Neither phospholipase A₁ (PLA A₁) nor phospholipase A₂ (PLA A₂), nor their respective genes, have been identified in Giardia lamblia, even though they are essential for lipid metabolism in this parasite. A method to identify, isolate, and characterize these enzymes is needed. The activities of PLA A₁ and PLA A₂ were analyzed in a total extract (TE) and in vesicular (P30) and soluble (S30) subcellular fractions of G. lamblia trophozoites; the effects of several chemical and physicochemical factors on their activities were investigated. The assays were performed using substrate labeled with ¹⁴C, and the mass of the ¹⁴C-product was quantified. PLA A₁ and PLA A₂ activity was present in the TE and the P30 and S30 fractions, and it was dependent on pH and the concentrations of protein and Ca² . In all trophozoite preparations, PLA A₁ and PLA A₂ activities were inhibited by ethylenediaminetetraacetic acid and Rosenthal's inhibitor. These results suggest that G. lamblia possesses several PLA A₁ and PLA A₂ isoforms that may be soluble or associated with membranes. In addition to participating in G. lamblia phospholipid metabolism, PLA A₁ and PLA A₂ could play important roles in the cytopathogenicity of this parasite.

The composition and development of the parasite community of overwintering young-of-the-year (YOY) roach (Rutilus rutilus) was studied in outdoor artificial ponds. Cumulative mortality of the roach from November until May was about 20%. The prevalences of the epizoic ciliates Trichodina sp. and Apiosoma sp., and of the monogeneans Dactylogyrus suecicus, Dactylogyrus nanus, and Gyrodactylus sp. in general tended to peak in the beginning of April at a water temperature of about 8 C. However, mean parasite intensity remained constant over this interval. Prevalence of metacercariae of the digeneans Diplostomum cf. spathaceum and Tylodelphys clavata remained constant with values around 60% and 10%, respectively. Larvae of the nematode Philometra obturans and the cestode Ligula intestinalis and females of the copepod Neoergasilus japonicus were found sporadically. A concept of 2 thresholds, a critical condition factor (attained by a temperature-induced energy deficiency), and a condition-dependent critical infection intensity, which determine winter mortality of YOY, is suggested.

Agricultural activity and landscape features have previously been associated with diversity and prevalence of trematode species in amphibian second intermediate hosts. In this study, the density, diversity, and size of snail first intermediate hosts, and the diversity and prevalence of their trematode species, were assessed in 2 types of ponds, i.e., those adjacent to cornfields and those from the same region in southwestern Ontario that were adjacent to nonagricultural settings. Species of trematodes included, but were not restricted to, those that are known parasites of larval and adult frogs. We also assessed landscape factors likely to influence use by definitive hosts. Presence of the herbicide atrazine in ponds was measured to check that ponds adjacent to agriculture had potential to be affected by agricultural runoff. Both snail size and the proportion of snails releasing cercariae were greater in nonagricultural ponds, contrasting with a previous finding of lower trematode infection in tadpoles from nonagricultural ponds. Percentage of forest cover was associated with prevalence of certain trematode species, but not with estimates of combined prevalence. Absence of relations of trematode prevalence to measures of road density also contrasted with previous studies. We interpret our results in light of how agricultural activity might influence trematode viability, snail growth, and use by wildlife definitive hosts, independently of landscape factors.

Fiddler crabs (Uca spp.) are common inhabitants of temperate and tropical coastal communities throughout the world, often occupying specific microenvironments within mangrove and salt marsh habitats. As second intermediate hosts for trematodes, we investigated patterns of host distribution and parasitism for 3 species of sympatric fiddler crabs in mangrove habitats adjacent to the Indian River Lagoon, Florida. Fiddler crab distribution varied among species, with Uca speciosa dominating the low and mid intertidal regions of mangrove banks. This species also exhibited higher prevalence and abundance of Probolocoryphe lanceolata metacercariae compared with Uca rapax, which is relatively more abundant in the high intertidal zone. We conducted a field experiment to test whether U. speciosa was more heavily parasitized by P. lanceolata as a result of its habitat distribution by raising U. speciosa and U. rapax under identical environmental conditions. After exposure to shedding cercariae under the same field conditions, all individuals of U. speciosa became parasitized by P. lanceolata, whereas no U. rapax were parasitized, suggesting that differences in parasitism were driven by host selection.

All dinoflagellates that infest the skin and gills of fish have traditionally been placed within the class Blastodiniphyceae. Their relatedness was primarily based upon a similar mode of attachment to the host, i.e., attachment disc with holdfasts. Results of recent molecular genetic analyses have transferred these parasites, including Amyloodinium, to the class Dinophyceae, subclass Peridiniphycidae. In our study, a small subunit rDNA gene from a parasitic dinoflagellate that has features diagnostic for species in the genus Piscinoodinium, i.e., typical trophont with attachment disc having rhizocysts, infesting the skin of freshwater tropical fish, places this organism within the dinophycean subclass Gymnodiniphycidae. This suggests a close relationship of Piscinoodinium spp. to dinoflagellates that include symbionts, e.g., species of Symbiodinium, and free-living algae, e.g., Gymnodinium spp. These molecular and morphological data suggest that evolution of this mode of fish ectoparasitism occurred independently in 2 distantly related groups of dinoflagellates, and they further suggest that the taxonomic status of parasites grouped as members of Piscinoodinium requires major revision.

The structure of the pharynx of the adult female nematode Anguillicoloides crassus (Spirurina) has been studied for the first time using light and transmission electron microscopy. The cylindrical pharynx consists of a short anterior muscular corpus and an enlarged posterior glandular and muscular postcorpus. The main cellular components of the pharynx of A. crassus include the muscle cells, the marginal cells, the nerve cells, and 1 dorsal and 2 subventral glands. New observations for nematodes include: (1) the non-contractile regions of pharyngeal musculature in the corpus have specific appearance; (2) the ventrosublateral longitudinal nerve in the pharynx has an enlarged, enucleated anterior part, with a pronounced palmate projections; and (3) abundant lysosomelike membranous bodies consisting of myelinlike figures of varied size present in marginal cells and pharyngointestinal valve. The 2 subventral glands and, apparently, the single dorsal gland, have their openings at the same level, i.e., at the border between the corpus and postcorpus. The pharyngeal–intestinal valve joins the pharynx to the intestine. Knowledge of the ultrastructure of these complex characters may be useful in understanding of functional features, and for comparative morphology as well as evolutionary considerations within the Chromadorea.

Neospora caninum seroprevalence and risk factors affecting seroprevalence in beef cattle in Andorra were investigated. Antibodies to N. caninum were evaluated by enzyme-linked immunosorbent assay performed on a yearly basis in 1,758 animals older than 6 mo, belonging to 26 herds. Mean seroprevalence of antibodies to N. caninum for the herds was 7.4 ± 1.2% (130/1,758). Logistic regression analyses were performed on data from each animal, considering N. caninum seropositivity as the dependent variable, and herd, grazing area, year of sampling, repeat-test animal (animals sampled twice or more), sex, breed, age (animals <4 yr old or ≥5 yr old), and country of birth as possible risk factors. Based on the odds ratio, the prevalence of infection was 2.1 times higher (P < 0.01) in animals from the Ordino grazing area, 1.64 times higher in animals older than 5 yr (P < 0.01), and 6.7 times (1/0.15) lower in Limousin–mixed Limousin cattle (P < 0.002). The results suggest that the particular grazing location could promote the horizontal transmission of this parasite and that certain breeds are less susceptible to N. caninum infection than others.

Toxoplasma gondii and Neospora caninum are structurally similar parasites, with many hosts in common. The prevalence of antibodies to T. gondii and N. caninum was determined in sera from dogs from Durango City, Mexico. Using a modified agglutination test, antibodies to T. gondii were found in 52 (51.5%) of the 101 dogs with titers of 1:25 in 27, 1:50 in 11, 1:100 in 5, 1:200 in 4, 1:400 in 2, 1:800 in 2, and 1:3,200 or higher in 1. Antibodies to N. caninum were determined by the indirect immunofluorescent antibody test (IFAT) and the Neospora sp. agglutination test (NAT). Two of the 101 dogs had N. caninum antibodies; these dogs did not have T. gondii antibodies, supporting the specificity of the tests used. The N. caninum antibody titers of the 2 dogs were: 1:400 by IFAT and 1:200 by NAT in 1, and 1:25 by NAT and IFAT in the other. Results indicate that these 2 structurally similar protozoans are antigenically different.

Neodiplostomum seoulense is highly pathogenic and lethal to experimental mice; most worms are expelled within 2 mo of acquisition. In this study, T-helper (Th) cell immune responses were studied in N. seoulense-infected BALB/c mice. Spleen and mesenteric lymph node (MLN) cells of infected mice proliferated in response to parasite antigens; CD4 T cells proliferated more than CD8 T cells. Antigen-induced interferon (IFN)-γ (a Th1 cytokine) secretion began to increase at day 7 postinfection (PI) in spleen and MLN cells, and this was maintained at day 28 PI, whereas interleukin (IL)-4 (a Th2 cytokine) secretion was somewhat lower. Similar results were observed for mRNA signals of IFN-γ and IL-4. Antigen-specific serum total immunoglobulin (Ig)G, IgG1, IgM, and IgA levels (Th2-induced) were elevated from days 7 to 14 to day 28 PI, and IgG2a (Th1-induced) was elevated at days 21 to 28 PI. Interestingly, the numbers of macrophages (Th1- or Th2-induced), which were found to kill N. seoulense worms in vitro, increased remarkably during days 14–28 PI in spleens and small intestines of infected mice. This study shows that mixed Th1 and Th2 responses occur during the course of N. seoulense infection in BALB/c mice. Heavy infiltrations of macrophages in the small intestine may participate in host damage and worm expulsion.

NcMIC4 is a Neospora caninum microneme protein that has been isolated and purified on the basis of its unique lactose-binding properties. We have shown that this protein binds to galactosyl residues of lactose; antibodies directed against NcMIC4 inhibit host cell interactions in vitro, thus making it a vaccine candidate. Because of this feature, NcMIC4 was first purified on a larger scale in its native, functionally active form using lactose–agarose affinity chromatography. Second, NcMIC4 was expressed in Escherichia coli as a histidine-tagged recombinant protein (recNcMIC4) and purified through Ni-affinity chromatography. Third, NcMIC4 cDNA was cloned into the mammalian pcDNA3.1 DNA vector and expression was confirmed upon transfection of Vero cells in vitro. For vaccination studies, we employed the murine cerebral infection model based on C57Bl/6 mice, employing experimental groups of 10 mice each. Two groups were injected intraperitoneally with purified native NcMIC4 and recNcMIC4, respectively, employing RIBI adjuvant. The third group was vaccinated intramuscularly with pcDNA-NcMIC4. Control groups included an infection control, an adjuvant control, and a pcDNA3.1 control group. Following 3 injections at 4-wk intervals, mice were challenged by i.p. inoculation of 2 × 10⁶ N. caninum tachyzoites (Nc-1 isolate). During the course of parasite challenge (3 wk), mice from the 3 different test groups showed varying degrees of symptoms bearing a semblance to neosporosis, i.e., walking disorder, rounded back, apathy, and paralysis of the hind limbs. Control groups showed no symptoms at all. Most notably, vaccination with pcDNA-MIC4 proved antiprotective, with 60% of mice succumbing to infection within 3 wk, and all mice lacking a measurable anti-NcMIC4 IgG response. NcMIC4 in its native form elicited a substantial humoral IgG1 immune response and a reduction in cerebral parasite load compared to the controls, but 20% of mice succumbed to infection. Vaccination with recNcMIC4 also resulted in 20% of mice dying; however, in this group, cerebral parasite load was similar to the controls, and recNcMIC4 vaccination elicited a mixed IgG1/IgG2 response. In conclusion, vaccines based on NcMIC4, especially pcDNA-NcMIC4, render mice more susceptible to cerebral disease upon challenge with N. caninum tachyzoites.

We studied the helminths of 18 common dolphins, Delphinus delphis, from northern Patagonia. Parasites were found only in the gastrointestinal tract. Four species were in the stomach, the nematode Anisakis simplex, the acanthocephalan Corynosoma cetaceum, and the digeneans Braunina cordiformis and Pholeter gastrophilus, plus 1 digenean in the hepatopancreatic ducts, Oschmarinella rochebruni. Infection levels were low (0–155 parasites). Braunina cordiformis and C. cetaceum were the most prevalent species. Anisakis simplex was mainly concentrated in the forestomach, B. cordiformis in the main stomach, and C. cetaceum in the pyloric stomach. Component diversity was low and component evenness was intermediate. Infracommunity diversity was also low, and the mean evenness was higher than at the component community level. Low prevalence in common dolphins is consistent with parasite assemblages of other cetaceans off Patagonia. None of the parasites found is specific to this host species within the study area. We suggest that potential prey are probably important in parasite transmission in this and other dolphins from the Patagonian region.

Plasmodium inui is a parasite of macaques and other nonhuman primates in Asia that is studied as a model for the human malaria parasite P. malariae. Presented here are descriptions of the isolation, passage histories into Macaca mulatta monkeys, and infectivity to different Anopheles spp. mosquitoes of 18 different isolates of this parasite.

The nematode Soboliphyme baturini Petrov, 1930, was found to represent a single species with a relatively broad geographic range across Beringia and northwestern North America on the basis of the assessment of molecular sequence data for adult and juvenile parasites. Refuted are hypotheses suggesting that several cryptic species could be partitioned either among an array of mustelid definitive hosts or across the vast region that links North America and Eurasia. Host specificity for this species is examined on the basis of a comprehensive list for definitive hosts, derived from new field surveys and existing literature for S. baturini. Only 5 mustelids (Gulo gulo, Martes americana, M. caurina, M. zibellina, and Neovison vison) appear to have significant roles in the life history, persistence, and transmission of this nematode. Soboliphyme baturini readily switches among M. americana, M. caurina, Mustela erminea, or N. vison at any particular locality throughout its geographic range in North America, although Martes spp. could represent the source for nematodes in a broader array of mustelids. Molecular analyses (243 base pairs of mitochondrial gene nicotinamide dehydrogenase ;obND4;cb) suggest that hypotheses for host specificity across an array of mustelid definitive hosts are not supported. The life cycle of S. baturini is explored through a review of diet literature for 2 marten species, M. americana and M. caurina, and other mustelids across the Holarctic. Shrews (Soricomorpha: Soricidae) comprise >8% of prey for these species of Martes, suggesting their putative role as paratenic hosts. Juvenile nematodes found in the diaphragms of soricids are genetically identical to adult S. baturini found in the stomachs of mustelids at the same locations in both Asia and North America, corroborating a role in transmission for species of Sorex.

Parastrongyloides trichosuri is a nematode parasite of the Australian brush-tailed possums that can be propagated through many generations in vitro. This makes P. trichosuri uniquely suited for genetic investigations, including those involving transgenesis. However, an obstacle to its use as an experimental model has been the fact that its host is limited to Australia and New Zealand and that it cannot be exported because of its status as a protected species or agricultural pest, respectively. In previous studies, conventional laboratory animals such as rats, mice, rabbits, ferrets, and chickens have failed to support infections. In the present study, gerbils and short-tailed opossums proved similarly refractory to infection. In contrast, the sugar glider (Petaurus breviceps, family Petauridae) proved to be a good host for P. trichosuri. Patent infections resulted using as few as 6 infective larvae (L3i) and as many as 2,000 L3i. Large numbers of L3i (1,000–2,000) produced patent infections of much shorter duration than those seen when 100 L3i were initially given to the sugar glider. In one case, an infection initiated with 100 L3i was patent for over 1 yr. Parastrongyloides trichosuri is easily cryopreserved using a method developed for Strongyloides stercoralis. Thus, we have identified an experimental host for P. trichosuri that will make it possible to conduct research on this parasite in laboratories outside the endemic sites.

The life cycle of Stephanoprora uruguayense Holcman et Olagüe, 1989, was experimentally resolved. In an artificial pond in the Zoological Garden in Buenos Aires City, Argentina, Heleobia parchappei (Hydrobiidae) was found to be releasing large-tailed cercariae with a prepharyngeal body, but lacking collar spines and corpuscles in the excretory system. Metacercariae, which encysted on the gills of naturally and experimentally infected Cnesterodon decemmaculatus (Poecilidae), developed collar spines and corpuscles in the excretory system in 7 days. Sexually mature adults were recovered from chicks and immature adults from mice fed metacercariae from C. decemmaculatus. Eggs shed in chick feces developed to miracidia within 10 days; sporocysts were found on the gills of snails. Stephanoprora uruguayense and S. denticulata from Europe are similar in adult morphology, but can be distinguished by morphological and behavioral features of larvae. Likewise, although S. denticulata and S. paradenticulata from Venezuela are similar to S. uruguayense in adult morphology, they differ considerably in larval morphology and intermediate hosts.

Experimental results showed that the gill monogenean Cichlidogyrus sclerosus and its host, the Nile tilapia Oreochromis niloticus, exhibited significant numerical and physiological responses after exposure to sediments polluted with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and heavy metals in comparison with control fishes. After 15 days of exposure, C. sclerosus abundance significantly increased in treatments with low to fairly high sediment pollutant concentrations, but declined at high sediment pollutant concentrations. Hypertrophy and hyperplasia in secondary gill lamellae and the spleen melanomacrophage centers were significantly higher at extremely high sediment pollutant concentrations compared with the controls. Spleen lymphocyte and monocyte counts were significantly lower at extremely high sediment pollutant concentrations and were significantly correlated with high fluorescent aromatic compound concentrations measured as PAH exposure indicators. A multivariate redundancy analysis showed significant statistical association between sediment pollutant concentration, C. sclerosus abundance, and tilapia physiological variables. The polluted sediments negatively affected monogenean abundance and induced immunosuppression in hosts, consequently increasing histological damage in hosts and allowing persistent C. sclerosus infection. This study documents evidence suggesting that C. sclerosus and its host are indeed excellent models to test environmental quality in tropical freshwater ecosystems.

The developmental expression of the antigen SO7, which has been previously shown to protect chickens against infection by several Eimeria species, was investigated. Using RT-PCR, mRNA for SO7 was found to be restricted primarily to unsporulated oocysts (0 hr). Western blot (WB) analysis with an antibody to recombinant SO7 (rbSO7) revealed expression of the protein from 6 to 72 hr (fully sporulated) of sporulation and in sporozoites (SZ). SO7 was absent in host-derived second-stage merozoites (MZ) and was present in culture-derived first-stage MZ but at a level of only 25% of that exhibited by SZ. During invasion of Madin-Darby bovine kidney (MDBK) cells by SZ in vitro, the level of SO7 within cells, as determined by WB analysis, remained relatively constant until 48 hr of development and then decreased by about 40% at the next time point (72 hr). The SO7 secreted into the culture media during in vitro development increased to a relative maximum at 48 hr and then decreased to about 20% of maximum at 72 hr. Immunostaining with anti-rbSO7 indicates that SO7 is highly concentrated in both refractile bodies (RB) of SZ, with some limited distribution in the apical complex. Anti-rbSO7 intensively stained the intracellular parasites and the first-stage schizonts during in vitro development of E. tenella in MDBK cells. Upon release from the schizonts, the first-stage merozoites stained with 1 or 2 bright spots typically at each end. The results suggest that SO7 is closely associated with the SZ RB and is developmentally regulated but may not play a direct role in cellular invasion.

The purpose of this study was to determine whether activating the conjunctival macrophages would affect the course of Acanthamoeba spp. keratitis in a Chinese hamster model of this disease. Chinese hamster spleen cells were stimulated with concanavalin A (Con A), and interferon gamma (IFN-γ) –containing supernatants were collected 24 hr later. The IFN-γ–containing supernatants were loaded into liposomes, which were fed to peritoneal macrophages in vitro. Macrophage activation was assessed by testing for production of nitric oxide (NO) with the use of Griess reagent. Conjunctival macrophages were activated in situ by subconjunctival injection of liposomes containing Con A–activated spleen cell culture supernatants. Control liposomes were loaded with phosphate-buffered saline (PBS). Macrophages exposed to supernatants from Con A–stimulated spleen cells produced 4-fold-higher amounts of NO than unstimulated macrophages. Activation of macrophages via subconjunctival injection of liposomes containing supernatants from Con A–stimulated spleen cell cultures resulted in rapid resolution of the corneal infection. Approximately 80% of animals treated with PBS-containing liposomes demonstrated evidence of corneal disease at day 14 compared to 10% incidence of infection in the Con A–treated group. Moreover, at all time points examined, the clinical appearance of the keratitis in animals treated with liposomes containing Con A supernatant was significantly reduced compared to the group treated with liposomes containing PBS (P < 0.05). Macrophages stimulated with IFN-γ–containing supernatants killed significant numbers of the trophozoites in vitro (P < 0.05). Killing was inhibited by cytochalasin d, but not by l-N6-1-iminoethyl-l-lysine dihydrochloride (l-NIL), which is a selective inhibitor of inducible NO synthase (INOS).

Dilated cardiomyopathy (degeneration of heart muscle and heart enlargement) is an important cause of heart failure among young adults. Dilated cardiomyopathy may be a complication during or after various viral, bacterial, or parasitic diseases. Substance P (SP) is a neurotransmitter that is involved in the pathogenesis of various diseases. To determine whether SP is associated with cardiac changes in murine cysticercosis, we compared heart-weight to body-weight ratio, cardiac pathology, cardiomyocyte size, and cardiac-apoptosis (TUNEL assay) in hearts from Taenia crassiceps–infected (wild-type vs. SP-knockout) mice. We noted that, as compared with control uninfected wild-type mice, elevated protein levels of SP and its receptor as studied by ELISA or immunohistochemistry, respectively, were elevated in the hearts of parasite-infected wild-type mice. The heart-weight to body-weight ratios were significantly higher in the parasite-infected wild-type mice versus those of the infected SP-knockout mice. Furthermore, wild-type infected mice developed dilated cardiomyopathy with increased chamber size of both ventricles, decreased ventricular wall thickness, compensatory cardiomyocyte hypertrophy, and increased cardiac apoptosis. This cardiac pathology did not develop in mice lacking SP activity (i.e., in infected SP knockout mice) or in uninfected mice. These data indicate that SP is associated with cardiac changes in an animal model of parasitic dilated cardiomyopathy.

A new enteric nematode, Camallanus jiyuensis n. sp., is described from the intestine of the shokihaze goby, Tridentiger barbatus (Günther, 1861), collected from the beach of Jiyu Island, Amoy, southeast of China. The new species differs from its congeners mainly in the following combination of characters. The body is rather small in size, with 2 squarish, chitinized thickenings on the anterior border of the buccal capsule. The prongs of the trident are unequal. The nerve ring is near the posterior end of tridents. Cervical papillae are located in the middle of muscular esophagus. The excretory pore is located in the posterior third of muscular esophagus. Twelve pairs of pedunculate caudal papillae are present, of which 7 pairs are preanal and 5 are postanal. Spicules are similar, but subequal in length; the right and the left account for 9.8% and 8.9% of body length, respectively. The vulva does not protrude conspicuously from body surface and is located postequatorially.

A new nematode, Dentiphilometra lutjani n. sp. (Philometridae), is described from gravid females (the male is unknown) collected from the body musculature of the marine perciform fish gray snapper, Lutjanus griseus (Lutjanidae), from the Bay of Chetumal and southern coast of Quintana Roo, off the Caribbean coast of Mexico. The new species differs from the only other congener, Dentiphilometra monopteri, from the swamp eel Monopterus albus in China, mainly in the body length of gravid female (15.40–53.21 mm), the shape of the posterior body end (not markedly narrowed, with low caudal projections), the esophageal gland (maximum width near its posterior end), and the length (344–483 μm) of larvae from the uterus; both species also differ in their host types (marine perciform fish vs. freshwater swamp eel) and geographical distribution (Mexico vs. China).

Oochoristica whitfieldi n. sp., parasitizing the intestine of the Oaxacan black iguana Ctenosaura oaxacana (Kohler and Hasbun, 2001), in Ruinas de Guiengola, Oaxaca state, Mexico, is described. The new species can be distinguished from all 4 congenera infecting Iguanidae in the neotropical realm in possessing a lower mean number of testes (122 in O. acapulcoensis Brooks, Pérez-Ponce de León, and García-Prieto, 1999; 62 in O. guanacastensis Brooks, Pérez-Ponce de León, and García-Prieto, 1999, and 95 in O. leonregagnonae Arizmendi-Espinosa, García-Prieto, and Guillén-Hernández, 2005, vs. 35 in O. whitfieldi), and a wider scolex (0.450–0.600, 0.475–0.537, 0.5–0.8, vs. 0.25–0.26, respectively). Oochoristica iguanae Bursey and Goldberg, 1996 differs from the new Mexican species in having a longer strobila (60–110 mm vs. 14.4–33.7 mm, respectively), fewer ovarian sublobes (6 vs. 11–17), and a cirrus pouch that hardly reaches excretory canals (whereas in O. whitfieldi the cirrus pouch widely overpasses these canals).

Among genera of the ostertagiine nematodes, structural attributes of Spiculopteragia caballeroi are consistent with criteria that diagnose the genus Sarwaria. Specifically, the following characters are compatible with referral to this genus: (1) species characterized by monomorphic males; (2) tapering lateral synlophe in the cervical zone; (3) minuscule, thornlike cervical papillae; (4) length of Ray “4” < Ray “5”; (5) relatively thick or robust Ray “4”; (6) a substantially reduced dorsal lobe and dorsal ray that are disposed or curved ventrally relative to Rays “8”; and (7) a broad, laterally inflated dorsal lobe. Consequently, we propose Sarwaria caballeroi n. comb., and we provide further validation for the genus Sarwaria. Additionally, we propose that the ostertagiines are represented by 12 valid genera, including those characterized by a bursal formula of 2-2-1 (Cervicaprastrongylus, Hyostrongylus, Mazamastrongylus, Spiculopteragia, and Teladorsagia in addition to Sarwaria), and those in which the lateral rays describe a 2-1-2 pattern (Camelostrongylus, Longistrongylus, Marshallagia, Orloffia, Ostertagia, and Pseudomarshallagia).

Hydromermis osami n. sp. (Nematoda: Mermithidae) is described from the hemocoel of 2 species of Rheotanytarsus chironomid imagos eclosing from Lake Ozawindib and Gulsvig Landing in northern Minnesota during August 2002 and June and July 2006. The species is distinguished from the other 26 described members of the genus by the terminal mouth; oval, opaque, thick walled amphids, wider than long; acute posterior end; single spicule not bifurcated proximally; well-developed uterine and vulval limbs of the S-shaped vagina; absence of bursal sleeve; absence of nutrient vesicles in the trophosome; and an esophagus length over 40% of body length. Members of the new species emerge from the hosts as adults. The other described Hydromermis species, number of specimens, location, and known hosts are tabulated.

The following new gregarine taxa are described from larvae of flour beetles (Coleoptera: Tenebrionidae): Awrygregarina billmani, n. gen., n. sp., from Tribolium brevicornis; Gregarina cloptoni, n. sp., from Tribolium freemani; Gregarina confusa, n. sp., from Tribolilum confusum; and Gregarina palori, n. sp., from Palorus subdepressus. In addition, the description of Gregarina minuta Ishii, 1914, from Tribolium castaneum, is emended. Scanning electron micrograph studies of these species' oocysts reveal differences in surface architecture. The Gregarina species have oocysts with longitudinal ridges, visible with SEM, whereas Awrygregarina billmani oocysts have fine circumferential striations; surface architecture is the main feature distinguishing the 2 gregarine genera. Although parasites from adult beetles are not included in the descriptions, adults of all host species can be infected experimentally using oocysts from the new taxa.

Rhabdias kuzmini n. sp., a parasite of the lungs of Bufo occidentalis, is described and illustrated. This Mexican taxon differs from the related species in the genus by the possession of 4 lips (2 subdorsal and 2 subventral) and 2 lateral pseudolabia, corpus not inflated, a larger barrel-shaped buccal capsule, equatorial vulva, and the presence of a slightly swollen cuticle in the anterior and posterior ends of the body. This is the 16th species described in the Neotropical Realm and the first species of Rhabdias described from endemic anurans in México.

In this study, we describe 2 new species of Ascarophis van Beneden, 1871 (Nematoda: Cystidicolidae), found in fishes from southern Chile. Ascarophis carvajali n. sp. was found in Austrolycus depressiceps and Patagonotothen cornucola, whereas Ascarophis draconi n. sp. was taken from Champsocephalus gunnari. These new Ascarophis species differ from other species in a combination of several morphometric and morphological characteristics. Although A. carvajali n. sp. was morphologically close to Ascarophis minuta, the new species has a larger ratio between glandular and muscular esophagus, filaments on both egg poles, and a shorter right spicule than A. minuta. Ascarophis draconi n. sp. was morphologically similar to Ascarophis adioryx and Ascarophis filiformis. However, A. adioryx has eggs without filaments, a smaller ratio between glandular and muscular esophagus length, and a smaller ratio between left and right spicule lengths in contrast to A. draconi n. sp., whereas A. filiformis has a shorter glandular esophagus and left spicule length than A. draconi n. sp. Only 1 Ascarophis species has been recorded in a single fish from Chile (i.e., Ascarophis sebastodis in Sebastes capensis). Consequently, this study constitutes not only new species and records of Ascarophis in fishes from Chile, but also new records for the Pacific coast of South America.

Hepatozoon ayorgbor n. sp. is described from specimens of Python regius imported from Ghana. Gametocytes were found in the peripheral blood of 43 of 55 snakes examined. Localization of gametocytes was mainly inside the erythrocytes; free gametocytes were found in 15 (34.9%) positive specimens. Infections of laboratory-reared Culex quinquefasciatus feeding on infected snakes, as well as experimental infection of juvenile Python regius by ingestion of infected mosquitoes, were performed to complete the life cycle. Similarly, transmission to different snake species (Boa constrictor and Lamprophis fuliginosus) and lizards (Lepidodactylus lugubris) was performed to assess the host specificity. Isolates were compared with Hepatozoon species from sub-Saharan reptiles and described as a new species based on the morphology, phylogenetic analysis, and a complete life cycle.

A description is presented of a new species of Subulura Molin, 1860, Subulura novomexicanus, collected from the spotted ground squirrel, Spermophilus spilosoma Bennett, 1833, in New Mexico. The males are 24 to 29 mm long, precloacal sucker 1.7–2.0 mm from posterior end, spicules subequal 0.83–1.0 long, and gubernaculum Y-shaped 0.21–0.39 mm long. Females are 34–39 mm long, vulva near middle of body 14.06–22.00 mm from anterior end, and eggs 0.04–0.05 mm long by 0.03–0.04 mm wide. The new species is distinguished from Subulura ungulatus Erickson, 1938 in being longer and having spicules that are distinctively different in size and form. It also differs from Subulura nevadense Babero, 1973 in being longer and having a larger egg size and smaller spicules. The new species is most similar to Subulura andersoni (Cobbold, 1876) (Thwaite, 1927); however, the males of this species are smaller and they have broad cervical alae, and the adults occur in squirrels of India. Reexamination of S. ungulatus showed 11 pairs of caudal papillae, including 4 pairs of preanals, 1 pair adanal and lateral, and 6 pairs of postanal papillae located at the end of the tail. Spermophilus richardsoni (Sabine, 1822) is a new host record for S. nevadense, and Montana is a new distributional record for this nematode. Eimeria callospermophili Henry, 1932, is a new record for S. spilosoma.

Alkyl-lysophospholipids (ALPs), developed initially to be antitumor agents, have proved highly effective in the treatment of visceral leishmaniasis, a disease caused by the species making up the protozoan complex Leishmania donovani. Although their effectiveness is known, the mode of action against this parasite is not completely understood. In the present work, we have studied the effect of 3 derivatives, edelfosine, miltefosine, and ilmofosine. Using nuclear magnetic resonance spectroscopy (¹H-NMR), we have examined the excreted catabolites from glucose metabolism in the promastigote forms treated with these compounds. The ALPs at concentrations of 19 and 38 μM inhibit the excretion of acetate, succinate, and pyruvate. The effect of edelfosine, miltefosine, and ilmofosine on the activity of the enzymes hexokinase, glycerolkinase 3-PD, phosphoglucose isomerase, superoxide dismutase, and phospholipase C were also examined. Glycerolkinase 3-PD and phosphoglucose isomerase are generally insensitive to the compounds, whereas hexokinase and superoxide dismutase are inhibited by miltefosine and ilmofosine. The ALPs exhibited an activated effect against the phospholipase C activity. Alkyl-lysophospholipids were shown to have a significant effect on several enzymes in important biochemical pathways indispensable for the survival of L. donovani promasigotes.

Because the synthetic trioxolane OZ78 is active against the liver fluke Fasciola hepatica, we were motivated to investigate the in vivo and in vitro activity against another liver fluke, namely Clonorchis sinensis. Rats infected with C. sinensis for 2 and 5 wk were treated orally with single doses of OZ78 (75, 150, or 300 mg/kg). Worm burden reductions were assessed against untreated control rats. Scanning electron microscopy (SEM) was used to observe adult C. sinensis after recovery from rats 1–3 days posttreatment with a single 300 mg/kg oral dose of OZ78 and after in vitro exposure to concentrations of 1, 10, and 100 μg/ml of OZ78. A single 300 mg/kg oral dose of OZ78 resulted in worm burden reductions of 78.5% and 98.5% against juvenile and adult C. sinensis, respectively. SEM observations revealed tegumental surface alterations, including blebbing and sloughing. OZ78 emerges as a new compound with a broad spectrum of activity against major foodborne trematode infections.

The prevalence of antibodies to Toxoplasma gondii was determined in sera from 105 domestic cats from Durango City, Mexico. Using a modified agglutination test, antibodies to this parasite were found in 21% of the 105 cats, with titers of 1:25 in 3 cats, 1:50 in 4 cats, 1:200 in 5 cats, 1:400 in 2 cats, 1:800 in 2 cats, 1:1,600 in 4 cats, and 1:3,200 or higher in 2 cats. Cats older than 1 yr had a significantly higher frequency of infection than that found in cats younger than 0.5 yr (41 vs. 13.2%, respectively; odds ratio = 4.55; 95% CI = 1.24– 17.18; P = 0.01). Overall, the seroprevalence of T. gondii antibodies in cats in Durango, Mexico, is much lower compared with those reported in other countries.

In the Czech Republic, sera from 720 wild ruminants were examined for antibodies to Neospora caninum by screening competitive-inhibition enzyme-linked immunosorbent assay and confirmed by indirect fluorescence antibody test (IFAT); the same sera were also examined for antibodies to Toxoplasma gondii by IFAT. Neospora caninum antibodies were found in 14% (11 positive/79 tested) roe deer (Capreolus capreolus), 14% (2/14) sika deer (Cervus nippon), 6% (24/ 377) red deer (Cervus elaphus), 1% (2/143) fallow deer (Dama dama), 3% (3/105) mouflon (Ovis musimon), and none of 2 reindeer (Rangifer tarandus). Toxoplasma gondii antibodies were found in 50% (7/14) sika deer, 45% (169/377) red deer, 24% (19/79) roe deer, 17% (24/143) fallow deer, 9% (9/105) mouflon, and 1 of 2 reindeer. In 42 samples of wild ruminants that tested positive for N. caninum antibodies, 28 (67% of the positive N. caninum samples) reacted solely to N. caninum. This is the first evidence of N. caninum infection in mouflon, the first N. caninum seroprevalence study in farmed red deer, and the first survey of N. caninum in wild ruminants from the Czech Republic.

A survey was undertaken to identify metazoan ectoparasite species on the European flounder, Platichthys flesus (Linnaeus, 1758), in 4 different locations off the north-central Portuguese coast. Parasites of 7 different taxa were found: Caligus diaphanus, Caligus sp., and Lepeophtheirus pectoralis (Copepoda: Caligidae); Acanthochondria cornuta (Copepoda: Chondracanthidae); Holobomolochus confusus (Copepoda: Bomolochidae); Nerocila orbignyi (Isopoda: Cymothoidae); and praniza larvae (Isopoda: Gnathiidae). Lernaeocera branchialis, a common European flounder parasite in the North and Baltic Seas, was not observed among the surveyed fish. Caligus diaphanus, Caligus sp., and Nerocila orbignyi are new host records. The high prevalence and intensity values recorded for L. pectoralis and A. cornuta suggest that both parasite species are common to the European flounder along the north-central Portuguese coast. In contrast, infection levels with respect to the other parasite taxa were, in most cases, comparatively lower, thereby indicating that they only occur occasionally among flounders in the surveyed area.

Sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis (EPM), a neurologic disease of the horse. In the present work, the kinetics of S. neurona invasion is determined in the equine model. Six ponies were orally inoculated with 250 × 10⁶ S. neurona sporocysts via nasogastric intubation and killed on days 1, 2, 3, 5, 7, and 9 postinoculation (PI). At necropsy, tissue samples were examined for S. neurona infection. The parasite was isolated from the mesenteric lymph nodes at 1, 2, and 7 days PI; the liver at 2, 5, and 7 days PI; and the lungs at 5, 7, and 9 days PI by bioassays in interferon gamma gene knock out mice (KO) and from cell culture. Microscopic lesions consistent with an EPM infection were observed in brain and spinal cord of ponies killed 7 and 9 days PI. Results suggest that S. neurona disseminates quickly in tissue of naive ponies.

Plagiorchis vespertilionis (Digenea: Plagiorchiidae) is generally considered a bat parasite, but here it is reported for the first time in a human. The patient was a 34-yr-old male who lived in a coastal village of Haenam-gun (county), Jeollanam-do (province), Republic of Korea. Only 1 worm, 2.6 mm long and 0.7 mm wide, was recovered after praziquantel treatment and purging with magnesium salts. The fluke was characterized by a large body size, a sucker ratio of 1:1, a straight cirrus organ, a short distance between the ventral sucker and ovary, well-developed vitellaria, a uterus with descending and ascending loops, and fully developed eggs with an average size of 32.5 × 17.5 μm. The patient had habitually eaten the raw flesh of snakehead mullet and gobies that had been caught near his village. The present case represents the first record of a human P. vespertilionis infection.

A study was conducted to ascertain the influence of a thermal discharge on the health and parasites of a coastal cold-water flatfish, the winter flounder (Pleuronectes americanus), a species sensitive to environmental change. Flounder were sampled in spring 1998 and 1999 beneath the plume and at reference sites north and south up to 1 km from the discharge. Species diversity and estimates of abundance of macroscopic algae, invertebrates, and fish were also recorded. After capture by scuba divers, a comparison of condition factor, organ indices, blood values, histology, and parasites was made between groups of fish from the discharge and reference sites. Diversity and abundance of algae, invertebrates, and fish were considerably greater beneath the plume than at the reference sites. The thermal water had no apparent effect on flounder taken beneath the plume, but it affected both its ecto- and endoparasites. Prevalence and mean abundance of Cryptocotyle lingua metacercariae were significantly greater, whereas Trichodina jadranica and Gyrodactylus pleuronecti were less on the gills of fish sampled beneath the plume than at the reference sites. Four endoparasites, i.e., Ceratomyxa drepanopsettae, Steringophorus furciger, Macvicarius soleae, and Lecithaster gibbosus were significantly more abundant in the reference samples. These results suggest that environmental change affected transmission of the parasites of winter flounder exposed to the thermal effluent.

Eighty-eight fecal samples from 2 species of pika, Ochotona collaris and Ochotona hyperborea, collected in Alaska (N = 53) and Russia (N = 35), respectively, were examined for the presence of coccidia (Apicomplexa: Eimeriidae). Five oocyst morphotypes were observed. In O. collaris, we found Eimeria calentinei, Eimeria cryptobarretti, and Eimeria klondikensis, whereas in O. hyperborea, we found Eimeria banffensis, E. calentinei, E. cryptobarretti, E. klondikensis, and Isospora marquardti. This study represents new geographic records for all 5 coccidia and new host records for E. cryptobarretti and I. marquardti. Only minor quantitative differences were seen between the sporulated oocysts we studied and those reported in their original descriptions.

Increased reporting of amphibian malformations in North America has been noted with concern in light of reports that amphibian numbers and species are declining worldwide. Ribeiroia ondatrae has been shown to cause a variety of types of malformations in amphibians. However, little is known about the prevalence of R. ondatrae in North America. To aid in conducting field studies of Ribeiroia spp., we have developed a polymerase chain reaction (PCR)-based diagnostic. Herein, we describe the development of an accurate, rapid, simple, and cost-effective diagnostic for detection of Ribeiroia spp. infection in snails (Planorbella trivolvis). Candidate oligonucleotide primers for PCR were designed via DNA sequence analyses of multiple ribosomal internal transcribed spacer-2 regions from Ribeiroia spp. and Echinostoma spp. Comparison of consensus sequences determined from both genera identified areas of sequence potentially unique to Ribeiroia spp. The PCR reliably produced a diagnostic 290-base pair (bp) product in the presence of a wide concentration range of snail or frog DNA. Sensitivity was examined with DNA extracted from single R. ondatrae cercaria. The single-tube PCR could routinely detect less than 1 cercariae equivalent, because DNA isolated from a single cercaria could be diluted at least 1:50 and still yield a positive result via gel electrophoresis. An even more sensitive nested PCR also was developed that routinely detected 100 fg of the 290-bp fragment. The assay did not detect furcocercous cercariae of certain Schistosomatidae, Echinostoma sp., or Sphaeridiotrema globulus nor adults of Clinostomum sp. or Cyathocotyle bushiensis. Field testing of 137 P. trivolvis identified 3 positives with no overt environmental cross-reactivity, and results concurred with microscopic examinations in all cases.

The distribution of single cysticerci between cerebral hemispheres was studied in 227 adult cases of calcified and vesicular neurocysticercosis (NC). A rightward lateralization of calcified cysticerci was significant only in women, whereas vesicular cysticerci were equally distributed in both hemispheres. Factors related with the differences in the inflammatory response and in the regional cerebral blood flow between genders could be involved.

Trematodes amplify asexually in their snail intermediate hosts, resulting in the potential release of hundreds to thousands of free-living cercariae per day for the life of the snail. The high number of cercariae released into the environment undoubtedly increases the probability of transmission. Although many individual cercariae successfully infect another host in their life cycle, most fail. Factors that prevent successful transmission of cercariae are poorly understood. Microcrustaceans and fish have been observed to eat cercariae of some species, although the possibility that predation represents a significant source of mortality for cercariae has been largely unexplored. We tested the cercariophagic activity of several freshwater invertebrates on Ribeiroia ondatrae, a trematode that causes limb deformities in amphibians. Individuals of potential predators were placed into wells of multiwell plates with 10–15 cercariae, and numbers of cercariae remaining over time were recorded and compared with numbers in control wells that contained no predators. Of the species tested, Hydra sp., damselfly (Odonata, Coenagrionidae) larvae, dragonfly (Odonata, Libellulidae), larvae, and copepods (Cyclopoida) consumed cercariae. In some cases, 80– 90% of the cercariae offered to damselfly and dragonfly larvae were consumed within 10 min. In most cases, predators continued to consume cercariae at the same average rates when offered cercariae together with individuals of an alternate prey item. Hydra sp. ate fewer cercariae in these trials. Our findings suggest the need for field and laboratory studies to further explore the effects of predators on transmission of R. ondatrae to amphibian larvae. In addition, the results suggest that conservation of the biodiversity and numbers of aquatic predators may limit adverse impacts of trematode infections in vertebrate hosts.

The present study examined phenotypic variation in infectivity of Diplostomum spathaceum (Trematoda) cercariae within a natural population. Twelve infected Lymnaea stagnalis were collected from the field, and the infectivity of cercariae from individual snails was assessed under constant laboratory conditions. At a water temperature of 16.3 C, the mean infectivity of cercariae from the snails varied between 55.5% and 87.5%. Depending on the source of variation, this may have important ecological and evolutionary implications for both natural parasite populations and those occurring in aquaculture.

The decreasing extent of sea-ice in the arctic basin as a consequence of climatic warming is modifying the behavior and diets of pagophilic pinnipeds, including the Pacific walrus, Odobenus rosmarus divergens Illiger, the species emphasized here. Mammals such as the walrus and bearded seal, Erignathus barbatus (Erxleben), cannot remain associated with the sea-ice, and continue to feed on their usual diet of benthic invertebrates inhabiting coastal waters to a depth of approximately 100 m, when the northwestward retreating ice reaches deep waters beyond the margins of the continental shelf. With reduction of their customary substrate (ice), the walrus has become more pelagic and preys more often on ringed seals, Phoca hispida Schreber. Dietary changes, with modifications of helminth faunas, may be induced by various factors. Increased consumption of mammals or their remains by walruses may lead to a higher prevalence of trichinellosis in them and to more frequent occurrence in indigenous peoples inhabiting the arctic coasts. To assess predicted effects on the composition of helminth fauna of the walrus, we recommend systematic surveys of their helminths as part of research on effects of climatic warming.