Nonfeeding infective juvenile (IJ) entomopathogenic nematodes (EPNs) are used as biological agents to control soil-dwelling insects, but poor storage stability remains an obstacle to their widespread acceptance by distributors and growers as well as a frustration to researchers. Age is one factor contributing to variability in EPN efficacy. We hypothesized that age effects on the infectiousness of IJs would be evident within the length of time necessary for IJs to infect a host. The penetration behavior of “young” (<1-wk-old) and “old” (2- to 4-wk-old) Heterorhabditis bacteriophora (GPS11 strain), Steinernema carpocapsae (All strain), and Steinernema feltiae (UK strain) IJs was evaluated during 5 “exposure periods” to the larvae of the wax moth, Galleria mellonella. Individual larvae were exposed to nematode-infested soil for exposure periods of 4, 8, 16, 32, and 64 hr. Cadavers were dissected after 72 hr, and the IJs that penetrated the larvae were counted. Larval mortality did not differ significantly between 72- and 144-hr “observation periods,” or points at which larval mortality was noted, for any age class or species. However, age and species effects were noted in G. mellonella mortality and nematode penetration during shorter time periods. Initial mortality caused by S. carpocapsae and H. bacteriophora IJs declined with nematode age but increased with S. feltiae IJ age. Young S. carpocapsae IJs penetrated G. mellonella larvae at higher rates than old members of the species (27–45% vs. 1– 4%). Conversely, old S. feltiae IJs had higher penetration rates than young IJs (∼8 to 57% vs. 4 to ∼31%), whereas H. bacteriophora IJs had very low penetration rates regardless of age (3–5.6%). Our results show that the effect of age on IJ infectiousness can be detected in IJs aged only 2 wk by a 4-hr exposure period to G. mellonella. These results have important implications for storage and application of EPNs and suggest the possibility of shortening the time required to detect nematodes in the soil.

The in vitro exposure of Taenia crassiceps cysticerci to 17-β estradiol (E₂) and progesterone (P₄) stimulated their reproduction and infectivity. Testosterone (T₄) and dihydrotestosterone (DHT) inhibited their reproduction and reduced their motility and infectivity. E₂ and P₄ increased, whereas T₄ and DHT reduced, the expression of parasite c-fos and c-jun and DNA synthesis. In vitro exposure of cysticerci to sex steroids before their inoculation into recipient noninfected mice resulted in large parasite loads when pretreated with E₂ and P₄ and in smaller loads when pretreated with T₄ and DHT. To determine the possible molecular mechanisms by which sex steroids affect T. crassiceps, sex steroid receptors were amplified. Taenia crassiceps expressed estrogen receptors (both α and β isoforms) and androgen receptors but no P₄ receptors. These results demonstrate that sex steroids act directly on parasite reproduction by binding to a classic and specific sex steroid receptor on the parasite. The differential response of cysticerci to sex steroids may also be involved in their ability to grow faster in the murine female or feminized male host. This is the first report of direct sex steroid effects on the parasite possibly through sex steroid receptors in the cysticerci.

To characterize the genes expressed by Eimeria tenella oocysts, the sequence of 499 expressed sequence tags (ESTs) was obtained from complementary DNA (cDNAs) enriched for transcripts expressed by unsporulated or sporulated oocysts. Of these, 225 clones were isolated from cDNA of sporulated oocysts and 274 from unsporulated oocysts. A total of 163 unique sequences were found, and the majority of these (64%) represent novel genes with no significant homology to the proteins in GenBank. Approximately half of the unique transcripts generated from sporulated oocysts are also expressed by sporozoites and merozoites, whereas the expression of most (79%) of the transcripts from unsporulated oocysts has not yet been detected at other stages of development. The expression of 4 transcripts obtained from the subtracted cDNAs was confirmed by quantitative reverse transcriptase–polymerase chain reaction. The results confirmed that these transcripts are in fact differentially expressed between sporulated and unsporulated oocysts.

Allocreadiid flukes often parasitize and castrate sphaeriid freshwater clams. The effects of parasitic castrators on host population life history can lead to earlier reproductive onset, changes in body size, or changes in the number of reproductive events per year. However, little is known about whether species- or clade-level traits are associated with parasite prevalence. In this study, we examine if phenotypic effects, e.g., size change, seen at the population level, sort to the species or clade level. To answer this question, we determined if different-sized host species in the ecologically important, widespread, and common sphaeriid subgenus Cyclocalyx have different prevalences of allocreadiid infection. After showing that large species are more than 12 times more likely to have patent infections than small species, we examined the evolution of size within Cyclocalyx lineages. Transitions from large size to small size or vice versa have occurred at least twice and probably many times during lineage diversification, perhaps relating to trade-offs between clutch size and parasite risk. Finally, based on existing data, we show that it is unlikely that age and body size are correlated; therefore, a simple age-exposure model is not a sufficient explanation for parasite prevalence in this clade.

The intestinal helminth communities of 8 horses, 12 donkeys, 21 Hartmann's mountain zebras, and 44 Burchell's zebras were compared using the original data from 6 studies in South Africa and Namibia. Necropsy and worm recovery techniques were comparable between the studies. Sixty helminth species (58 nematode, 1 cestode, and 1 trematode species) were recorded. There were significant differences in the helminth community structures of the 4 Equus species. The helminth communities of the 2 closely related zebra subspecies were most similar, and they jointly shared 7 helminth species with donkeys and only 1 with horses. Geographic variation and host-mixing contributed to the helminth species composition. Multiple confamilial species infections were the norm in the donkeys and zebra subspecies, and no single-species infection was recorded for the Strongylidae. Congeneric species were commonly recorded in 3 genera (Cyathostomum, Cylicocyclus, and Cylicostephanus). The shape of the occupancy frequency distributions for the donkeys and zebra subspecies was multimodal, with no clear satellite or core modes. Despite the presence of environmental variability and comparatively low parasite-host specificity, the phylogenetic signal within Equus helminth communities remains strong.

A lizard assemblage at Macraes Flat, New Zealand, comprising the common skinks Oligosoma maccanni and Oligosoma nigriplantare polychroma, the endangered species Oligosoma grande and Oligosoma otagense, and the common gecko Hoplodactylus maculatus, was studied to determine the prevalence of ectoparasites and hemoparasites. The mites Odontacarus lygosomae and Ophionyssus scincorum infected all Oligosoma spp. only, and the mite Neotrombicula naultini infected only H. maculatus. The hemoparasite Hepatozoon lygosomarum infected all Oligosoma skinks, except O. n. polychroma. Oligosoma otagense had the highest infection levels of all parasites by several orders of magnitude. For all lizard species, there was no difference in mite prevalence between adult males and adult females, but juveniles were less often infected. For all skink species, there was a significant relationship between presence of the hemoparasite He. lygosomarum and infection intensity of the supposed vector, O. scincorum. It is unclear if patterns of parasite infection reflect species-specific susceptibility, host–parasite species-specific spatial ecology, or environmentally induced host physiological impairment. Considering the threatened nature of O. otagense, evidence of high parasitemia should stimulate further investigation.

The objective of this study was to apply transition models to distinguish between factors associated with both incident and persistent trypanosome infections. Data collected from 1,561 cattle were analyzed from a long-term study involving 8 herds in which both trypanosome infections (a total of 56,931 cattle sampling-months) and tsetse (Glossina spp.) challenge were monitored monthly from March 1986 to March 1998. Both pour-on and insecticide-target tsetse control programs and mass treatment with diminazene aceturate before tsetse control were associated with significant decreases in both incidence and persistence of trypanosome infection relative to noncontrol periods, as were seasonal and sex effects. The magnitudes of the effects were, however, often different for new and persistent infections. For persistence of infection, there were 2 trends. In general, the duration of infection increased during the study, despite the regular treatment with diminazene aceturate. The transition model had 2 major benefits. The first was to identify an increasing duration of infections with time, taking into account other factors associated with increasing infection risk. The second was to highlight different patterns in the effects of certain factors on new and persistent trypanosome infections.

Copepods are common parasites of marine fishes, but little information is available on the biology of species that parasitize mesopelagic fishes in oceanic waters. In this study, we report the finding of large numbers of Sarcotretes spp. (n = 2,340) in dietary samples of king penguins collected at Crozet and the Falklands Islands. Analysis of penguin food indicates that S. scopeli Jungersen parasitizes myctophid fishes, Protomyctophum tenisoni (Norman), in the southern Indian Ocean and P. choriodon Hulley in the southern Atlantic. It suggests that the much rarer S. eristaliformis (Brian) also parasitizes myctophids, but the host species of that copepod remains to be determined. The new data add significant information concerning the hosts and distribution of Sarcotretes spp. in the Southern Ocean and emphasize the usefulness of ichthyophagous predators in revealing valuable information on the biology of organisms that parasitize their prey.

Ectoparasite and epifaunistic arthropod biodiversity and infestation parameters were compared between 2 sympatric small rodent species, the cotton mouse (Peromyscus gossypinus (Le Conte)) and golden mouse (Ochrotomys nuttalli (Harlan)), in southern Georgia from 1992 to 2003. Because the cotton mouse is known to be a reservoir of more vector-borne zoonotic pathogens than the golden mouse, we hypothesized that it would be parasitized by more ectoparasites that are known to be vectors of these pathogens. Cotton mice (n = 202) were parasitized by 19 species of arthropods, whereas golden mice (n = 46) were parasitized by 12 species. Eleven species of arthropods were recovered from both host species, whereas 7 were recorded only from cotton mice, and 1 species only from golden mice. Infestation prevalences (percent of mice parasitized) were significantly higher for 1 species of arthropod (the tropical rat mite Ornithonyssus bacoti (Hirst)) infesting cotton mice and for 4 species (the flea Peromyscopsylla scotti Fox and the mites Glycyphagus hypudaei Koch, Androlaelaps casalis (Berlese), and Androlaelaps fahrenholzi (Berlese)) infesting golden mice. Mean intensities (mean per infested mouse) were significantly higher for 2 species (the flea Orchopeas leucopus (Baker) and the blacklegged tick Ixodes scapularis Say) infesting cotton mice and for 2 species (G. hypudaei and A. fahrenholzi) infesting golden mice. Ectoparasites that are known to be vectors of zoonotic pathogens were significantly more common on cotton mice than on golden mice. These ectoparasites included the rhopalopsyllid flea Polygenis gwyni (Fox), a vector of the agent of murine typhus; I. scapularis, the principal vector of the agents of Lyme borreliosis, human granulocytic ehrlichiosis, and human babesiosis; and O. bacoti, a laboratory vector of several zoonotic pathogens. However, 2 species of ixodid ticks that can transmit zoonotic pathogens were recovered from both host species. These were the American dog tick Dermacentor variabilis (Say), the principal vector of the agent of Rocky Mountain spotted fever in eastern North America, and Ixodes minor Neumann, an enzootic vector of the agent of Lyme borreliosis. Overall, the cotton mouse was parasitized by significantly more ectoparasites that are known to be vectors of zoonotic pathogens than was the golden mouse. These data support the hypothesis that the cotton mouse has greater epidemiological importance for zoonotic vector-borne pathogen transmission than does the golden mouse.

Fifty Borrelia isolates from ticks and rodents from several geographic regions of the southern United States were analyzed by genomic macrorestriction analysis. Significant genetic diversity was observed among them. These isolates segregated into 4 major clusters and 10 subclusters, which are correlated with the genospecies distribution. Nineteen pulsed-field gel electrophoresis (PFGE) types were recognized among the isolates. The genospecies Borrelia andersonii and Borrelia bissettii consisted of 5 and 2 subclusters, respectively. Two subclusters comprised the Borrelia burgdorferi sensu stricto (s. s.) strains. These results indicated that PFGE is a suitable molecular typing method for B. burgdorferi at both the genospecies and strain levels. Seventeen representative isolates from different PFGE groups were analyzed by restriction fragment length polymorphism (RFLP) and sequence analysis of flaB. Twenty-three AluI, 3 CelII, and 11 DdeI RFLP patterns were found among strains from the B. burgdorferi sensu lato (s. l.) complex and the relapsing fever borreliae complex. Three genospecies in the B. burgdorferi s. l. complex and 1 species in the relapsing fever borreliae complex were recognized. Phylogenetic analysis based on nucleotide sequences of flaB indicated that all the Borrelia strains analyzed here could be divided into 2 parts, i.e., B. burgdorferi s. l. complex and the relapsing fever borreliae complex. The flaB appears to be a useful target gene to screen and identify strains from both B. burgdorferi s. l. and relapsing fever borreliae complexes.

A progenitor blast cell in the posterior of the newly hatched larva of Nippostrongylus brasiliensis yielded a large population of coelomic cells among which were 2 previously undiscovered coelomocytes, C5 and C6. The coelomocytes lay subdorsal and posterior to the genital primordium, C5 on the right and C6 on the left. Also, in the first-stage larva, 7 single seam cells appeared in the hypodermis on both the right and left sides arrayed in tandem along its length. Each seam cell (1–5, 7) went through 2 divisions with spaces maintained between the formed quartets. However, seam cell 6 underwent an unusual series of divisions resulting in the formation of a huge amoeboid nurse cell that enclosed a quartet of small cells in a vacuole; the quartet also was derived from seam cell 6. Ultimately, all the seam cells, including the nurse cells on each side of the larva, regressed and disappeared, except for the quartet cells, now released from their vacuole. These latter cells then remained dormant during the life of the free-living stages. During the process of seam cell development, coelomocytes 5 and 6 aligned themselves closely to seam cells 6 and their progeny; some attached themselves to and even partially penetrated the nurse cells at the level of the vacuole. At the time of the second molt and the formation of the early–third stage infective larva, tiny vesicles began to appear in the cytoplasm of coelomocytes 5 and 6. As vesicles increased in number, they aggregated into a mass at either the anterior or posterior pole of the cells. Coelomocytes 1–4 situated anterior to the genital primordium differed from coelomocytes 5 and 6 in that they accumulated much larger numbers of vesicles that remained discrete in the cytoplasm and concentrated extraordinary amounts of vitamin B₁₂ that was recognized as a red pigment filling the vesicles. However, no red pigment ever was seen in the vesicles of coelomocytes 5 and 6. On the basis of the very early sexual differentiation of larvae in the rat lung, it was determined that the infective free-living larvae from which they were derived, and which contained coelomocytes 5 and 6, were female; those lacking coelomocytes 5 and 6 were presumed to be male.

A wide range of recombinant proteins from Eimeria species have been reported to offer some degree of protection against infection and disease, but the specific biological function of these proteins is largely unknown. Previous studies have demonstrated a 19-kDa protein of unknown function designated SZ-1 in sporozoites and merozoites of Eimeria acervulina that can be used to confer partial protection against coccidiosis. Reverse transcriptase–polymerase chain reaction indicated that the gene for SZ-1 is expressed by all the asexual stages of Eimeria tenella. Rabbit antisera to recombinant SZ-1 recognized an approximately 19-kDa protein from extracts of E. tenella sporozoites, merozoites, sporulated oocysts, and oocysts in various stages of sporulation. Immunofluorescence antibody staining indicated specific staining of E. tenella sporozoites and merozoites. Staining was most intense in the cytoplasm of the posterior end of the parasite. The primary amino acid sequence of the gene for E. tenella SZ-1 deduced from the E. tenella genome indicated a conserved domain for the actin-regulatory protein profilin. A conserved binding site for poly-l-proline (PLP), characteristic of profilin was also observed. SZ-1 was separated from soluble extract of E. tenella proteins by affinity chromatography using a PLP ligand, confirming the ability of SZ-1 to bind PLP. SZ-1 also partially inhibited the polymerization of actin. The current results are consistent with the classification of SZ-1 as a profilin-related protein.

Parasites often elude effective recognition or attack (or both) by the host immune system, for example, though a tegument that possesses nonimmunogenic features. However, a general activation of host defense due to independent stimuli may increase immune activity to a level where such disguises are no longer effective, resulting in the clearance of an infection. We experimentally infected three-spined sticklebacks (Gasterosteus aculeatus) with the cestode Schistocephalus solidus. To independently foster a general immune response a few days later, we cut the tips of spines in some fish and sham-treated other fish. Cutting spines significantly reduced the prevalence of the infection. The injury evoked a physiological reaction that helped to clear a hidden parasite infection.

Copper in the form of copper sulfate (CuSO₄) decreases the survival of Biomphalaria glabrata snails, but the effects of this molluscicide on Echinostoma caproni and Echinostoma trivolvis, 2 species of digeneans that use B. glabrata as intermediate hosts, are not known. Studies were done on the effects of various concentrations of CuSO₄ in artificial spring water (ASW) on the survival and infectivity of E. caproni and E. trivolvis cercariae. Solutions containing 1.0, 0.1, and 0.01% CuSO₄ were 100% lethal within 2 hr of exposure for both species. Time to 50% mortality in 0.001% CuSO₄ was 8 hr for E. caproni and 16 hr for E. trivolvis; at 24 hr, the controls showed 50 and 65% mortality, respectively. Treatment of cercariae of both species for 0.5 hr in 0.001% CuSO₄ had no effect on the ability of cercariae to form normal cysts in juvenile B. glabrata snails. However, treatment with 0.01% CuSO₄ for 0.5 hr caused a significant reduction in the ability of cercariae of both species to encyst in snails. Treatment of encysted metacercariae of both species in 0.001% CuSO₄ for 1 hr had no effect on subsequent excystation of these echinostomes in a trypsin–bile salts medium, whereas concentrations of 1.0, 0.1, and 0.01% CuSO₄ and 1.0 and 0.1% CuSO₄ decreased chemical excystation of E. caproni and E. trivolvis cysts, respectively. Survival studies on the effects of CuSO₄ in Locke's solution on chemically excysted metacercariae of both species were also done. Excysted metacercariae of both species were killed by 2 hr in either 0.1 or 0.01% CuSO₄ in Locke's solution. However, time to 50% mortality for both species of excysted metacercariae in 0.001% CuSO₄ was approximately 5 hr. Time to 50% mortality for the controls was about 12 hr. Survival of juvenile B. glabrata snails was also examined. All B. glabrata snails were dead by 6 hr in 1 and 0.1% CuSO₄ in ASW. Biomphalaria glabrata snails showed 50% mortality by about 6 hr in 0.01% CuSO₄ and about 80% were still alive at 24 hr in 0.001% CuSO₄. All controls were alive at 24 hr, at which time the experiment was terminated. Concentrations greater than 0.001% CuSO₄ increased snail mortality, as well as that of the cercariae and excysted metacercariae of E. caproni and E. trivolvis. Our findings suggest that concentrations of copper sufficient to eliminate juvenile B. glabrata snails are also sufficient to kill the cercariae and excysted metacercariae of these digeneans but not the encysted metacercariae, which may be protected by their cyst walls.

The parasite fauna of 4 intertidal grapsid crabs from New Zealand was studied between 1998 and 2000. The occurrence of an undescribed entoniscid species, Portunion sp. (Isopoda: Epicaridea), is presented. Portunion sp. was found in Cyclograpsus lavauxi (34.1%, n = 1,650), Hemigrapsus crenulatus (19.0%, n = 2,300), and Helice crassa (11.6%, n = 825) but was absent from Hemigrapsus sexdentatus (n = 636). Parasitized hosts contained mostly 1 female Portunion sp. but occasionally up to 7 females were found. One to 3 dwarf males typically occurred on each mature female Portunion sp. Most developmental stages of female Portunion sp. were found throughout the year, demonstrating that reproduction and infection occurred continuously. Portunion sp. differentially affected male and female hosts. Prevalence was generally higher in male hosts than in female hosts and increased significantly with host size. Female hosts were castrated, whereas males were not. Portunion sp., therefore, influenced the operational sex ratio in its host species, causing a more male-biased ratio.

The study objective was to assess the risk of transplacental transmission of Sarcocystis neurona and Neospora hughesi in foals from 4 California farms during 3 foaling seasons. Serum of presuckle foals and serum and colostrum of periparturient mares were tested using indirect fluorescent antibody tests for S. neurona and N. hughesi. Serum antibody titers were ≤10 in 366 presuckle foals tested. There was no serologic or histologic evidence of either parasite in aborted fetuses or placentas examined. Positivity for S. neurona and N. hughesi in mares increased with age. Mares ≤9 yr that originated from Kentucky were 3.8 and 1.4 times more likely to be positive for S. neurona and N. hughesi, respectively, than mares from California. The strength of association between positivity to either parasite and state of birth decreased as age increased. Mares positive for S. neurona and N. hughesi were 2.2 and 1.7 times more likely, respectively, to have a previous abortion than negative mares, adjusted for age and state of birth. The annual mortality rate for mares was 4%. The annual incidence rate of equine protozoal myeloencephalitis was 0.2%. In conclusion, there was no detectable risk of transplacental transmission of S. neurona and N. hughesi. Prevalence of antibodies against both parasites in mares increased with age.

Studies on Myxozoa have emphasized their potential impact on aquatic animal health but less on ecological aspects. In this investigation, we assess the importance of host and latitudinal variations in the morphometry of spores of Ceratomyxa Thélohan, 1892 (Myxozoa) from the gall bladder of 3 ling Genypterus (Pisces; Ophidiidae) species. Discriminant analyses indicated that several morphospecies of Ceratomyxa coexist in these hosts, despite the fact that the specific level of taxonomic resolution of each spore was not attempted. At least 4 species, i.e., Ceratomyxa hokarari Meglitsch, 1960; Ceratomyxa inversa Meglitsch, 1960; Ceratomyxa laxa Meglitsch, 1960; and Ceratomyxa elongata Meglitsch, 1960 occur in the study area, and at least 2 species co-occur in each host and geographical location. The most widespread pattern found is that spores are larger in golden ling (Genypterus blacodes) and spore size decreases with increasing latitude; this may be associated with the species composition of these assemblages, as well as with the habitat and diet segregation of the host species.

From January 1998 to December 2002, we collected 293 fecal samples from free-ranging individuals of the 4 guenon species of western Uganda, i.e., redtail guenons (Cercopithecus ascanius), blue monkeys (Cercopithecus mitis), l'hoesti monkeys (Cercopithecus lhoesti), and vervet monkeys (Cercopithecus aethiops), to quantify the prevalence of gastrointestinal parasites. Helminth eggs, larvae, and protozoan cysts were isolated by sodium nitrate flotation and fecal sedimentation. Helminth parasites were identified, and infection prevalence was determined for all 4 guenon species. Coprocultures facilitated identification of strongylate nematodes. For the most common species, the redtail guenon, we documented prevalence of protozoan parasites and examined the effect of season and host sex on infection prevalence. Six nematodes (Strongyloides fulleborni, Oesophagostomum sp., unidentified strongyle, Trichuris sp., Streptopharagus sp., and Enterobius sp.), 1 cestode (Bertiella sp.), 1 trematode (Dicrocoeliidae), and 5 protozoans (Entamoeba coli, Entamoeba histolytica, Iodameoba butschlii, Giardia lamblia, and Chilomastix mesnili) were detected. Seasonal patterns of infection were not readily apparent for any parasite species infecting redtail guenons. Although prevalence never differed between male and female guenons, only adult females were infected with Oesophagostomum sp. and S. fulleborni.

To determine whether deer can transmit Neospora caninum, brains of naturally infected white-tailed deer (Odocoileus virginianus) were fed to 4 dogs; 2 of these dogs shed oocysts. Oocysts from 1 of the dogs were tested by polymerase chain reaction and found to be positive for N. caninum and negative for Hammondia heydorni. The internal transcribed spacer 1 sequence of the new strain (designated NC-deer1) was identical to N. caninum from domestic animals, indicating that N. caninum is transmitted between wild and domestic animals, often enough to prevent divergent evolution of isolated populations of the parasite. NC-deer1 oocysts were administered to a calf that developed a high antibody titer, providing evidence that N. caninum from wildlife can infect cattle. In addition, N. caninum antibody seroprevalence was detected in 64/164 (39%) free-ranging gray wolves (Canis lupus), 12/113 (11%) coyotes (Canis latrans), 50/193 (26%) white-tailed deer, and 8/61 (13%) moose (Alces alces). These data are consistent with a sylvatic transmission cycle of N. caninum between cervids and canids. We speculate that hunting by humans favors the transmission of N. caninum from deer to canids, because deer carcasses are usually eviscerated in the field. Infection of canids in turn increases the risk of transmitting the parasite to domestic livestock.

Whirling disease, caused by the parasite Myxobolus cerebralis, has infected rainbow trout (Oncorhynchus mykiss) and other salmonid fish in the western United States, often with devastating results to native populations but without a discernible spatial pattern. The parasite develops in a complex 2-host system in which the aquatic oligochaete Tubifex tubifex is an obligate host. Because substantial differences in whirling disease severity in different areas of North America did not seem explainable by environmental factors or features of the parasite or its fish host, we sought to determine whether ecological or genetic variation within oligochaete host populations may be responsible. We found large differences in compatibility between the parasite and various laboratory strains of T. tubifex that were established from geographic regions with different whirling disease histories. Moreover, 2 closely related species of tubificids, Limnodrilus hoffmeisteri and Ilyodrilus templetoni, which occur naturally in mixed species assemblages with T. tubifex, were incompatible with M. cerebralis. Virulence of the parasite was directly correlated with the numbers of triactinomyxon spores that developed within each strain of T. tubifex. Thus, the level of virulence was directly related to the compatibility between the host strain and the parasite. Genetic analyses revealed relationships that were in agreement with the level of parasite production. Differences in compatibilities between oligochaetes and M. cerebralis may contribute to the spatial variance in the severity of the disease among salmonid populations.

Quantitative changes in the parasite communities of the flounder Hippoglossina macrops (Steindachner) were studied along a depth gradient. Samples were obtained from the waters off Coquimbo, Chile (29°18′S to 30°50′S), at depths ranging from 160 to 342 m. Samples were assigned to 3 depths, i.e., shallow water (less than 200 m), midwater (from 200 to 300 m), and deep water (more than 300 m). Twelve parasite species were recorded: Neoheterobothrium chilensis and Entobdella hippoglossi (Monogenea); Holobomolochus chilensis and Protochondria longicauda (Copepoda); Gliptonobdella sp. (Hirudinea); Nybelinia surmenicola, Scolex pleuronectis, and Neobothriocephalus adspinosus (Cestoda); Floridosentis sp. and Corynosoma australe (Acanthocephala); Anisakidae (Nematoda); and an unidentified hemiurid (Digenea). Univariate analyses showed that C. australe has its highest prevalence and mean intensity of infection in hosts from shallow waters. Floridosentis sp. showed significant differences along the depth gradient, with higher mean intensity and prevalence of infection in fish from midwater. Among the ectoparasites, only N. chilensis exhibited differences in mean intensity with depth, where intensity of infection increased with depth of host habitat. A canonical multivariate analysis demonstrated that parasite burdens can be a good predictor of the environment (shallow, mid-, or deep water) occupied by the flounders.

A survey of abomasal parasites in cervids from Central Spain was conducted at 3 sites, Quintos de Mora (Toledo), Maluéñez de Arriba (Cáceres), and La Herguijuela (Cáceres). Commonly occurring helminths belonged to 3 polymorphic species of the Ostertagiinae: Spiculopteragia asymmetrica/S. quadrispiculata, Ostertagia leptospicularis/O. kolchida, and O. drozdzi/O. ryjikovi. Trichostrongylus axei was found in very few cases. Ostertagia drozdzi/O. ryjikovi and the minor male morphotype, S. quadrispiculata, are reported for the first time in red deer from Spain. The 3 ostertagiine species are also reported for the first time in fallow deer from Spain. These 3 species of Ostertagiinae are primarily parasites of cervids, and nematode species characteristic of domestic ruminants were not present. Prevalence of infection by gastrointestinal parasites in cervids was high, ranging from 97.5 to 100%, across the 3 areas sampled. Mean intensity of infection and abundance showed a positive relationship to the population density of red deer. Helminth burdens were higher in fallow deer than in the sympatric red deer and may reflect the gregarious social structure and different foraging patterns of fallow deer.

A lack of comparative studies limits our understanding of interspecific variation in parasite life histories, especially for species that incorporate asexual and resting stages into their life cycles. Ornithodiplostomum ptychocheilus and Posthodiplostomum minimum are sympatric diplostomid trematodes that share the same first (pond snail, Physa gyrina) and second (fathead minnow, Pimephales promelas) intermediate hosts within lakes in Alberta, Canada. Interspecific differences in the body sizes of adults, cercariae, and metacercariae were evaluated from parasites recovered from laboratory-raised chickens, snails, and minnows, respectively. Differences in adult worm fecundity and cercariae production were estimated from chickens and snails exposed to known numbers of parasite larvae. Posthodiplostomum minimum adults, metacercariae, and eggs were 97, 86, and 5% larger than those of O. ptychocheilus, respectively. The average numbers of eggs produced per day by P. minimum was 3 times higher than for O. ptychocheilus, and P. minimum produced approximately twice as many cercariae per day. Although the larger of the 2 species had higher egg and cercariae production, conclusions regarding covariation between adult worm size and the reproductive rates of other life cycle stages require further studies on related species.

Blood smears from wild-caught, long-term captive tortoises, Testudo marginata, revealed the presence of gametocytes of a Hemolivia mauritanica–like hemogregarine in the erythrocytes of 72% tortoises examined. Significant parasitemia was also found in animals living several years in captivity. Experimentally infected tortoises showed no evidence of a decrease in parasitemia level more than 15 mo after infection. Morphologically, stages found in tortoises' erythrocytes were indistinguishable from those referred to by previous workers as H. mauritanica from Testudo graeca. Moreover, successful experimental transmission to Hyalomma aegyptium confirms the conspecificity with H. mauritanica. The occurrence of H. mauritanica gametocytes in tortoise living up to 8 yr in captivity is suggested to result from continuous, long-lasting cyclic merogony in tortoises' parenchymatous organs, which is an unknown phenomenon in the life cycle of Hemolivia spp.

Neospora caninum infection is a common cause of bovine abortion. One method by which cattle can acquire infection is through ingestion of oocysts; however, this has not yet been proved to cause transplacental infection or abortion. In this study, 19 cows, pregnant between 70 and 176 days, were administered 1,500 to 115,000 oocysts through an esophageal tube. Seventeen of the cows became seropositive, indicating acquisition of infection, whereas 8 negative control cows remained seronegative (P < 0.001). Offspring were examined using serology, histology, immunohistochemistry, parasite isolation, and polymerase chain reaction (PCR). Six offspring were infected and 1 of them was aborted. The aborted fetus had typical lesions and positive immunohistochemistry and PCR for N. caninum. All 6 cows with infected offspring had continuously rising antibody titers, whereas 10 of 11 infected cows with uninfected offspring had falling titers after an early apex. The risk of transplacental transmission was increased by later exposure times during gestation and by the dose of oocysts (P < 0.01 for the 2 combined variables). The lowest dose of oocysts, when administered after the 160th day of gestation, caused transplacental infection in 1 of 2 animals. This study demonstrates that infection with N. caninum oocysts can cause transplacental transmission and abortion in cattle.

Spores of Myxobolus pendula develop within the cores of complex cysts on the gill arch of creek chub Semotilus atromaculatus. Adjacent to, and surrounding, the spores are concentric layers of stratified interdigitating cells, whose nature was examined by transmission electron microscopy and by immunohistochemical and molecular biological techniques. In situ hybridization data using parasite-derived ribosomal DNA as a probe indicate that infection leads to the encapsulation of developing plasmodia by host immune cells that form an epithelioid granuloma. Epithelioid cell–cell adhesion is effected by desmosomes anchored intracellularly to cytokeratin intermediate filaments. High levels of alkaline phosphatase activity are associated with regions of cellular interdigitation. The granuloma may serve to limit the spread of the parasite to surrounding tissues but does not appear to inhibit diffusion of oxygen and nutrients to the developing spores.

Previous challenge studies performed at Ohio State University involved a transport-stress model where the study animals were dosed with Sarcocystis neurona sporocysts on the day of arrival. This study was to test a second transportation of horses after oral inoculation with S. neurona sporocysts. Horses were assigned randomly to groups: group 1, transported 4 days after inoculation (DAI); group 2, at 11 DAI; group 3, at 18 DAI; and group 4, horses were not transported a second time (controls). An overall neurologic score was determined on the basis of a standard numbering system used by veterinarians. All scores are out of 5, which is the most severely affected animal. The mean score for the group 1 horses was 2.42; group 2 horses was 2.5; group 3 horses was 2.75; and group 4 horses was 3.25. Because the group 4 horses did not have a second transport, they were compared with all other groups. Statistically different scores were present between group 4 and groups 1 and 2. There was no difference in the time of seroconversion between groups. There was a difference between the time of onset of first clinical signs between groups 1 and 4. This difference was likely because of the different examination days. Differences in housing and handling were likely the reason for the differences in severity of clinical signs. This model results in consistent, significant clinical signs in all horses at approximately the same time period after inoculation but was most severe in horses that did not experience a second transport.

We propose Listrocephalos n. gen. (Monogenea: Capsalidae: Entobdellinae) for 2 new capsalid species that infect the skin of 2 species of diamond stingrays (Dasyatidae) in the Gulf of California. We also provide additional observations on 2 previously described capsalid species, which infect the external body surface of stingrays and are currently in Entobdella Blainville in Lamarck, 1818, and transfer them to the proposed new genus. The members of this genus, Listrocephalos corona (Hargis, 1955) n. comb. (type species), Listrocephalos guberleti (Caballero and Bravo-Hollis, 1962) n. comb., Listrocephalos kearni n. sp., and Listrocephalos whittingtoni n. sp., differ from other entobdellines by the combination of having an anterolateral adhesive pad comprising 2 ventral columns of raised ovoid structures, 1 pair of glands that flank the preoral depression, a discoid and aseptate haptor that lacks a marginal valve but has clover-shaped papillae dispersed radially over its entire ventral surface, minute and nonoverlapping median haptoral sclerites, a bizarre chamber yielding a duct that opens on the surface of the penis, separate genital pores, and a gland of Goto located between the testes and ovary. Listrocephalos kearni n. sp. infects Dasyatis brevis and is most easily distinguished from its congeners by the combination of lacking penis tubules and having a convoluted proximal portion of the vas deferens that occupies the space between the ootype and ovary. Listrocephalos whittingtoni n. sp. infects Dasyatis longa and is most easily distinguished from its congeners by the combination of having penis tubules and a vaginal pore that is located posterior to the level of the uterus. We report specimens of L. corona from the ventral body surface of Dasyatis say from a new locality, Mississippi Sound, as well as specimens of L. guberleti from the skin of 2 new hosts, Urobatis maculatus and Urobatis concentricus, and a new locality, Elkhorn Slough, California. We provide a diagnostic key and a table of records for Listrocephalos spp.

Spinicauda fisheri n. sp. from the intestine of Platymantis pelewensis collected in the Palau Islands, Republic of Belau, is described and illustrated. Spinicauda fisheri represents the 12th species assigned to the genus and the first from Oceanica. It is most similar to Spinicauda spinicauda in that the tail ends in a filament, but it has 19 pairs of caudal papillae as compared with 5 pairs in S. spinicauda. In addition to S. fisheri, 2 species of Cestoda, cysticercoids of Joyeuxiella sp. and tetrathyridia of Mesocestoides sp., 2 species of Nematoda, Oswaldocruzia bakeri and Physocephalus sp. (larvae in cysts), 1 species of Acanthocephala, Acanthocephalus bufonis, and 1 species of Pentastomida, nymphs of Kiricephalus pattoni were identified.

Sphaeromyxa zaharoni n. sp. (Myxosporea) is described from the gallbladder of devil firefish, Pterois miles (Scorpaenidae), from coral reefs of the Gulf of Eilat, Israel, northern Red Sea. The parasite was found also in bearded scorpionfish, Scorpaenopsis barbata, from the same area. This is the first report on Sphaeromyxa sp. from this zoogeographical region. The plasmodia are amoeboid when young, becoming disc-shaped and elongated when mature. In paraffin sections, the plasmodium periphery appears as a finely granulated, strongly eosinophilic layer with an intricate surface membrane network. Sphaeromyxa zaharoni n. sp. is polysporous, disporoblastic, and has asynchronous sporogenesis. The mature spore is elongated and fusiform, has delicately ridged valves, and contains a single, binucleated sporoplasm. In valvular view, the tips are truncated. The mean spore size is length 14.5 μm, width 4.8 μm, and polar capsule 4.8 × 3.4 μm. The 2 equally sized ovoid polar capsules are positioned at opposite ends of the spore, each containing a filament loosely folded in 2 loops. The fine structure of the sporoblast and spore corresponded with previously studied Sphaeromyxa species. According to small-subunit ribosomal DNA gene sequence analysis, S. zaharoni n. sp. is most closely related to 2 Myxidium spp. The close phylogenetic relatedness of Sphaeromyxa and Myxidium and similar spore morphology raises the question whether these 2 genera should be maintained in separate families and suborders.

Two new nematode species, Orientatractis campechensis n. sp. and Orientatractis chiapasensis n. sp. (Atractidae, Cosmocercoidea), are described from the intestine of cichlid fishes collected in localities of southeastern Mexico and Nicaragua. These atractid nematodes are characterized by the presence of a cephalic end armed with 4 marked, Y-shaped, well-sclerotized pieces, consisting of 2 “horns” extending outward and downward and immediately below a single-horned structure. Both new species differ from the other 2 species of Orientatractis (Orientatractis leiperi and Orientatractis levanhoai) mainly in the body measurements, presence of a vulvar appendix, lengths of spicules and of the gubernaculum, distribution of caudal papillae, and the number of anterior sclerotized structures. Morphological and biometrical variations were evident among specimens from different hosts and localities, with the larger organisms being collected from Vieja bifasciata and Cichlasoma pearsei. Orientatractis campechensis and O. chiapasensis represent the first 2 species of this genus parasitizing freshwater fishes; the other species have been found in amphibians and reptiles.

Stictospora villani n. sp. is described from larvae of the Japanese beetle Popillia japonica (Coleoptera: Scarabaeidae) from southern Michigan. Stictospora villani is distinguished from known species of the genus by differences in gamont size and by structural details of the epimerite. In general, S. villani is smaller than other known species of the genus and possesses an epimerite with a margin of 20–24 sympetalous, pendulate, narrowly to very narrowly elliptoid lamina. Previously described species are characterized by epimerites with notably fewer marginal lamina. A heretofore unrecognized protistan is diagnosed from the coelomic fat bodies and tentatively placed within the Neogregarinorida. We conclude that previous workers have mistaken this neogregarine for the gametocyst and oocyst of Stictospora, which are described in this study for the first time. The generic diagnosis of Stictospora is revised to encompass the epimeritic variation of its constituent species and to correctly reflect the morphology of the oocyst.

In the summer of 2003, chironomid imagoes eclosing from Lake Alice Bog in Minnesota yielded mermithid nematodes of 2 new species. Lanceimermis palustris n. sp. is distinguished from the other 14 species of the genus by the subventral mouth position, thinness of the hook-shaped spicule, body index, and structure of the male tail muscles. Telomermis palustris n. sp. is distinguished from the only other species of the genus by the structure of the amphids, body length, maximum body width, length of the esophagus, and the presence of a minute larval terminal horn. Lanceimermis palustris n. sp. hosts were Chironomus maturus Johannsen and T. palustris n. sp. hosts were Tanytarsus mendax Kieffer, Paratanytarsus nr. dissimilis n. sp., and Micropsectra polita (Malloch). In both mermithid species, the percent of mermithid males per host increased with the intensity of the infection.

The nematode Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 is redescribed from specimens collected from the intestine of the bighead carp Aristichthys nobilis, from Liangzihu Lake (Yangtze River basin), Hubei Province, central China. The light and scanning electron microscopical examination made it possible to study in detail the morphology of this so far little-known species and to confirm its validity. The main specific features of C. hypophthalmichthys distinguishing it from the most similar Camallanus spp. is the presence of 3 small caudal processes on the male tail tip, 13–16 longitudinal ridges on the inner surface of the valve of the buccal capsule, and the arrangement of preanal and postanal genital papillae in the male. This finding represents a new host record, the first record of this parasite in the Yangtze River basin, and the first documented record of C. hypophthalmichthys from China. Camallanus hypophthalmichthys is considered a specific intestinal parasite of fishes of the cyprinid Hypophthalmichthyinae.

The Brachypteraciidae is an avian family endemic to Madagascar. Members of this family were mist-netted in Madagascar, and blood smears were made to screen for the presence of hematozoa. Smears were stained with Giemsa and examined at ×100, ×160, and ×1,000 for hematozoa. Three new species of avian hematozoa from wild-caught ground-rollers in Madagascar are described. Haemoproteus goodmani n. sp. is found in the pitta-like ground-roller (Atelornis pittoides), whereas Haemoproteus forresteri n. sp. and Leucocytozoon frascai n. sp. are from the rufous-headed ground-roller (Atelornis crossleyi). These represent the first hematozoa described from this family.

Blood smears from birds in the Philepittidae, endemic to Madagascar, were examined for the presence of hematozoa. All slides were read on a compound microscope at ×100, ×160, and ×1,000. To date, no species of avian hematozoa has been reported from asities in Madagascar, although parasites have been observed. Leucocytozoon greineri n. sp. is described from the common sunbird asity (Neodrepanis coruscans) and is also reported from the velvet asity (Philepitta castanea). It is a relatively small species of Leucocytozoon, less than 2 times the size of uninfected erythrocytes. The parasite is capped by the host cell nucleus, covering 38% of the parasite perimeter. This represents the first description of hematozoa from this family.

To date, limited surveys have been conducted on the endemic avifauna of Madagascar with regard to hematozoa. Wild-caught birds from the Vangidae, endemic to Madagascar and the Comoros Islands, were mist-netted, and blood smears were made. Slides were examined for the presence of hematozoa at ×100, ×160, and ×1,000 using a light microscope. Parasites were measured using established techniques, and morphometrics were compared. On the basis of their distinctive morphologies and morphometrics, 4 new species of avian hematozoa are described in this study. Haemoproteus vangii n. sp. and Leucocytozoon lairdi n. sp. occur in the blue vanga (Cyanolanius madagascarinus), whereas Haemoproteus madagascariensis n. sp. and Leucocytozoon bennetti n. sp. are described from the hook-billed vanga (Vanga curvirostris). These represent the first hematozoa described from this family.

Treatment of axenic Naegleria gruberi cultures with alligator serum resulted in time-dependent amoebacidal activity, with measurable activity at 5 min and maximal activity occurring at 20 min. The amoebacidal activity was concentration dependent, with measurable activity at 25% serum, whereas treatment of amoebas with undiluted serum resulted in only 16% survival. The efficacy was dependent on the concentration of amoebas, with higher survival rates at high amoeba densities and lower survival rates at low amoeba densities. The amoeba-killing effects of alligator serum were broad in spectrum because the serum was effective against 3 strains of Naegleria species tested and 4 Acanthamoeba species, which have been reported to be resistant to human serum complement–mediated lysis. The amoebacidal effects of alligator serum were temperature dependent, with optimal activity at 15–30 C and a decrease in activity below 15 C and above 30 C. The amoebacidal activity of alligator serum was heat labile and protease sensitive, indicating the proteinaceous nature of the activity, and was also inhibited by ethylenediaminetetraacetic acid, which indicated a requirement for divalent metal ions. These characteristics strongly suggest that the amoebacidal properties of alligator serum are because of complement activity.

K39 is a repetitive immunodominant epitope in a kinesin-related protein expressed predominantly in the amastigotes of visceral Leishmania spp. Enzyme immunoassays of patient's sera with recombinant K39 (rK39) proved to be highly specific and sensitive for diagnosis of active visceral leishmaniasis (VL, kala-azar). The same assays in dipstick format were also found effective for diagnosis of both human VL (HVL) and canine VL (CanVL) in most endemic areas of these diseases. Fifty-eight human patients and 22 dogs, clinically suspected of kala-azar, were screened with rK39 dipstick in comparison with the conventional methods of diagnosis, i.e., microscopic examinations of bone marrow and lymph node aspirates and immunofluorescent antibody tests (IFAT), respectively. Sixteen patients and 12 dogs were found to be rK39 dipstick positive. The results were corroborated with those of parasitological examinations, except 1, rK39-positive but smear-negative, case in each group. IFAT of the 2 discordant cases gave positive results. The rK39 dipstick is thus reliable for diagnosis of both HVL and canVL cases in Turkey.

Sarcocystis neurona and Sarcocystis fayeri infections are common in horses in the Americas. Their antemortem diagnosis is important because the former causes a neurological disorder in horses, whereas the latter is considered nonpathogenic. There is a concern that equine antibodies to S. fayeri might react with S. neurona antigens in diagnostic tests. In this study, 4 ponies without demonstrable serum antibodies to S. neurona by Western immunoblot were used. Three ponies were fed 1 × 10⁵ to 1 × 10⁷ sporocysts of S. fayeri obtained from dogs that were fed naturally infected horse muscles. All ponies remained asymptomatic until the termination of the experiment, day 79 postinoculation (PI). All serum samples collected were negative for antibodies to S. neurona using the Western blot at the initial screening, just before inoculation with S. fayeri (day 2) and weekly until day 79 PI. Cerebrospinal fluid samples from each pony were negative for S. neurona antibodies. Using the S. neurona agglutination test, antibodies to S. neurona were not detected in 1:25 dilution of sera from any samples, except that from pony no. 4 on day 28; this pony had received 1 × 10⁷ sporocysts. Using indirect immunofluorescence antibody tests (IFATs), 7 serum samples were found to be positive for S. neurona antibodies from 1:25 to 1:400 dilutions. Sarcocystis fayeri sarcocysts were found in striated muscles of all inoculated ponies, with heaviest infections in the tongue. All sarcocysts examined histologically appeared to contain only microcytes. Ultrastructurally, S. fayeri sarcocysts could be differentiated from S. neurona sarcocysts by the microtubules (mt) in villar protrusions on sarcocyst walls; in S. fayeri the mt extended from the villar tips to the pellicle of zoites, whereas in S. neurona the mt were restricted to the middle of the cyst wall. Results indicate that horses with S. fayeri infections may be misdiagnosed as being S. neurona infected using IFAT, and further research is needed on the serologic diagnosis of S. neurona infections.