Alloglossidium hirudicola sp. n. is described from adult specimens recovered from the ceca of leeches, Haemopis sp., purchased from a commercial source. It differs from A. corti (Lamont, 1921) Van Cleave and Mueller, 1934, and from A. geminus (Mueller, 1930) Van Cleave and Mueller, 1934, in having shorter ceca, smaller cirrus pouch, and in distribution of cuticular spines.

Parasitology has a rich tradition of studies linking taxonomy, ecology, and life cycles and development. This tradition has produced an enormous amount of empirical evidence demonstrating that parasites form highly integrated reproductive–developmental–ecological systems that are highly persistent through space and time. As well, phylogenetic studies of parasites, especially of parasitic platyhelminths, represent 1 of the most progressive areas of systematic biology. Consequently, parasitologists should be at the forefront of research in evolutionary developmental biology (evo–devo) and integrative biology, and parasite systems should be model systems of choice for those research programs. Species of the digenean, Alloglossidium, provide a superb exemplar for such studies because we know so much about their phylogeny, population biology, ecology, and life cycles. Equally important is the recognition that Alloglossidium spp. is such an outstanding model system because of more than 30 yr of effort by a number of people working with little funding at small institutions, beginning with a short unassuming species description by Gerald D. Schmidt. For dedicated and creative scientists, the size of the institution and the research budget need not be an impediment to producing high-quality research. These are the people who produce the quiet classics, and they need to be recognized for their invaluable contributions.

Toxoplasmosis, particularly toxoplasmic encephalitis, has emerged as a major cause of morbidity and mortality in patients with acquired immunodeficiency syndrome. Patients infected with human immunodeficiency virus typically experience chronic oxidative stress, and concurrent infection with the intracellular parasite Toxoplasma gondii would be expected to further exacerbate this condition. The present study was conducted to determine whether vitamin E and selenium supplementation might be beneficial in a murine model of toxoplasmosis. To investigate the effect of these antioxidants on the severity of parasitic infection, Swiss Webster (SW) or C57Bl/6J mice infected with oocysts of the ME49 strain of T. gondii were maintained on diets containing no vitamin E or selenium, no vitamin E and 8 ppm selenium, 400 IU/kg vitamin E plus 8 ppm selenium, or vitamin E and selenium at the levels present in standard rodent chow (16 IU/kg and 0.2 ppm, respectively). The results of the study showed that increased dietary supplementation with vitamin E and selenium resulted in trends toward increased tissue cyst number, tissue pathology, and weight loss during infection. In contrast, both resistant SW and susceptible C57Bl/6J mice fed a deficient diet (complete absence of vitamin E and selenium) showed the lowest mean numbers of tissue cysts and very little evidence of tissue pathology during chronic infection.

RH strain Toxoplasma gondii tachyzoites that had naturally lysed their host cells were allowed to infect new host cells for a limited amount of time; subsequent parasite cell divisions were observed closely. On the basis of 4 independent trials, the estimated time to first cell division was 9.8 hr postinfection (PI) and was quite variable (95% confidence interval [CI]: 3.1–16.5 hr PI). The estimated time to second cell division was 14.9 hr PI and was less variable (95% CI: 12.1–17.7 hr PI). Few parasites divided before 6 hr PI in these 4 trials. When tachyzoites were derived by forced lysis (scraping an infected host cell culture and passing it through 27-gauge needles), the first parasite cell division occurred much more rapidly than had been observed in any of the trials with parasites derived by natural lysis. When parasites derived by forced lysis were held away from host cells for 3 hr PI, the first cell division was delayed in a manner similar to that seen in parasites derived by natural lysis. No differences were observed in the timing of the second cell division of parasites derived by forced lysis whether or not they had been held away from cells. These studies demonstrate that the conditions to which tachyzoites are exposed during transit from one host cell to another can affect the kinetics of parasite cell division in the new host cell.

The helminth parasites of the greater kudu from the Kruger National Park (KNP), South Africa, and the Etosha National Park (ENP), Namibia, were examined to determine the major patterns of spatial and demographic variation in community structure and to evaluate nonrandomness in parasite community assembly. Nonmetric multidimensional scaling ordination procedures were used to test for differences in parasite community composition between hosts of the 2 parks and between hosts of different demographic groups within KNP. Infracommunities within KNP were also examined for patterns of nonrandomness using 2 null models, i.e., nestedness and species co-occurrence. Infracommunities of KNP and ENP were significantly different from each other, as were infracommunities of different host demographic groups within KNP. Parasite species in the greater kudu from KNP displayed significant levels of nestedness and were found to co-occur less frequently than expected by chance; however, this lack of co-occurrence was significant only when all demographic groups were considered. When restricted to any particular age class, co-occurrence patterns could not be distinguished from random. Overall, these data suggest that biogeography and host demographics are important factors in determining community organization of helminth parasites in the greater kudu.

Androlaelaps ilhacardosoi, a new species of Laelapinae, is described from the pelage of a 3-lined marsupial, Monodelphis americana, collected on Ilha Cardoso, São Paulo State, Brazil. The description is based on the female, and the systematics of laelapine mites associated with neotropical marsupials is discussed.

An intertidal horned blenny, Parablennius cornutus, captured at De Hoop Nature Reserve, South Africa, was found to harbor an unusual blood parasite and the haemogregarine Haemogregarina bigemina. In Giemsa-stained blood films, the enigmatic parasite occurred primarily as intraerythrocytic ringlike stages, with unstained centers and peripheral bands of beaded chromatin, not unlike Haemohormidium spp. Larger forms of the same organism stained pink with Giemsa, with nuclei occurring as 4–8 minute structures around the parasite body or distributed within it. These larger parasites apparently segmented into up to 8 individuals that were rounded or oval with deep-stained, comma-shaped or polar regions surrounding blue cytoplasm. Extracellular, binucleate, sporelike structures in clusters of as many as 16 individuals were also seen in blood films. Praniza larvae of the isopod Gnathia africana were seen in histological sections of gill tissue. Examination of spleen tissue by transmission electron microscopy showed intraerythrocytic organisms with ultrastructural characteristics like those of Haematractidium scombri, namely, a single boundary membrane, sometimes closely apposed nuclei with nucleoli, and profiles of dense material of variable structure. It is concluded that the parasite is probably related to Haemohormidium spp. and H. scombri, but it also shares features with some Microsporida.

Passive transfer of maternal antibodies via colostrum is important to protect newborn ruminants against microbial pathogens. In this study, 10 sets of calf serum, a sample of the colostrum fed to the calf, and serial fecal samples through the first 6 days after birth were collected from arbitrarily selected newborn Holstein heifers. A recombinant Cryptosporidium parvum p23, termed rC7, was used to determine whether anti–C. parvum antibodies can be detected in clinically normal neonates. The results demonstrated that serum, the associated colostrum, and fecal samples contained anti-rC7 antibodies. IgM and IgG₁ anti-rC7 tended to be present in highest titers. The presence of specific antibodies to C. parvum was confirmed using Western blots of purified sporozoite membranes probed with serum and colostral whey. Collectively, the results indicated that neonatal calves had antibodies to C. parvum as early as 1 day after birth and suggested that the antibodies were passively transferred.

Immunocompetent C57BL/6 mice were infected with Sarcocystis neurona merozoites to assess the protective immune response to active infection. Using a direct agglutination test, all infected mice seroconverted to S. neurona merozoite antigens by day 14 postinfection (PI). Further, mice developed splenomegaly and bilateral symmetrical lymphadenopathy by day 14 PI, which appeared to be resolving by day 28 PI. Histologic analysis revealed a marked increase in germinal center formation in the spleen and lymph nodes by day 14 PI. Corresponding to gross and histopathological changes, the percentage of B-cells decreased significantly by day 14 PI but then increased significantly and persisted at day 28 PI in the blood, spleen, and multiple lymph nodes. There was a sharp nonspecific significant decrease in CD4 percentages by day 14 PI in the blood, spleen, and lymph nodes. Early-activation CD8 lymphocytes (CD62/CD8) were significantly down-regulated coinciding with a significant compensatory up-regulation of memory (CD44/CD8) lymphocytes in multiple organs. We propose that the protective cell-mediated immune response to S. neurona involves both CD4 and CD8 cells, with CD8 lymphocytes appearing to play a more critical role.

Interferon-gamma knockout (IFN-gamma KO) mice were infected with Sarcocystis neurona merozoites to characterize the immunopathology associated with infection. By day 14 postinfection (PI), mice developed splenomegaly and lymphadenopathy, characterized by marked lymphoid hyperplasia with increased numbers of germinal centers. Additional histopathologic changes included increased extramedullary hematopoiesis, multifocal mixed inflammatory infiltrates in the liver, perivascular infiltrate of the liver and lung, and interstitial pneumonia. The total number of B-cell splenocytes (P < 0.05) and the percentage of B-cells increased on day 14 PI in the spleen and on day 28 PI in the lymph nodes (P < 0.05). By day 28 PI, the number of B-cell splenocytes decreased significantly. A non–subset-specific decrease in percentages of CD4 lymphocytes throughout all lymphoid organs was observed on day 14 PI. However, total CD4 and CD44/CD4 splenocytes increased significantly by day 28 PI. Early-activation CD8 lymphocytes were reduced in the blood and spleen, whereas memory CD8 lymphocyte percentages and total numbers were significantly increased. On the basis of the results, we propose that S. neurona–infected IFN-gamma KO mice are immunocompromised and unable to clear the infection. Thus, they develop B-cell exhaustion and a delayed, but sustained, increased number of memory CD4 and CD8 lymphocytes due to chronic antigen stimulation.

Perkinsus marinus is responsible for disease and mortality of the American oyster, Crassostrea virginica. To investigate the interactions between P. marinus and oyster hemocytes, protease activity was measured in plasma of oysters collected 4 hr, 24 hr, 4 days, and 2 mo after experimental infection with P. marinus. A significant increase in protease activity was observed in oyster plasma 4 hr after injection with P. marinus, followed by a sharp decrease within 24 hr. Gelatin-impregnated gel electrophoresis showed the presence of 2 major bands (60 and 112 kDa) and 3 less prevalent bands (35, 92, and 200 kDa) with metalloproteinaselike activity in the plasma of noninfected oysters. Additional bands in the 40- to 60-kDa range, corresponding to P. marinus serine proteases, were observed in oyster plasma at early time points after infection. A transient, but significant, decrease in the activity of oyster metalloproteinases was observed at early time points after infection. Coincubation of oyster plasma with P. marinus extracellular products resulted in a decrease in oyster metalloproteinases and several P. marinus proteases. This study provides insights into the role of proteases in the pathogenesis of Dermo disease.

Two hundred and four rabbits from 8 Macaronesian islands (Pico, San Jorge, San Miguel, Terceira, and Flores from Azores Archipelago; Tenerife and Alegranza from Canary Islands; and Madeira from Madeira Archipelago) were examined for helminth parasites between 1995 and 2000. Three species of cestodes, Taenia pisiformis (larvae), Andrya cuniculi, and Mosgovoyia ctenoides, and 5 species of nematodes, Trichuris leporis, Graphidium strigosum, Trichostrongylus retortaeformis, Passalurus ambiguus, and Dermatoxys hispaniensis, were identified. Only 3 species (M. ctenoides, T. retortaeformis, and P. ambiguus) were regularly distributed over the 3 archipelagos. Taenia pisiformis was not collected in Madeira, nor was A. cuniculi in the Azores and G. strigosum in the Canary Islands. Trichuris leporis and D. hispaniensis were only found in Madeira. Significant differences in the general prevalence of the nematodes G. strigosum and T. retortaeformis were detected between Azores and Madeira. The prevalence of T. retortaeformis differs significantly between the Azores and the Canaries and that of P. ambiguus was higher in Madeira than in Azores and Canaries. The helminth richness found in the wild rabbit in these Macaronesian archipelagos was very low compared with the Palearctic helminth fauna of this host. The wild rabbit was introduced from the Iberian Peninsula into different Macaronesian islands. Helminths introduced with Oryctolagus cuniculus into these islands also are commonly found in Iberian wild rabbits, which are excellent colonizers, as demonstrated in this study.

Naive, full-sibling juveniles of Xenopus laevis laevis were exposed to 10, 30, or 50 larvae of the monogenean Protopolystoma xenopodis from an isolate known to produce relatively low adult establishment (typically less than 25% prevalence) in hosts of the same pedigree. Postlarval survival (worms per host) 7 days postinfection (PI), timing from the end of a 10-day infection window, was significantly related and proportional (∼31%) to infection dose. Establishment of newly mature adults 90 days PI was low (0–3 worms/host) and unrelated to infection dose. Results confirm that postlarval mortality is severe in primary infections, and that surviving adult infrapopulations appear to be regulated to a very low level (most often 1 worm/host), even at relatively high larval infection pressures. This density-dependent process could involve direct antagonistic parasite–parasite interactions or indirect interference mediated by parasite-induced host defenses.

Falcaustra greineri n. sp. from the large intestine of the turtle Orlitia borneensis is described and illustrated. Falcaustra greineri represents the 23rd Oriental species assigned to this genus and is distinguished from other Oriental species by the distribution pattern of caudal papillae (6 preanal, 0 adanal, 14 postanal, and 1 median), length of spicules (1.07–1.33 mm), and absence of pseudosucker.

Phylogenetic relationships among nematodes of the strongylid superfamily Metastrongyloidea were analyzed using partial sequences from the large-subunit ribosomal RNA (LSU rRNA) and small-subunit ribosomal RNA (SSU rRNA) genes. Regions of nuclear ribosomal DNA (rDNA) were amplified by polymerase chain reaction, directly sequenced, aligned, and phylogenies inferred using maximum parsimony. Phylogenetic hypotheses inferred from the SSU rRNA gene supported the monophyly of representative taxa from each of the 7 currently accepted metastrongyloid families. Metastrongyloid taxa formed the sister group to representative trichostrongyloid sequences based on SSU data. Sequences from either the SSU or LSU RNA regions alone provided poor resolution for relationships within the Metastrongyloidea. However, a combined analysis using sequences from all rDNA regions yielded 3 equally parsimonious trees that represented the abursate Filaroididae as polyphyletic, Parafilaroides decorus as the sister species to the monophyletic Pseudaliidae, and a sister group relationship between Oslerus osleri and Metastrongylus salmi. Relationships among 3 members of the Crenosomatidae, and 1 representative of the Skrjabingylidae (Skrjabingylus chitwoodorum) were not resolved by these combined data. However, members of both these groups were consistently resolved as the sister group to the other metastrongyloid families. These relationships are inconsistent with traditional classifications of the Metastrongyloidea and existing hypotheses for their evolution.

Fresh fecal samples from 12 shrews, 10 Cryptotis goodwini Jackson, 1933, and 2 Cryptotis merriami Thomas, 1898, were collected between December 1994 and May 1998; 11 (92%) were positive for eimeriid coccidia, including 8 of 8 C. goodwini and 2 of 2 C. merriami from Honduras and 1 of 2 C. goodwini from Guatemala. Two Eimeria species were found: 1 is consistent with the description of Eimeria whitakeri Upton and McAllister, 1991, and 1 is described in this study as new. Sporulated oocysts of the new species are subspheroidal, 16.8 × 15.7 (14–20 × 15–19) μm, with a length–width (L/W) ratio of 1.1 (1.0–1.2); they lack a micropyle and oocyst residuum, but 1–2 polar granules are always present. Sporocysts are elongate and ovoidal, 8.4 × 6.0 (6–10 × 4.5–7.5) μm, with a L/W ratio of 1.4 (1.2–1.7) and have a Stieda body and sporocyst residuum. This is the 49th Eimeria species described from all Insectivora but only the third from Cryptotis species.

One nine-banded armadillo (Dasypus novemcinctus) and 1 yellow armadillo (Euphractus sexcinctus) were necropsied in the field during an expedition to collect parasites of mammals in Bolivia. A total of 205 Aspidodera binansata Railliet and Henry, 1913 (Heterakoidea: Aspidoderidae), and 40 specimens of Lauroia bolivari n. sp. (Heterakoidea: Aspidoderidae) were recovered from the cecum and large intestines of D. novemcinctus and E. sexcinctus. Aspidodera esperanzae Fujita et al., 1995, is proposed as a junior synonym of A. binansata based on the structure of the cordons on the hood. Lauroia bolivari n. sp. has an undercut cephalic cap and unequal spicules. It differs from other species in the genus in the shape of the cephalic cap and from Lauroia travassosi Proença, 1938, in the relative proportion of the spicules. This is the first record of a member of Lauroia Proença, 1938, for Bolivia.

The use of ovejector structure in the phylogeny of the Haemonchinae is hampered by differences among nematologists in the application of terminology and the recognition of homologous parts. Some workers recognize a sphincter with 2 parts, but others recognize only the proximal, rounded part of the sphincter and include the distal cylindrical part of the sphincter with the vestibule. The results of this study demonstrate that all sphincters of Haemonchinae of ruminants have 2 parts. To encourage the application of a uniform terminology to homologous parts of the ovejector, we propose the use of the terms “sphincter 1” for the rounded part and “sphincter 2” for the cylindrical part. It is hoped that clarification of the terminology for ovejectors of the Haemonchinae will provide a model useful for improving descriptions of ovejectors throughout the Trichostrongyloidea.

Extensive new collections of specimens of Rhinebothroides spp. from a wide range of Neotropical freshwater potamotrygonid stingrays in numerous localities permitted critical evaluation of the validity of the 7 nominal species in the genus. Some qualitative characters previously used in the taxonomy of this group are highly variable within and among populations, and most morphometric and meristic characters thought to have taxonomic value for this group overlapped among several previously defined nominal species. Characters that were consistent throughout populations and that clearly define morphotypes supported recognition of 4 species: R. freitasi (syn. R. circularisi and R. venezuelensis), R. glandularis (syn. R. mclennanae), R. moralarai, and R. scorzai. We provide a taxonomic review of the genus, 8 additional host records, 7 new localities, and an identification key.

Adult tetraphyllidean tapeworms (Platyhelminthes: Eucestoda) from the spiral intestines of 3 species of potamotrygonid stingrays (Paratrygon aiereba, Potamotrygon castexi, and Potamotrygon motoro) in the Madre de Dios river in Peru were found to host numerous cysts embedded in their parenchymal tissues. Histological sections of the cysts revealed the presence of a scolex bearing 4 suckers and an unarmed apical organ consistent with larval stages of both Cyclophyllidea and Proteocephalidea. To further elucidate their identities, partial 28S ribosomal DNA (rDNA) sequences were characterized from 3 cysts and 4 adult Rhinebothrium spp. ‘host’ worms and screened against all available cestode 28S rDNA data. Initial BLAST screening and subsequent alignment ruled out the possibility that the cysts were cyclophyllidean, and the cyst and adult sequences were thus aligned together with all available lecanicephalidean, litobothriidean, proteocephalidean, and tetraphyllidean sequences. Sequences from all 3 cysts were identical, and phylogenetic analysis clearly placed them among derived members of the Proteocephalidea, although no exact match was found. Sequences from the adult host worms formed 2 identical pairs and grouped together with other tetraphyllidean species from rays. These results are compared with records of hyperparasites of South American catfish cestodes. This is the first confirmed record of a proteocephalidean cestode parasitizing a tetraphyllidean cestode.

Seven of 28 passerine birds that died in captivity were positive for malarial parasites by polymerase chain reaction targeting the mitochondrial cytochrome b (cytB) and apicoplast ribosomal RNA (rRNA) genes. Each bird was infected with a single parasite lineage having a unique genotype. Apicoplast rRNA sequences were present both in Haemoproteus spp. and Plasmodium spp. and had typically high adenosine thymidine content. Phylogenies for cytB and apicoplast rRNA sequences were largely congruent and supported previous studies that suggest that Plasmodium–Haemoproteus spp. underwent synchronous speciation with their avian hosts, interrupted by sporadic episodes of host switching. Apicoplast phylogeny further indicated that Haemoproteus spp. are ancestral to Plasmodium spp. All the 7 infected passerine birds had histologic lesions of malaria, and malarial parasites may have contributed to the death of at least 4 animals. These findings provide new genetic data on passerine hematozoa, including initial sequences of apicoplast DNA, and emphasize the relevance of parasite prevalence, evolutionary relationships, and host switching to modern management and husbandry practices of captive birds.

Syncuaria mycteriae n. sp. (Nematoda: Acuarioidea) was collected under the lining of the gizzard of a wood stork, Mycteria americana L., from the Area de Conservacion Guanacaste, Costa Rica. The new species can be distinguished from all known species of Syncuaria by having irregular dotted ornamentations on the caudal alae of males, a complex distal end of the left spicule comprising 3 protuberances, and a spicule ratio of 1:9.3. Preliminary phylogenetic analysis of 11 Syncuaria spp. based on 9 morphological characters produced 2 equally parsimonious cladograms with a consistency index of 85%, differing only in the placement of S. hargilae. The phylogenetic analysis suggests that the new species is the sister species of S. leptoptili, whose male members have a single protuberance on the left spicule. Furthermore, the analysis suggests that the plesiomorphic host group for the genus is Ciconiiformes, specifically Ciconiidae (host for 5 species), with 2 species occurring in Threskiornithidae (also Ciconiiformes), possibly as a result of cospeciation, and 2 species each occurring in Pelecaniformes and Podicipediformes, resulting from 4 episodes of speciation by host switching.

Two species of Acuaria were collected from passerine birds from the Area de Conservacion Guanacaste, Costa Rica. Acuaria mayori Lent, Freitas and Proenca, 1945, was collected from Myiarchus nuttingi. Specimens from Costa Rica differ from the original description by having a spicule ratio of 1:1.5–1.7 versus 1:1.43–1.47, as well as shorter spicules and female tails. Acuaria wangi n. sp. in Hylophylax naevioides and Gymnopithys leucaspis resembles A. alii, A. crami, A. cyanocitta, A. minuta, A. pattoni, and A. cissae by having cordons extending posteriorly to the anterior portion of the glandular esophagus. The new species differs from A. alii by having 4 pairs of preanal and 6 pairs of postanal papillae rather than 2 pairs of preanal and 7 pairs of postanal papillae, a shorter left spicule, a spicule ratio of 1:1.6–1.8 versus 1:1.1 and in having spicules with blunt rather than pointed distal ends. Acuaria crami and A. minuta differ from A. wangi by having 7 pairs of postanal papillae and spicule ratios of 1:1.6–1.8 versus 1:1.3 in A. crami and 1:1.1 in A. minuta; in addition, A. minuta has spatulate-shaped spicules and a tricupsid-shaped distal end of the right spicule. The new species can be distinguished from A. pattoni by having a longer left spicule and a spicule ratio of 1:1.6–1.8 versus 1:1 and from A. cissae by having a shorter left spicule and a spicule ratio of 1:1.6–1.8 versus 1:2.5–2.7. Acuaria wangi is similar to A. cyanocitta, which has similarly shaped spicules, including a very pointed distal end of the left spicule, but differs in body length, in having shorter spicules, in the arrangement of postanal papillae, and in having smaller eggs.

We describe a polymerase chain reaction (PCR) assay that detects avian malarial infection across divergent host species and parasite lineages representing both Plasmodium spp. and Haemoproteus spp. The assay is based on nucleotide primers designed to amplify a 286-bp fragment of ribosomal RNA (rRNA) coding sequence within the 6-kb mitochondrial DNA malaria genome. The rRNA malarial assay outperformed other published PCR diagnostic methods for detecting avian infections. Our data demonstrate that the assay is sensitive to as few as 10⁻⁵ infected erythrocytes in peripheral blood. Results of avian population surveys conducted with the rRNA assay suggest that prevalences of malarial infection are higher than previously documented, and that studies based on microscopic examination of blood smears may substantially underestimate the extent of parasitism by these apicomplexans. Nonetheless, because these and other published primers miss small numbers of infections detected by other methods, including inspection of smears, no assay now available for avian malaria is universally reliable.

DNA topoisomerases play a pivotal role in the regulation of cell division. Inhibition of Leishmania spp. topoisomerases represents an alternative to control parasite growth. Cancer research led to the development of several potent topoisomerase inhibitors such as topoisomerase I, topoisomerase II, or both (monobenzimidazole, terbenzimidazole, and protoberberine alkaloid-related compounds) that are effective antitumor agents. In the present study, we evaluated the efficacy of these compounds against Leishmania spp. growth in vitro. Some protoberberine compounds showed pronounced antileishmanial activity and were selected for further analysis in macrophages. These compounds did not affect macrophage viability and only slightly reduced macrophage nitric oxide generation in response to interferon-γ. Moreover, exposure of infected macrophages to these compounds significantly reduced parasite loads. Collectively, our data suggest that protoberberine-related compounds have powerful antileishmania action and that minor structural variations among them can substantially improve their activity to restrict Leishmania spp. infection in vitro.

Isolates of Cryptosporidium were collected from 3 species of woodland and field rodents (Clethrionomys glareolus, Microtus arvalis, and Apodemus flavicollis) and were characterized by polymerase chain reaction amplification and sequencing of fragments of the oocyst wall protein (COWP) gene and of the 18S ribosomal RNA gene. Sequence analysis of these markers revealed that the animals were infected with C. parvum, and that the genotype involved was almost identical to the mouse genotype previously described from Mus musculus. Thus, small rodents should be considered as an important reservoir of C. parvum genotypes closely related to the zoonotic genotype 2 and potentially hazardous to humans.

The establishment of in vitro cultivation techniques to maintain larval and adult stages of the trematode Schistosoma mansoni has facilitated research on diverse aspects of the biology of this parasite. Because of the difficulty in obtaining defined intramolluscan stages of this parasite, one aim of this study was to develop an in vitro technique for the generation of defined clonal daughter sporocyst (DSp) generations that originate from a single mother sporocyst. Sporocysts died when cultured singly; however, when single sporocysts were cultured in inserts within wells with about 1,000 others, the single individuals produced daughters asexually. In recent years, evidence has been accumulating for variability among, and within, schistosome populations. Such variability has been seen in both larval and adult stages. Even within clonal cercariae, genomic and biochemical heterogeneity has been observed, indicating the existence of a yet unknown mechanism that generates variability during larval development. Therefore, another aim of this study was to examine clonal DSps generated in vitro for diversity regarding the presence or absence of a specific repetitive DNA element (W1). Such sporocysts were found by molecular analysis to be heterogeneous with respect to the occurrence of W1. This phenomenon had previously been observed in clonal schistosome populations and described as genomic instability. In this study, we provide the first molecular evidence that variability can be generated within sporocyst generations, supporting the hypothesis of mitotic recombination events during the asexual life stage of schistosomes.

Prevalence of Toxoplasma gondii infection in chickens is a good indicator of the strains prevalent in their environment because they feed from ground. The prevalence of T. gondii was determined in 118 free-range chickens from 14 counties in Ohio and in 11 chickens from a pig farm in Massachusetts. Toxoplasma gondii antibodies (≥1:5) were found using the modified agglutination test (MAT) in 20 of 118 chickens from Ohio. Viable T. gondii was recovered from 11 of 20 seropositive chickens by bioassay of their hearts and brains into mice. The parasite was not isolated from tissues of 63 seronegative (≤1:5) chickens by bioassay in cats. Hearts, brains, and muscles from legs and breast of the 11 chickens from the pig farm in Massachusetts were fed each to a T. gondii–negative cat. Eight cats fed chicken tissues shed oocysts; the 3 cats that did not shed oocysts were fed tissues of chickens with MAT titers of 1:5 or less. Tachyzoites of 19 isolates of T. gondii from Ohio and Massachusetts were considered avirulent for mice. Of 19 isolates genotyped, 5 isolates were type II and 14 were type III; mixed types and type I isolates were not found.

The prevalence of Toxoplasma gondii in free-ranging chickens can be considered a good indicator of the prevalence of T. gondii oocysts in the environment because chickens feed from the ground. In the present study, prevalence of T. gondii in 29 free-range chickens (Gallus domesticus) from Argentina was investigated. Blood, heart, and brain from each chicken were examined for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (MAT), were found in 19 of 29 (65.5%) chickens. Hearts and brains of seropositive (MAT ≥ 1:5) chickens were bioassayed in mice. Toxoplasma gondii was isolated from 9 of 19 seropositive chickens. Genotyping of chicken isolates of T. gondii using the SAG2 locus indicated that 1 was type I, 1 was type II, and 7 were type III. This is the first report of isolation of T. gondii from chickens from Argentina.

Several potential cues for increased surface antigenic expression of lung-stage schistosomula, such as lack of glucose and amino acids and extremes of pH or HCO₃⁻ concentration, failed to alter the negligible larval reactivity with control, infection, or irradiated cercariae-vaccine serum in indirect membrane immunofluorescence. In contrast, incubation of larvae in 90% corn oil for 6 hr led to surface membrane changes, which allowed specific and strong binding of antibody from antischistosome sera. The data together indicated that the lung-stage worms' confinement of antigenic molecules in lipid-rich sites of the outer membrane could be reversed in vitro after exposure to corn oil, in a concentration- and time-dependent manner.

Cats are important in the epidemiology of Toxoplasma gondii infection because they are the only hosts that can excrete the environmentally resistant oocysts. Antibodies to T. gondii were determined in serum samples from 220 domestic cats (Felis catus) from Barcelona, Spain, using the modified agglutination test (MAT). Antibodies to T. gondii were found in 99 (45%) of 220 cats, with MAT titers of 1:25 in 26, 1:50 in 57, and ≥1:500 in 16 cats. Seropositivity (MAT 1:25 or more) was significantly higher in adult (≥1 yr old, 49.7% of 153) than in juvenile (<1 yr old, 34.3% of 67) cats, in feral (51.9% of 131) than in domiciled (34.8% of 89) cats, and in cats living in a group (community) of more than 5 cats (50.7% of 142) than in cats living alone (28.0% of 50). These seropositive cats are likely to have already shed T. gondii oocysts in the environment around Barcelona.

Human babesiosis in the northeastern United States caused by Babesia microti (Apicomplexa: Piroplasmida) is mainly reported from coastal New England sites, where deer ticks (Ixodes dammini) are common. However, the piroplasm has been detected in microtine rodents elsewhere in association with I. angustus or other nidicolous ticks, suggesting that the agent is widely distributed but zoonotically significant only where a human-biting “bridge” vector is present. To determine whether this piroplasm may be enzootic in areas where I. dammini is absent, we surveyed small mammals collected from 2 sites in Maine, where I. angustus or I. muris is common but I. dammini is not. Of 43 chipmunks, voles, deer mice, and shrews examined, 3 (6.9, 95% confidence interval 0 to 14.5) were parasitemic, as determined by blood smear or polymerase chain reaction targeting a piroplasm-specific portion of the 18S ribosomal DNA gene. Phylogenetic analysis of the sequenced amplification products demonstrates the presence of 2 forms of B. microti. We conclude that B. microti may be enzootic in the absence of I. dammini but that human risk relates to dense infestations of this human-biting tick.

Four of the 27 Pacific sleeper sharks (Somniosus pacificus Bigelow and Schroeder) captured in the western North Pacific Ocean off eastern Taiwan between 19 March and 18 May 2002 hosted the parasitic copepod Dinemoura ferox (Krøyer, 1838) on their body surface including the fins. This report documents a new host record as well as a new ocean record for D. ferox, which until now has only been reported from the benthopelagic sharks, Somniosus microcephalus (Bloch and Schneider) and Centrophorus squamosus (Bonnaterre), occurring in the north Atlantic Ocean off Greenland and Iceland.

Dioctophymidae eggs were found in human coprolites dated from 3,384 to 3,370 BC from the site Arbon–Bleiche 3, Switzerland. This is the first record of dioctophymiasis in archaeological material. The important percentage of this disease in the studied coprolites raises the question of a higher prevalence during the Neolithic than at present.

A simple method to screen trichomonacides, based on the quantification of acid phosphatase (AP) activity, has been designed. Using p-nitrophenyl phosphate as chromogenic substrate, we first determined the optimal conditions for enzyme reaction. After seeding, a linear correlation between number of trichomonads and optical densities at 405 nm was obtained at 24 hr but not at 48 hr. Then, the inhibitory effect of metronidazole was assessed both by microscope counts and by AP determination. Similar values for 50% inhibitory concentrations (2.6 μM), with 95% confidence limits of 1.91–3.33 for microscopic and 2.21–3.05 for colorimetric method, were obtained. We concluded that the colorimetric method described in this investigation is suitable for pharmacological studies and for the screening of new, potential antitrichomonal agents.

Dicationic compounds, which are derivatives of pentamidine, are being developed for use as antiprotozoal drugs. These compounds bind to the minor groove of DNA and are thought to inhibit DNA-dependent enzymes and thereby prevent cellular replication by protozoans. The objective of this study was to test the ability of a group of these compounds to inhibit the intracellular and extracellular reproduction of Trypanosoma cruzi in vitro. At present, there are few drugs in use capable of inhibiting the intracellular stages of this parasite, and therefore compounds with this ability would be of value. Cultures of mouse fibroblasts were infected and treated with doses of dicationic compounds, and the numbers of parasites released at the end of the 5- to 7-day growth cycle were determined. Five of the compounds tested were found to be effective at inhibiting T. cruzi growth at doses that were not toxic to the host cells. The compound found most effective (DB709) inhibited parasite release at the low concentration of 0.8 ng/ml, justifying further study. These results suggest that dicationic compounds may have potential as chemotherapy against T. cruzi infection.

Role of intestinal goblet cells (GCs) in the expulsion of Gymnophalloides seoi was studied using 4 strains of mice, ICR, C3H/HeN, BALB/c, and C57BL/6, after infection with 200 metacercariae isolated from oysters. On day 7 postinfection (PI), significantly higher (P < 0.05) worm recovery rates (WRRs) were observed in ICR (29.5 ± 12.0%) and C3H/HeN (14.8 ± 8.2%) than in BALB/c (5.7 ± 5.3%) and C57BL/6 (0.8 ± 1.1%) mice. Alteration of the GC mucins was marked in C57BL/6 mice. On day 14 PI, 5.2 ± 5.2% and 0.6 ± 0.7% of worms were recovered only from ICR and C3H/HeN mice. When C57BL/6 mice were immunosuppressed with prednisolone, WRR on day 7 PI increased to 11.7 ± 13.9%, whereas the GC hyperplasia and mucin alteration diminished significantly. The results suggest that expulsion of G. seoi from the intestine is dependent on immune responses of the host, and GCs may be an important effector.

Neospora caninum and Hammondia heydorni are morphologically and phylogenetically related coccidians that are found in dogs. New diagnostic genetic loci, based on random-amplified polymorphic DNA–polymerase chain reaction (RAPD-PCR), were developed to aid in the detection of H. heydorni–like parasites and to discriminate them from N. caninum and other related coccidians of dogs. On the basis of the data obtained from 5 random decamers, H. heydorni (Manhattan-1) and N. caninum (NC1) were characterized by distinct banding patterns (similarity index = 0.068). High-stringency PCR assays were developed from the sequences of 2 cloned bands (GenBank BZ592549 and BZ592593), uniquely amplified from H. heydorni. Interestingly, using these primers, PCR amplification was achieved only from 2 of the 5 isolates presumed to represent H. heydorni. The same result was obtained from these 5 isolates using a recently described PCR assay directed to the H. heydorni internal transcribed spacer-1. It is concluded that H. heydorni and N. caninum are genetically distinct and that such tools may be useful for more detailed characterization of the diversity of related parasites occurring in dogs.

The development of a European isolate of Echinococcus multilocularis was compared in cats and dogs at the end of the prepatent period. Echinococcus multilocularis established in all dogs and cats, but worm recovery was significantly greater from dogs than from cats. Overall, worms in cats were not as advanced as those in dogs in terms of development and maturation, but there was no evidence of retarded development or stunted forms. These results confirm that dogs are highly susceptible to E. multilocularis, whereas cats have lower and more variable recovery rates. However, because cats produce thick-shelled eggs of E. multilocularis after experimental and natural infections, they have to be regarded as potential sources of infection both for intermediate and accidental hosts, including humans. However, their general role in the epidemiology of the infection has yet to be determined.

Snails (Elimia livescens) from a central Indiana stream were examined for encysted metacercariae of Macravestibulum obtusicaudum (Pronocephalide) to determine the distribution and abundance of this parasite on its second intermediate host. Five samples of snails were collected, with 2 samples being restricted to high-flow (riffle) or low-flow (pool) areas of the stream. Snails (n = 386) were measured for shell length; the shell and the inner and outer surfaces of the operculum (in most samples) were examined for metacercariae. Seventy-five percent of snails (overall) had encysted metacercariae (range, 52–97%), primarily on the opercula. A significantly lower proportion of snails from riffles were infected, and these snails had significantly fewer cysts as well. Snails collected from pools showed up to 10 times as many metacercariae than those from riffles, although there was no significant difference in the proportion of snails with intramolluscan infections of M. obtusicaudum. The inner opercular surface appeared to be the preferred site of encystment in both flow regimes. Differences in microhabitats, in terms of both snails in the stream and metacercariae on the snails, clearly must be considered when evaluating the infection patterns of this trematode.