In this comparative behavioral study, the effect of infection with Schistosoma mansoni on its snail intermediate host Biomphalaria glabrata was investigated. Three groups of snails were compared for their activity: (1) uninfected, (2) infected with male parasites, and (3) infected with female parasites. In solitary movement trials, uninfected snails traveled greater distances at faster rates, explored more surface area, and had shorter rest periods than snails infected with either male or female schistosomes. In Y-maze experiments designed to determine attraction, the uninfected snails more often and more quickly moved toward other snails than the infected individuals. Snails from all 3 groups were more attracted to infected individuals than to uninfected ones. There was no difference in attraction toward snails infected with male or female parasites. These experiments provide evidence that behavioral alterations as a result of infection may lead to aggregation of infected snails in the field. We propose that such an effect may result in enhanced parasite transmission.

Limited storage stability severely restricts the biological control potential of slug-parasitic nematodes. In a series of experiments, we evaluated the effects of temperature and osmotic desiccation on the short- and long-term survival of the slug-parasitic nematode Phasmarhabditis hermaphrodita. Nematode survival in petri dishes at 1,500 infective juveniles/ml did not differ significantly at 5, 10, and 15 C but declined rapidly at 25 and 30 C. At 25 C about 50% of the nematodes survived for 4 wk, but at 30 C no nematode survived past 1 day. About 50% of the nematodes survived for 32 wk at 20 C. About 35–40% of the nematodes survived up to a year at 5, 10, and 15 C. Phasmarhabditis hermaphrodita showed poor survival under osmotic desiccation in glycerol with 15 and 20% glycerol significantly reducing survival at 5 and 15 C. Although the nematodes tolerated 10% glycerol, this level of desiccation also did not enhance long-term survival at either 5 or 15 C. There was a significant decrease in nematode survival in 10% glycerol at 25 C during the first 2–3 wk, but about 16% of the nematodes survived for 6 wk in 10% glycerol as compared with only 1% survival in water. The greatest benefit of osmotic desiccation in glycerol was observed in the enhanced survival of P. hermaphrodita at temperature extremes. Over 96% of the nematodes survived a 6-hr exposure to 35 C in 10% glycerol, whereas only 9% survived in water. Similarly, over 90% of the nematodes survived an exposure to −20 C for 4 hr in 10% glycerol, but less then 2% survived in water. We conclude that 5–15 C is an optimum temperature range for the storage of P. hermaphrodita. We also conclude that osmotic desiccation in 10% glycerol can substantially increase survival of P. hermaphrodita at temperature extremes (35 and −20 C) for short periods but has no effect on nematode longevity at the optimum temperature range of 5–15 C.

The growth of Enterobius vermicularis in a chimpanzee was investigated by observing worms discharged in feces after administration of pyrantel pamoate. Just after the final molting, immature adult male pinworms developed to a fully mature stage in 2 wk, after passing through a stage corresponding to the so-called Enterobius gregorii, which was surmised to be a younger adult form of E. vermicularis. The frequency distribution of body length forms 2 peaks in both male and female pinworms, with a depression in the transitional forms from the immature to the fully mature stage. This depression seems to be the result of more rapid growth or lower susceptibility to the drug in this transitional stage. Pyrantel pamoate effectively eradicated mature males, but gravid females were continuously observed in the feces after treatment. The complete eradication of pinworm infection by pyrantel pamoate could be achieved by repeated treatment at intervals shorter than 2 wk. This treatment would eradicate male worms first, resulting in females producing only unfertilized eggs, from which only males might hatch.

Between 1992 and 1996, 587 wild red-legged partridges (Alectoris rufa) from 16 Spanish provinces were examined to study the variations of helminth communities in this game species across a broad geographical area. The survey revealed 13 species of helminth parasites. Dicrocoelium sp., Rhabdometra nigropunctata, and Cheilospirura gruweli were the most common species, whereas Raillietina bolivari, Choanotaenia infundibulum, Tetrameres sp., and Capillaria anatis were the most rare. Subulura suctoria, Heterakis gallinarum, Heterakis tenuicaudata, Capillaria contorta, Trichostrongylus tenuis, and Raillietina tetragona occurred with intermediate frequencies. The abundance of C. gruweli, S. suctoria, H. tenuicaudata, T. tenuis, and R. tetragona was inversely correlated to latitude and directly correlated to yearly mean temperature, whereas the abundance of Dicrocoelium sp. was directly correlated to latitude and inversely correlated to yearly mean temperature. The abundance of R. tetragona was inversely correlated to latitude and yearly mean humidity. The number of helminths per partridge and the number of helminth species per partridge were lower in young birds than in adults. Partridge body condition was inversely correlated to abundance of C. contorta. Richer infracommunities were linked to richer component communities. At the infracommunity level, total number of helminths per partridge and number of helminth species per partridge were inversely correlated to latitude and directly correlated to yearly mean temperature. At the component community level, both species richness and diversity (Simpson's index) were inversely correlated to latitude and directly correlated to mean temperature. Across the broad geographical range of the study area, the helminth parasite communities of red-legged partridges had marked geographical variation in their structure. Our results suggest that this variation is determined by the distribution of both intermediate and definitive hosts. We discuss the implications of this variation for the hypothesis that supplementary releases of captive-bred partridges for sport hunting can affect the helminth fauna of wild red-legged partridges.

The Ixodes ricinus species complex is a group of ticks distributed in almost all geographic regions of the world. Lyme borreliosis spirochetes are primarily transmitted by tick species within this complex. It has been hypothesized that the Lyme vector ticks around the world are closely related and represent a monophyletic group. This implies that vector competence in ixodid ticks for Lyme agents might have evolved only once. To test this hypothesis, we used a molecular phylogenetic approach. Two fragments of mitochondrial 16S ribosomal deoxyribonucleic acid were sequenced from 11 species in the I. ricinus complex and from 16 other species of Ixodes. Phylogenetic analysis using Bayesian methodology indicated that the I. ricinus complex is not a monophyletic group unless 3 additional Ixodes species are included in it. The known major vectors of Lyme disease agents in different areas of the world are not sister taxa. This suggests that acquisition of the ability to transmit borreliosis agents in species of Ixodes may have multiple origins.

Both the prevalence and intensity of patent infection by avian schistosomes (Trichobilharzia ocellata) increase with increasing size of lymnaeid snails (Stagnicola elrodi) collected in Flathead Lake, Montana. Because the size and age of a snail are positively correlated, snails of different sizes may have experienced differential duration of exposure to and development of infection. Another possibility is that infection itself induces snail gigantism. Each of these possibilities could lead to increased prevalence and intensity of infection among the oldest–largest snails. To decouple size variation from many correlated effects of age and to test for parasite-induced gigantism, laboratory experiments standardized snail size–age-at-infection, exposure history, inoculating dose, and duration of infection. The positive relationship between size and prevalence was eliminated in the laboratory, but the relationship between size and infection intensity remained. Laboratory results thus suggest that infection intensity is related to snail size per se, whereas prevalence in the field is related to snail size only through the correlation between size and age. In addition, under these experimental conditions, infected snails were no larger than uninfected snails, so the patterns observed in the field might not be attributable to gigantism.

The main objective of this investigation was to examine the ultrastructural features of gills from rainbow trout experimentally infected with Loma salmonae to determine the morphological events that occur during the late stages of development of this parasite. Peripheral distribution of the mature parasites inside round xenomas was observed at weeks 5 and 6 postexposure (PE), but eventually the parasite occupied the entire xenoma. Degenerative changes were observed only in immature parasites at week 7 PE, and eventually an inflammatory reaction with a cellular infiltration was directed against mature spores. Round, flattened, and irregular shaped xenomas were observed at week 8 PE. The round xenomas showed a severe inflammatory response with disintegration of the xenoma membrane. This event was accompanied by eversion of polar tubes within the attacked xenoma and by the simultaneous presence of 2 tubular appendages, the type I and II tubules. Flattened xenomas were observed below the endothelium of gill lamella arteries. The irregular xenomas were located in the connective tissue of the gill filament and showed multiple projections occupied by spores. Both flattened and irregular xenomas showed no evidence of inflammatory reaction. An earlier proposed hypothesis is expanded to explain how L. salmonae is implanted beneath lamellar endothelium and within filament connective tissue.

The effect of echinostome infections on the survival of Rana pipiens tadpoles was examined in relation to developmental stage of tadpoles. Individual tadpoles of Gosner stages 25, 27, 32–33, and 37–39 were exposed to 1 of 4 levels of cercariae (0, 20, 50, or 100). Only tadpoles at stage 25, the earliest stage infected, died within a 5-day experimental period. This stage-specific mortality rate could be explained, in part, by the stage-specific location of encystment of cercariae, which was documented in a separate experiment. In accordance with kidney development, cercariae predominately encysted in the pronephroi during early stages of tadpole development (stages 25 through 31–32) and only in the mesonephroi and associated ducts at later stages (stages 37 through 46). As the mesonephros develops, renal capacity presumably increases. Thus, tadpoles died only when metacercariae concentrated in the functional portion of the kidney with the most limited renal capacity. As tadpoles aged, they also became less susceptible to infections. On average, 69.5% of cercariae that were exposed to stage 25–26 tadpoles successfully encysted, compared with only 8.4% of cercariae exposed to stage 37–38 tadpoles. Exposures of metamorphic frogs (poststage 46) to cercariae revealed that these individuals can become infected with echinostomes. Collectively, our data highlight the host stage–dependent dynamics of tadpole–echinostome interactions.

Infection of humans with filarial parasites has long been associated with the maintenance of a dominant Th2-type host immune response. This is reflected by increases in interleukin (IL)–4– and IL-5–producing T cells, elevated immunoglobulin (Ig)E and IgG₄ levels, and a pronounced eosinophilia. The Mongolian gerbil (Meriones unguiculatus) is permissive for the filarial nematodes Brugia malayi and B. pahangi. As in humans, persistent microfilaremic infections of gerbils with Brugia spp. results in increases in Th2 cytokines such as IL-4 and IL-5. The association of dominant Th2 cytokine profiles with the maintenance of infection suggests that the introduction of Brugia spp. into a strongly Th1-biased environment may adversely affect parasite establishment. Indeed, studies conducted in mice with B. malayi suggest that depleting Th1 effectors such as interferon (IFN)–γ and nitric oxide results in increased worm recoveries. In the present studies, the Mongolian gerbil was used as a model to investigate the effect of a dominant Th1 cytokine environment on the establishment of B. pahangi. Intraperitoneal (i.p.) administration of immunostimulatory oligodeoxynucleotide (IS ODN) induced the production of IFN-γ in the peritoneal exudate cells and spleen of gerbils. The presence of IFN-γ at the time of B. pahangi infection did result in an altered host immune response to B. pahangi. Gerbils that received IS ODN before i.p. B. pahangi infections showed lower levels of the Th2-type cytokines IL-4 and IL-5, compared with animals that received B. pahangi alone (0 Bp). This alteration in cytokine profile, however, did not alter the establishment or development of B. pahangi in the peritoneal cavity. Furthermore, there was no difference in the granulomatous response of gerbils to soluble adult B. pahangi antigen bound to beads embolized in their lungs, regardless of treatment group, suggesting that IL-4 and IL-5 are not essential contributors to the systemic host inflammatory response to B. pahangi in this model.

The prevalence of intestinal protozoans and helminths in stool samples of individuals with allergic cutaneous symptoms was evaluated to study a possible link between parasites and allergy. Altogether, 218 patients who had chronic urticaria, atopic dermatitis, or pruritus of unknown origin were included in the study. Standard laboratory tests for the detection of allergic etiology were performed for all patients. The presence of intestinal parasites was investigated using microscopy, immunofluorescence, and immunoenzymatic assays. Overall, protozoans and helminths were recovered from the stools of 48 subjects (P = 0.004), 18 of whom were affected with intestinal symptoms (P = 0.023). The presence of Giardia lamblia in the stools was significantly associated with allergic cutaneous manifestations (P = 0.030). In addition, patients with allergy were significantly more likely to have ≥5 Blastocystis hominis organisms per field (P = 0.046). There was a set of patients with allergic cutaneous diseases in whom the presence of intestinal parasites may not be incidental.

The main purpose of this study was to determine the effects of cortisone on the number and size of primary Echinococcus multilocularis cysts developing in a moderately resistant strain of mice, i.e., C3H/HeJ. Computerized image analysis was used to measure the surface area occupied by hydatid cysts 10 wk after inoculation of the mice with E. multilocularis eggs. Our second objective was to compare the infectivity of primary E. multilocularis hydatid cysts in C57BL/6J-A^y/a (lethal yellow) mice with that in C57BL/6J-a/a (non-agouti black) mice. The data obtained show no difference between the C3H/HeJ and C57BL/6J-a/a strains of mice; yet, the image analysis method was able to detect a slight increase in the total cyst size within the A^y/a mutant of the C57BL/6J strain. Treatment of C3H/HeJ mice with cortisone drastically increased both the number of cysts and the average size of each cyst when the treatment occurred early in the infection.

The purpose of the present study was to use direct plasmid deoxyribonucleic acid (DNA) injection to identify specific antigens that confer protection against congenital transfer of Neospora caninum. Inbred BALB/c mice were vaccinated before pregnancy with a recombinant plasmid containing sequences encoding N. caninum antigen NcGRA7 or NcsHSP33. The mice were challenged with N. caninum tachyzoites at 10–12 days of gestation. Whereas 100% of pups born from dams immunized with control plasmid contained detectable levels of N. caninum DNA in a Neospora-specific polymerase chain reaction assay, only 46% of pups from pCMVi-NcGRA7–immunized mice and 53% of pCMVi-NcsHSP33–immunized mice were N. caninum positive, and none of the mice immunized with tachyzoite extract contained N. caninum DNA. Thus, immunization of mice with plasmid DNA expressing N. caninum antigens conferred partial protection against congenital neosporosis.

Ultrathin sections of L3 of Wuchereria bancrofti embedded in hydrophilic resin were incubated with antisera pools from individuals (1) asymptomatic microfilaremic with different microfilaria (mf) densities (1–100, 101–500, and >1,000 mf/ml); (2) chronic with hydrocele or lymphedema; and (3) with no evidence of microfilaremia or clinical filariasis but residing in an endemic area. The groups of microfilaremic subjects studied presented differences relative to the intensity of labeling, with the density of gold particles per square micrometer proportional to microfilaremia. Incubation of ultrathin sections of W. bancrofti L3 larvae in the presence of antisera from patients exhibiting chronic obstructive lymphatic pathology of hydrocele and from individuals with clear clinical evidence of lymphedema exhibited a strong reaction in the same tissues. Except for the endemic normal group, all groups studied showed reactivity against epitopes in all tissues of infective larvae of W. bancrofti. The cuticle presented an intense labeling, suggesting a possible target structure for immune response.

A homologue of cytokine macrophage migration inhibitory factor (MIF) from complementary DNA (cDNA) of Trichinella spiralis and Trichinella pseudospiralis was expressed in Escherichia coli and characterized. The sequence analysis indicated that the predicted amino acid sequence has an identity of 57 and 44% with the MIF of nematodes Trichuris trichiura and Brugia malayi, respectively, and 41 and 40% with that of a human and a mouse, respectively. The identity in sequences of cDNA and amino acids between T. spiralis and T. pseudospiralis was 91 and 86%, respectively. Western blot analysis showed that anti-MIF antibodies positively stained proteins from the extracts of adult worms or muscle larvae migrating at about 12.5 kDa (3 isoforms with isoelectric point 5.23, 5.72, and 6.29). Semiquantitative reverse transcriptase–polymerase chain reaction revealed that the gene was expressed in various developmental stages, including in adult worms, newborn larvae, precyst muscle larvae, and postcyst muscle larvae, although there was difference in the expression level among these stages. The immunohistochemical analysis showed the MIF exists in the muscle cells of the body wall and some stichocytes of larvae. Histopathology of T. spiralis–infected muscles revealed an accumulation of mononuclear cells around the worms, and immunocytochemical staining showed these cells were not macrophages. Mononuclear cells, including macrophages, were, however, observed in cardiac muscles where the parasite did not encyst. Macrophages accumulated around the Sephadex beads transplanted in mice subcutaneously, but this accumulation was profoundly inhibited when the beads were pretreated with MIF recombinant protein.

Parasites may exert negative effects on host survivorship and reproductive success. The effects of parasites on female host fitness have been well documented; however, the effects of parasites on the reproductive success of male hosts and particularly the underlying mechanisms that alter male fitness are not well understood. Previous studies demonstrated that infection by rat tapeworm (Hymenolepis diminuta) reduced the fitness of male red flour beetles (Tribolium castaneum) in an environment of female mate choice and strong male–male competition. The present study determined the role of female mate choice and male insemination capacity on observed fitness reduction of male beetles by the tapeworm parasites. We found that infected males showed reduced mating vigor and consequently inseminated fewer females than did uninfected males. Specifically, tapeworm infection reduced the number of offspring sired by a male by 14–22% even when male–male competition and female mate choice were absent. Further, the insemination capacity of males diminished by 30% because of infection. Female beetles did not discriminate against infected males in precopulatory mate choice experiments. Copulatory courtship, a determinant of postcopulatory female choice, was not significantly different between infected and uninfected males. Hence, we concluded that female beetles did not show either pre- or postcopulatory choice against tapeworm-infected males. Therefore, tapeworm-induced reduction in the reproductive success of male beetles possibly results from altered reproductive biology, such as lower mating vigor and decreased sperm quantity or quality.

Two hundred and twenty-four anurans of 6 species (47 adults and 16 tadpoles of Rana blairi, 35 R. catesbeiana, 31 Hyla chrysoscelis, 30 adults and 46 tadpoles of Pseudacris triseriata triseriata, 11 Bufo woodhousii, and 8 Acris crepitans) from Pawnee Lake, Lancaster County, Nebraska, were surveyed for coccidian parasites during March 2001 to May 2002. Of these, 23 of 30 (77%) adults and 4 of 46 (9%) tadpoles of P. t. triseriata shed oocysts of Isospora cogginsi n. sp. Oocysts of I. cogginsi were ovoid, 19.3 × 15.1 (18–23 × 11–20) μm, with a thin, smooth, colorless, single-layered wall, with no micropyle or oocyst residuum. Sporocysts were ovoid, 13.3 × 9.9 (11–15 × 9–13) μm, with a thin, colorless, smooth wall, and Stieda body absent. Sporocyst residuum was present, 5.5 × 5.3 (4–7 × 4–7) μm, consisting of numerous granules. Histological examination of frogs and tadpoles infected with the new species revealed endogenous stages including mature meronts, developing microgamonts, mature microgametes, mature macrogamonts, and young unsporulated oocysts located in the cytoplasm of the epithelial cells of the small intestine. Concurrently, 2 adult P. t. triseriata shed oocysts of Eimeria streckeri. Oocysts of E. streckeri were spherical, 15.7 × 15.4 (14–17 × 14–19) μm, with a thin, smooth, single-layered, colorless wall with an oocyst residuum composed of numerous granules surrounding a large vacuolated area, with a previously undescribed globularlike body present within the vacuole, and no micropyle. Sporocysts were ovoid, 9.1 × 6.1 (7–10 × 5–7) μm, with a thin, colorless, smooth wall with a Stieda body and sporocyst residuum. Our results are the first to document infection of adult and tadpole stages of frogs of the same species with the same species of coccidian, indicating that adult frogs may contaminate breeding ponds with oocysts during their breeding season and infect tadpoles directly by the ingestion of sporulated oocysts.

We tested for correlations between the geographic, demographic, and temporal distribution of an aquatic insect host and the prevalence of its gut parasites in southwestern Ohio. Trypanosomatids were present in Aquarius remigis collected from all 4 streams surveyed in the watershed. Prevalence declined dramatically from May to July and remained low through the fall. This pattern was consistent over all sites of our study, with no effect of stream, stream site (upstream vs. downstream), or host sex on prevalence. Stage, however, was strongly correlated with prevalence; adults were more likely to be infected than were nymphs. We argue that behavioral differences between the 2 age classes may account for the decline in prevalence; opportunities for transmission are highest in the spring, when mating activities increase adult host contact rates, and decline in the summer, when contact rates decrease.

Unsporulated oocysts were detected in the feces of an Arabian red fox (Vulpes vulpes arabica) between 6 and 8 days after it had been fed meat from Arabian mountain gazelles (Gazella gazella) known to contain sarcocysts. No oocysts were discovered in the feces of other experimental cubs, although sporocysts of Sarcocystis spp. were passed subsequently by all cubs that were fed gazelle meat, including those fed with reem (G. subgutturosa marica). The oocysts sporulated in 3 days at room temperature (25 ± 2 C); they were 10.9 ± 1.4 × 10.1 ± 1.3 μm, with 2 sporocysts measuring 6.0 ± 0.6 × 4.7 ± 0.8 μm, each with 4 sporozoites. Sporulated oocysts were identified as those of Hammondia heydorni using molecular and standard morphometric techniques. Sequence differences between 2 fox and 3 dog isolates of H. heydorni were detected and allowed differentiation between the 2 populations of the organism. The involvement of Neospora caninum was excluded using molecular methods. The Arabian red fox and the Arabian mountain gazelle in Saudi Arabia are new, definitive and intermediate hosts for H. heydorni.

Introduction of exotic fishes into Hawai'ian streams has resulted in the simultaneous introduction of exotic parasites. Camallanus cotti (Nematoda) and Bothriocephalus acheilognathi (Cestoda) are the most prevalent and abundant fish helminths in Hawai'ian streams. The population structure and host specificity of C. cotti and B. acheilognathi in exotic poeciliids were examined during May and June 1995 in Waianu Stream, O‘ahu, Hawai'i. Prevalence and mean abundance of C. cotti were significantly different among Poecilia reticulata (65.2%, 1.05), Poecilia mexicana (49.0%, 0.87), and Xiphophorus helleri (32.3%, 0.44). Prevalence of B. acheilognathi was significantly higher in P. mexicana (6.1%) than in P. reticulata (2.1%) and X. helleri (1.6%). However, tapeworm differences in mean abundance were not significant among P. mexicana (0.08), P. reticulata (0.04), or X. helleri (0.03). Nematode and tapeworm prevalence and mean abundance were not significantly different with regard to fish sex. Camallanus cotti prevalence and mean abundance increased as P. mexicana body size increased (r² = 0.84 and r² = 0.72, respectively), whereas B. acheilognathi displayed no significant trend with respect to poeciliid body size.

A 436-bp complementary DNA (cDNA) was isolated from an adult Fasciola hepatica cDNA expression library by screening with the serum from a rabbit infected with F. hepatica for 4 wk. The deduced amino acid sequence encoded by this cDNA is an 11.5-kDa polypeptide that has significant homology to F. hepatica NK-lysin protein, to several members of saposin-like or NK-lysin protein families, as well as 3 amoebapore precursors of Entamoeba histolytica. The most striking feature observed within this protein, denoted FhSAP-2, is the presence of 6 conserved cysteine residues arranged within 5 amphipathic α-helical domains and the presence of 7 hydrophobic residues in strictly conserved positions. Using enzyme-linked immunosorbent assay it was found that rFhSAP-2 is highly reactive with sera from rabbits infected with F. hepatica for 2–14 wk as well as with sera from humans with chronic fascioliasis. An anti-rFhSAP-2 rabbit antiserum reacted with F. hepatica excretory–secretory antigens by Western blot, revealing a major 11.5-kDa and 2 minor 46- and 67-kDa antigenic polypeptides. This suggests that FhSAP-2 may be an antigen released from cytoplasmic storage granules present within F. hepatica parasites. rFhSAP-2 also exhibits a strong lytic activity on human erythrocytes and peripheral blood mononuclear cells. This suggests that cell lysis could be 1 of the biological functions of this protein.

Changes in proteins during sporulation of Eimeria tenella oocysts were investigated. Unsporulated E. tenella oocysts collected from cecal tissue at 7 days postinoculation were sporulated in aerated media at 28 C for 0–48 hr. Gel analysis of soluble protein extracts prepared from oocysts from their respective time points indicated the presence of 2 prominent bands with relative molecular weight (M_r) in the range of 30 kDa and making up 20% of the total protein. These 2 bands, designated as major oocyst proteins (MOPs), were absent or barely detectable by 21 hr of sporulation. MOP bands were weakly reactive with glycoprotein stain but showed no mobility shift on deglycosylation. By gel analysis it was shown that the purified MOPs consisted of 2 bands of M_r 28.7 and 30.1 kDa. However, by matrix-assisted laser deabsorption–time of flight analysis it was shown that masses were about 17% lower. Internal sequence analysis of the 28.7-kDa protein generated 2 peptides of 17 and 14 amino acids in length, consistent with a recently described protein coded by the gam56 gene and expressed in E. maxima gametocytes. Rabbit antibodies made against MOPs were localized to outer portions of sporocysts before excystment and to the apical end of in vitro–derived sporozoites. These same antibodies were found to react with bands of M_r 101 and 65 kDa by Western blot but did not recognize MOPs in soluble or insoluble sporozoite extracts. The data suggest that the MOPs are derived from part of a gametocyte protein similar to that coded by gam56 and are processed during sporulation into sporocyst and sporozoite proteins. Alternatively, the binding of anti-MOP to 101- and 65-kDa proteins may result from alternatively spliced genes as the development of parasite proceeds.

Acanthamoeba castellanii, a free-living amoeba, causes a sight-threatening form of keratitis. Even after extensive therapies, corneal damage can be severe, often requiring corneal transplantation to restore vision. However, A. castellanii cysts are not eliminated from the conjunctiva and stroma of humans and can excyst, resulting in infection of the corneal transplant. The aim of this study was to determine whether elements of the innate immune apparatus, neutrophils and macrophages, were capable of detecting and eliminating A. castellanii cysts and to examine the mechanism by which they kill the cysts. Results show that neither innate immune cell is attracted chemotactically to intact cysts, yet both were attracted to lysed cysts. Both macrophages and neutrophils were capable of killing significant numbers of cysts, yet neutrophils were 3-fold more efficient than macrophages. Activation of macrophages with lipopolysaccharide and interferon-γ did not increase their cytolytic ability. Conditioned medium isolated from macrophages did not lyse the cysts; however, prevention of phagocytosis by cytochalasin D inhibited 100% of macrophage-mediated killing of the cysts. Conditioned medium from neutrophils did kill significant numbers of the cysts, and this killing was blocked by quercetin, a potent inhibitor of myeloperoxidase (MPO). These results indicate that neither macrophages nor neutrophils are chemoattracted to intact cysts, yet both are capable of killing the cysts. Macrophages killed the cysts by phagocytosis, whereas neutrophils killed cysts through the secretion of MPO.

Acanthocephalus saurius n. sp. from the small intestine of Norops limifrons collected in Costa Rica is described and illustrated. Acanthocephalus saurius n. sp. represents the third acanthocephalan species in which gravid individuals have been found in lizard hosts. In addition to A. saurius; 1 species of Trematoda, Mesocoelium monas; 3 species of Nematoda, Piratuba digiticauda, Strongyluris panamaensis, and Acuariidae gen. sp. (larvae in cysts) were found.

A new species of an oxyurid nematode is described from the large intestine of the lacertid lizard Podarcis sicula (Rafinesque, 1810) (Reptilia: Lacertidae) from Italy. Spauligodon aloisei n. sp. differs from other species of the genus by a combination of morphological and metrical characters, including a spined tail in males and females, absence of a spicule in males, arrangement of the last pair of the male caudal papillae, vulva location, and egg morphology. The species most similar to S. aloisei n. sp. is Spauligodon caspius Annayev, 1987, described from Tenuidactylus (=Gymnodactylus) caspius in Turkmenistan. Tail length and location of the excretory pore and vulvar opening separate S. caspius from S. aloisei n. sp. This article increases the number of species of this genus from reptiles in the Paleartic Realm to 19.

Fresh fecal samples from 35 Japanese serows Capricornis crispus (Temminck, 1845), and 5 Formosan serows Capricornis swinhoei Gray, 1862, were collected between October 1998 and March 1999. Eimeriid coccidians were found in 12 (34%) Japanese serows and in 1 (20%) Formosan serow. Three Eimeria species were found, and 2 are described here as new. The third species is consistent with the description of Eimeria kamoshika Inoue, 1989. Sporulated oocysts of 1 new species are broadly ellipsoidal, 20.7 × 16.8 μm (18–23 × 14–19 μm) with a length (L):width (W) ratio of 1.2 (1.1–1.4); these lack a micropyle (M) and oocyst residuum (OR) but 1–2 polar granules (PGs) are sometimes present. Sporocysts are elongate-ellipsoidal, 10.5 × 5.9 μm (9–13 × 5–7 μm), with a L/W ratio of 1.8 (1.5–2.4), and have a Stieda body (SB) and sporocyst residuum (SR). Oocysts of the second new species are broadly ovoidal, 28.2 × 22.0 μm (25–33 × 19–23 μm), with a L/W of 1.3 (1.1–1.5), and have a M at the slightly pointed end, but lack an OR and PG. Sporocysts are ellipsoidal, 12.9 × 8.1 μm (11–15 × 7–10), with a L/W of 1.6 (1.3–1.9), and have a SB and SR.

This study compared specific polymerase chain reaction (PCR) primers and phylogenetic tree analysis of restriction fragment length polymorphism using the small subunit ribosomal RNA gene in various Blastocystis populations. A phylogenetic tree was constructed using 12 restriction enzymes and a sample pool of 22 isolates, including 2 reference strains and Proteromonas lacertae as an outgroup. The analysis showed that the 22 isolates could be separated into 7 clusters. Four of the 7 clusters were mixed groups that comprised isolates from both humans and nonhuman hosts. The other 3 clusters contained isolates from humans or nonhuman hosts only. The phylogenetic analysis also showed that B. hominis isolates from geographical separated areas did not necessarily cluster in the genetically different groups. The results of genetic homology and phylogenetic tree analysis among Blastocystis isolates from humans and animals indicated that all isolates from animals appear to be B. hominis. Polymerase chain reaction amplifications using previously described and newly defined specific primers mirrored the clusters obtained by the phylogenetic tree analysis. Our results show that primer PCR can be used as a powerful tool for the typing of Blastocystis populations.

Branchotenthes robinoverstreeti n. gen. and n. sp. (Monogenea: Hexabothriidae) infects the gill filaments of the bowmouth guitarfish, Rhina ancylostoma Bloch and Schneider, 1801 (Rhynchobatidae) in the southwest Indian Ocean off Trafalgar, South Africa. The new species is most easily distinguished from other hexabothriids by the combination of having a symmetrical haptor, C-shaped haptoral sucker sclerites that are approximately equal in size, haptoral suckers that are equal in size and arranged in 3 tandem pairs that each straddle the longitudinal axis of the haptor, glandular-walled vasa efferentia that are dilated in the distal portion and unite medially before connecting to the vas deferens, a thick-walled male copulatory organ with an oblong proximal portion and an unarmed and finger-like distal portion, parallel vaginae that each possess a thin-walled and sperm-filled proximal portion that is strongly sinuous as well as a thick-walled and musculoglandular distal portion that extends sinuously anteriad, and an egg with a filament at each end. This is the first report of a hexabothriid from a sharkfin guitarfish (Rhynchobatidae). A key to the genera of Hexabothriidae is provided.

We evaluated the effect of using Medium 199 alone and Medium 199 supplemented with 5% normal mouse serum, 5% fetal calf serum, 5% bovine serum albumin or 5% Albumax® on Plasmodium yoelii sporozoite yield from infected mosquitoes and infectivity in BALB/c mice. The sporozoites yield, as well as their infectivity, was statistically lower (P = 0.0031) when unsupplemented Medium 199 was used to separate sporozoites from infected mosquitoes. Although Medium 199 supplemented with Albumax® led to lower sporozoite yield (P < 0.0009), infectivity of the sporozoites was similar to those obtained with the other medium supplements. Because normal mouse serum supports good sporozoite infections and is also the supplement that can be used repeatedly in mice during multiple sporozoite injections without inducing anaphylaxis, we selected it to evaluate the infectivity of P. yoelii sporozoites in different strains of mice. After injecting mice with serial dilutions of sporozoites and detecting patent infections, we determined that the infective dose 50 (ID₅₀) for BALB/c, C57Bl/6, A/J, and B10BR mice ranged between 4.9 and 10.6 sporozoites. The ID₅₀ obtained for CD-1 mice (147 sporozoites) was significantly higher.

The antifungal agents clotrimazole (CLT) and ketoconazole (KC) and the herbicide clodinafop-propargyl (CP) inhibit growth of Plasmodium sp., Toxoplasma sp., and Trypanosoma sp. In the present study, we evaluated these drugs against the in vitro growth of the equine protozoan parasites Babesia equi and B. caballi. Clotrimazole (IC₅₀: 2 and 17 μM), KC (IC₅₀: 6 and 22 μM), and CP (IC₅₀: 450 and 354 μM) were effective growth inhibitors. Interestingly, intraerythrocytic KC-treated Babesia sp. were observed to be in immediate contact with the plasma fraction of the blood in electron microscopy. These results demonstrate the babesiacidial activities of these compounds and suggest their chemotherapeutic potential for the treatment of equine babesioses.

The role of signal transduction mechanisms with regard to the host cell invasion mechanics used by apicomplexans appears to have been overlooked; indeed, it is obvious that a signal must be transduced from the surface of an invading parasite to an intracellular location within it once the parasite makes contact with a host cell for the invasion process to be initiated. Data outlined in this communication show strong evidence for the role of tyrosine phosphorylation in the molecular mechanics and control of invasion of host cells when set within the context of the available literature, as detailed in this study.

Three of 6 female long-clawed shrews, Sorex unguiculatus Dobson, 1890, collected on the island of Hokkaido, Japan, were found to have unsporulated oocysts and sexual stages (both macro- and microgamonts) in varying stages of development of an unidentified coccidium in both lactating and nonlactating mammary glands. Gamonts developed in the alveoli of the mammary glands, and oocysts were found in the lactiferous ducts and in pools of milk. Mature macrogamonts were 11.9 × 15.2 μm (10–14 × 14–20 μm), whereas completely developed microgamonts with many gametes were 14.8 × 16.8 μm (10–18 × 13–20 μm). Oocysts in tissue sections were 19.5 × 13.8 μm and had a smooth outer wall that was <1 μm thick. Little histopathology was associated with the infections. Infected cells were enlarged and appeared cloudy, and in some areas there was leucocytic infiltration by macrophages, small and large lymphocytes, neutrophils, and eosinophils. No basophil was seen. We also found sections of a nematode, probably a Mammanidula sp., in sections of an active mammary gland in 1 of the shrews not infected with the coccidium.

To determine the persistence of Hepatozoon americanum in a naturally infected dog, skeletal muscle biopsies were performed at approximately 6-mo intervals over a period of 5.5 yr, and the samples were examined for presence of lesions of American canine hepatozoonosis (ACH). Nymphal Amblyomma maculatum (Gulf Coast tick) were allowed to feed to repletion on the dog periodically over the 5.5-yr period, and adult ticks were dissected and examined for presence of H. americanum oocysts. With 3 exceptions, the biopsied muscle contained lesions characteristic of ACH; no evidence of infection was found at 36, 54, and 67 mo after the original diagnosis. In every instance, nymphal Gulf Coast ticks became infected, indicating that dogs naturally infected with H. americanum can remain infectious for Gulf Coast ticks for at least 5.5 yr. Skeletal muscle biopsy is a reasonably reliable method of determining whether dogs are infected with the parasite. Xenodiagnosis using nymphal Gulf Coast ticks is an even more sensitive method, but the procedure is practicable only experimentally. Design of prevention and control measures for ACH must take into account knowledge that the parasite can survive in dogs, and presumably other vertebrate host(s), for long periods. Preventing ingestion of Gulf Coast ticks is an effective control measure.

A soluble antigen isolated from Eimeria stiedai merozoites with a molecular mass of 49 kDa was detected in the bile of infected rabbits. Rabbits immunized with the antigen shed a lower number of oocysts than did nonimmunized rabbits postchallenge (p.c.). The immunized rabbits showed a marked and transient increase of alanine-aminotransferase (ALT) activity on day 8 p.c. The blood indocyanine green (ICG) clearance and r-glutamyltransferase (GGT) activity showed no change throughout the experiment. However, nonimmunized rabbits showed a gradual increase of ALT and GGT in the plasma and a delay of ICG p.c. Many merozoites were observed in the biliary ducts of the nonimmunized rabbits on day 8 p.c. using standard histology. In contrast, in the immunized rabbits, many inflammatory cells were observed around the biliary ducts, but there were few parasites in the tissue. These results suggest that the 49-kDa soluble protein antigen detected in the bile of the infected rabbits was a merozoite-specific antigen, and the immune reaction to the antigen may induce protective effects against the infection.

Juvenile freshwater parasitic nematodes Rhabdochona denudata honshuensis Moravec and Nagasawa, 1989 and Rhabdochona coronacauda Belouss, 1965 (Spirurida: Thelazioidea: Rhabdochonidae) were found in mayfly nymphs collected in a mountain stream in Japan. Considering the relative density of mayfly nymphs, nematode prevalence, and intensity of parasitism, Ephemera strigata Eaton and Potamanthus formosus Ulmer (Ephemeroptera: Ephemeridae) are frequent natural intermediate hosts for R. d. honshuensis in this locality. The intermediate host of R. coronacauda also is the E. strigata nymph.

The ability of Cryptosporidium meleagridis to produce patent infection was studied in adult C57BL/6 mice that were immunosuppressed with dexamethasone phosphate provided in the drinking water at a dosage of 16 μg/ml. Four days after the onset of immunosuppression, mice were orally challenged with 1, 3, 10, or 1,000 C. meleagridis TU1867 oocysts per mouse. The mice were monitored daily for 18 days postinoculation for oocyst shedding. Five of 10 mice given a single oocyst, 4 of 5 mice given 3 oocysts, and all 9 mice given either 10 or 1,000 oocysts became infected and began shedding oocysts 5–7 days after challenge and continued to shed oocysts until the end of the experiment on day 18 postchallenge. Approximately 10⁷ oocysts per mouse per day were excreted, regardless of the challenge dose. Neither the noninfected, immunosuppressed nor the inoculated, nonimmunosuppressed control mice shed oocysts. The excreted oocysts were confirmed to be those of C. meleagridis by polymerase chain reaction–restriction fragment length polymorphism analysis. We show that C. meleagridis, originally classified as an avian pathogen but recently found in humans with cryptosporidiosis, can produce patent infection in mice infected with a single oocyst. Moreover, we demonstrate that the immunosuppressed C57BL/6 adult mouse is an ideal host for the propagation of clonal populations of C. meleagridis isolates for laboratory studies.

Phalloidin–fluorescein isothiocyanate staining of filamentous actin was used to identify muscle systems within the cercariae of Schistosoma mansoni. Examination of labeled cercariae by confocal scanning laser microscopy revealed distinct organizational levels of myofiber arrangements within the body wall, anterior cone, acetabulum, and esophagus. The body wall throughout showed a typical latticelike arrangement of outer circular and inner longitudinal myofibers, with an additional innermost layer of diagonal fibers in the anterior portion of the body. Circular and longitudinal fibers were also evident in the anterior organ and esophagus and, to some extent, the ventral acetabulum. Most striking was the striation of the cercarial tail musculature.

The trematode Curtuteria australis uses the whelk Cominella glandiformis as first intermediate host and the cockle Austrovenus stutchburyi as second intermediate host before maturing in shorebirds. The whelk also happens to be an important predator of cockles on intertidal mudflats. In this study we show that whelks can act as temporary paratenic hosts for the trematode. A single whelk feeding on 1 cockle can ingest large numbers of metacercariae, which remain within the whelk for 1–3 days before passing out in feces. The viability of these metacercariae, assessed as the percentage capable of successfully excysting under conditions simulating those inside a bird's digestive tract, is lower after passage through a whelk (48%) than before (59%). Still, given that shorebird definitive hosts prey on whelks as well as cockles, survival inside the whelk allows C. australis to complete its life cycle; overall, though, whelk predation is likely to be an important sink for the trematode population. To our knowledge, this is the first report of a trematode using a snail as both first intermediate host and paratenic host, offering an alternative transmission route for the parasite as a result of the unusual trophic relationships of its hosts.

Feces from 15 dogs at 2 different foxhound kennels in the U.K. were examined microscopically for the presence of oocysts of Neospora caninum. One sample containing approximately 400 candidate oocysts per gram was positive in a polymerase chain reaction (PCR) using N. caninum–specific primers. In a sample taken 4 mo later from the same hound, N. caninum oocysts were again detected visually and by PCR. This is the third reported case of a dog naturally excreting oocysts of N. caninum and suggests that oocyst excretion can occur over a relatively long period of time in some circumstances or that reshedding may occur.

C3H mice, which are highly susceptible to infection with the Brazil strain of Trypanosoma cruzi, not only survive infection when maintained at elevated environmental temperature, but also experience reduced parasitemias, reduced tissue pathology, and enhanced immune responsiveness. The contribution of CD8 T cells to this phenomenon was investigated using the in vivo cell-depletion technique. The depletion of CD8 T lymphocytes with purified monoclonal antibody resulted in an abrogation of the protective effects of elevated environmental temperature during T. cruzi infection, as evidenced by high parasitemia levels and 100% mortality in monoclonal antibody–treated mice.

The complete nucleotide sequence of the tapeworm Taenia solium mitochondrial DNA (mtDNA) has been determined. The sequence is 13,709 base pairs in length and contains 36 genes (12 for proteins involved in oxidative phosphorylation, 2 for ribosomal RNAs, and 22 for transfer RNAs). The gene content and organization of the T. solium mtDNA are identical to those of other taeniid mtDNAs. All genes are transcribed in the same direction, and all protein-coding genes appear to initiate with the AUG or GUG codon. In a gene for NADH dehydrogenase subunit 1, the abbreviated stop codon U was confirmed for the first time in flatworm mtDNAs.

Twenty-two coprolites of human origin, collected from excavations along the north-central coast of Peru, were examined using fluorescent microscopy for the presence of fecal parasites, with emphasis on Cryptosporidium sp., Giardia sp., and Cyclospora sp. Three samples were positive. One coprolite dated between ca. 2,375 and 1,525 BC contained Giardia sp. cysts. This coprolite corresponded to the Peruvian preceramic period. Another positive coprolite ca. AD 770–830 corresponded to Epoch 3 of the Middle Horizon and contained Cryptosporidium sp. oocysts. The third positive coprolite (corresponding to the Middle Horizon, ca. AD 500–900) contained Giardia sp. cysts. This report demonstrates that Giardia sp. and Cryptosporidium sp. were present in Peruvian coastal populations for at least 4,300 and 1,100 BP.

Attempts are being made to adapt Old World monkey malarial parasites to New World monkeys for vaccine and molecular studies. Several of these (Plasmodium cynomolgi Berok, Plasmodium fragile, and Plasmodium knowlesi) grow readily but have failed to produce infective gametocytes. Plasmodium gonderi and Plasmodium fieldi develop in the liver after sporozoite inoculation but have failed to establish infection in the erythrocyte. Anopheles dirus mosquitoes infected with Plasmodium inui shortti by feeding on infected macaques transmitted the infection to Saimiri boliviensis monkeys. Infective gametocytes were produced, and sporozoite transmission from Saimiri to Saimiri monkey was obtained. Exoerythrocytic stages have also been observed in the liver tissue of Saimiri monkeys. The availability of the complete transmission cycle provides an additional resource for immunologic and vaccine studies.

Cryptosporidium parvum is 1 of the major causative organisms in waterborne diarrheal illness. Not only does C. parvum spread ubiquitously in our environment, it is also highly resistant to harsh environmental conditions and disinfectants. Therefore, a control measure for this protozoon is urgently required. This study investigated the effect of γ-irradiation, in the range of 1,000–50,000 Gy, on the viability of C. parvum oocysts. Oocyst viability was determined by a combined indirect immunofluorescence and nucleic acid staining and animal infectivity study. The proportion of viable oocysts estimated by nucleic acid staining ranged from 94.2 to 89.4% in the 0- to 10,000-Gy groups, whereas it was reduced significantly to 58.6 or 45.7% in the 25,000- or 50,000-Gy group, respectively, at 24 hr postirradiation. In an animal infectivity study, oocysts irradiated with less than 10,000 Gy induced infections in mice wherein there were low numbers of oocysts per gram of feces amounting to 8–10.8% of the values in control mice, whereas with 50,000 Gy–irradiated oocysts, no oocysts were produced in the mice. This study suggests that at least 50,000 Gy of γ-irradiation is necessary for the complete elimination of oocyst infectivity in mice.