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Physaloptera bispiculata (Nematoda: Spiruroidaea) is a parasite of Nectomys squamipes (Rodentia: Cricetidae), a water rat that only occurs in Brazil. Naturally infected rodents were captured in the municipality of Rio Bonito, Rio de Janeiro, Brazil. Adult P. bispiculata worms were collected, prepared and analysed by light and scanning electron microscopy. Under scanning electron microscopy, several eggs were seen glued by cement to the cloacal aperture. Light microscopy revealed that some male worms had an uncountable number of embryonated eggs in the ejaculatory duct, cloaca and also in the posterior portion of the intestine. The probable explanation is that the eggs developing in the female uterus are pumped by the female or sucked by the male to the cloacal opening and from this point to the intestine and ejaculatory duct. The male probably does not have the ability to expel the eggs and for this reason a large number were found in these organs. On the other hand, this could be an important adaptation for the parasite, i.e. male worms expelled by the host can carry a large number of eggs and spread them to intermediate hosts when ingested by these hosts. As far as we know this is the first record of a physalopterid nematode harbouring eggs in the cloacal region, ejaculatory duct or intestine.

Trichuris thrichomysi n. sp., recovered from the cecum of the wild rodent Thrichomys apereoides from a transition zone between the Atlantic Forest and Cerrado morfoclimatic domains, and its life cycle observed under experimental conditions are described. This new species is closely related to Trichuris travassosi, Trichuris chiliensis and Trichuris fulvi, but can be distinguished from them mainly by differences in the posterior end of males. Details of the surface such as the bacillary gland, cuticular inflations and several morphological details obtained by scanning electron microscopy and field emission scanning electron microscopy confirmed the characteristics that differentiate the new species. The histopathology of the intestinal wall of naturally infected rodents is also reported. The present study extends the geographical distribution of T. thrichomysi n. sp to the Pantanal ecosystem and reports a new host, Thrichomys pachiurus., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Gerbils (Meriones unguiculatus) experimentally infected with Litomosoides chagasfilhoi were treated with a single oral dose of 40 or 80 mg of albendazole, respectively. Observation of the microfilaremia after the treatment showed that both single oral doses of albendazole decreased the microfilaremia in L. chagasfilhoi infection. The body wall was composed of a cuticle, a hypodermis, and a muscular layer, and treated nematodes showed no morphological alterations. The ultrastructural alterations produced by treatment with 40 mg of albendazole included a higher number of membrane invaginations in the basal labyrinth of the uterine epithelium and the presence of myelin figures in this region. Inside the uterus, most embryos and microfilariae were disintegrated. The treatment with 80 mg of albendazole did not produce alterations in the uterine wall, and the number of vesicles near the microfilariae sheath was smaller than that observed in the untreated and in the 40-mg treatment groups. However, all the microfilariae observed in the uterus were extensively damaged with cytoplasmic vacuolization and cellular degeneration. No alterations in the intestinal cells were observed after treatment with 40 or 80 mg of albendazole. The present study contributes to the knowledge of albendazole's effects in filariids and demonstrates the potential embryotoxic and microfilaricidal consequences of this drug.

The human cases of eosinophilic meningitis recently reported from Brazil have focused the attention of the public health agencies on the role the introduced snail Achatina fulica plays as hosts of the metastrongylid nematodes. Determining the potential of this snail to host and develop infective larval stages of metastrongylids in the wild and identify the species harbored by them is crucial for designing effective control measures. Here we assess if A. fulica may act as intermediate host of A. cantonensis at the peridomiciliary areas of a patient's house from state of Pernambuco (PE), who was diagnosed with eosinophilic meningitis and a history of ingesting raw molluscs. Larvae obtained from naturally infected A. fulica were orally administered to Rattus norvegicus. The worms were collected from the pulmonary artery and brain, and were morphologically characterized and compared to the Japan isolate of A. cantonensis. Adult worms and infective L(3) larvae (PE isolate) recovered from A. fulica specimens were also analyzed by polymerase chain reaction and restriction fragment length polymorphism of ITS2 region from rDNA and compared to A. cantonensis (ES isolate), A. vasorum (MG isolate) and A. costaricensis (RS isolate). The large size of the spicules (greater than those observed in other species of Angiostrongylus) and the pattern of the bursal rays agree with the original species description by Chen (1935). Furthermore, the morphology of the PE isolate was similar to that of Japan isolate. The PCR-RFLP profiles obtained were distinctive among species and no variation in patterns was detected among adult individuals from A. cantonensis isolates from PE and ES. The importance of A. fulica as an intermediate host of eosinophilic menigoencepahlitis in Brazil is emphasized., (2010 Elsevier B.V. All rights reserved.)

Bancroftian filariasis constitutes the principal mosquito-borne nematode infection of humans and the surface of adult of Wuchereria bancrofti seems to be especially important in the intricate interplay between host and parasite. The study of the parasite's surface structure might help to understand the localization and function of various organelles. W. bancrofti adult worms were recovered from untreated patients during hydrocele repair surgery and studied by transmission electron microscopy. The body wall of adult parasite is composed of cuticle, hypodermis and muscular layer. Cuticle is the external layer and shows transverse cuticular striation. It is composed by an epicuticle, cortical layers, median layer, fibrous layers and basal layer. The epicuticle is the most external cuticular layer and appears as a single laminar electron-dense layer. The cortical external region is more electron-dense and granular in appearance than the inner cortical layer. Electron-dense structures, called bosses are randomly distributed filling the cuticular striation. The median layer is formed by an electron-dense and continuous thick line. The fibrous layer is subdivided in inner and external layers connected by projections. The basal layer includes a large quantity of membranous projections directed toward the hypodermis. The hypodermis is a syncytium where some cellular organelles are observed. The somatic musculature is meromyarian. The muscle fibers consist of contractile and non-contractile regions and the contractile region is composed of myofilaments separated by dense body. This is the first study of W. bancrofti adult worms obtained from untreated patients and studied by transmission electron microscopy., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Infection caused by the trematode Echinostoma paraensei has been shown to interfere in the natural resistance to infection by Schistosoma mansoni. Biomphalaria glabrata is susceptible to infection, while Taim isolate Biomphalaria tenagophila is resistant to infection by S. mansoni. These two snail species were assessed for infection with E. paraensei two days after exposure to S. mansoni miracidia. The number of B. tenagophila and B. glabrata infected with E. paraensei was lower in co-infected group, suggesting an antagonistic relationship. B. glabrata showed an increase in its susceptibility to S. mansoni, whereas B. tenagophila maintained its refractoriness to S. mansoni infection. Weekly comparisons made between the E. paraensei cercariae released from B. tenagophila and B. glabrata mono-infected snails revealed no quantitative differences. In contrast, S. mansoni cercariae released were higher in the B. glabrata co-infected group. Mortality rates were significantly greater in both species pertaining to co-infected group and unexpected mortalities were also observed in B. tenagophila exposed only to S. mansoni miracidia. Our study revealed that the B. tenagophila Taim isolate is susceptible to E. paraensei infection, although infection did not alter its resistance to S. mansoni infection.

Cucullanus ageneiosus n. sp. (Nematoda: Cucullanidae) is described from the intestine of the Ageneiosus ucayalensis , from the Guajará Bay, Belém, Pará, Brazil. The new species is characterized mainly by arrangement of male caudal papillae, and the position of lateral phasmids immediately posterior of 10th papillae, markedly short and unequal spicules, a precloacal sucker, and the presence of an unpaired median papilla just of the anterior cloacal lip.

The physiological interaction between the digenean Echinostoma paraensei larvae and the intermediate snail host Lymnaea columella was studied. The carbohydrate content was significantly altered in the digestive gland tissue of snails, decreasing after 20 days postinfection. At the end of the prepatent period, the carbohydrate content was reduced by 60% when compared to uninfected snails. The total protein was reduced by 80.01% and 76.42% in the hemolymph and digestive gland, respectively. The end products resulting from nitrogen degradation were also analyzed. The urea was significantly increased in both the hemolymph and digestive gland. In the former, the highest concentration was detected at day 10 postinfection and then decreased until the end of the prepatent period. In digestive glands from infected snails, urea was significantly higher than in uninfected ones after 20 days. The uric acid content was reduced by 94.72% in the hemolymph and 43.75% in digestive glands after 10 days postinfection. The ammonia was undetectable under the experimental conditions employed.

Angiostrongylus lenzii n. sp. (Nematoda: Metastrongyloidea) is described and illustrated from the pulmonary artery of the wild rodent Akodon montensis Thomas, 1913, collected in the municipality of Teresopólis, Rio de Janeiro State, Brazil. It represents the 17th species of the genus and the 2nd in South America as parasites in rodents. This new species is the most similar morphologically to Angiostrongylus vasorum, Angiostrongylus gubernaculatus, Angiostrongylus schmidti, and Angiostrongylus morerai. It can be distinguished from them by the morphology of the caudal bursa, ventral rays 2 and 3 with conspicuous knobs, differences in width and length of lateral and dorsal rays, presence of rays 8, and length of spicules.

Canine filariasis in domestic and wild dogs, foxes, and wolves is caused by several species of filarids. Although these filarial species inhabit different loci in the vertebrate definitive hosts, they generally release microfilariae into the bloodstream. Data about filarial infection in dogs in Brazil, especially on the Marajo Island, is scarce. For this reason, we conducted an analysis of 188 domestic dogs within two Marajo Island municipalities. The overall prevalence of microfilaremic was 32.45%; taken by blood smear and modified Knott's method. No significant difference of positivity between male and female was observed (X(2) Yates's correction = 0.341; p = 0.559). Significant age-infection ratios were detected (X(2) = 32.943; p < 0.0001). A high occult infection was detected (53.84%). PCR of rDNA and phylogenetic tree indicated that the microfilariae and adult worms found in domestic dogs from Marajo Island were Dirofilaria immitis.

Gastrointestinal nematodes were recovered from thirty four Gracilinanus agilis from forty four collected in Pantanal, Mato Grosso do Sul State, Brazil. Two hundred seventy four spirurids were recovered from the esophagus, stomach and intestines, comprising three species from three different genera. These were identified as Pterygodermatites (Paucipectines) jägerskiöldi, Spirura guianensis and Physaloptera herthameyerae n. sp. is first described. This is the first record of nematodes of the genera Physaloptera and Spirura in hosts of the genus Gracilinanus. The high prevalence of spirurids in 72.3% of the G. agilis collected probably is influenced by the arboreal and diet behaviors.

Species of Cruzia are parasites of the large intestine of marsupials, reptiles, amphibians, and mammalians. Cruzia tentaculata specimens were collected from the large intestine of Didelphis marsupialis (Mammalia: Didelphidae) from Colombia (new geographical record) and from Brazil and analyzed by light and scanning electron microscopy. The morphology of males and females by light microscopy corroborated most of the previous description and the ultrastructure by scanning electron microscopy evidence: the topography of the cuticle, deirids, amphids, phasmids in both sexes, a pair of papillae near the vulva opening, and the number and location of male caudal papillae, adding new features for species identification only observed by this technique.

Procamallanus (Spirocamallanus) belenensis n. sp. is described using light and scanning electron microcopy, based on specimens taken from Ageneiosus ucayalensis, Castelnau, 1855 (Pisces: Siluriforme), a freshwater fish commonly called mandubé, in Pard State, Brazil; Procamallanus (Spirocamallanus) rarus is recorded from the same host. To our knowledge there are no previous reports of nematodes from this fish species. Procamallanus (S.) belenensis is characterized by the presence of 8-13 cuticular spiral thickenings coating 2/3 of posterior region of the buccal capsule of males and females (the anterior third is smooth); small sub-equal spicules; 3 and 4-5 pairs of pre- and post-cloacal papillae, respectively; the proportion of muscular and glandular esophagus is 1:1.5-2; males present 2 spike-like projections at the tail tip, which are absent in females by light microscopy. The most closely related species are Procamallanus (Spirocamallanus) inopinatus and Procamallanus (Spirocamallanus) pintoi. The new species differs from the most closely related species by the presence of 8-10 cuticular spiral thickenings in the buccal capsule of males and 9-13 in the females, 8 pairs of male clocal papillae (3 pre- and 5 post-cloacal, respectively), and only males bearing 2 minute, spike-like projections at the posterior end.

This study describes the morphology of the nematode cysts and larvae found in Achatina fulica (giant African snail) in Brazil. Sixty snails were collected in Mesquita, Rio de Janeiro State. Fourteen of the snails were naturally infected. The cysts were spherical, pink colored and measured 0.97 to 1.57 mm in diameter. In the majority of cases they had a single larvae involved in amorphous material. A total of 222 encysted larvae were recovered. Of these, 30 were utilized in the morphological study. The length of the larvae varied from 2.57 to 5.8 mm and they were classified as small--up to 3.5 mm; medium--from 3.53 to 4.5 mm; and large--greater than 4.52 mm. The average length of the larvae in the three groups was 2.85, 3.87 and 5.23 mm, respectively. The larval cuticle was white, shiny and transversally striated until the posterior end of the body. At the anterior end there is a mouth with three lips, with amphids and papillae, followed by a muscular esophagus with average length of 0.61 mm, terminating in an esophageal bulb and having a nerve ring in the middle third of the esophagus, and an intestine with an opening near the posterior end. The tail begins from this opening and has two types of ends: short and abrupt or long and gradually tapering. The difference in the tail end can suggest sexual dimorphism, although no primordial reproductive structures were observed. These characteristics were not sufficient to identify the larvae, so there is a need for further study.

An unidentified microfilaria sharing characteristics with Mansonella ozzardi and Onchocerca volvulus was detected in blood samples from seven human volunteers, inhabitants of a community in the border of Amazonas and Acre State. They were detected during epidemiological studies carried out in some communities along Antimary, Acre, and Purus Rivers in the Brazilian Amazon. The most striking difference was presented in the shape of the cephalic space from this microfilaria which was different from those of M. ozzardi and with similarities to O. volvulus in this region, but no remarkable differences were observed at the caudal region. More accurate studies are being carried out in order to provide additional data and supporting evidences before establishment of a new species can be done.

A description is provided for Gracilioxyuris agilisis n. g., n. sp. found in the cecum of Gracilinanus agilis Burmeister, 1854 (Gardner, 2005) (Didelphidae) in Brazilian Pantanal. The new species can be distinguished from Didelphoxyuris thylamisis by a dome-shaped anterior end, a weakly developed cephalic vesicle, males with no postcloacal ornamentation, and operculate eggs with 3 longitudinal ridges. Gracilioxyuris n. g. is characterized by a small and apical oral opening and double-crested lateral alae. Males possess an area rugosa as a ventral, keellike elevation with transverse striations, 4 pairs of genital papillae, the first and second pairs of which are adanal, and a third minute pair just posterior to cloacal aperture; the last pair are at the caudal end with no tail tip. Females possess a thick muscular vagina, a didelphic genital tract, and operculated eggs with ridges.

Achatina (Lissachatina) fulica was introduced in Brazil in the 1980s for commercial purposes ("escargot" farming) and nowadays, mainly by human activity, it is widespread in at least 23 out of 26 Brazilian states and Brasília, including the Amazonian region and natural reserves, where besides a general nuisance for people it is a pest and also a public health concern, since it is one of the natural intermediate host of Angiostrongylus cantonensis, ethiological agent of the meningoencephalitis in Asia. As Brazil is experiencing the explosive phase of the invasion, the Laboratório de Malacologia do Instituto Oswaldo Cruz/Fiocruz has been receiving samples of these molluscs for identification and search for Angiostrongylus cantonensis and Angiostrongylus costaricensis larvae. While examining samples of A. fulica different nematode larvae were obtained, including Aelurostrongylus, whose different species are parasites of felids, dogs, primates, and badger. Morphological and morphometric analyses presented herein indicated the species Aelurostrongylus abstrusus, as well as the occurrence of other nematode larvae (Strongyluris-like) found in the interior of the pallial cavity of A. fulica. This is the first report in Brazil of the development of A. abstrusus infective larvae in A. fulica evidencing the veterinary importance of this mollusc in the transmission of A. abstrusus to domestic cats. Since the spread of A. fulica is pointed out in the literature as one of the main causative spread of the meningoencephalitis caused by A. cantonensis the authors emphasize the need of sanitary vigilance of snails and rats from vulnerable areas for A. cantonensis introduction as the port side areas.

The ultrastructure of the female reproductive system of the filariid Litomosoides chagasfilhoi by transmission electron microscopy (TEM) is described for the first time. The ovary is composed of primary oocytes surrounded by a single layer of epithelial cells apposed on the basal laminae. The ovarian wall is completely filled with primary oocytes, which are arranged radially and are centrally connected around the rachis. The uterine wall consists of muscular fibers surrounded by a basal lamina and the epithelium underlying the lamina. Ameboid and aflagellate spermatozoa are present inside the distal portion of the uterus, some of them near oocytes, which present bacteria in its cytoplasm. An eletrondense well-defined eggshell covers the zygotes, which presents in its cytoplasm bacteria arranged in groups. These bacteria are also observed in embryos and in the hypodermal cord. These ultrastructural aspects of L. chagasfilhoi female worms presented herein contribute to the knowledge of the morphology and embryonary development of this filariid, providing means for further comparative analyses of the action of anti-filarial drugs. Besides this, the presence of bacteria Wolbachia-like is being reported for the first time in this species, showing the great importance of this experimental model of study.

Oswaldocruzia belenensis n. sp. (Strongylida: Molineidae) from the small intestine of Chaunus marinus (L.) from Belém, Pará State, Brazil is described and illustrated by light and scanning electron microscopy. Oswaldocruzia belenensis n. sp. is a neotropical species of this genus, harboring caudal bursa Type II, spicules divided in 3 branches, i.e., a blade, shoe, and fork. The blade is divided in 4 points, of which at least 2 are bifurcated. Cervical alae are absent; there is a simple cephalic vesicle and synlophe with low ridges perpendicular to the body without chitinous supports. The most closely related species are O. bonsi and O. lescurei. Oswaldocruzia belenensis n. sp. differs from O. lescurei and O. bonsi by the number and location of cephalic papillae, rays 2-3 and 5-6 running parallel and slightly separated, ray 6 not overlapping ray 8, and body structure morphometry. Oswaldocruzia belenensis n sp. also differs from O. lescurei by the discontinuity of the longitudinal ridges, the number of subdivisions of the blade, and the absence of extra processes at the bifurcation level of the fork of the spicules. The new species differs from O. bonsi by male and female body dimensions, the symmetry of the caudal bursa, dimension and subdivisions of the spicules without extra processes of the fork, 2 extra processes at the distal division of the blade, and location of ray 7 at the anterior margin of the cloacal aperture. Oswaldocruzia belenensis n. sp. represents the 82nd species assigned to the genus.

Wuchereria bancrofti is the main species responsible for human lymphatic filariasis and remains a major public health problem in tropical countries around the world. Diethylcarbamazine (DEC) has been used for decades in control programs as an effective microfilaricide, although its efficacy in killing adult worms is only around 50% and its direct mode of action is unclear. Recently, in an attempt to control and eliminate lymphatic filariasis, WHO has recommended albendazole (ALB), a broad-spectrum anthelminthic combined with DEC or ivermectin for mass treatment. Some studies have shown that DEC alone blocks oogenesis, fertilization in adult worms, and loss of the microfilarial sheath of several filarial species, whereas ALB is thought to target nematode tubulin. So far, the direct effect of ALB in combination with DEC has not been described in W. bancrofti adult worms. Therefore, the purpose of this study is to investigate by scanning electron microscopy if DEC coadministered with ALB can induce in vivo morphological alterations of the W. bancrofti adult worm surface obtained from a patient in whom the adult worm remained alive, checked serially by ultrasonography for 2 months after antifilarial treatment. Our analysis demonstrates that worms presented morphologic alterations in some regions suggesting cuticular surface damage. On the other hand, adult worms that were recovered from a patient treated with DEC alone after a single dose did not show such any abnormalities.

Nematodes of the family Aspidoderidae (Nematoda: Heterakoidea) Freitas 1956 are widely distributed from Americas. The species of the genus Aspidodera Railliet and Henry 1912 are parasites of mammals of the orders Edentata, Marsupialia, and Rodentia. In the present work, Aspidodera raillieti (L. Travassos, Mem Inst Oswaldo Cruz 5(3):271-318, 1913), collected from the large intestine of Didelphis marsupialis (Mammalia: Didelphidae) from Valle del Cauca, Colombia, is redescribed. The association of light and scanning electron microscopy (SEM) allowed a detailed analysis of the morphology and ultrastructure of this nematode. Some taxonomic features, such as cephalic region, topography of the cuticle, sucker, spicules, posterior end of males, localization of vulva, the anus, and posterior end of females were observed. Important structures such as amphid, details of cephalic region, phasmid, and number and localization of caudal papillae are documented by SEM, for the first time adding characters to identify this species. Colombia is a new geographical record for A. raillieti.

Specimens of the elasmobranch, Isurus oxyrinchus Rafinesque, captured in 1999 in the state of Santa Catarina, Brazil, were parasitized with the poecilacanthoid trypanorhynch cestode Gymnorhynchus isuri Robinson, 1959, that is redescribed here. New details of scolex and proglottid morphology are given. These details are mainly related to tentacle armature, terminal genitalia and observations of external morphology of proglottids.

Pterygodermatites (Paucipectines) jägerskiöldi Lent and Freitas, 1935, a parasitic nematode of the small intestine of the marsupial Gracilinanus agilis (Mammalia: Didelphidae) from the Pantanal of Mato Grosso do Sul state, and G. microtarsus from Atlantic Forest of Rio de Janeiro state, Brazil, were analyzed by light and scanning electron microscopy. Details of the surface topography such as the oral aperture, cephalic papillae, 2 papillae in posterior end, and longitudinal cuticular elements represented by combs and spines are presented along with measurements, adding new taxonomic characters to the previous diagnostic feature of P. (P.) jägerskiöldi based on light microscopy. In addition, two new hosts records and two new geographical distributions for this nematode are reported.

The water rat Nectomys squamipes is endemic in Brazil and found naturally infected with Schistosoma mansoni. Helminth communities, their prevalences, intensity of infection and abundance in N. squamipes in an endemic area of schistosomiasis in the state of Rio de Janeiro, Brazil were studied. Four species of nematodes (Physaloptera bispiculata, Syphacia venteli, Hassalstrongylus epsilon and Litomosoides chagasfilhoi) were recovered in 85.3%, two trematodes (Schistosoma mansoni and Echinostoma paraensei) in 38.8% and one cestode species (Raillietina sp.) in 1.7% of rats examined. Rats were infected with up to five helminth species each, and these were highly aggregated in distribution. For H. epsilon and S. venteli, intensities and abundances were higher in adult male and subadult female hosts, respectively. Hassaltrongylus epsilon, P. bispiculata, S. venteli and S. mansoni were classified as dominant species, L. chagasfilhoi and E. paraensei as co-dominant and Raillietina sp. as subordinated. No significant correlation was found in the intensity of infecton between each pair of helminth species. Schistosoma mansoni was not related to any other helminth species according to their infection rates, althougth S. mansoni was well established in the natural helminth comunity of the water rat.

Specimens of elasmobranchs, collected in the State of Santa Catarina, Brazil, were parasitized with Poecilacanthoidea trypanorhynch cestodes. Sharks of the species Prionace glauca harboured Callitetrarhynchus gracilis and Floriceps saccatus, and those of the species Sphyrna zygaena were infected with Callitetrarhynchus speciosus. Details of the proglottids of F. saccatus, provided by bright-field, and/or scanning electron microscopy, are described. Adults of F. saccatus are reported for the first time in the Brazilian coast.

The Litomosoides chagasfilhoi helminth was studied as a model for microfilaria invasion of the midgut of Culex quinquefasciatus mosquito, vector of Wuchereria bancrofti helminth, causative agent of the human filariasis. Histology and transmission and scanning electron microscopy were utilized to show the topography of mosquito midgut invasion by the helminth. An analysis of midguts dissected at different time points after a blood meal demonstrated that the microfilariae interacted and crossed the peritrophic matrix and the midgut epithelium of C. quinquefasciatus. The microfilariae invaded preferentially the mosquito abdominal midgut and the invasion process occurred between 2 and 3h after the blood feeding. In some cases, microfilariae caused an opening in the midgut that separated the epithelial cells, while in others cases, the worms caused the detachment of cells from the epithelium. Ultimately, L. chagasfilhoi crossing activity appeared to damage the midgut. It was also observed that the microfilariae lost their sheaths during their passage through the fibrous material of the peritrophic matrix, before they reached the midgut epithelium. Since the exsheathment process is necessary for the continuity of larvae development, it seems that the passage through the peritrophic matrix is an important step for the parasite's life cycle. This experimental model revealed details of the interaction process of helminthes within the vector midgut, contributing to the knowledge of factors involved in the vector competence of C. quinquefasciatus as a vector of filariasis.

Antigens resembling those of host proteins have been identified on the surface of several filarial parasites, such as immunoglobulins and serum albumins. The origin of albumin-like antigens on filarial parasites remains unclear. Several authors suggested that they have been adsorbed, or that they were metabolic waste products from nutritional utilization of human albumin, or perhaps a contamination with human products. This study searched for human albumin-like antigens by Western blot and ultrastructural analyses on filarial parasites, third stage of W. bancrofti and adult females of Litomosoides chagasfilhoi, and on the free-living Caenorhabditis elegans nematode. Our results showed approximately 67kDa proteins recognized by anti-human albumin antibodies on extracts and excretory-secretory (ES) products of the third-stage W. bancrofti. Similar albumin-like proteins were also detected on the filarial parasite L. chagasfilhoi and on C. elegans extracts. The immunocytochemistry analysis showed human albumin-like antigens on similar tissues of these nematodes. These results provide evidence that these proteins have antigenic similarity and similar distribution in nematodes tissues. Our observations suggest that albumin-like antigens presented on filarial parasites are not acquired from the host, but rather are shared antigenic determinants found even in the third-stage larvae recovered from the invertebrate host.

The biological behaviour and morphometric data from two allopatric isolates of Echinostoma paraensei (Rio Bonito - RB and Sumidouro - SU) collected from naturally infected Nectomys squamipes from two secluded Atlantic Forest fragments were studied. Mice that had been experimentally infected with ten encysted metacercariae of each isolate were monitored weekly in two trials to analyse worm burden and the kinetics of worm distribution along the intestine. The total number of uterine eggs, wet weights and measurements of the worms and body, acetabulum, testes and ovaries were also analysed. The RB isolate showed a higher worm burden, 7.7+/-0.8, and a longer life span, 16 weeks, compared to a worm burden of 5.8+/-1.1 and life span of 9 weeks for the SU isolate. Worms of the RB isolate were clustered in the duodenum and in the bile duct while the SU isolate worms were dispersed along the small intestine of infected mice. Both isolates developed similarly as regards morphometric data and wet weight, although the total number of uterine eggs was greater in RB. The degree of intraspecific variation observed in the worm distribution along the intestine, worm burden and life span raises questions regarding the use of these criteria for species differentiation. These findings suggest that variation in biological parameters found between the E. paraensei isolates could result from geographical isolation and, in particular, the environmental conditions of transmission. Further studies on E. paraensei polulations from different forest fragments will contribute towards an understanding of the speciation of this parasite.

The ultrastructure of the camallanid nematode Procamallanus (Spirocamallanus) halitrophus, a parasite of flounder, is described for the first time by the use of transmission electron microscopy. The body wall is composed of an outer cuticle, a hypodermis, and a muscular layer. The cuticle comprises the epicuticle, the cortical, median, fibrous, and basal layers. The cortical layer is subdivided into an outer zone and an inner zone; the median layer is subdivided into an outer layer, rich in electrondense fibrils, and an inner layer, which does not contain these fibrils; the fibrous layer is subdivided into three regions delimited by electrondense lines; the basal layer presents electrondense sustaining structures. Underlying the basal layer is the hypodermis where many organelles are observed. The musculature is striated, and each muscle cell consists of individualized contractile and non-contractile regions. Inclusion bodies are present in the muscle fibers, hypodermis, hypodermal chord, and in the intestine.

The morphology of Echinostoma paraensei was studied using transmission electron microscopy. The terebratorium region has many electrondense secretory granules and many folds on the surface. The epidermal cells that cover the larval body have unique nuclear morphology, many mitochondria and vesicles being attached to the interepidermal ridges by a septate junction. The cilia present the organization 9 + 2 and a typical structure with a shaft, axosome, basal body and rootlet. Below the epidermal cells there is a layer of circular muscle and, adjacent to it, a layer of longitudinal muscle fibers. The excretory system has two flame cells, with internal and external ribs and leptotriches at the barrel region, an excretory vesicle and an excretory pore.

Procamallanus (Spirocamallanus) halitrophus Fusco and Overstreet, 1978 from the intestines of flounders (Syacium papillosum and Citharichthys macrops) from the coast of the State of Rio de Janeiro, Brazil, is redescribed. This study, which is based on results obtained by light and scanning electron microscopy, clarifies many morphological aspects of this species. Some taxonomic features, such as the cephalic structures, the topography of the cuticle, the vulva, the localization of caudal papillae on males, and the excretory pore, are observed for the first time. C. macrops represents a new host record, and Rio de Janeiro is a new geographical record for this species.

Elasmobranch specimens of lamnid and sphyrnid captured in 1999 in the State of Santa Catarina, Brazil, were parasitized with homeacanthoid trypanorhynch cestodes: Isurus oxyrinchus Rafinesque, 1810 with Nybelinia lingualis (Cuvier, 1817) Dollfus, 1929; Sphyrna zygaena (Linnaeus, 1758) with Heteronybelinia rougetcampanae (Dollfus, 1960) Palm, 1999. New details of internal morphology and/or scolex and/or proglottid surface ultrastructure are given. Adults of N. lingualis are reported for the first time in the Brazilian coast.

The morphology of the rediae of Echinostoma paraensei obtained from Lymnaea columella was studied using light, scanning and transmission electron microscopy. The measurements of the mature rediae differ from those described originally, and the taxonomic importance of the ambulatory buds and papilliform process is discussed. Uniciliated papillae were observed in the mouth region. The birth papilla is a bulb-like structure, well defined at the anterior end of the body of the rediae, which opens through a split. There are no microvilli in the tegument surface of the larvae, but numerous tegumental folds, varying according to the contraction of the body of the rediae. The outer syncytial layer is located on a thick basal lamina below which the circular and the longitudinal muscle fiber layers are located.

Echinostoma paraensei was described 1967 by Lie and Basch. Recently its natural definitive host, the aquatic rodent Nectomys squamipes, endemic in Brazil, was identified. As most of the echinostomatids, this species presents a zoonotic potential. The morphology and topography of the E. paraensei miracidium obtained from adult worms collected from the natural definitive host N. squamipes is described by light and electron microscopy. The arrangement and the dimensions of the epidermal plates are given. The eyespots are composed by two pairs of lenses measuring 6.03 microm. SEM observations shows that the miracidium body is covered by cilia except at the terebratorium region and the presence of alpha-tubulin in the cilia of the larvae is first recorded by immunelabeling. Nineteen papilla-like structures arranged in three axes and four groups were observed at the terebratoriun, this structure is retractable, presenting folds and a corrugated surface with profiles of cytoplasmic expansions, forming network of anatomizing folds.

Specimens of elasmobranch fishes, captured in the states of Paraná and Santa Catarina, of the southern coast off Brazil, represented by three families, four genera, and four species, were parasitized with otobothrioid trypanorhynch cestodes: Heptranchias perlo (Bonnaterre, 1788), Squalus sp. and Carcharhinus signatus (Poey, 1868) were parasitized with Progrillotia dollfusi Carvajal & Rego,1987; Prionace glauca (Linnaeus, 1758) with Molicola horridus (Goodsir, 1841) Dollfus, 1942. Details of internal morphology and/or scolex and/or proglottids surface ultrastructure, that expanded the description of M. horridus, through observations with lightfield, and/or scanning eletronic microscopy, are provided. The known geographical distribution for the species M. horridus is enlarged. P. dollfusi is reported for the first time in elasmobranchs.

This study reports on the morphology and morphometry of the nematode Cheilospirura hamulosa on the basis of bright-field and scanning electron microscopy. Specimens were recovered after necropsies of 28 Brazilian ring-necked pheasants ( Phasianus colchicus) and 30 domestic chickens ( Gallus g. domesticus) from backyard flocks. Measurements relate to the buccal capsule in the males and the distance of the excretory pore from the anterior end in both sexes, while the vulva and ovijector are studied for the first time. The most important taxonomic characters for the diagnosis of this nematode are the four long, longitudinal cordons which are neither anastomosed nor recurrent. They are composed of a groove with margins formed by cuticular specializations that change in appearance and width backward along the body and which run backward from the cephalic region ending near the posterior end as a cuticular depression. According to their morphology, these cordons could probably have nutritional, attachment and/or sensory functions.

The entire life cycle of the Brazilian Echinostoma luisreyi n. sp., of the 37-collar spine E. revolutum group, has been observed under experimental conditions. The snail Physa marmorata serves as its first natural intermediate host. This species and the planorbid Biomplalaria glabrata act as experimental second intermediate hosts. The worm recovery rate was 51.3 and 0.6% for mice and hamsters, respectively, but the infection did not develop in the quail Coturnix coturnix. The natural vertebrate host is not known. The most important morphological character of the new species separating it from the other Echinostoma species studied is the oral corner spines that increase in size from the latero-oral to the ventro-oral regions. The ratio of the sizes of the smaller oral spines and the larger aboral ones was 1.7:1.0. Also, the excretory pore is radially wrinkled and dorsally subterminal. Images obtained by scanning electron microscopy confirmed the characters that differentiate the new species and the most closely related species.

Hassalstrongylus epsilon is a small nematode, whose adult forms are found among the intestinal microvilli of the water rat Nectomys squamipes, Brants 1827 (Rodentia: Muridae). The external appearance of the cuticle, which presents transversal striations and longitudinal ridges, is described using scanning electron microscopy. Transmission electron microscopy of thin sections and replicas of quick-frozen, freeze-fractured, deep-etched and rotatory shadowed samples showed the presence in the cuticle of struts that arise from the fluid median layer, extending outward to the epicuticle. The cuticle showed the presence of five layers: epicuticle, cortical, fibril-rich, fluid median and fibrous. The cuticle layers were made of an assemblage of fibers that create compartments, which were larger in the fluid region than in the fibril-rich median layer.

In order to obtain further information on the structural organization of the cuticle of nematodes, this structure was isolated from adult forms of the filariid Litomosoides chagasfilhoi. The purity of the fraction was determined by light and transmission electron microscopy, deep-etching, high resolution scanning electron microscopy, atomic force microscopy, immunocytochemistry, gel electrophoresis (SDS-PAGE) and Western blot. The epicuticle presented a rugous surface with parallel rows and several globular particles that could be involved in the absorption of nutrients and secretion of products. Analysis by SDS-PAGE of purified cuticles revealed five major polypeptides corresponding to 151, 41, 28, 13 and 11 kDa. A polyclonal antibody against a synthetic 18 amino-acid peptide that corresponds to the sequence of domain E of the Haemonchus contortus3A3 collagen gene recognized several protein bands on the Western blot of purified cuticle, and labeled all cuticular layers, as shown by immunocytochemistry.

The fine structure of the cuticle of the filariid nematode Litomosoides chagasfilhoi is described, based on observations made by transmission electron microscopy and deep-etched replicas. The cuticle consists of a trilaminate epicuticle, the outermost layer that interfaces with the host and four other layers: cortical, intermediate, fibrous and basal. In deep-etched replicas, the cortical layer is formed by a meshwork of globular particles and fibers with a thickness of 4-8 nm. The intermediate layer is electron-lucid and contains a densely-stained line. In deep-etched replicas, it is composed by a meshwork of fibers with longitudinal orientation. The fibrous layer is the thickest and most electron-dense and consists of two types of fibers: thick (9-26 nm) and thin (3-6 nm). The innermost basal layer is intimately associated with the hypodermis. In common with other nematodes, the cuticle of L. chagasfilhoi presents channels that are probably involved in nutrient acquisition and transport.

Phlebotomine sandflies are vectors of important pathogens world-wide, including Leishmania spp. in the Neotropics. Entomoparasites have been described from phlebotomines, including virus, bacteria, protozoa, fungi, nematodes, and mites, some of which are capable of killing the host. In the present study, interference, fluorescence, and scanning electron microscopies were used for the first time to detect and morphologically characterize a new entomoparasite infecting Lutzomyia longipalpis. Several filiform larvae and eggs in different stages were encountered in the abdomen of female and male insects. Pairs of large egg-bearing nematodes found within cyst-like structures or free in the hemocel accompanied by larvae could be the adult sexual stages. This entomoparasite infects sand flies naturally in the field. We believe that stress caused by the colonization procedure produced an increase in the infection rate among sand flies affecting their development. These findings could be applied to future biological control studies of sand fly vectors.

The fine structure of the sheath and the cuticle of microfilariae of the filariid Litomosoides chagasfilhoi is described based on observations made using transmission electron microscopy (TEM) and especially on deep-etched replicas of fully developed intrauterine microfilariae and mature stretched microfilariae released by adult females through cultivation in vitro. TEM showed that the sheath was trilaminated. In contrast, in deep-etching replicas the sheath presented two layers: an inner layer composed of tightly arranged globular material, and an outer layer whose external surface was relatively smooth. Both in thin sections and in classical freeze-fracture and deep-etched replicas, the cuticle presented two distinct regions: an external one, corresponding to the trilaminated epicuticle, and an inner one, corresponding to the inner cuticle. Deep-etching replicas revealed that the epicuticle presented several structures on the annulations of the microfilariae and that the inner region was composed by two parallel rows of globular structures.

Echinostoma paraensei Lie and Basch, 1967 (Echinostomatidae:Platyhelminthes), a 37 collar spine echinostome of the "revolutum group", has been used extensively as a model organism to study the interactions of digenetic trematodes with both their snail and vertebrate hosts. This worm was first isolated from the snail Biomphalaria glabrata from Belo Horizonte (BH isolate), Minas Gerais State, Brazil, by Lie and Basch [J Parasitol (1967) 53:1192-1199]. The natural definitive host for the BH isolate was never determined, and it has been maintained in the laboratory since 1967 in B. glabrata and hamsters. In this study, using light and scanning electron microscopy and molecular analysis, we describe an echinostome recently obtained from its natural vertebrate host, the wild rodent Nectomys squamipes (Rodentia: Sigmodontinae) from Sumidouro, Rio de Janeiro State, Brazil (RJ isolate). This echinostome was also compared to the laboratory-maintained BH isolate of E. paraensei. We observed that adult worms of both BH and RJ isolates could be differentiated from other echinostome species by the relatively small size of the dorsal collar spines relative to lateral and corner collar spines. SEM confirmed the similarity of this morphological character between the two isolates. As additional diagnostic features, the tegumentary spines are scale-like and the region between the genital pore and the acetabulum lacks scales. There is a folded protuberance with a pore just posterior to the genital pore. The tegument of the acetabulum is unspined and radially wrinkled, and there are numerous randomly distributed small, domed, ciliated papillae. The sequences of the internal transcribed spacers of the nuclear rDNA complex of the RJ and BH isolates are identical. Together these shared features provide strong evidence that both isolates are the same and can be referred to as E. paraensei. In conclusion, we have identified, for the first time, one of the natural definitive hosts for E. paraensei, the rodent N. squamipes, and have extended the known geographical distribution of this species to include Sumidouro in Rio de Janeiro State, Brazil.

A new isolate of Echinostoma paraensei (Lie & Basch, 1967) was obtained from a natural vertebrate host, the water rat Nectomys squamipes. Relationships with sympatric snails, Biomphalaria glabrata; Physa marmorata and Lymnaea columella, as well as allopatric snails and the definitive hosts N. squamipes, Mus musculus, Rattus norvegicus, Mesocricetus auratus and birds were investigated. E. paraensei developed in all sympatric snail species following exposure to one or five miracidia. P. marmorata showed the highest infection rate (34% and 36%) followed by L. columella (18% and 24%) and B. glabrata (8% and 28%), respectively. Mortality was elevated in the patent period, with L. columella having the highest values. B. glabrata, P. marmorata, and L. columella did not differ in relation to cercarial encystment, and metacercariae from each species were able to infect N. squamipes with similar worm burdens. Recovered adult worms were found in clusters from the first to third sections of the small intestine. Miracidia of E. paraensei hatched after 10 days incubation in darkness in dechlorinated water at 28+/-1 micro C. Miracidia began to hatch 1 h after exposure to incandescent light.

The water rat, Nectomys squamipes, closely involved in schistosomiasis transmission in Brazil, has been found naturally infected simultaneously by Schistosoma mansoni and Echinostoma paraensei. Laboratory experiments were conducted to verify parasitic interaction in concurrent infection. It was replicated four times with a total of 42 water rats and essayed two times with 90 mice pre-infected with E. paraensei. Rodents were divided into three groups in each replication. A wild strain recently isolated from Sumidouro, RJ, and a laboratory strain of S. mansoni from Belo Horizonte (BH) was used. Rats infected with E. paraensei were challenged 4 weeks later with S. mansoni and mice 2 or 6 weeks after the infection with S. mansoni. Necropsy took place 8 weeks following S. mansoni infection. The N. squamipes treatment groups challenged with S. mansoni RJ strain showed a significant decrease (80 and 65%) in the S. mansoni parasite load when compared with their respective control groups. There was a significant change or no change in the hosts challenged with the BH strain. The persistence time of E. paraensei within host was extended in relation to control groups, with a consequent enhancement of the number of recovered worm. An E. paraensei strain-specific influence on S. mansoni parasitism is reported. This paper presents some experimental data about this interaction in N. squamipes and Mus musculus.

The tegument of the polyopisthocotylean monogenean Atriaster heterodus Lebedev & Parukhin, 1969 was studied using transmission electron microscopy. The outer syncytial layer of the tegument is connected to the internal cell bodies by cytoplasmic extensions which interweave between the muscular fibres. The free surface of the syncytium has projections of the external membrane which are similar to microvilli. The undulating basal membrane, with numerous narrow elongate projections, is associated with the basal lamina situated between the syncytial and muscular layers. The cell bodies and syncytial layer of the tegument exhibit two types of vesicles, one with fibrous contents and one with electron-dense contents; these were analysed using two cytochemical tests, the E-PTA and alcian blue methods, used for the first time on monogeneans.

A rare case of hepatic granulomata caused by Ascaris lumbricoides ova is reported. The patient presented clinically with hepatic mass simulating malignancy, and final diagnosis was performed after surgery, which provided enough material for histopathological examination.

The objective of this study was to obtain a better characterization of Dirofilaria immitis (Leidy, 1856) Railliet & Henry, 1911, in Brazil, ratifying previous accounts and adding new data on the rugose area on the ventral surface of the spiralled posterior portion of males observed by scanning electron microscopy, which presents a different arrangement compared to other species of the genus, and differs also from the genera Litomosoides Chandler, 1931, and Wuchereria Silva Araújo, 1877, adding another taxonomic character to Dirofilariinae and Onchocercinae. Scanning electron microscopy studies also showed some aspects of the distribution of caudal papillae in D. immitis that have not been described before.

This study was undertaken to clarify several aspects of morphological and taxonomic characters of Physaloptera bispiculata Vaz and Pereira, 1935, a parasite of the water rat, Nectomys squamipes. The cephalic structures (including lips, papillae, teeth, amphids, and porous areas) and details of the posterior end of male and female adult worms were examined by scanning electron microscopy, leading to the addition of new taxonomic characters for this species. We consider P. bispiculata a valid species, based on a comparative analysis of the specific characters for P. bispiculata and P. getula Seurat, 1917, including the morphology and morphometry of body structures as well as number and disposition of caudal papillae of the males.

Lagochilascaris minor Leiper, 1909 is a parasitic nematode with its biological cycle still unknown, even though it was found in humans, domestic and silvatic animals. Adult worms, collected by surgical drainage from a human patient from the State of Pará, Brazil, were micrographed using a scanning electron microscope. Morphological aspects of males and females such as cephalic structures, caudal papillae and cuticular patterns were analyzed and compared with the previous descriptions adding new data for the identification of this species.