Abstract: Cellular details of early embryogenesis have been studied extensively among cyclophyllidean cestodes, but have been reported for only one species of the order Proteocephalidea. Thus, we performed a detailed ultrastructural analysis of early embryos of a second species, Corallobothrium fimbriatum, including early events in the formation of the embryonic envelopes. Adult worms were collected from the small intestine of brown bullhead catfish, Ameiurus nebulosus, from the St. Lawrence River in North America and processed by standard methods for transmission electron microscopy. Voucher specimens were deposited in the Museum of Comparative Zoology at Harvard University. The vitelline capsule consists of two closely apposed electron-dense membranous layers, separated by a more electron-lucent material. The two vitellocytes that accompany each oocyte contain numerous ribosomes, vesicles, and lipid droplets. These fuse to form a vitelline syncytium, which elongates and almost completely encircles the cleaving embryo by the four-blastomere stage, forming a partial lipid-rich cellular envelope that underwent apoptosis as cleavage continued. This envelope is later replaced by outer and inner embryonic envelopes. The outer envelope derives from the fusion of the vitelline syncytium with the cytoplasm of macromeres, whereas the inner envelope originates from three mesomeres. Simultaneous to the formation of the embryonic envelopes, other blastomeres multiply, differentiate, while some micromeres undergo degeneration or apoptosis. In most respects, ultrastructural features of early C. fimbriatum embryos closely resemble those of previously studied Proteocephalus longicollis, but differ somewhat from those of other orders. This demonstrates that, despite marked ultrastructural heterogeneity within some cestode orders such as the Cyclophyllidea, some embryonic traits distinguish cestode orders from each other.
Abstract: Tetrathyridia of Mesocestoides sp. (Platyhelminthes: Cestoda) were collected from the body cavities of Apodemus sylvaticus (Rodentia: Muridae) in Murcia, Spain, and processed by routine microscopical and histological techniques, including examination with brightfield, phase-contrast, and differential-interference-contrast optics. All specimens examined had solid hindbodies (i.e., lacked a primary lacuna), thus conforming to the plerocercoid metacestode type. The vast majority of tetrathyridia were highly aberrant, often lacking a scolex, varying greatly in body size, and exhibiting buds or duplexed body forms indicative of asexual proliferation. All of the aberrant forms, including those with normal scoleces and apparent absence of proliferation, possessed anomalous multi-lobed invaginations of the hindbody tegument, which were attached at many points to abnormally dilated excretory ducts. The tegumental and excretory epithelia were joined basally, but did not share a common lumen. These abnormal connections between these aberrant tegumental modifications and the abnormally dilated excretory ducts have not been described previously for any metacestode. This report contributes to understanding previously published reports of abnormalities in other plerocercoid metacestodes, including Mesocestoides spp. and diphyllobothriidean spargana.
Abstract: The ultrastructure of the uterine epithelium and underlying extracellular matrices has been studied in several cyclophyllideans, but relatively little has been published on uterine fine structure in other cestode orders. To develop comparative data, we initiated a study focusing on a common and widespread genus of the order Proteocephalidea. Adult specimens of Corallobothrium fimbriatum were removed from the small intestine of brown bullhead catfish, Ameiurus nebulosus, from the St. Lawrence River in North America. Early gravid proglottids were examined by light microscopy as whole mounts or diced in buffered glutaraldehyde, processed by standard techniques and examined by as stained sections by light microscopy and by transmission electron microscopy. Voucher specimens were deposited in the Museum of Comparative Zoology at Harvard University. The uterus consisted of an epithelial wall supported basally by an extracellular matrix and parenchyma cells, which together formed epitheliomesenchymal villi at many points. The uterine epithelium consisted of a single thin syncytial layer, folded distally into long epithelial villi that protruded into the lumen at some points. The epithelium's numerous nuclei were very close to the lumen, but bulged along with the perinuclear cytoplasm proximally into the surrounding medullary parenchyma. Each nucleus contained small amounts of evenly dispersed heterochromatin and euchromatin, with a central nucleolus. Numerous mitochondria occurred in the cytoplasm, which was densely filled with free ribosomes but contained scant endomembrane components and showed little evidence of secretory activity. The uterine cells possessed few of the apical microvilli that are typical of some cyclophyllidean species, but the apical plasma membrane and cortical cytoplasm were extensively developed into long microlamellae similar to other species. The basic syncytial nature of the epithelium is similar to that of other cestodes studied previously, but the specific combination of features is unlike any previously described. Based on this one proteocephalidean species, we discerned no pattern that would distinguish between Proteocephalidea and Cyclophyllidea based on uterine structure.
Abstract: We examined tegumental development of the diplostomulum of Ornithodiplostomum ptychocheilus, with respect to structural transformations that have functional relevance to the invasion, migration, and site establishment processes in the brain of the fish second-intermediate host, Pimephales promelas. Using a combination of brightfield, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal microscopy (CM), we demonstrated that the diplostomula become established in the outer region of the optic lobes within 24-48 hr of penetration and continue to grow and transform over a period of 4-14 days. During this period, the J-shaped body consists of 2 distinct regions: (1) a highly motile prosoma with distinctive tegumental spines and (2) an opisthosoma, the tegument of which is elaborated into a dense uniform layer of long, thin microvilli. The prosoma is alternately invaginated into and everted from the opisthosoma, thus constituting a protrusible proboscis. By day 14 postinfection (PI), the body has lost this bipartite structure and has taken on the uniformly flattened form characteristic of metacercariae. The transitory complex structure of the diplostomula appears to be well suited to burrowing through host tissues (primarily by action of the prosoma), followed by rapid dissociation of host tissue and nutrient accumulation (primarily by action of the opisthosoma) in preparation for metacercaria encystment.
Abstract: Tropical veterinary parasites have been maintained by the Museum of Comparative Zoology (MCZ) at Harvard University since the mid 1800s. Most of these are maintained by the Department of Invertebrate Zoology, but many vectors and intermediate hosts are maintained by the Departments of Entomology and Malacology. The largest collections are of avian and mammalian ticks (Acarina) that are important as both parasites and vectors. Nematodes are second in numbers, followed by cestodes, trematodes, and several minor helminth groups, crustacean parasites of fish, and protozoan parasites of various hosts. The MCZ directed or participated in several major expeditions to tropical areas around the globe in the early 1900s. Many of these expeditions focused on human parasites, but hundreds of veterinary and zoonotic parasites were also collected from these and numerous, smaller, tropical expeditions. Host sources include companion animals, livestock, laboratory species, domestic fowl, reptiles, amphibians, exotics/zoo animals, commercially important fishes, and other wildlife. Specimens are curated, either fixed whole in vials or mounted on slides as whole mounts or histopathological sections. The primary emphasis of MCZ's current work with tropical veterinary parasites is on voucher specimens from epidemiological, experimental, and clinical research.
Abstract: Molecular methods are useful for both to monitor anthropogenic viral, bacterial, and protozoan enteropathogens, and to track pathogen specific markers in a complex environment in order to reveal sources of these pathogens. Molecular genetic markers for fecal viruses, bacteria, and protozoans hold promise for monitoring environmental pollution and water quality. The demand for microbiologically safe waters grows exponentially due to the global demographic rise of the human population. Economically important shellfish, such as oysters, which are harvested commercially and preferentially consumed raw can be of public health importance if contaminated with human waterborne pathogens. However, feral molluscan shellfish which do not have an apparent economic value serve as indicators in monitoring aquatic environments for pollution with human waterborne pathogens and for sanitary assessment of water quality. Current technology allows for multiplexed species-specific identification, genotyping, enumeration, viability assessment, and source-tracking of human enteropathogens which considerably enhances the pathogen source-tracking efforts.
Abstract: BACKGROUND: Sparganosis is the infection of a paratenic host with the plerocercoid metacestode of Spirometra spp. A 12-year-old captive, pregnant, wild-caught baboon from Tanzania had multiple subcutaneous nodules. METHODS: Examination of the biopsied nodules revealed the presence of viable metacestodes. The histological morphology of the metacestodes was consistent with the genus Spirometra and other pseudophyllidean cestodes. Since species of Spirometra produce growth hormones that are active in mammals, we measured fetal and placental growth and hormone levels. Blood samples were taken from the mother and the cesarean-derived fetus for hematological, biochemical, and hormonal analyses and to test for the presence of antispargana antibodies. RESULTS: Baboon placental weight and fetal hematological, biochemical, and morphometric parameters were within normal ranges. Antibody titers to spargana did not differ significantly between mother (1.08 OD(405)) and fetus (0.91 OD(405)). Baboon maternal insulin-like growth factor and growth hormone values were also within the normal range. Estradiol and progesterone analysis in four of these animals (antibody titers ranged from 0.71 to 1.7 OD(405)) showed no statistically significant difference with age- or phase-matched cycle parameters compared with antibody-negative females. CONCLUSIONS: Based on the results that have been obtained, sparganosis did not appear to affect the endocrinological profile of pregnant and cycling female baboons.
Abstract: The capacity of synanthropic flies belonging to the families Calliphoridae, Sarcophagidae, and Muscidae to serve as mechanical vectors of Cryptosporidium and Giardia among livestock and wildlife in a multispecies agricultural complex in northwest Georgia (USA) was studied using fluorescent in situ hybridization (FISH) and immunofluorescent antibody (IFA) techniques. Flies from all three families were carrying viable Cryptosporidium oocysts and Giardia cysts internally and externally, and deposited them on trap surfaces. Furthermore, the contaminated flies and trap surfaces occurred in association with each of the four domestic animal units (beef, dairy, equine, and sheep), and in wildlife areas dominated by deer (Odocoileus virginianus) and Canada Geese (Branta canadensis). Cryptosporidium was isolated from 55.56% of the fly samples, whereas Giardia was isolated from only 7.94%. The highest numbers of Cryptosporidium were associated with cattle and wildlife areas, while Giardia occurred in greatest numbers in the sheep area. Cryptosporidium was isolated comparably from exoskeletal elutants and fly homogenates, but Giardia was isolated primarily from homogenates, indicating primarily internal transport in the latter. Surfaces visited by the flies (i.e., traps) became contaminated by both Cryptosporidium (18.89%) and Giardia (1.11%). In conclusion, these flies can serve as mechanical vectors of both Cryptosporidium and Giardia in all of these settings, and undoubtedly play a role in movement of these pathogens among the various host species.
Abstract: Spermiogenesis and the ultrastructural characters of the spermatozoon of Mesocestoides lineatus are described by means of transmission electron microscopy, including cytochemical analysis for glycogen. Materials were obtained from a golden hamster (Mesocricetus auratus) after experimental infection with tetrathyridia metacestodes obtained from naturally infected lizards (Anolis carolinensis) from Louisiana. Spermiogenesis in M. lineatus is characterized by the orthogonal growth of a free flagellum, a flagellar rotation, and a proximodistal fusion. The zone of differentiation contains 2 centrioles associated with striated rootlets and a reduced intercentriolar body. The mature spermatozoon of M. lineatus lacks a mitochondrion, and it is characterized by the presence of (1) a single, spiraled, crested body 150 nm thick; (2) a single axoneme of the 9+'1' pattern of trepaxonematan Platyhelminthes; (3) a parallel and reduced row of submembranous cortical microtubules; (4) a spiraled cordon of glycogen granules; and (5) a spiraled nucleus encircling the axoneme.
Abstract: The ultrastructure of the infective oncosphere of the cestode Mosgovoyia ctenoides (Anoplocephalidae) is described. The surface of the infective oncosphere is covered by a thin cytoplasmic layer of tegument connected by a narrow cytoplasmic process with the binucleate subtegumental cell, situated deeper in the body. Below the basal matrix of the cytoplasmic layer of the tegument are situated wide bands of the peripheral, somatic musculature responsible for body movements. The 3 pairs of hooks and their muscles form a complex hook muscle system, responsible for coordinated hook action. Five major types of cells have been distinguished: (1) a binucleate subtegumental cell, (2) a binucleate penetration gland, (3) 2 nerve cells, (4) numerous somatic cells, and (5) about 6 germinative cells. The approximate number of cells is 24 (26 nuclei, including 2 syncytial structures). The results of this study, when compared with other published reports from other cestode taxa, support previous hypotheses that the progressive reduction of oncosphere cells is an adaptive feature in cestode evolution.
Abstract: A 38-year-old man living near Phnom Penh (Cambodia) was admitted to a hospital in Paris in June 2001 for a single episode of a generalized grand mal seizure. This episode was preceded by a 9-month history of headaches. Magnetic resonance imaging (MRI) of the head revealed a rounded lesion immediately ahead of the left central sulcus. The resected lesion was about 20 mm in diameter. Histologic examination revealed an elongated but unsegmented metacestode at the center of the lesion. Polymerase chain reaction (PCR) analysis was inconclusive due to formalin-based histologic processing of the tissue. Morphologic analysis based on the histologic sections revealed that the metacestode was a tetra-acetabulate plerocercoid of the order Cyclophyllidea, with a distinct rostellum and pseudosegmentation of the dorsoventrally flattened hindbody. This is the first report of a tetra-acetabulate plerocercoid from a human host and the first report of any cyclophyllidean plerocercoid from the human brain. After 6 weeks, the patient was asymptomatic, neurologic examination was normal, and the brain MRI showed only surgical cavitation. The patient returned to Cambodia.
Abstract: Trematode metacercariae typically are regarded as nonfeeding and metabolically inactive. However, the metacercariae of many trematode species undergo complex and prolonged periods of development within their intermediate hosts. In the present study, we used electron microscopy to document chronological changes in development of the tegument of Ornithodiplostomum ptychocheilus metacercariae recovered from the brains of experimentally infected fathead minnows (Pimephales promelas). Commencing at 4 days postinfection (PI), the smooth, thin, syncytial tegument transforms into a complex microlamellar and microvillar system that encircles the entire body surface. The microvilli are oriented in parallel in an extended pattern, reaching directly away from the parasite and toward the receding host tissue. The microvilli disappear at approximately 28 days PI, followed by deposition of the cyst wall and further transformation of the tegument into the spinose, a glandular structure typical of an immature adult. To our knowledge, the progressive disaggregation of host cells at the leading edge of elongating parasite microvilli has not been demonstrated previously for any trematode. These results provide morphological evidence that the metacercariae of some trematode species undergo complex developmental changes associated with feeding in their intermediate host.
Abstract: Zebra mussels ( Dreissena polymorpha) from throughout the Shannon River drainage area in Ireland were tested for the anthropozoonotic waterborne parasites Cryptosporidium parvum, Giardia lamblia, Encephalitozoon intestinalis, E. hellem, and Enterocytozoon bieneusi, by the multiplexed combined direct immunofluorescent antibody and fluorescent in situ hybridization method, and PCR. Parasite transmission stages were found at 75% of sites, with the highest mean concentration of 16, nine, and eight C. parvum oocysts, G. lamblia cysts, and Encephalitozoon intestinalis spores/mussel, respectively. On average eight Enterocytozoon bieneusi spores/mussel were recovered at any selected site. Approximately 80% of all parasites were viable and thus capable of initiating human infection. The Shannon River is polluted with serious emerging human waterborne pathogens including C. parvum, against which no therapy exists. Zebra mussels can recover and concentrate environmentally derived pathogens and can be used for the sanitary assessment of water quality.
Abstract: Zebra mussels (Dreissena polymorpha) and Asian freshwater clams (Corbicula fluminea) are nonindigenous invasive bivalves present in North American fresh waters that are frequently contaminated with human enteric parasites, Cryptosporidium parvum and Giardia lamblia. Six-week laboratory exposure of D. polymorpha and Corbicula fluminea to both parasites seeded daily at concentrations reported from surface waters demonstrated efficient removal of Cryptosporidium parvum oocysts and G. lamblia cysts by both bivalve species. The number of parasites in mollusk tissue progressively increased in relation to the concentration of waterborne contamination, and decreased after cessation of the contamination. Oocysts outnumbered cysts in the tissue of both bivalves, and more parasites were identified in D. polymorpha than in Corbicula fluminea; overall 35.0% and 16.3% of the parasites seeded, respectively. Because C. fluminea and D. polymorpha can accumulate human waterborne parasites in proportion to ambient concentrations, these species of bivalves can be effective bioindicators of contamination of freshwater habitats with Cryptosporidium and Giardia.
Abstract: The Asian freshwater clam, Corbicula fluminea, inhabits environments recognized to be contaminated with waterborne Giardia cysts. Sixty-four tissue samples of Giardia-free clams were spiked with various numbers of Giardia duodenalis cysts within the range of 50-700 cysts. Regression analysis showed that paired numbers of spiked (x) versus recovered (y) cysts regressed significantly (P < 0.01) according to the equation y = 42.57 +/- 1.81x (+/- 64.3). The cyst detection threshold was 43 cysts/clam, the coefficient of determination was 77%, and the overall sensitivity of cyst detection was 42.9%. All 20 values of cyst numbers in clam tissue samples that were processed blind were located within the 95% prediction limits of the linear regression equation. The cyst retention rate of 160 clams kept in an aquarium with 38 l of water spiked with 1.00 x 10(5) G. duodenalis cysts was approximately 1.3 x 10(3) cysts/clam. No waterborne cysts were detected by the membrane filtration method 90 min after spiking the aquarium water. G. duodenalis cysts were detected in clam tissue up to 3 weeks post-exposure. Filtration of water by clams substantially depleted the aquarium water of its particulate matter. The sampling program demonstrated that the population of 160 clams examined during the study could be accurately assessed for exposure to waterborne Giardia cysts by random sampling of 86 (54%) clams. The results indicate that C. fluminea clams can be used for biological monitoring of contamination with Giardia.
Abstract: Asian freshwater clams, Corbicula fluminea, exposed for 24 h to 38 liters of water contaminated with infectious Cryptosporidium parvum oocysts (1.00 x 10(6) oocysts/liter; approximately 1.9 x 10(5) oocysts/clam) were examined (hemolymph, gills, gastrointestinal [GI] tract, and feces) on days 1, 2, 3, 7, and 14 postexposure (PE). No oocysts were detected in the water 24 h after the contamination event. The percentage of oocyst-containing clams varied from 20 to 100%, depending on the type of tissue examined and the technique used--acid-fast stain (AFS) or immunofluorescent antibody (IFA). The oocysts were found in clam tissues and feces on days 1 through 14 PE; the oocysts extracted from the tissues on day 7 PE were infectious for neonatal BALB/c mice. Overall, the highest number of positive samples was obtained when gills and GI tracts were processed with IFA (prevalence, 97.5%). A comparison of the relative oocyst numbers indicated that overall, 58.3% of the oocysts were found in clam tissues and 41.7% were found in feces when IFA was used; when AFS was used, the values were 51.9 and 48.1%, respectively. Clam-released oocysts were always surrounded by feces; no free oocysts or oocysts disassociated from fecal matter were observed. The results indicate that these benthic freshwater clams are capable of recovery and sedimentation of waterborne C. parvum oocysts. To optimize the detection of C. parvum oocysts in C. fluminea tissue, it is recommended that gill and GI tract samples be screened with IFA (such as that in the commercially available MERIFLUOR test kit).
Abstract: Asian freshwater clams (Corbicula fluminea) were exposed for 24 hr in 38 liters of water contaminated with 1.0 x 10(5) Cyclospora cayetanensis oocysts (2.6 x 10(3) oocysts/L). The hemolyph and gill smears of 30 clams were examined by acid-fast stain on days 1, 3, 5, 7, 10, 13, and 18 postexposure (PE). Since no oocysts were detected in the water 24 hr after contamination by the membrane filter-dissolution method, the oocyst retention rate was 4.6 X 10(2) oocysts/clam. The prevalence of oocyst-positive clams significantly decreased (P < 0.01) from 93% to 47% during 13 days PE. None of the clams contained oocysts on day 18 PE; no oocysts were detected in the clam feces. The numbers of oocysts recovered from six clam size classes varied and significantly decreased with smaller clam size (P < 0.01). The lowest prevalence values of oocyst-positive clams, 45% and 34%, were observed in the two lowest size classes: 12.1-14.0 mm and 14.1-16.0 mm, respectively. The prevalence values in the remaining four classes ranged from 84% to 100%. The sampling program demonstrated that the population of 180 clams examined during the study up to 13 day PE could be assessed for C. cayetanensis positivity by random testing of a minimum of 75 clams (42%). When the two lowest clam size classes are eliminated, the population of 114 clams could be assessed by sampling a minimum of 32 clams (28%). The results demonstrate that Corbicula fluminea can recover waterborne oocysts of C. cayetanensis, and could be used as biological indicators of contamination of water with C. cayetanensis oocysts.
Abstract: Corbicula fluminea hemocytes phagocytosed infectious oocysts of Cryptosporidium parvum in vitro. After 15, 30, 60, 90, and 120 min of incubation, averages of 35.8, 58.0, 69.7, 77.7, and 81.6% of the oocysts were phagocytosed by 24.3, 70.0, 78.5, 87.3, and 93.0% of the hemocytes, respectively. A single clam can retain by phagocytosis an average of 1.84 x 10(sup6) oocysts per ml of hemolymph. C. fluminea bivalves can serve as biological indicators of contamination of wastewaters and agricultural drainages with Cryptosporidium.
Abstract: Hemocytes of the Asian freshwater clam Corbicula fluminea, phagocytosed in vitro infectious Giardia duodenalis cysts. After 15, 30, 60, 90, and 120 min of incubation an average of 22%, 32%, 43%, 54%, and 72% of the cysts were phagocytosed by 22%, 55%, 63%, 81%, and 86% of the hemocytes, respectively. The number of hemocytes showing phagocytosis and the mean number of cysts ingested per hemocyte increased significantly over time (P < 0.01); the numbers of nonphagocytosed cysts significantly decreased (P < 0.02). Extrapolation reveals that C. fluminea can retain by phagocytosis an average of 1.6 x 10(6) G. duodenalis cysts/ml hemolymph. The phagocytic capacity of C. fluminea hemocytes indicates the applicability of this freshwater benthic bivalve for bioindication of contamination of waste waters and agricultural drainage with Giardia cysts.
Abstract: Dreissenid mussels, Dreissena polymorpha and D. bugensis, were found to be infected by the naidid oligochaete Chaetogaster limnaei at four sites in the St. Lawrence River. This is the first report of this species infecting dreissenids anywhere in the world. Most worms inhabited the mantle cavity, where they caused erosion of the mantle and gill epithelia as determined by histopathological examination. Others penetrated various tissues; one had invaded the ovary and was feeding on oocytes and ovarian tissues. Of 606 mussels examined, 166 (27.4%) harbored at least 1 C. limnaei. The prevalence varied between 1% and 80%, depending on the collection site and date. The worms were slightly but significantly more prevalent in D. bugensis than in D. polymorpha. The intensity ranged from 1 to 18 worms per infected host. Variations in prevalence and intensity were not related to the size or sex of the host, but the data did suggest some seasonality.
Abstract: The zebra mussel Dreissena polymorpha a species recently introduced to North America from Europe, was studied to determine whether it could potentially serve as host for echinostomatid metacercariae. Forty adult mussels were collected from the St. Lawrence River and exposed to cercariae of Echinoparyphium sp. that was emerging from naturally infected Physa sp. collected from a native population in northern New York state. When necropsied 24-30 hr postexposure, 2 (5%) of the 40 harbored a metacercaria of Echinoparyphium sp. in the gonad. None of 200 control mussels collected from the same site was infected. This is the first report of any species or stage of echinostomatid from this host species worldwide. This is also the first report of an echinostomatid metacercaria from the gonad of any host species.
Abstract: The fine structure of the uterus in gravid proglottids of Hymenolepis diminuta was examined by standard techniques for scanning and transmission electron microscopy. The uterus consisted of a syncytial uterine epithelium attached to the medullary parenchyma through a thin extracellular basal matrix. The epithelium contained prominent nuclei in the juxtalumenal cytoplasm. The cytoplasm was dominated by extensive granular endoplasmic reticulum, with dilated cisternae containing an electron-lucent material and widely scattered electron-dense spherical bodies. No Golgi body or other agranular endomembrane component was observed, but the epithelium contained numerous free ribosomes and a few mitochondria. The apical plasma membrane was folded into long microlamellae. Epithelial and epitheliomesenchymal folds and villi resulted in a compartmentalized uterine lumen, with each chamber containing 1 to several eggs. These data suggest a high level of synthetic activity within the uterine epithelium, but the chemical products and functional significance of this activity are not yet known.
Abstract: A new host and distribution record is reported for tetrathyridia of Mesocestoides sp. One of 5 (20%) Namib tiger snakes, Telescopus beetzi, from South Africa was infected. Numerous tetrathyridia were found encapsulated in mesentery attached to the small intestine. Morphological examination of tetrathyridia revealed absence of buds, multiple scoleces, or any other evidence of asexual proliferation. A summary of the snakes of the world reported as hosts of tetrathyridia of Mesocestoides sp. is presented.
Abstract: Two hundred and one whiptail lizards, Cnemidophorus spp., from Texas and Colorado (USA), were examined for Mesocestoides sp. tetrathyridia. Eleven (5%) were infected, including three of 58 (5%) C. dixoni, six of 70 (9%) C. gularis septemvittatus, one of 35 (3%) C. marmoratus, and one of 34 (3%) C. tesselatus; four C. inornatus heptagrammus were not infected. In addition, 41 non-cnemidophorine lizards from the same study area were not infected. Free tetrathyridia were found in the body cavity of lizards and encapsulated tetrathyridia were observed in the heart, liver, stomach, mesenteries, ovaries, intestines, and lungs. None of the Mesocestoides sp. exhibited any evidence of asexual proliferation such as multiple scoleces or buds. This note, the fifth in a series of reports on helminths of Cnemidophorus spp., represents the first time Mesocestoides sp. has been reported from these four taxa, and Colorado is a new geographic locality record for this parasite.
Abstract: Light and scanning electron microscopy were used to examine the localization and pathogenicity of echinostomatid metacercariae infecting the kidneys of leopard frogs, Rana pipiens, and green frogs, Rana clamitans. Cysts occurred predominantly in the ventrolateral renal cortex, and at least some were confined to the lumen of the Bowman's capsules. Each vermiform metacercarial body was enclosed by a spherical cyst wall that had a uniform thickness. The wall was composed of a homogeneous material containing basic and keratinlike proteins, with sulfated acid mucopolysaccharides on the outer surface. Most cysts were enclosed by a fibrous capsule of host origin, or were surrounded by an inflammatory focus. Fibrosis was always focal, but its degree varied between individual hosts and between different cysts within the same host. Some heavily encapsulated cysts were darkened and contained disintegrating worms. In heavily infected kidneys, confluence of fibrotic or inflammatory foci resulted in the displacement of functional renal tissue. These data suggest that infection by echinostomatids may impair renal function and that the host's response affects parasite viability.
Abstract: A new host and geographic locality record is reported for tetrathyridia of Mesocestoides sp. in two species of ranid frogs (Rana berlandieri and R. pipiens) from Texas and New York, respectively. Tetrathyridia were found encapsulated in liver and mesenteries of the hosts. Morphological examination and experimental inoculation of these tetrathyridia into mice demonstrated the absence of capacity for asexual proliferation. Overall prevalence of infection was low in anurans from Arkansas, Texas and New York, but intensities can be generally high. In addition, a summary of frogs and toads from North America reported as hosts of tetrathyridia of Mesocestoides sp. is presented.
Abstract: Gravid proglottids of Oochoristica anolis from naturally infected anole lizards, Anolis carolinensis, were placed in covered Petri dishes with laboratory-reared beetles, Tribolium confusum and Tenebrio molitor. After maintenance at 25 C, metacestodes developed in 29 of 61 T. confusum (48%), but in none of 5 T. molitor. Beetles contained from 1 to 22 metacestodes (means = 3.3), which were fully developed by day 40 postexposure. A primary lacuna was never observed, but the possibility of its presence could not be ruled out without histological study. No cercomer was formed and metacestodes retained larval hooks throughout development. Scolices were invaginated at removal from the hemocoel, but usually evaginated quickly in Ringer's. On day 60 postexposure, metacestodes were fed by stomach tube to 5 anoles, 2 lacertid lizards (Podarcis muralis) and 2 mice. Worms developed only in anoles, 3 of which were infected upon examination. Oncospheral hooks were present in worms after 7 days development in the lizard; a median excretory pore was present at the posterior tip of all stages examined, including the terminal mature proglottid of a worm after 105 days in a lizard. Scolex growth rate was linear throughout metacestode and adult development, but growth rate in body length was diphasic, punctuated by change of hosts, associated with strobilization. Attempts to establish parenteral infections in anoles were unsuccessful. Present data constitute the most complete life history study thus far for any species of Oochoristica.
Abstract: Asexually proliferative Mesocestoides corti tetrathyridia were studied to test the hypothesis of in utero transmission in mice and define more clearly the path of transmammary transmission. In utero transmission was not observed in 132 fetuses (22 litters) taken by caesarean section from infected mothers. However, 19 of these mothers had tetrathyridia in their mammary glands at the time of operation, nine had worms in the uterine lumen, and one had a single worm in the maternal blood space of a placenta. No tetrathyridia were found in amniotic cavities. No infection was found in 32 young (7 litters) examined immediately after birth to infected mothers, but before nursing. No infection was found in 30 young (5 litters) removed from infected mothers before nursing and raised by uninfected fosters. Of 29 uninfected young (5 litters) allowed to nurse on infected mothers, 18 became infected. Whole mounts and sections of infected mammary glands showed proliferating tetrathyridia free in larger milk ducts and free and encapsulated in mammary parenchyma. These data suggest that maternal transmission of M. corti tetrathyridia in mice occurs primarily or perhaps exclusively by the transmammary route.
