The protozoan parasite Entamoeba histolytica is an ancient eukaryotic cell that shows morphologically atypical organelles and differs metabolically from higher eukaryotic cells. The aim of this study was to determine the subcellular localization of ameba NAD -dependent alcohol dehydrogenase (ADH2). The enzyme activity was present in soluble and mainly in particulate material whose density was 1.105 in a sucrose gradient. By differential centrifugation, most of the ADH activity sedimented at 160,000 g (160,000-g pellet), similar to the Escherichia coli polymeric ADHE. In the Coomassie staining of the 160,000-g pellet analyzed by electrophoresis, a 96-kDa protein was more prominent than in other fractions; this band was recognized by antibodies against Lactococcus lactis ADHE. By gold labeling, the antibodies recognized the granular material that mainly constitutes the 160,000-g pellet and a material that sedimented along with the internal membrane vesicles. By negative staining, the 160,000-g fraction showed helical rodlike structures with an average length of 103 nm; almost no membrane vesicles were observed in this pellet. In internal membrane fractions, no rodlike structures were found, but protomerlike round structures were observed. These results indicate that the main amebic NAD -dependent ADH2 activity is naturally organized as rodlike helical particles, similar to bacterial ADHE. Detection of ADH2 in membrane fractions might be explained by cosedimentation of the multimeric ADH during membrane purification.

A medicinal chemistry program on the nodulisporic acid chemical class, guided by an artificial membrane flea-feeding assay, has recently identified permissive and nonpermissive regions of the pharmacophore for exploitation against fleas. This pathway was validated when several promising compounds from this program were administered orally to dogs at 15.0 mg/kg and found to have >90% flea activity for 2 wk. To determine if a surrogate insect assay would have provided the same guidance, a nodulisporic acid analog series was examined in both a Lucilia sericata larval assay and an artificial membrane flea-feeding assay using Ctenocephalides felis. Results from both insect assays were concordant in that even subtle chemical modification or substitution to the left-hand side of the nodulisporic acid pharmacophore resulted in substantial loss of insecticidal activity. Both assays were also in general agreement that the only modifications to the pharmacophore that did not result in loss of activity occurred to the C-8 side chain on the right-hand side of the molecule. Although there was good agreement between the 2 assays on the general regions of the pharmacophore, there was variance on individual compounds in the mono- and disubstituted amide series from the C-8 side chain. For example, the L. sericata assay showed several analogs from this subclass to possess similar activity to the parent acid, whereas the membrane assay indicated superior activity against fleas relative to the same parent. Consequently, although there was substantial general agreement between the assays, it was concluded that finer optimization of a lead compound should be done against the target parasite, even if it is ex vivo, as early as possible in a medicinal chemistry program.

The rat tapeworm Hymenolepis diminuta alters the myoelectric activity of the small intestine. To determine if secreted factors from the tapeworm are responsible for these alterations of intestinal smooth muscle activity, tapeworm-conditioned medium (TCM) obtained from in vitro culture was infused via an indwelling cannula into the duodenum of an uninfected rat. Myoelectric recordings were analyzed for sustained spike potentials (SSP) and repetitive bursts of action potentials (RBAP), the previously characterized tapeworm modifications of the normal interdigestive myoelectric pattern. Results indicated that TCM initiated SSP, but not RBAP in the intestine of the uninfected rat. The SSP-inducing signal factor activity, present in TCM, was retained after boiling, prolonged freezing, proteinase treatment, and passage through a 10-kDa exclusion filter. The signal factor was soluble in the aqueous phase on lipid extraction. It was concluded that the SSP-inducing signal factor is a nonproteinaceous, heat-resistant, low–molecular weight, water soluble molecule.

Biomphalaria glabrata snails infected with Schistosoma mansoni were collected during consecutive seasons from a site in Brazil known to have a very high percentage of infected snails. Schistosoma mansoni cercariae from single snails were used to infect individual mice, and the recovered adult worms were genetically assessed using a mtVNTR marker. The number of unique parasite genotypes found per snail was compared to expected abundance values, based on the infection prevalence at the site, to determine the distribution of S. mansoni infections within the snail population. The observed distributions and those from previous studies were used to examine the relationship between schistosome prevalence and aggregation across a wide range of prevalence values. Our analysis showed that prevalence was inversely related to the degree of parasite overdispersion, and at high prevalence, S. mansoni infections were randomly distributed among snails.

The present study was undertaken to characterize the oocyst morphology, host specificity, organ location, virulence, and sequences of the small subunit ribosomal RNA, 70-kDa heat shock protein, and oocyst wall protein genes of Cryptosporidium baileyi, and to compare this strain with other Cryptosporidium species. This study also aims to serve as a model for polyphasic (phenetic and genetic) characterization of Cryptosporidium species and strains. On the basis of these results, further genetic and phenetic characterization of an avian isolate is needed if the difference between the length or width, or both, of oocysts of an isolate and of C. baileyi is ≥10% or if the difference between the oocyst shape index of the isolate and of C. baileyi is ≥3% (or both). The isolate is infectious for mammals or lower vertebrates, or the host range is narrow, i.e., infectious only for some bird species; after oral or intratracheal inoculation, the parasites are not located in the cloaca and in the bursa of Fabricius or the respiratory tract; clinical disease or weight gain reduction can be observed after oral inoculation; the genetic distance for the examined gene between C. baileyi and the isolate is similar in magnitude to that observed between most closely related Cryptosporidium species.

The early ultrastructural stages of Loma salmonae were studied in the gills of experimentally infected rainbow trout. No parasitic stages were identified during the first 2 wk of the infection. By week 3 postexposure (PE), uninucleate and binucleate meronts were recognized within host cells (no xenomas) associated with the capillary channels of secondary lamellae and lamellar arteries. An inflammatory reaction was absent. In secondary lamellae, infected cells were isolated from the capillary lumen, and some were recognized as pillar cells. In lamellar arteries, infected cells were localized beneath the endothelium and not in the lumen. Inflammatory reaction and destruction of parasites inside blood cells in the lumen of secondary lamellae were observed by week 4 PE. Three hypotheses, i.e., isolation, internalization, and evasion, are proposed to explain the localization of the infected cells in the gills. It is concluded that meronts are the earliest parasitic stage observed by week 3 PE, pillar cells are secondarily infected by phagocytosis of infected cells in the blood, endothelial cells of gills are not infected, and inflammatory response to the parasite starts by week 4 PE.

It has been shown that benzimidazole (BZ) resistance in sheep gastrointestinal nematodes is linked with an increase in beta-tubulin codon 200 tyrosine-expressing alleles in the resistant parasite populations. Here, an allele-specific PCR has been developed for the discrimination of the TAC/TTC polymorphism in the beta-tubulin 200 codon of small strongyles. One reverse primer was used in 2 separate amplifications with 1 of 2 forward primers that differed only in their final 3′ nucleotide. The primers flank a facultative intron/exon. Therefore, the amplified fragments are either 251 or 308 bp in size, depending on the presence or absence of the intron in individual worms. Amplification of genomic DNA isolated from single adult small strongyles from a set of 7 species consistently generated allele-specific products. Three worms each of the following species were used: Cylicocyclus nassatus, Cylicocyclus insigne, Cylicocyclus elongatus, Cylicocyclus radiatus, Cyathostomum pateratum, Cyathostomum catinatum, and Cyathostomum coronatum. PCR with DNA isolated from single larvae also reproducibly generated specific fragments. This method might be applied for the future assessment of allele frequencies in susceptible and resistant populations to further investigate the mechanism of BZ-resistance in small strongyles.

The sex ratio (z*; proportion of gametocytes that are male) of malaria and related hemospororin blood parasites has been predicted to be related to the inbreeding rate (f) by the simple equation z* = (1 − f)/2. Although there is some empirical support for this prediction, there are several cases where the sex ratio is less female biased or more variable than expected. Here, we present a theoretical model that may be able to explain some of these discrepancies. We show that if low gametocyte densities lead to a danger that female gametes may not encounter any male gametes, then natural selection favors a less female-biased sex ratio as a form of ‘fertility insurance’ to ensure that female gametes are mated. This model can be applied to a number of situations. In particular, (1) empirical data suggest that the number of gametocyes per blood meal can be low enough to favor fertility insurance in some Plasmodium infections in humans and (2) our model predicts facultative shifting toward less-biased sex ratios in response to immune pressure that reduces gametocyte or gamete survival or mobility, consistent with some recent experimental data from Plasmodium species of birds and mice.

Jirds (Meriones unguiculatus) were vaccinated with irradiated L3 third-stage larvae (L3) of Acanthocheilonema viteae, and the time required for killing of the challenge L3 was determined. The number of parasites recovered from vaccinated jirds was reduced to about 10% of the control values on the second day after challenge infection and later on. Histological studies revealed an eosinophil-rich infiltrate containing macrophages, neutrophils, and mast cells in the vicinity of the L3 on day 2 after challenge and destruction of the worms by day 4 after challenge. Ultrastructural studies confirmed these data and showed that eosinophils, macrophages, and mast cells were close to the L3 on day 2 after challenge. Flattening of the eosinophils onto the surface of the worms, degranulation of electron-dense material, and rupture of the L3 surface was observed on day 4 after challenge, followed by invasion of the inner of the worms by phagocytic cells. These data show that immune attack against the challenge L3 in vaccinated jirds is initiated between the first and the second day after challenge and that killing occurs around the fourth day after challenge, before the worms undergo their first molt.

This paper investigates the role of specific immune factors on the course of infection in genetic knockout (gko) mice infected with 3 different strains of Neospora caninum. Survival time and parasite persistence were examined in interferon-γ (IFN-γ), tumor necrosis factor receptor-2 (TNFR2), interleukin 10 (IL-10), beta 2 microglobulin (β2M), and inducible nitric oxide synthase (iNOS2) gko or wild-type (wt) mice following infection with either pathogenic (NC-1 or NC-2) or attenuated (NCts-8) N. caninum strains. Infection with NC-1 was 100% lethal in IFN-γ gko mice, as evidenced by mean survival times of 10–13 days, depending on the challenge dose used. TNFR2 and β2M gko mice infected with NC-1 or NC-2 strain demonstrated partial susceptibility to disease, as evidenced by histopathology and survival curves. TNFR2 or β2M gko mice were not susceptible to infection with NCts-8, on the basis of absence of pathology and lack of mortality. Lack of mortality and minimal histopathology scores demonstrated that NC-1, NC-2, and NCts-8 infections were avirulent in IL-10 and iNOS2 gko mice. Adoptive transfer of immune cells from NCts-8 vaccinated normal syngeneic mice into IFN-γ gko mice significantly (P < 0.05) prolonged mean survival times at all 3 challenge doses of NC-1 but failed to protect against mortality. Interestingly, there was a notable change in the tissue tropism of tachyzoites from the lung and brain in immunocompetent wt, TNFR2 gko, IL-10 gko, β2M gko, and iNOS2 gko mice to the liver and spleen in IFN-γ gko mice when challenged with N. caninum. On the basis of these results in gko mice, IFN-γ is a critical cytokine in the host response against acute neosporosis.

The objective of this study was to determine whether changes in the ileal intraepithelial lymphocyte (IEL) phenotype and function occurred prior to development of diarrhea in Cryptosporidium parvum–infected calves. Calves were orally inoculated with 10⁸ oocysts and maintained in enteric pathogen-free conditions until their use in experiments. Age-matched uninfected calves were used for comparisons. Ileal IELs were isolated and phenotyped to determine whether changes in lymphocyte population dynamics had occurred by 3 days postinoculation (PI). Ex vivo reverse transcriptase–polymerase chain reaction of messenger ribonucleic acid (mRNA) from IELs from infected calves was compared with controls to determine whether changes in cytokine expression had occurred by 3 days PI. No significant changes in lymphocyte population dynamics were documented; however, IELs isolated from 4 out of 8 infected calves, but not from 8 out of 8 control calves, expressed mRNA for interleukin-10 (IL-10). IL-10 expression by IELs was associated with the expression of a significantly larger (P < 0.001) proportion (0.75) of monoclonal antibody–defined C. parvum epitopes within infected ileal epithelium, as compared with a much smaller proportion (0.30) of epitopes with IL-10⁻ lymphocytes. The results suggest that a temporal association exists between the expression of IL-10 by ileal IELs and the expression of C. parvum antigens in infected calf epithelium prior to development of cryptosporidiosis.

A total of 584 adult nematomorphs, Gordius difficilis, was collected from 2 man-made ponds and their overflow stream in southeastern Wisconsin. Ponds were surveyed throughout the year, but all free-living worms were found during July–August of 1996, July–September of 1997, and June–August of 1998. Overall sex ratio was male biased; however, sex ratio was variable during different months. Observations during 1998–2000 indicated that worms mated within 24–48 hr of emergence from their hosts and began laying eggs by mid-August, continuing until mid-October. Eggs with well-developed larvae were recovered during October and November. Encysted larval nematomorphs were recovered from aquatic and semiaquatic invertebrates (gastropods, earthworms, and insects), whereas developing hairworms were found in terrestrial European ground beetles Pterostichus melanarius. It is hypothesized that semiaquatic invertebrates may serve as intermediate/paratenic hosts in this system and are preyed upon by terrestrial carabid beetles, thus completing the life cycle. In addition, scanning electron microscopy observations of G. difficilis add previously unreported observations on intraspecific variation in body length, cuticle morphology, and gametes of this species. This is the first report of G. difficilis from Wisconsin as well as the first report of this species from P. melanarius and aquatic and semiaquatic invertebrates.

Studies were conducted to determine the susceptibility of Anopheles farauti to different species and strains of Plasmodium. Mosquitoes were infected by feeding on animals or cultures infected with different strains of P. vivax, P. falciparum, P. ovale, P. coatneyi, P. gonderi, P. simiovale, P. knowlesi, and P. brasilianum. Infections of P. vivax and P. coatneyi were transmitted via sporozoites from An. farauti to monkeys. Comparative infection studies indicated that An. farauti was less susceptible to infection than An. stephensi, An. gambiae, An. freeborni, and An. dirus with the Salvador I strain of P. vivax, but more susceptible than An. stephensi and An. gambiae to infection with the coindigenous Indonesian XIX strain.

Due to a printer's error at Allen Press, a key was compressed in the article by  Braswell et al. (88: 28–35). On p. 35, the key should have been printed as follows:

Baylisascaris procyonis is well recognized as a cause of visceral (VLM), ocular, and neural (NLM) larva migrans in birds and mammals, including man. A study of the prevalence of larva migrans in free-ranging wildlife associated with raccoon latrines as well as a retrospective study of wildlife mortalities with neurological disease was conducted in 2000 in Orange County, California. Eighty-seven birds of 18 species and 64 mammals of 8 species were found to have NLM or VLM or both. NLM clinical signs included convulsions, torticollis, opisthotonus, head-tilts, circling, ataxia, paralysis, and visual defects. NLM lesions were characterized by focally disseminated, frequently linear, “tracklike” areas of parenchymal degeneration with varying degrees of astrocytosis in the white matter of the cerebrum, cerebellum, brain stem, and spinal cord. Larvae were rarely found in these lesions but were rather isolated in the brain–spinal cord parenchyma. At least 1 larva was isolated by digestion from each case of NLM and identified as Baylisascaris sp., most likely B. procyonis. VLM lesions consisted of granulomatous reactions surrounding intact or degenerative larvae in the parenchyma of the liver, kidney, diaphragm, and, occasionally, the lymph nodes. This report broadens the range of species of wild birds and mammals that have been found to be susceptible to larva migrans caused by B. procyonis and reaffirms the importance of raccoon latrine sites as contaminative foci for wildlife.

The occurrence of the crowding effect was demonstrated in plerocercoids of the cestode Schistocephalus solidus infecting threespine stickleback Gasterosteus aculeatus from Walby and Scout lakes, Alaska. Contrary to an earlier report, relatively large numbers of parasites (>3–4 plerocercoids) were observed to grow large enough in an intermediate host fish to become competent to infect and to mature in the definitive host under any of 3 assumed threshold values and 1 scenario of graded sizes for parasite competency. In Walby Lake, intensity and host body mass were significant predictors of mean plerocercoid mass per host, whereas intensity, host body mass, and combined parasite index were significant predictors in Scout Lake. Slopes of equations expressing the relationship between mean parasite mass and intensity for both lakes were less than 1, implying that processes other than or in combination with simple resource limitation might be producing the observed crowding effect. The causal mechanism for the crowding effect could include exploitative competition, interference competition, and host immune response. There were significant differences in infection between the two lakes, including different distributions of parasite intensities among hosts and different expressions of the crowding effect; however, an explanation of the differences awaits further investigation.

Using samples collected on the island of Corsica, a comparative study was done of the morphometry of Fasciola hepatica eggs shed by cattle and by naturally and experimentally infected murid rodents (wild Mus musculus and Rattus rattus and Rattus norvegicus Wistar laboratory strain). Eggs shed by murids are smaller in size than those shed by naturally infected cattle. A second study analyzed the number of F. hepatica eggs shed in murid feces at different time intervals, i.e., months, days, and 6-hr periods, by the Kato-Katz technique. Both experimentally and naturally infected black rats (R. rattus) were used, and Wistar rats were experimentally infected and included for comparison. The present studies prove that black rats R. rattus are able to shed eggs independently from the liver fluke isolate and that egg shedding occurs throughout the life of this host species, uninterrupted during all the months analyzed in a 2-yr period. Moreover, the results suggest that this shedding is continuous, with eggs appearing in the feces daily. The results on egg shedding by wild black rats R. rattus reach their maximum shedding in spring and autumn and a maximum during twilight hr. These chronobiological patterns appear to favor parasite transmission, both seasonally and daily.

The susceptibility of Psammomys obesus (sand rat) and Meriones tristrami (Tristram's jird) to Neospora caninum was investigated by subcutaneous (s.c.) and intraperitoneal (i.p.) inoculation of 10-fold doses of culture-derived tachyzoites. Groups of 5 animals were inoculated with doses of 10–10⁷ parasites via each route of inoculation. All but 2 of the sand rats inoculated with doses of 10–10⁴ parasites succumbed to the infection by 7–18 days postinfection. All jirds inoculated with 10⁷ tachyzoites succumbed by 5–16 days postinfection and those inoculated with 10⁶ tachyzoites by 9–25 days. A considerable proportion of the jirds inoculated with 10–10⁵ tachyzoites survived. Fibrinous peritonitis with ascites containing numerous tachyzoites was observed in the i.p.-inoculated sand rats and jirds that succumbed to the infection. In the jirds, tachyzoites were also found in pleural exudate. A considerable number (42.8%) of the jirds inoculated s.c. or i.p. exhibited neuromuscular symptoms, expressed in ataxia, head tilt, circling movement, and posterior paralysis. Seven successive passage of tachyzoites were achieved in sand rats with doses of 10⁵ parasites and in jirds with doses of 10⁷ parasites. All surviving jirds became seroconverted and were immune to lethal challenge.

Atractis marquezi n. sp. from the large intestine of the tortoise Geochelone nigrita is described and illustrated. Atractis Dujardin, 1845, sensu Baker, 1987, is revised to contain only those atractids having a lagonoid spicule. The remaining species of Atractis sensu Baker, 1987, are assigned to Cyrtosomum, Pseudatractis, and Klossinemella. A. marquezi represents the 12th species to be assigned to this genus and is distinguished from other Neotropical species by the distribution pattern of caudal papillae of the male: 2 pairs precloacal, 2 pairs adcloacal, and 6 pairs postcloacal.

Nematogens and vermiform embryos of a new species of Dicyema are described from an octopus collected off Veracruz, México. Dicyema shorti n. sp. is a small dicyemid species that rarely exceeds 500 μm in length. It is further characterized by the presence of 18 peripheral cells in the vermiform stages, a conical-shape calotte, and an axial cell that extends to the base of the propolar cells. Other stages in the life cycle of the parasite are not known. This is the first dicyemid to be described from Octopus burryi Voss, 1950, and also from both the southern Gulf of Mexico and the country of México.

Two new species of dicyemids are described from 2 species of deep benthic cephalopods, Graneledone antarctica and G. macrotyla, collected in the Southern Ocean south of the Antarctic Convergence. Dicyemennea bathybenthum n. sp. was found in G. antarctica. It is a medium-sized dicyemid whose length does not exceed 1,000 μm. The calotte is bluntly rounded or conical in small individuals, but the shape becomes discoidal in large individuals. Nematogens and vermiform embryos have 23 peripheral cells. An anterior abortive axial cell is present in vermiform embryos. Other stages in the life cycle were not observed. Dicyemennea dorycephalum n. sp. was found in G. macrotyla. It is a medium to large dicyemid that rarely exceeds 4,000 μm. The calotte is distinctly pointed, similar in shape to a spearhead. Vermiform stages typically have either 25 or 27 peripheral cells. An anterior abortive axial cell is present in vermiform embryos. Infusoriform embryos have 37 cells, the refringent bodies are solid in composition, and 2 nuclei are present in each urn cell.

Neoheterobothrium chilensis n. sp. (Monogenea: Diclidophoridae) from the gills of the bigeye flounder Hippoglossina macrops (Paralichthyidae: Pleuronectiformes) from northern Chile (30°11′S, 71°51′W) is described and compared with the known species in the genus. Diagnostic characters include the position of the seminal receptacle, the number of hooks in the male copulatory organ, the number of testes, and the relative size of the clamp peduncles.

Notomegarhynchus n. gen. (Eucestoda: Tetraphyllidea) is proposed to accommodate Notomegarhynchus navonae n. gen., n. sp. from Atlantoraja castelnaui in Mar del Plata, Argentina. Notomegarhynchus shetlandicum n. comb. from Bathyraja eatonii and B. maccaini in South Shetlands region, Antarctica, is a second species in the genus. Notomegarhynchus belongs to the Echeneibothriinae within the Phyllobothriidae. It can be distinguished from all other tetraphyllidean genera by the structure of the scolex in form of a massive myzorhynchus consisting of a proscolex and an apical organ, both of which are nonretractable and noninvaginable; in addition, there are 4 pedunculated and nonloculate acetabula. Notomegarhynchus shetlandicum is differentiated from N. navonae particularly in details of acetabular and myzorhynchus morphology, arrangement of testes, and shape of eggs. The inclusion of Notomegarhynchus in the Echeneibothriinae requires emendation of the diagnosis of the subfamily to include taxa possessing postvaginal testes. In addition, new terminology is proposed for distinct regions of the scolex.

During malaria surveys in Myanmar, 2 peculiar forms of Plasmodium malariae-like parasites were found. The morphologies of their early trophozoite stages were distinct from that of the typical P. malariae, resembling instead that of Plasmodium vivax, var. minuta, reported by Emin, and Plasmodium tenue, reported by Stephens, both in 1914. Two polymerase chain reaction (PCR)-based diagnoses, which target the same regions in the small subunit ribosomal RNA (SSUrRNA) genes, indicated that these parasites were new variant forms of P. malariae and that they could be separated into 2 genetic types that correlated with the 2 morphological types. Sequence analysis of the SSUrRNA and the circumsporozoite protein genes revealed that they were distinct both from each other and from other known P. malariae isolates and that the P. tenue-like type was closer to a monkey quartan malaria parasite, Plasmodium brasilianum. These results illustrate that the microscopic appearance of human P. malariae parasites may be more varied than previously assumed and suggest the value of molecular tools in the evaluation of malaria morphological variants.

Two new species of Pseudohapladena Yamaguti, 1952 (Digenea: Waretrematidae) are described. Pseudohapladena megaorchis n. sp. was obtained from the intestine of Mugil engeli (Bleeker) (Mugilidae), and Pseudohapladena lizae n. sp. from the intestine of Liza carinatus (Cuvier and Valenciennes) (Mugilidae). Pseudohapladena megaorchis is the most closely related in general morphology to Pseudohapladena scatophagi Yamaguti, 1952, but differs from the latter in the position of the hermaphroditic sac, and in the nature and distribution of the vitellaria. Features of P. lizae distinguishing it from other species of the genus include the shorter uterus, which contains only 1 egg, and the lesser extent of the vitellaria.

The species Phanurus oligoovus gen. et sp. nov. is described from the intestine of Liza carinatus (Cuvier et Valencienne) from the South China Sea. From the general internal anatomy, it belongs to the Waretrematidae and is distinguished from the other known species of the Waretrematidae by the tail appendage. A new subfamily, Phanurunae, is proposed for the genus Phanurus.

Information on putative synapomorphies was used to distinguish between Dollfusentis, Illiosentis, and Tegorhynchus. Members of Tegorhynchus and Illiosentis possess a thick padlike vestibular muscle on the inner posterior wall of the trunk of female worms. The 2 genera differ in that the proboscis of members of Illiosentis have ventral hooks in the posteriormost circle that are greatly enlarged and male worms have a heavy muscular sheath covering the urogenital duct, both of which are absent in members of Tegorhynchus. Based on these features, Illiosentis is formally reestablished, and the diagnosis of the genus is emended. Dollfusentis is characterized by members having vestibular muscles that are bandlike rather than padlike, normal-sized hooks in the poster ring of the proboscis, and a crescent of 6 large hooks on the ventral proboscis, separated posteriorly from the posteriormost ring of hooks. The heavy muscular sheath covering the urogenital duct is not present in male worms of species of Dollfusentis. Type specimens of D. heteracanthus, originally described as I. heteracanthus but later transferred from Illiosentis to Dollfusentis, and the material included in a recent redescription of D. heteracanthus possess the padlike vestibular muscle, greatly enlarged ventral proboscis hooks in the posteriormost circle, and heavy muscular sheath covering the urogenital duct that is characteristic of other members of Illiosentis and lack the features characteristic of the other species assigned to Dollfusentis. Thus, D. heteracanthus is removed from Dollfusentis and reinstated as I. heteracanthus.

Three-hundred and forty-nine specimens of Spauligodon loboi n. sp. (Nematoda, Pharyngodonidae) were found in the large intestines of 55 of 225 adult specimens representing 5 species of Liolaemus collected in 11 localities of northwestern Argentina. Prevalence of infection was 24% (mean intensity = 6.3 ± 3.4, range = 2–28). Spauligodon loboi n. sp. differs from other neotropical species in that the filamentous portion of the tail of males is spiny, whereas that of females is smooth. A key to the species of Spauligodon in the Neotropical Realm is provided.

Four species of Mediorhynchus are identified from Australian birds. New locality records are given for Mediorhynchus alecturae (Johnston and Mawson, 1947) Golvan, 1962 and new host and locality records for M. corcoracis Johnston and Edmonds, 1951. Mediorhychus grandis has been reported from Australian hosts, but this record could not be verified. Two females from Acanthogenys rufogularis and the anterior portion of a single female from a “gull” had characters of proboscis armature, lemnisci, and eggs that precluded them being assigned to any of the presently known species of Mediorhynchus. Mediorhynchus colluricinclae n. sp. was found in pomatostomatids from South Australian localities. A high degree of host specificity is recorded for M. corcoracis and M. colluricinclae. Selection of specific dietary items may be one filter that influences the degree of host specificity encountered.

The digenetic trematode Bucephalus anguillae n. sp. is described from the intestine of eel, Anguilla anguilla L., originating from a brackish water fish farm on the Italian coast of the Adriatic Sea. The new taxon is 1 of 12 Bucephalus species characterized by an anterior rhynchus surrounded by 7 tentacular appendages, each when fully protruded with 2 prongs. Scanning electron microscopy reveals, for the first time in a Bucephalus species, the crescent-shaped, unspined field located between the rhynchus and the dorsal tentacles. A comparison of B. anguillae n. sp. with 11 congeneric species revealed its remarkable similarity with B. polymorphus Baer, 1827; however, the new species has a larger cirrus sac, larger pharynx, vitelline gland fields not extending the level of pharynx, ovary located in the pharyngeal area rather than fairly posterior to pharynx, smaller testes, relatively wider rhynchus, and tegumental armature comprising slightly larger spines. Multivariate discriminant analyses confirmed a differentiation of B. anguillae from populations of B. polymorphus; the combination of 4 variables, namely cirrus sac length, pharynx width, cirrus sac width, and rhynchus width yielded a total separation of compared species.

To further validate previous observations in the taxonomy of Cryptosporidium parasites, the phylogenetic relationship was analyzed among various Cryptosporidium parasites at the actin locus. Nucleotide sequences of the actin gene were obtained from 9 putative Cryptosporidium species (C. parvum, C. andersoni, C. baileyi, C. felis, C. meleagridis, C. muris, C. saurophilum, C. serpentis, and C. wrairi) and various C. parvum genotypes. After multiple alignment of the obtained actin sequences, genetic distances were measured, and phylogenetic trees were constructed. Results of the analysis confirmed the presence of genetically distinct species within Cryptosporidium and various distinct genotypes within C. parvum. The phylogenetic tree constructed on the basis of the actin sequences was largely in agreement with previous results based on small subunit rRNA, 70-kDa heat shock protein, and Cryptosporidium oocyst wall protein genes. The Cryptosporidium species formed 2 major clades; isolates of C. andersoni, C. muris, and C. serpentis formed the first major group, whereas isolates of all other species, as well as various C. parvum genotypes, formed the second major group. Intragenotype variations were low or absent at this locus.

The activity of ivermectin and albendazole against larval Anisakis simplex was tested in vitro and in experimentally infected guinea pigs. Before drug exposure the medium for half of the larvae was adjusted to pH 2.0 with 1 N HCl, whereas the other half was held at pH 7.0. To these solutions, ivermectin was added to full concentrations of 1, 2, 5, 10, 50, 100, or 200 μg/ml, and for albendazole, 300, 400, and 500 μg/ml. Animals from group I were given 0.1 ml of 1% (3.3 mg/kg) ivermectin, whereas guinea pigs from group II were each given 5–7 mg (16.6–23.3 mg/kg) of albendazole orally. The efficacy of both drugs against L₃ A. simplex was high in vitro and in vivo against the larvae in different organs of guinea pigs.

One approach to the prevention of schistosomiasis is the use of topical formulations to inhibit cercarial penetration of skin. A number of formulations containing either cercaricidal ingredients or components designed to inhibit penetration have been studied, but with variable results. Such studies have rarely considered the persistence of inhibitory effects through time, and to date, there have been no systematic investigations of barrier formulations. The aim of this study was to use Franz cells to investigate the effect of such barrier creams on the penetration of S. mansoni cercariae into human skin. The results show that a single application of a barrier cream based on dimethicone offers a high level of protection against penetration that is sustained for at least 48 hr.

We collected 83 females and 80 males of Corynosoma cetaceum from 2 common dolphins, Delphinus delphis, collected in northern Patagonia (Argentina). Worms were most similar to specimens collected in other South American localities. However, 1 male had 2 spines adjacent to the genital pore and isolated from the rest of body spines. This finding confirms the recent reassignment of C. cetaceum to Corynosoma. Absence of genital spines is suggested to be avoided as the sole criterion to exclude specimens from Corynosoma or Andracantha.

Schistosoma mansoni eggs were found in a latrine dated AD 1450–1550 in Montbéliard, France. This is the first record of intestinal schistosomiasis in archaeological material. Because the parasite has an African origin, its presence in Europe at that time may be due to African slaves. However, intestinal schistosomiasis has never been established in Europe.

Host larvae of Drosophila melanogaster injected with the eicosanoid biosynthesis inhibitor, dexamethasone, prior to parasitization by the wasp Leptopilina boulardi, exhibited significantly reduced rates of melanotic encapsulation in comparison with control and saline-injected larvae. The results of this investigation suggest that prostaglandins and other eicosanoids are involved as cell-signaling molecules in the hemocytic encapsulation reaction of D. melanogaster larvae.

Serum samples from 134 dogs from 22 cattle dairy farms in the northern region of Parana State, Brazil, were tested for antibodies to Neospora caninum in an indirect fluorescent antibody test. Antibodies (≥1:50) to N. caninum were found in 29 (21.6%) of the 134 dogs, and seropositive dogs were found on 14 (63.6%) of the 22 dairy cattle farms. The antibody titers of dogs were 1:50 (3 dogs), 1:100 (7 dogs), 1:200 (7 dogs), 1:400 (6 dogs), and ≥1:800 (6 dogs). The low prevalence (9%) in <1-yr-old dogs compared with the 2- to 3-fold higher prevalence in older dogs (17–29%) suggests postnatal exposure to N. caninum infection.

As part of an ongoing research project concerning the diversity and distribution of parasites of Caviidae in South America, 143 wild guinea pigs (Cavia aperea) were collected from 3 localities in the Andean Highlands of Peru. Samples were collected between November 1996 and May 1999 and included representatives of arthropods, nematodes, and trematodes. Seven species of arthropods: Leptopsylla segnis (27.3%), Tiamastus cavicola (6.9%), Gliricola porcelli (55.2%), Hoplopleura alata (6.9%), Polyplax spinulosa (12.6%), Myobia musculi (1.4%), and Eutrombicula bryanti (49.6%); 4 species of nematodes: Capillaria hepatica (6.9%), Graphidioides mazzai (18.8%), Trichuris gracilis (3.5%), and Paraspirudera uncinata (37%); and a single trematode, Fasciola hepatica (4.2%), were identified.

A seroepidemiological survey of Toxoplasma gondii infection among Atayal and Paiwan mountain aborigines and Southeast Asian laborers in Taiwan was assessed from February 1998 to July 2000 using a latex agglutination test. To determine risk factors for T. gondii infection among Taiwan aborigines, the consumption of raw meat and valley water were given particular attention in a self-administered questionnaire. The overall seroprevalence of T. gondii infection was 19.4% for Atayal, 26.7% for Paiwan, 42.9% for Indonesian, 14.7% for Thai, and 11.3% for Filipinos. No significant gender difference in seroprevalence was found among Atayals, Paiwans, Indonesians, and Filipinos (P > 0.05). In the Thai group, however, males had a higher seroprevalence than females (P < 0.001). Results of the multiple logistic regression analysis indicate a higher odds ratios (OR) with age in both aboriginal groups. In contrast, the OR was lower among older Indonesians and Thais. Those Atayals and Paiwans with a history of eating raw meat seemed more susceptible to T. gondii infection than those who had never consumed raw meat. Ethnically, a significant difference in seroprevalence was observed between Indonesians and Paiwans, Atayals, Thais, and Filipinos (P < 0.001).

The present study investigated whether Schistosoma japonicum or Schistosoma bovis could establish prenatally in lambs. Three ewes were exposed to S. japonicum by intramuscular injection of cercariae, and 3 ewes were exposed to S. bovis cercariae using the leg-emerging technique approximately 2 mo before delivery, and 1 age-matched pregnant ewe served as an uninfected control. The study lasted 18–20 wk after infection, which was 8–9 wk after delivery. All 6 exposed ewes became infected with either S. bovis or S. japonicum. Eight lambs were borne by the 7 ewes, of which 1 (S. bovis exposed) was dead and 1 (S. japonicum exposed) died at delivery. Of the 3 S. japonicum-exposed lambs, 2 were found infected. Four lambs born of S. bovis-exposed ewes were negative. Despite having no worms, these 4 S. bovis-exposed lambs as well as the 1 negative S. japonicum-exposed lamb had, in contrast to the nonexposed control lamb, few, but distinct, liver granulomas dominated by eosinophils and giant cells with large central necrotic areas but with no remnants of eggs or worms. Hence, congenital infection was demonstrated in S. japonicum-infected lambs, but not in S. bovis-infected ones.

Serum samples from 305 white-tailed deer (Odocoileus virginianus) from 14 states in the southeastern United States were examined for antibodies to Neospora caninum using a direct agglutination test. Positive agglutination titers were found in 145 (48%) of the white-tailed deer examined: 21 (7%) had titers of 1:25, 92 (30%) had titers of 1:50, and 32 (10%) had titers of ≥1:500. These findings that antibodies to N. caninum are common in white-tailed deer support the concept that a sylvatic cycle might exist for this economically important parasite of domestic cattle.

Sequences of ITS-1 and ITS-2 rDNA for adult males of Spiculopteragia asymmetrica and Spiculopteragia quadrispiculata in red deer (Cervus elaphus) were determined. They were found to be identical, suggesting that S. asymmetrica and S. quadrispiculata represent a single species and do not refute the concept of dimorphic species in the Spiculopteragia.

Antibodies to Toxoplasma gondii were determined in serum samples of 502 domestic cats from Brazil by the modified agglutination test (MAT), using formalin-fixed whole tachyzoites and mercaptoethanol. Antibodies (MAT ≥ 1:20) were found in 132 (26.3%) of 502 cats. With respect to origin, antibodies were found in 26.7% of 430 stray cats from São Paulo, 10% of 40 stray cats from Guarulhos, and 40.6% of 32 cats from a cat breeder in São Paulo. Antibody titers were: 1:20 in 10 cats, 1:25 in 40 cats, 1:50 in 73 cats, and ≥1:500 in 9 cats. Exposure rates of T. gondii in cats from São Paulo, Brazil are similar to that in domestic cats in North America.

To further determine the distribution and prevalence of Echinococcus multilocularis in the central United States, 245 wild canids (125 red foxes, 120 coyotes) and 33 bobcats were collected from Nebraska, Kansas, and Wyoming and examined for this parasite. Animals examined included 11 red foxes from the western panhandle of Nebraska; 5 red foxes and 30 coyotes from southern Nebraska; 56 red foxes and 1 coyote from northeastern Nebraska; 20 red foxes, 63 coyotes, and 13 bobcats from northern Kansas; 2 red foxes, 26 coyotes, and 20 bobcats from southern Kansas; and 31 red foxes from east-central Wyoming. Of these, 27 of 72 (37.5%) red foxes from Nebraska were positive, including 2 of 11 (18.2%) from the western panhandle and 25 of 56 (44.6%) from the northeastern part of the state. Mean intensity of infection was 282 worms (range, 1–5,150). New distribution records were established for E. multilocularis in western Nebraska as well as for several northeastern counties. These findings support previous estimates that the southernmost front of the parasite's range extends along the southern border of Wyoming, eastward through central Nebraska and central Illinois into Indiana and Ohio.

Attempts were made to infect 4 species of New World monkeys (Saimiri boliviensis, Aotus nancymai, A. vociferans, A. azarae boliviensis) with Plasmodium gonderi, a malaria parasite of African monkeys. Sporozoites were obtained from Anopheles dirus or A. stephensi mosquitoes that fed on an infected rhesus monkey (Macaca mulatta). Inoculation of sporozoites was by injection of dissected sporozoites by either the intravenous or intrahepatic routes, or by mosquito bite. Liver biopsies done 7 or 8 days after sporozoite inoculation showed that hepatocytes of all 4 species of these New World monkeys supported exoerythrocytic stages of P. gonderi, but daily blood film examination during a 60-day observation period failed to detect blood stages of the parasite.

The gammarid amphipod Gammarus insensibilis frequently harbors adult individuals of the ectoparasitic nematode Gammarinema gammari as well as metacercariae of the trematode Microphallus papillorobustus. After the demonstration in a previous study of a negative relationship between the abundance of these 2 parasites, the nature of the relationship between these 2 parasites was explored in more detail by studying, in the field and in the laboratory, the influence of nematode abundance on trematode fecundity. In gammarids collected in the field, a negative relationship between metacercarial fecundity and the number of co-occurring nematodes was found. By manipulating the nematode abundance in the laboratory, it was confirmed that G. gammari has a negative effect on egg production in M. papillorobustus.