Thioredoxin reductase (TrxR), an enzyme belonging to the flavoprotein family of pyridine nucleotide-disulfide oxidoreductases, was isolated from the deoxycholate-soluble extract of the common liver fluke, Fasciola hepatica. Purification to homogeneity of the 60-kDa enzyme from the adult worm was achieved by a combination of ammonium sulfate fractionation, anion exchange, and affinity chromatography on 2′,5′-adenosine diphosphate–Sepharose. Using the 5,5′-dithiobis(2-nitrobenzoic acid) assay, the purified TrxR showed a specific activity of 7,117 U min⁻¹ mg⁻¹. The enzyme activity was completely inhibited by the presence of the gold compound aurothioglucose (IC₅₀ = 120 nm), indicating that F. hepatica TrxR is a selenoenzyme. Also, the enzyme was capable of reducing disulfide bonds in insulin and was activated by the presence of the reduced form of flavin adenine dinucleotide, properties shared with mammalian TrxRs. Furthermore, the isolated enzyme showed very low glutaredoxin (Grx) activity (0.47 U mg⁻¹), but no glutathione reductase activity was detected. Affinity-purified IgGs (20 μg ml⁻¹) from the antisera produced against the purified TrxR inhibited its activity about 80% with respect to the control. The enzyme was immunolocalized in cells located within the parenchyma and in the testes, but it was not found in the tegument of the adult fluke.

To explore the mechanisms by which Cryptosporidium parvum infects epithelial cells, we performed a detailed morphological study by serial electron microscopy to assess attachment to and internalization of biliary epithelial cells by C. parvum in an in vitro model of human biliary cryptosporidiosis. When C. parvum sporozoites initially attach to the host cell membrane, the rhoptry of the sporozoite extends to the attachment site; both micronemes and dense granules are recruited to the apical complex region of the attached parasite. During internalization, numerous vacuoles covered by the parasite's plasma membrane are formed and cluster together to establish a preparasitophorous vacuole. This preparasitophorous vacuole comes in contact with host cell membrane to form a host cell–parasite membrane interface, beneath which an electron-dense band begins to appear within the host cell cytoplasm. Simultaneously, host cells display membrane protrusion along the edge of the host cell– parasite membrane interface, resulting in the formation of a mature parasitophorous vacuole that completely covers the parasite. During internalization, vacuole-like structures appear in the apical complex region of the attached sporozoite, which bud out into host cells. A tunnel directly connecting the parasite to the host cell cytoplasm forms during internalization and remains when the parasite is totally internalized. Immunoelectron microscopy showed that sporozoite-associated proteins were localized along the dense band and at the parasitophorous vacuole membrane. These morphological observations provide evidence that secretion of parasite apical organelles and protrusion of host cell membrane play an important role in the attachment and internalization of host epithelial cells by C. parvum.

The monogenean Ligophorus chabaudi was originally described on the gills of the flathead mullet, Mugil cephalus, and was subsequently reported on the So-iuy mullet, Mugil soiuy. However, the morphology of sclerotized parts and multivariate statistical analyses suggest that the form from the So-iuy mullet represents a new species. This study provides a description of the new species Ligophorus pilengas n. sp. and provides additional morphological data concerning the morphology of the ventral bar that might be useful for the diagnosis of Ligophorus. Ligophorus pilengas n. sp. is the second species of Ligophorus reported on the So-iuy mullet. Zoogeographical records indicate that L. pilengas n. sp. was probably introduced to the Black Sea and the Sea of Azov from the western Pacific Ocean together with its host.

A study was conducted to determine the effects, geographical distribution, and prevalence of a microsporan parasite, Glugea stephani, in winter flounder (Pleuronectes americanus) in Newfoundland. Fish were captured by SCUBA divers in several coastal areas, including 2 embayments where pulp and paper mill effluent was discharged, as well as a number of pristine sites. Fish health was assessed by comparing histological profiles, condition factors (K), organosomatic indices and blood values between infected and uninfected samples. Multifocal xenomas of G. stephani were observed in several organs of fish taken near contaminated sites, whereas infected samples captured at a pristine site harbored the cysts only in the wall of the digestive tract. Proliferative inflammation, granuloma formation, and focal necrosis were associated with the infection primarily in the liver and kidney. Condition factors and blood values were lower and ovarian development inhibited or delayed in infected flounder. The multifocal infection occurred only in flounder in 2 embayments in western Newfoundland where pulp and paper mill effluent was discharged. Prevalence varied seasonally, with a peak in autumn and a low in spring. It is likely that the multifocal infection was associated with immunodepression after exposure to the contaminant.

A sample of 114 isolates of Echinococcus granulosus (Cestoda: Taeniidae) collected from different host species and sites in Argentina has been sequenced for 391 bp from the mitochondrial cytochrome c oxidase subunit I gene to analyze genetic variability and population structure. Nine different haplotypes were identified, 5 of which correspond to already characterized strains. Analysis of molecular variance and nested clade analysis of the distribution of haplotypes among localities within 3 main geographic regions indicate that geographic differentiation accounts for the overall pattern of genetic variability in E. granulosus populations. Significant geographic differentiation is also present when the sheep strain alone is considered. Our results suggest that geographic patterns are not due to actual restricted gene flow between regions but are rather a consequence of past history, probably related to the time and origin of livestock introduction in Argentina.

To complete their life cycle, gordiids must make a transition from aquatic to terrestrial environments. However, epibenthic aquatic larvae and their terrestrial definitive hosts do not overlap in habitat. This has led many investigators to suggest that infections are acquired through the ingestion of insects, which become infected as aquatic larvae with gordiid cysts and subsequently carry gordiids to land. This proposed life cycle was experimentally tested using 3 common American species of gordiids: Gordius robustus, Paragordius varius, and Chordodes morgani. Cysts of all 3 species survived the metamorphosis of Tanytarsus sp., a midge. Subsequent infection trials of definitive hosts with cysts from imagos show that cysts surviving the metamorphosis of insects remained viable and free of host internal defense reaction. Data from naturally infected mayflies, Callibaetus sp., show that encystment and survival of gordiids within aquatic insects occur in nature. Paratenesis between paratenic hosts was also shown to be possible in these 3 species. This latter finding appears to indicate that cysts formed in spurious paratenic hosts may not be lost but may eventually transfer to normal paratenic hosts.

Experimental Parelaphostrongylus tenuis infections were established in white-tailed deer (Odocoileus virginianus) and an atypical host, red deer (Cervus elaphus elaphus). Groups of deer were fed 10, 25, or 100 third-stage larvae (L3) of P. tenuis and received a single equivalent challenge exposure at varying intervals. Infections were monitored up to 6 yr in white- tailed deer and up to 2.8 yr in red deer. The prepatent period in white-tailed deer varied from 91 to 1,072 days (381 ± 374) and in red deer from 105 to 358 days (167 ± 77). Adult worms lived for up to 6 yr in white-tailed deer. Although most had patent infections until necropsy, latent periods were observed regardless of season. Adult worms lived for up to 2.8 yr in red deer, and patent infections persisted for 20–363 days (152 ± 106). Patent infections were correlated with the presence of adult worms in blood vessels and sinuses of both deer species. Worms were restricted to the subdural space in all deer with latent and occult infections. Adult worm recovery in white-tailed deer fed 10 or 25 L3 corresponded to the mean intensities reported in natural infections of white-tailed deer. Recovery from deer fed 100 L3 was not typical of natural infection intensities. Adult P. tenuis established in all groups of red deer, but neurologic disease was restricted to animals fed 100 L3. Acute neurologic disease was associated with subdural hemorrhage and occurred at 11 mo postinfection in 2 red deer. The absence of postchallenge patent periods and the persistence of occult infections indicated that challenge exposures did not establish. These data indicate that acquired immunity to P. tenuis was established by 6 mo postinfection in both white-tailed and red deer. Latent periods in white- tailed deer and latent infections in red deer reinforce the need for a reliable diagnostic assay.

Laboratory-reared animals were used to assess the susceptibility of seals (Halichoerus grypus) to Toxoplasma gondii infection. Four seals were each orally inoculated with 100 or 10,000 oocysts of T. gondii (VEG strain), and another 4 seals served as negative controls. Occasionally, mild behavioral changes were observed in all inoculated seals but not in control animals. A modified agglutination test revealed the presence of antibodies to T. gondii in sera collected from inoculated seals and mice inoculated as controls. No evidence of the parasite was found on an extensive histological examination of seal tissues, and immunohistochemical staining of tissue sections from inoculated seals revealed a single tissue cyst in only 1 seal. Control mice inoculated with 10 oocysts from the same inoculum given to seals became serologically and histologically positive for T. gondii. Cats that were fed brain or muscle tissue collected from inoculated seals passed T. gondii oocysts in feces. This study demonstrates that T. gondii oocysts can establish viable infection in seals and supports the hypothesis that toxoplasmosis in marine mammals can be acquired from oocysts in surface water runoff and sewer discharge.

A total of 8 helminth species were recorded in an examination of 43 tropical gar, Atractosteus tropicus Gill, collected at the Pantanos de Centla Biosphere Reserve, Tabasco, Mexico. The parasite species included 1 adult trematode, 3 metacercariae, 1 cestode, 1 adult nematode, and 2 nematode larvae. Six of these 8 species were rare, with low prevalence (<17%) and abundance (<1.0 helminths per examined fish). The larvae of Contracaecum sp. were the most abundant in the sample, constituting 60% of the total helminths (64% prevalence, 3.8 ± 5.2 abundance), followed by the cestode Proteocephalus singularis, constituting 18% of the worms (30.5% prevalence, 1.1 ± 3.0 abundance). Species richness, individual parasite abundance, and diversity were low in the infracommunities. The recording of 3 specialist species in the tropical gar confirms that the helminth fauna of gar has an appreciable degree of specificity. This study indicates the importance of ecological determinants of richness in helminth communities of the tropical gar.

A survey of gastrointestinal helminth communities of Gallotia caesaris caesaris (Lehrs, 1914) and G. c. gomerae (Boettger and Müller, 1914), from the islands of El Hierro and La Gomera, respectively, in the Canary Archipelago, Spain, was conducted to determine the prevalence, intensity, and diversity of intestinal parasites of these lacertid lizards. Larval forms of cestodes, nematodes, and acanthocephalans were found in the body cavity of G. c. caesaris; this lizard is the intermediate or paratenic host in the life cycle of these helminths. Pharyngodonid nematodes were the most common intestinal helminths in both hosts, 4 of them being Gallotia spp. specialists. Helminth infracommunities of both hosts were depauperate and isolationist, according to the low values of helminth diversity.

Maritrema novaezealandensis n. sp. is described from Otago Harbor, South Island, New Zealand, on the basis of adult specimens collected from the Red-billed gull, Larus novaehollandiae scopulinus, and excysted metacercariae obtained from crabs. It belongs to the “eroliae group” and differs from other related species mainly in the shape, size, and patterns of distributions of the spines on the cirrus, the shape of the metraterm, the presence of an unlobed ovary, and the complete ring of the vitelline follicles. Based on morphometric features of metacercariae and adult specimens, the trophic relationships among invertebrate and vertebrate hosts, experimental infections, and previous reports of species of Maritrema with similar transmission patterns, the life cycle of M. novaezealandensis n. sp. is described. A 3-host life cycle is proposed for this parasite. The first intermediate host is the mud snail, Zeacumantus subcarinatus, in which the cercarial stage is produced in sporocysts located within the gonad of the snail. At least 3 crab species (Hemigrapsus crenulatus, Macrophtalmus hirtipes, and Halicarcinus whitei) and several species of amphipods act as second intermediate hosts, with metacercariae encysted in the body cavity of the crustacean host. Finally, the definitive host, the gull, L. n. scopulinus, harbors the adult worms in its intestine.

A gene encoding superoxide dismutase (SOD) from Neospora caninum, a causative agent of neosporosis, has been cloned and its gene product functionally expressed and characterized. The gene had an open reading frame of 606 bp and deduced 201 amino acids. Sequence analysis showed that the gene had conserved metal-binding residues and conserved amino acid residues that were found in Fe-SODs. Comparison of the deduced amino acid sequence of the enzyme with previously reported Fe-SOD amino acid sequences of the other parasitic protozoans revealed significant high homology. The coding region of the N. caninum Fe-SOD was cloned and functionally expressed in Escherichia coli. Enzyme activity of the expressed protein was inhibited by hydrogen peroxide but not by sodium azide and potassium cyanide, and the enzyme showed similar biochemical properties with typical Fe-SODs of other parasitic protozoans. Southern blot analysis showed that the SOD gene appears to be present as a single-copy gene in N. caninum genome. Semiquantitative reverse transcription–polymerase chain reaction and immunoblot using antiserum raised against the purified recombinant protein showed that Fe-SOD is expressed in both developmental stages of N. caninum, i.e., in bradyzoites and tachyzoites. In an immunofluorescence assay, the enzyme was localized on the cell surface of N. caninum tachyzoites. These results suggest that Fe-SOD might be essential for the intracellular survival of N. caninum and may play an important role in the pathogenesis of the parasite by protecting the parasite from oxidative killing.

The spiral intestines of 7 Tawny nurse sharks (Nebrius ferrugineus; Rhincodontidae) from Australia and French Polynesia were examined for tapeworms. These sharks hosted 5 new species of Pedibothrium. The 5 species were prepared for light and scanning electron microscopy. Whereas 3 of the species exhibit the bipronged hooks typical of members of Pedibothrium, 1 species was found to possess tiny unipronged hooks or to lack some, or all, hooks, and all individuals of the fifth species appeared to lack bothridial hooks entirely. Nonetheless, the otherwise remarkable similarities between these species and the species of Pedibothrium bearing bipronged hooks were considered to be sufficient to justify the placement of these 2 species in this genus. All 5 species possess proglottid features typical of Pedibothrium, including a uterus that extends anteriorly only to the level of the cirrus sac and a cirrus sac that is bent anteriorly and is crossed by the vagina. All 5 species also exhibit uniloculated bothridia. Of particular note was the fact that all 5 species exhibit bladelike spinitrichs with elongated distal tips, a form of microthrix currently known only from species of Pedibothrium. As a consequence, these species were treated as possessing modified hooks or as having lost hooks. The diagnoses of Pedibothrium and Onchobothriidae were emended to include these species. Each of the 5 new species bears a strong resemblance to 1 or more species of Pedibothrium hosted by a species of rhincodontid shark other than N. ferrugineus. Much of Southwell's type and voucher material of Pedibothrium was located and used to verify the identity of Pedibothrium kerkhami and many of the hosts from which Southwell's material of Pedibothrium was collected. This material suggests that P. kerkhami parasitizes Stegostoma fasciatum and not N. ferrugineus.

Naiadocystis phykoterion n. gen., n. sp. (Apicomplexa: Eugregarinida: Hirmocystidae), is described from the Mexican pygmy grasshopper, Paratettix mexicanus (Orthoptera: Tetrigidae), collected from sandbars along Harmon Creek, Walker County, Texas, in the western edge of the Texas Big Thicket. Naiadocystis n. gen. is distinguished by the form of the epimerite complex, a simple cordoid or toroid epimerite with an interior obconoid structure resembling a funnel that tapers to a distinct axial canal bisecting the protomerite, which is conspicuous in all stages of development, and a satellite protomerite reduced to a linearly crateriform cup or sucker that receives and enfolds posterior end of primite deutomerite. Association is precocious, caudofrontal, and biassociative. Gametocysts are spherical. Sporoducts are present but vestigial and irregular in number. Oocysts are broadly elliptoid with 4 small spherical polar knobs, 1 each at 30°, 150°, 210°, and 330°, and dehisce en masse. The species described herein are differentiated by their overall size and relative proportion of cellular structures. Naiadocystis acantholobae (Hoshide, 1952) n. comb., Naiadocystis acrydiinarum (Semans, 1939) n. comb., and Naiadocystis tetrigis (Corbel, 1968) n. comb. are recognized as members of Naiadocystis previously placed within Gregarina (Apicomplexa: Eugregarinida: Gregarinidae).

In this article, we describe a new species of Himasthla Dietz, 1909 (Digenea: Echinostomatidae) from Larus dominicanus Lichtenstein (Aves: Laridae) in northern Patagonia, Argentina. We also describe the hosts, localities, and key diagnostic features and the measurements of the so far 25 described species. Of these species, Himasthla militaris, H. leptosoma, H. elongata, H. secunda, H. megacotyla, H. multilecithosa, H. piscicola, H. compacta, H. schachtachtinskoi, H. littorinae, H. continua, H. avosettae, and H. interrupta are similar to H. escamosa n. sp. in having 29 head collar spines. Himasthla leptosoma, H. piscicola, H. multilecithosa, H. interrupta, H. continua, and H. militaris can be differentiated from the new species mainly by the extension of the vitellaria. Himasthla avosettae, H. megacotyla, H. elongata, H. compacta, and H. littorinae have a different size or arrangement (or both) of head collar spines compared with H. escamosa. Himasthla secunda can be distinguished from H. escamosa n. sp. in having a larger body, testes, and ovary and a different position of the ovary. The comparison with H. schachtachtinskoi could not be done because the bibliography was not available. This is the first record of the genus in Argentina and from L. dominicanus.

Bathycestus brayi n. gen., n. sp. (Pseudophyllidea: Triaenophoridae) is proposed to accommodate a new cestode from a deep-sea fish, the shortfin spine eel Notacanthus bonaparte (Notacanthiformes: Notacanthidae), from the northeastern Atlantic. The new genus is placed in the Triaenophoridae because it possesses a uterine pore on the ventral surface, a marginal genital pore, and a follicular vitellaria. Bathycestus most closely resembles Eubothrioides, Fistulicola, Probothriocephalus, and Pseudeubothrioides, which have also an unarmed scolex, a single set of genital organs per proglottid, an unarmed cirrus, cortical vitellaria, and a compact rather dendritic ovary. It differs from these genera by combination of the following features: a sagittate scolex with a weakly developed apical disc and free posterior margins of bothria, no neck, a long cirrus sac, reaching to the median third of proglottids and angled anteromedially in its proximal part, the posterior position of the vagina in relation to the cirrus sac, the testes in 2 lateral fields confluent postovarially, circumcortical vitellaria continuous longitudinally, and unoperculate eggs. Bathycestus brayi n. sp. is the first cestode to be described from a deep-sea fish of the genus Notacanthus.

A new nematode species, Micropleura australiensis n. sp., is described on the basis of specimens found in the peritoneal cavity of the Australian freshwater crocodile, Crocodylus johnsoni Krefft, from the Ord River area, Western Australia. The new species is mainly characterized by the length of spicules (0.360–0.366 mm) and gubernaculum (0.096–0.105 mm), the number and arrangement of male caudal papillae (4 preanal and 6 postanal pairs), and the postequatorial vulva. To date, it is the first species of Micropleura reported from Australia. Micropleura trionyxi Agrawal, 1966, and M. lissemysia Chattervati, 1985, are considered junior synonyms of M. indica Khera, 1951.

Seven species of Euryhaliotrematoides n. gen. and 1 species of Aliatrema n. gen. (Monogenoidea; Dactylogyridae) are described and reported from the gills of 15 species of butterfly fishes (Chaetodontidae) from the coral reefs of Moorea (French Polynesia), Wallis (Wallis and Futuna), Heron and Lizard (Australia), Palau (Micronesia), and New Caledonia: Aliatrema cribbi n. sp. from Chaetodon auriga, Chaetodon lunula, Chaetodon trifasciatus, Chaetodon ulietensis, Chaetodon vagabundus, Forcipiger flavisissimus, and Heniochus chrysostomus; Euryhaliotrematoides annulocirrus n. comb. from C. auriga, C. lunula, and C. vagabundus; Euryhaliotrematoides aspistis n. sp. from C. auriga, Chaetodon citrinellus, C. lunula, Chaetodon reticulatus, C. ulietensis, and C. vagabundus; Euryhaliotrematoides berenguelae n. sp. from C. citrinellus, Chaetodon ornatissimus, and F. flavisissimus; Euryhaliotrematoides grandis n. comb. from C. auriga, C. citrinellus, Chaetodon ephippium, Chaetodon kleinii, Chaetodon lineolatus, C. lunula, C. ornatissimus, C. trifasciatus, C. vagabundus, and H. chrysostomus; Euryhaliotrematoides microphallus n. comb. from C. auriga, C. citrinellus, C. ephippium, C. kleinii, C. lunula, C. ornatissimus, C. reticulatus, Chaetodon trifascialis, C. trifasciatus, C. vagabundus, F. flavisissimus, and H. chrysostomus; Euryhaliotrematoides pirulum n. sp. from C. auriga, C. citrinellus, C. lunula, C. trifasciatus, and C. vagabundus; and Euryhaliotrematoides triangulovagina n. comb. from C. auriga, C. citrinellus, C. kleinii, C. lunula, C. ornatissimus, C. vagabundus, F. flavisissimus, H. chrysostomus, and Hemitaurichthys polylepis. All reports of previously described species ar

Herein, we describe the first case of a natural infection of biting midges by a kinetoplastid protozoan. Flagellates from a female Culicoides kibunensis captured in a bird's nest were introduced into culture and characterized by light and electron microscopy. However, because the morphological data were inconclusive, the novel endosymbiont-free trypanosomatid was assigned into Herpetomonas primarily on the basis of the 18S and 5S ribosomal RNA (rRNA) gene sequences.

Feces from 60 bats representing 5 species and 4 genera collected in central Wyoming in 2001 were examined for the presence of coccidia. Two species of Eimeria were identified in 4 bats representing 2 species of Myotis. All infected animals harbored a single species; there was no multispecies infection. Eimeria catronensis was recovered from 3 little brown bats (Myotis lucifugus), and Eimeria californicensis was identified from a single long-legged myotis (Myotis volans). Both represent new geographic records and the second a new host record. Eimeria catronensis–like oocysts were recovered from a single silver- haired bat (Lasionycteris noctivagans). Descriptions and taxonomic summaries for the eimerian species are presented in this study.

Hemogregarines from Thamnophis s. sirtalis, Coluber constrictor priapus, Elaphe obsoleta quadrivittata, and E. g. guttata in northern Florida appeared to be conspecific on the basis of similar gamonts from all the hosts and sporogonic stages obtained from 3 hosts. The resemblance of gamonts to those of Hepatozoon sauritus, described from T. sauritus sackenii in southern Florida, justified comparison of DNA isolates from the type infection of H. sauritus with samples from each of the northern Florida hosts and with a morphologically distinct species, H. sirtalis, from northern Florida. A nucleotide sequence (530 bp) alignment of the 18S ribosomal RNA gene revealed 2 hemogregarine haplotypes that varied at 15 sites (p distance = 2.8%), which included 10 transitions and 5 transversions. Two well-supported clusters (100% bootstrap support) were revealed by a neighbor-joining tree topology. One cluster included the type infection of H. sauritus and all 4 of the other samples from the northern Florida hosts, with samples of H. sirtalis comprising a second cluster. Hepatozoon sauritus, therefore, is a polytopic species in contrast to the 8 other Hepatozoon species thus far described from snakes in Florida, each of which appears to parasitize a single host species.

We report 3 species of the digenean genus Parallopharynx, 1 previously undescribed, from the Area de Conservación Guanacaste (ACG) in northwestern Costa Rica. Parallopharynx gonzalezi, which was originally described in Basiliscus sp. and Ctenosaura similis from central Costa Rica, inhabits C. quinquecarinata; P. jonesi, originally described in Anolis lionotus (syn. Norops oxylophus) from Nicaragua, inhabits N. oxylophus, N. biporcatus, and Basiliscus basiliscus; and the new species, which inhabits B. basiliscus. Parallopharynx matternae n. sp. differs from all other members of the genus by having a metraterm extending posteriad from the genital pore to the posterior margin of the ventral sucker, whereas in P. arctus and P. gonzalezi, the metraterm never surpasses the midlevel of the ventral sucker and in P. jonesi it never passes the anterior margin of the ventral sucker, and by having an oral sucker that does not exceed 150 μm in diameter with a subsequent greater oral–ventral sucker width ratio ranging from 1:0.88–1.12 (averaging 1:1), whereas values range from 1:0.71–0.83 for P. gonzalezi and P. arctus, and from 1:0.59–0.68 for P. jonesi. Parallopharynx spp. possesses Y-shaped excretory vesicles with a long central stem and short arms bifurcating immediately posterior to the ovary; similar to those found in members of the Telorchiidae. Additional similarities in the relative positions of the gonads and the structure of the cirrus sac and metraterm indicate a close relationship between Parallopharynx and members of the Telorchiidae.

Four species of Procyrnea were collected in birds from the Area de Conservacion Guanacaste, Costa Rica. Procyrnea brevicaudata n. sp. in Crypturellus cinnamomeus resembles P. ficheuri, P. murrayi, P. ameerae, P. dollfusi, and P. aptera in lacking lateral alae but differs from all these species in having 2 longitudinal ridges on the left side of the body, in having a sinistral rather than ventral vulvar opening, and in having dorsally bent rather than straight female tails. Procyrnea mawsonae n. sp., in Buteo magnirostris, is similar to P. strialata in body size and in having 2 transverse striated lateral alae, but differs by having longer and differently shaped spicules, and by lacking a single preanal sessile papilla. Procyrnea mclennanae n. sp., in Heliomaster constantii, is similar to P. strialata (Zhang, 1991) and P. mawsonae n. sp. in having 2 transverse striated lateral alae, but it can be distinguished from P. strialata and P. mawsonae in having 4 rather than 3 small teeth on the interior border of the pseudolabia, in having unequal rather than equal lateral alae, and in having longer spicules. Procyrnea sp., on the basis of a single adult male in Campephilus guatemalensis, resembles P. suraiyae, P. tulostoma, and P. unilateralis in possessing a single and long lateral ala, but can be distinguished from P. suraiyae and P. tulostoma in the length of the left spicule, in the left spicule having a bifid distal end, the right spicule having a rounded distal end rather than both spicules having pointed distal ends, and in having the lateral ala beginning at the lip region instead of posterior to the cervical papillae. It differs from P. uncinipenis in having a spicule ratio of 1:3.5 rather than 1:2.5, in the left spicule having a bifid rather than alate distal end, and in the absence of a single preanal papilla.

Entamoeba histolytica is a protozoan parasite that can invade the intestinal mucosa. Infection induces production of secretory immunoglobulin A (SIgA) antibodies that can diminish the adhesion between E. histolytica trophozoites and epithelial cells in vitro and reduce the rate of new infections in children. SIgA antibodies produced by asymptomatic cyst carriers could play a protective role against the damage caused by E. histolytica. To identify membrane antigens capable of inducing SIgA response in E. histolytica cyst carriers, salivary SIgA antibodies were confronted with blotted plasma membrane proteins from amebae. A surface 115-kDa ameba protein was recognized by 62% of the human SIgA antibodies tested. The 115-kDa protein is not a mannose-containing glycoprotein and has no protease activity. Rabbit anti–115-kDa protein antibodies were capable of reducing erythrophagocytosis but were unable to protect culture cells from the cytopathic damage caused by E. histolytica. However, anti–115-kDa protein antibodies induced surface receptor redistribution.

The objectives of this study were to evaluate the accuracy of the indirect fluorescent antibody test (IFAT) using serum and cerebrospinal fluid (CSF) of horses naturally and experimentally infected with Sarcocystis neurona, to assess the correlation between serum and CSF titers, and to determine the effect of S. neurona vaccination on the diagnosis of infection. Using receiver-operating characteristic analysis, the areas under the curve for the IFAT were 0.97 (serum) and 0.99 (CSF). Sensitivity and specificity were 83.3 and 96.9% (serum, cutoff 80) and 100 and 99% (CSF, cutoff 5), respectively. Titer-specific likelihood ratios (LRs) ranged from 0.03 to 187.8 for titers between <10 and 640. Median time to conversion was 22–26 days postinfection (DPI) (serum) and 30 DPI (CSF). The correlation between serum and CSF titers was moderately strong (r = 0.6) at 30 DPI. Percentage of vaccinated antibody-positive horses ranged from 0 to 95% between 0 and 112 days after the second vaccination. Thus, the IFAT was reliable and accurate using serum and CSF. Use of LRs potentially improves clinical decision making. Correlation between serum and CSF titers affects the joint accuracy of the IFAT; therefore, the ratio of serum to CSF titers has potential diagnostic value. The S. neurona vaccine could possibly interfere with equine protozoal myeloencephalitis diagnosis.

The entire P50 gene encoding a surface protein of Babesia gibsoni was cloned into the bacteria expression vector pGEX-4T-3 and subsequently expressed in Escherichia coli as a glutathione S-transferase fusion protein. The purified recombinant P50 was evaluated in an enzyme-linked immunosorbent assay (ELISA) for the serological diagnosis of B. gibsoni infection in dogs. ELISA was able to differentiate clearly among B. gibsoni–infected, Babesia canis–infected, and uninfected dog sera. The antibody response against the recombinant P50 was maintained at a high level until the chronic stage of infection in dogs experimentally infected with B. gibsoni. When serum samples collected from domestic dogs in Japan were examined for the diagnosis of B. gibsoni infection by the ELISA, 3 of 209 samples (1.4%) were positive for the antibody to B. gibsoni. This result was completely identical to those of Western blot analysis and the indirect fluorescent antibody test. These results indicate that the recombinant P50 expressed in E. coli is a useful diagnostic antigen for practical use in the diagnosis of B. gibsoni infection in dogs.

This study elucidated the fate of prenatal infections in piglets born by dams repeatedly infected before and during pregnancy with Schistosoma japonicum. Independent variables included repeated infections of the dams and treatment or challenge infection (or both) of the prenatally exposed piglets. Dependant variables were worm counts, fecal and tissue egg counts, weight gain, and gross pathological observations. Fifteen female piglets (the dams) were included, of which 6 received repeated infections with S. japonicum during 6 mo. All dams were inseminated and 10 wk pregnant; 12 of the dams were infected with S. japonicum, of which 6 had been repeatedly infected. Three dams remained uninfected. Eight weeks after delivery, the prenatally exposed piglets (the offspring) were grouped, and 6 of the 12 groups were treated with praziquantel. Four weeks after treatment, 5 groups of piglets were infected with S. japonicum. Groups of piglets were killed either 12 or 22 wk after delivery. Repeated infections of the dam did not prevent establishment of a congenital infection in the pig fetuses. Piglets born with a congenital infection were not resistant to a S. japonicum challenge infection given 12 wk after birth. Neither did praziquantel effectively cure the piglets nor did treatment of the prenatally infected piglets prevent establishment of a challenge infection given 4 wk after treatment. Results of the present study indicate that prenatal exposure, independently of the dam's infection status, may change the host response to challenge infections and treatment after birth.

For the first time, a multiplex bead assay (MBA) was used to assay oral fluid and serum specimens for immunoglobulin G (IgG) antibodies to specific Cryptosporidium parvum antigens that were coupled to polystyrene beads. Recombinant C. parvum 17- and 27-kDa antigens (r17 and r27, respectively) both linked with glutathione-S-transferase (GST) fusion proteins, native 17-kDa antigen, and GST alone were each coupled to microspheres that could be differentiated based on variable amounts of internally incorporated red fluorescent dye. Initial and follow-up serum and oral fluid specimens from a 1997 cryptosporidiosis outbreak in Spokane, Washington, were incubated with the coupled beads. Antibodies bound to the coupled beads were detected using biotinylated monoclonal anti-human IgG antibody and streptavidin-labeled r-phycoerythrin. Fluorescence intensity was measured by flow cytometry. For the 3 C. parvum antigens, the median of the mean fluorescence intensity (MFI) was significantly higher (P < 0.03) in the initial specimens than in the follow-up specimens. No significant change in IgG responses to GST in oral fluids or serum specimens was observed. For all Cryptosporidium antigens, the MFI in the initial serum specimens correlated with the MFI in the initial oral fluid specimens (P < 0.001, r > 0.673). For the recombinant antigens used in the MBA, the MFI correlated with the response as measured by an enzyme-linked immunosorbent assay that used r17 and r27 expressed without the GST fusion partner (P < 0.001, r > 0.854). MBA using sera or more conveniently collected oral fluids, especially from children, may be an option for immunodiagnosis of C. parvum infection and for prospective epidemiological studies designed to monitor infection risk.

Larval nematodes that parasitize the Mayan cichlid fish ‘Cichlasoma (Nandopsis)’ urophthalmus (Günther 1862) in southern Florida were identified as Contracaecum spp. (Nematoda: Anisakidae, Anisakinae). The objective of this study was to determine whether infection intensity and prevalence of these parasites differ between a brackish water and freshwater habitat or through ontogeny in the freshwater habitat only. The nematodes were removed from the abdominal cavity of the fishes and counted. Infection intensity was compared between habitats using analysis of covariance and evaluated through ontogeny using Spearman rank order correlation. Prevalence was compared between habitats and between adults and juveniles from the freshwater habitat using a z-test. Although infection intensity did not differ between habitats, infection prevalence was greater at the freshwater site (FWS). Both the prevalence and intensity of nematode infection increased through ontogeny at the FWS, and no nematode was found in fishes that were smaller than 93 mm standard length. Thus, the parasites appear to accumulate during the lifetime of the fishes.

The antiparasitic activity of racemic albendazole-sulphoxide (Ricobendazole = racRBZ) and its ( ) and (−) enantiomers was tested in an ex vivo murine model for Trichinella spiralis infection. Larvae were isolated from the muscle of infected mice and exposed to concentrations between 0.01 and 1 μg/ml of the racemic mixture or to each of its enantiomers. The activity of each compound was then assayed by measuring the ability of the treated larvae to infect naive mice (larval viability). At a concentration of 0.5 μg/ml, all 3 compounds were highly effective in reducing the viability of the larvae, achieving reductions of 91.26% (racRBZ), 96.7% ( ), and 89.2% (−), when compared with untreated controls. At lower concentrations (0.1 μg/ml), only treatment with ( )RBZ rendered a significant reduction in larval viability in comparison with controls (84.3%; P < 0.01), whereas at 0.01 μg/ml, none of the compounds altered larval viability (P > 0.05).

Toxoplasma gondii infections in fish-eating marine mammals is intriguing and indicative of contamination of the sea environment with oocysts. Toxoplasma gondii was identified in an elephant seal (Mirounga angustirostris) that had encephalitis. Tissue cysts were found in sections of cerebrum, and the diagnosis was confirmed by immunohistochemical staining with T. gondii–specific polyclonal rabbit serum. This is the first report of T. gondii infection in an elephant seal.

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the presence of T. gondii oocysts in the environment because chickens feed from the soil. In the present study, prevalence of T. gondii in 208 free-range chickens (Gallus domesticus) from Mexico was investigated. Blood, heart, and brain from each animal were obtained to test for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (1:10 or higher), were found in 13 (6.2%) chickens. Hearts and brains of 13 seropositive chickens were bioassayed in mice, and T. gondii was isolated from 6 chickens. All 6 isolates were avirulent for mice. Genotyping of chicken isolates of T. gondii using the SAG2 locus indicated that 5 were type III and 1 was type I. This is the first report of isolation of T. gondii from chickens from Mexico.

Infections by metacercariae of Clinostomum (Leidy, 1856) species adversely affect aquacultured fish and are potentially transmissible to humans. Molecular methodologies are efficient tools, which enable diagnosis of all life-history stages of trematodes in their diverse hosts. The small subunit of ribosomal DNA genes of adults of the Old World Clinostomum complanatum (Rudolphi, 1819) and the New World Clinostomum marginatum (Rudolphi, 1819), obtained from a little egret Egretta garzetta (Linnaeus, 1766) and the great blue heron Ardea herodias (Linnaeus, 1758), respectively, were amplified, sequenced, and aligned. The resulting alignment was used to develop a genetic assay to differentiate between these species.

This study provides basic information on the occurrence of platyhelminths in the wild bullseye puffer (Sphoeroides annulatus) from Sinaloa, Mexico. Specimens of pufferfish were collected from 2 localities: Teacapan (n = 161) and Mazatlan (n = 66). Six species of platyhelminths were recorded: 2 monogeneans (Diclidophoridae: Heterobothrium ecuadori and Capsalidae: Neobenedenia melleni) and 4 digeneans (Apocreadiidae: Homalometron longisinosum, Lepocreadiidae: Bianium plicitum, Gorgoridae: Phyllodistomum mirandai, and Fellodistomidae: Lintonium vibex). This is the first record of the platyhelminth L. vibex in S. annulatus in the Mexican Pacific. Bianium plicitum was the most abundant species, and H. ecuadori was the most prevalent species. The fish from Teacapan had the higher prevalence of platyhelminths. Teacapan had higher specific richness index, whereas Mazatlan had a higher dominance, 3.098 (Teacapan = 2.38). A relative risk analysis showed that B. plicitum was more likely to be present on fish in water within the temperature range of 21–25 C and from Teacapan compared with fish from the warmer water (26–30 C) or from Mazatlan. Heterobothrium ecuadori was more likely to be present at water temperatures of 23–24.5 C on fish from Teacapan and when other ectoparasites were present. Neobenedenia melleni also was more likely to be present when other parasites were present.

We examined the gastrointestinal helminth fauna of 2 Cuvier's beaked whales, Ziphius cavirostris, stranded on the Spanish Mediterranean coast. Information regarding intestinal parasites of this species is provided for the first time. Six helminth taxa were identified. Thirty type II larvae of the nematode Anisakis sp. were found in the stomach and the intestine of both hosts; 2 type I larvae of Anisakis sp. were found in the intestine of 1 host. One juvenile of the acanthocephalan Bolbosoma vasculosum was found in the intestine; the metacestode Scolex pleuronectis was found mainly in the terminal colon and the anal crypts of both hosts; adult cestodes of Tetrabothrius sp., which may represent a new species, were collected from the duodenum of 1 host. Composition of the intestinal parasitic community is similar to that of other oceanic cetaceans, which mostly include species of Bolbosoma and tetrabothriids (Cestoda).

The ability of an in vivo anticoccidial assay to identify potential feed-through insecticides was demonstrated using first-instar Lucilia sericata on droppings from chicks fed medicated diets. Cyromazine, a commercially available feed-through insect growth regulator, ivermectin, diflubenzuron, fipronil, permethrin, and 2 experimental compounds were effective in varying degrees in killing L. sericata larvae. Eleven coccidiostats were effective against the protozoan parasites (Eimeria spp.) at commercially used levels, whereas they were ineffective against Lucilia larvae.

The effects of snail size and diet on encystment of Echinostoma caproni cercariae in juvenile Helisoma trivolvis (Colorado strain) snails were studied. Encystment in neonatal (<1-mm shell diameter) and juvenile (2- to 3-mm shell diameter) snails was compared 24 hr postinfection (PI) after individual exposure of snails of each size to 1, 5, 10, 25, or 50 cercariae. Significantly more cysts were recovered from juvenile snails exposed to 10, 25, or 50 cercariae than from neonatals with comparable exposure. The maximum number of cysts recovered from juveniles exposed to 50 cercariae was 42, compared with a maximum of 15 cysts in neonatals comparably exposed. Size of H. trivolvis was a major factor in determining cyst burden in this planorbid. A diet of either Romaine lettuce leaf or hen's egg yolk did not have a significant effect on the number of cysts recovered at 24 hr PI from juvenile snails exposed to 25 or 75 cercariae. Survival of infected versus uninfected neonatals was also examined for 7 days. Neonatals exposed to 10 cercariae showed a significant decrease in survival at 6 and 7 days PI when compared with uninfected controls.

A morphological evaluation and genetic analysis (sequencing of ITS2 region of rDNA) of proteocephalidean cestodes from rainbow smelt (Osmerus mordax) in the Saint Lawrence Estuary, Canada, has shown their conspecificity with Proteocephalus tetrastomus, a specific parasite of smelt (Osmeridae), previously known only from northern Europe, Russia, and Japan. The parasite occurs only in larval, but not adult, smelt in the Saint Lawrence Estuary. Prevalence of larval smelt infection was 42% (n = 50), mean intensity 2.1 ± 2.4 and mean abundance 1.1 ± 1.0.

Equine protozoal myeloencephalitis (EPM) is a neurologic syndrome seen in horses from the Americas and is mainly caused by Sarcocystis neurona. Cell-mediated immune responses to mitogens have been shown to be reduced in horses with EPM, although it is not known whether the parasite causes this immunosuppression or if the immunosuppression is required for disease manifestation. Recently, a 29-kDa surface antigen from S. neurona merozoites was identified as being highly immunodominant on Western blot. This antigen has been sequenced and cloned, and the expressed protein has been named SnSAG1. Isolated peripheral blood lymphocytes from 43 EPM-negative horses and 28 horses with clinical EPM were cocultured with a mitogen or SnSAG1, and lymphocyte blastogenic responses to these antigens was measured by tritiated thymidine uptake. The ability of SnSAG1 to induce γ-interferon (γIFN) production was also investigated with reverse transcriptase–polymerase chain reaction. There was no significant differences between EPM-positive and -negative horses in lymphocyte responses to ConcanavalinA. However, lymphocytes from EPM-negative horses responded significantly higher to SnSAG1 than lymphocytes from EPM-positive horses. γIFN production was detectable by 24 hr in culture in response to SnSAG1 in all EPM-negative horses. There was still no detectable γIFN production in EPM-positive horses after 72 hr in culture. It appears that the parasite is also able to induce an immunosuppression toward parasite-derived antigens as parasite-specific responses are decreased.

Experimental infections of Galba truncatula with 4 isolates of Fasciola hepatica miracidia differing by their mammalian origin (cattle, nutrias, rabbits, or sheep) were carried out to determine if parasite origin had an effect on the number of free rediae, their growth, and their larval productivity in each redia category. The mammalian origin of miracidia had a significant influence on the numbers of free rediae (they were higher in cattle-group snails) and the lengths of rediae (they were lower in rabbit groups). The redia category had also a significant effect on body and pharyngeal measurements. In all groups, the majority of cercariae (55.8–63.2%) were produced by the daughter rediae (R2a rediae) originating from the first mother redia. Compared with the other groups, the mean number of cercariae at day 49 postexposure was twice as high in cattle groups. In contrast, the mean number of daughter rediae produced by each second-appearing mother redia or each R2a redia was higher in the nutria, rabbit, and sheep groups. The mammalian origin of F. hepatica miracidia had an effect on the number of live rediae, their length, and their redial and cercarial productivity.

A pen-reared northern bobwhite and a domestic turkey were infected with a strain of Plasmodium hermani obtained originally from a wild turkey in southern Florida. Blood films from these 2 birds were positive microscopically for 188 and 370 days postinfection (PI), respectively. Culicine mosquitoes (Culex nigripalpus and C. salinarius) were blood fed on the bobwhite and the turkey at different times during the infection and used to transmit the malaria to other bobwhites and turkeys up to days 298 and 473 PI, respectively. It was concluded that in nature, P. hermani could remain in a chronic phase in avian hosts for a year, or longer, allowing survival of the parasite between seasons of mosquito transmission.

Infracommunity data from 60 perch collected from Garner Lake, Alberta, in 1992 were examined to determine whether ontogenetic shifts in host diet or habitat could produce a nested subset pattern of infracommunity structure. The host by parasite matrix showed significant nesting. Host idiosyncratic temperatures, which are indicative of differing “biogeographic histories,” were determined primarily by the presence of Ergasilus caeruleus in depauperate communities, or its absence in richer communities, and covaried positively with host age and the associated variables of host length, mass, and infracommunity richness. Idiosyncratic host temperatures did not differ significantly between male and female perch when the effect of age was controlled for by analysis of covariance. Although an ontogenetic diet shift can be ruled out as producing the observed nested pattern, it is possible that the observed nested subset pattern is the result of an ontogenetic habitat shift.

Antibodies to Toxoplasma gondii were investigated in serum samples of field mice, Microtus fortis, from Yuanjiang, Hunan Province, People's Republic of China. The modified agglutination test (MAT) incorporating formalin-fixed whole tachyzoites and mercaptoethanol was used to determine antibodies. Antibodies to T. gondii (MAT ≥ 1:20) were found in 36 (29%) of 124 trapped mice. The antibody titers of positive sera (percentage in parentheses) were 1:20 (8.9), 1:40 (3.2), 1:80 (3.2), 1:160 (1.6), 1:320 (1.6), 1:640 (1.6), 1:1,280 (1.6), 1: 2,560 (0.8), and >1:2,560 (6.5). No antibody to T. gondii was found in 104 sera of laboratory-bred M. fortis infected with Schistosoma japonicum between 1 and 45 days after infection.