs were collected from 2 different streams in the Pedernales area of Manabí Province, Ecuador. All collected crabs were identified as Hypolobocera guayaquilensis based on morphological characteristics of the male gonopods. The hepatopancreas of each crab was examined by compressing it between 2 glass plates followed by observation under a stereomicroscope. Excysted Paragonimus metacercariae were detected in 39 (52.0%) crabs and their densities varied from 1 to 32 per infected crab. There was a positive relationship between crab size and metacercarial density. Sequences of the second internal transcribed spacer region of the ribosomal RNA gene of the Paragonimus metacercariae obtained in this study were identical to those of Paragonimus mexicanus deposited in the DDBJ/EMBL/GenBank database. Thus, the present study is the first to confirm that the crab species H. guayaquilensis is the second intermediate host of P. mexicanus in Manabí Province, Ecuador. Because this crab might be the possible source of human infections in this area, residents should pay attention to improper crab-eating habits related with a neglected parasitic disease, i.e., paragonimiasis.

Ultrastructure of Spermatogenesis in the Testis of Paragonimus heterotremus

Lung fluke, Paragonimus heterotremus, is a flatworm causing pulmonary paragonimiasis in cats, dogs, and humans in Southeast Asia. We examined the ultrastructure of the testis of adult P. heterotremus with special attention to spermatogenesis and spermiogenesis using scanning and transmission electron microscopy. The full sequence of spermatogenesis and spermiogenesis, from the capsular basal lamina to the luminal surface, was demonstrated. The sequence comprises spermatogonia, spermatocytes with obvious nuclear synaptonemal complexes, spermatids, and eventual spermatozoa. Moreover, full steps of spermatid differentiation were shown which consisted of 1) early stage, 2) differentiation stage representing the flagella, intercentriolar body, basal body, striated rootlets, and electron dense nucleus of thread-like lamellar configuration, and 3) growing spermatid flagella. Detailed ultrastructure of 2 different types of spermatozoa was also shown in this study.

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.

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.

Finding the lung fluke by X-ray in Sin Ho - Lai Chau, Da Bac - Hoa Binh

The outbreak of the lung fluke occurred in Sin Ho - Lai Chau in 1994 and Da Bac - Hoa Binh in 1998. The biological, clinical, epidemiological investigation and X-ray showed that there were more 2000 patients (the morbidity rate: 4%). All patients had a lung lesion in X-ray image... the major signs in X-ray were pulmonary nodules and cavity and pleurocele. It should distinguish the lung fluke and the pulmonary tuberculosis

The Sonographic Diagnosis of Subcutaneous Nodules Caused by Lung Fluke / 中华超声影像学杂志

The sonographie diagnosis of suhcutaneoyus nodules caused by lupg flukes in ten cases from the mountainous area of Xiangxi was reported.According to their ultrasonographic features,these nodules could be divided into three types:the substantial(one case),anechoic(two cases),and mixed type(seven cases).The sonographic characteristics,the pathotogic stages and the cytology of the subcutaneous nodules caused by lung fluke these cases were discussed.

Investigation on second Intermediate Host of Lung Fluke in Jinghong Region / 昆明医科大学学报

The second intermediate hosts of lung fluke in the jinghong region are Potamon chinghungense and P.hispidum.Their natural infection rates are 68.3% and 55.6% respectively and on the average,each crab contains 11.3 and 2.6 metacerc- ariae.There is no difference between male and female in the natural infection rate, but the infectiosity is different in different places.5.8% of the crabs are infected by three sp(?)cies of metacercariae simultaneously.About 70% metacercariae of Par- ogonimus microrchis or P.proliferus are parasitized in the cephalothorax of P.chinghungense or P.hispidum.

Investigation and Research on Hosts of Paragonimus Microrchis / 昆明医科大学学报

This paper gives the natural hosts and experimental hosts of Paragonimus microrchis a pri- mary investigation and an experimental research.The results confirm the first intermediate hosts are several species of Tricula,and the second intermediate hosts are Potamon chinghungense and P.hispidum.The suitable final hosts are dogs and cats.Both Paguma larvata and rats can be in- fected,but they are unfavorable final hosts.A rhesus monkey hasn't been successfully infected by the metaceraria of Paragonimus microrchis.