Showing papers in "Journal of Parasitology in 2006"

Nested cytochrome B polymerase chain reaction diagnostics underestimate mixed infections of avian blood haemosporidian parasites: Microscopy is still essential

Abstract: Numerous polymerase chain reaction (PCR)-based methods have been developed and used increasingly to screen vertebrate blood samples for the diagnosis of haemosporidian blood parasites (Sporozoa, Haemosporida), but a rigorous evaluation of the sensitivity of these methods for detecting mixed infections of different haemosporidian species belonging to the same and different genera and subgenera is lacking. This study links the information obtained by nested cytochrome b PCR and traditional microscopy in determining mixed haemosporidian infections in naturally infected birds. Samples from 83 individual passerine birds with single infections of Haemoproteus or Plasmodium spp., as determined by mitochondrial DNA amplification, also were investigated by microscopic examination of stained blood films. Thirty-six samples (43%) were found to harbor mixed Haemoproteus, or Plasmodium spp. infections, or both. Thus, the PCR assays alone underestimate the occurrence of mixed infections of haemosporidian parasites in naturally infected birds. To determine the true species composition of the haemosporidians in each individual host, PCR diagnostics need to be improved. Specific primers for Haemoproteus spp. and Plasmodium spp. should be developed. Ideally, a combination of the approaches of both microscopy and PCR-based methods is recommended for this purpose.

New molecular data on mammalian hepatozoon species (apicomplexa: adeleorina) from brazil and spain

Abstract: Molecular techniques were used to examine the phylogenetic relationships among Hepatozoon species isolated from 13 foxes and 15 opossums from Brazil, and from 15 dogs, 20 foxes, 45 rodents, and 330 domestic cats from Spain. Hemogregarine infection was confirmed by amplification of the 18S rRNA gene and later sequencing. No hemogregarine infections were found in opossums. The prevalence of Hepatozoon in canids ranged from 26.6% (symptomatic domestic dogs) to 90% (Spanish foxes). Four different H. canis genotypes were detected, as well as an H. americanum-related protozoan (97% identical to the USA strain). Two Spanish cats were parasitized by a Hepatozoon species (0.6% prevalence) that showed 96% sequence identity to H. canis. DNA amplification assays performed on Spanish rodents showed 2 bank voles (Clethrionomys glareolus) to be infected by a Hepatozoon species (4.44% prevalence) with 95% sequence identity to Hepatozoon sp. from cats. Phylogenetic analysis showed Hepatozoon to be a monophyletic genus, in which species from carnivorous mammals (Hepatozoon sp. from cats, H. americanum and H. canis) appear as a sister lineage of that of lower vertebrates and rodents. This association suggests that H. americanum evolved in ticks and carnivores (either canids, or felids, or both) rather than in other ectoparasites and other types of mammal.

Genetic relationships among Anisakis species (Nematoda: Anisakidae) inferred from mitochondrial cox2 sequences, and comparison with allozyme data.

Abstract: The genetic relationships among 9 taxa of Anisakis Dujardin, 1845 (A. simplex (sensu stricto), A. pegreffii, A. simplex C., A. typica, A. ziphidarum, A. physeteris, A. brevispiculata, A. paggiae, and Anisakis sp.) were inferred from sequence analysis (629 bp) of the mitochondrial cox2 gene. Genetic divergence among the considered taxa, estimated by p-distance, ranged from p = 0.055, between sibling species of the A. simplex complex, to p = 0.12, between morphologically differentiated species, i.e., A. ziphidarum and A. typica. The highest level was detected when comparing A. physeteris, A. brevispiculata, and A. paggiae versus A. simplex complex (on average p = 0.13) or versus A. typica (on average p = 0.14). Sequence data from the newly identified Anisakis sp. poorly aligned with other Anisakis species but was most similar to A. ziphidarum (p = 0.08). Phylogenetic analyses based upon Parsimony and Bayesian Inference, as well as phenetic analysis based upon Neighbor-Joining p-distance values, generated similar tree topologies, each well supported at major nodes. All analyses delineated two main claides, the first encompassing A. physeteris, A. brevispiculata, and A. paggiae as a sister group to all the remaining species, and the second comprising the species of the A. simplex complex (A. simplex (s.s.), A. pegreffii and A. simplex C), A. typica, A. ziphidarum, and Anisakis sp. In general, mtDNA-based tree topologies showed high congruence with those generated from nuclear data sets (19 enzyme-loci) and with morphological data delineating adult and larval stages of the Anisakis spp.; however, precise positioning of A. typica and A. ziphidarum remain poorly resolved, though they consistently clustered in the same clade as Anisakis sp. and the A. simplex complex. Comparison of anisakid data with those currently available for their cetacean-definitive hosts suggests parallelism between host and parasite phylogenetic tree topologies.

Variation in host specificity between species of avian hemosporidian parasites: evidence from parasite morphology and cytochrome b gene sequences

Abstract: A parasite's shift to a new host may have serious evolutionary consequences, since host switching usually is associated with a change in virulence and may lead to the evolution of emerging diseases. This phenomenon remains insufficiently studied in wildlife. Here, we combine microscopic examination of blood films and PCR-based methods to investigate the natural host specificity of Haemoproteus and Plasmodium spp. in birds of 4 families of the Passeriformes within a small geographic area. The material was collected on the Curonian Spit in the Baltic Sea between May and July in 2003–2004. A nested-PCR protocol was used for amplifying and sequencing a fragment of 480 nucleotides of the cytochrome b gene of the mtDNA of these parasites. Blood samples from 282 birds, which were positive both by microscopic examination of blood films and mtDNA amplification, were used in this study. We found that Haemoproteus majoris (lineages hPARUS1, hCCF5, hWW2, and hPHSIB1), Haemoproteus sp. (hWW1), Plasmodium (Haemamoeba) sp. (pSGS1), and Plasmodium (Haemamoeba) sp. (pGRW11) are capable of infecting birds belonging to different families of passeriform birds. Some species of Haemoproteus are less specific than have been traditionally believed. Haemoproteus majoris appears to have a genetic predisposition to have a broad host range. The level of host specificity varies markedly among different species of hemosporidian parasites of birds. The natural host range is thus not a reliable taxonomic character in the systematics of these parasites in the form in which it is still accepted in some recent taxonomic studies.

Characterization of Toxoplasma gondii Isolates in Free-Range Chickens From Portugal

Abstract: The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 225 free-range chickens (Gallus domesticus) from Portugal was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and found in 61 chickens with titers of 1:5 in 8, 1:10 in 6, 1:20 in 3, 1:40 in 23, 1:80 in 5, 1:160 in 4, 1:320 in 8, and 1:640 or higher in 4. Hearts, leg muscles, and brains of 15 seropositive (MAT 1:10 or higher) chickens were bioassayed individually in mice. Tissue from 38 chickens with titers of 1:5 or less were pooled and fed to a T. gondii–free cat. Feces of the cat were examined for oocysts, but none was found. Toxoplasma gondii was isolated from 16 of 19 chickens with MAT titers of 1:10 or higher. Genotyping of 12 of these 16 isolates with polymorphisms at the SAG2 locus indicated that 4 were type III, and 8 were type II. None of the isolates was l...

Detection of Blastocystis hominis in unpreserved stool specimens by using polymerase chain reaction.

Abstract: Blastocystis hominis is a common enteric parasite of worldwide distribution. Its pathogenetic potential has not yet been established, although numerous case reports suggest that B. hominis may cause the development of various gastrointestinal symptoms and disorders. The detection of the parasite in stool specimens is conventionally done by microscopy of direct smears, fecal concentrates, or permanently stained smears; however, morphology-based diagnosis is problematic. The aim of this study was to develop and evaluate a polymerase chain reaction (PCR) technique for the direct detection of B. hominis in human stool samples. Primers were based on small subunit ribosomal DNA and able to detect ≥32 parasites/200 mg stool artificially spiked with cultured B. hominis. In the evaluation of 43 clinical specimens, the PCR was tested against the formol ethyl acetate concentration technique (FECT) and a culture technique, proving 100% test specificity and a significantly higher sensitivity than the FECT. The PCR met...

Evidence for cryptic speciation of leucocytozoon spp. (haemosporida, leucocytozoidae) in diurnal raptors

Abstract: Species of Leucocytozoon (Haemosporida, Leucocytozoidae) traditionally have been described based on morphological characters of their blood stages and host cells, with limited information on their avian host specificity. Based on the current taxonomy, Leucocytozoon toddi is the sole valid species of leucocytozoids parasitizing falconiform birds. Using a nested polymerase chain reaction protocol, we determined the prevalence of Leucocytozoon infection in 5 species of diurnal raptors from California. Of 591 birds tested, 177 (29.9%) were infected with Leucocytozoon toddi. Subsequent phylogenetic analysis of the cytochrome b gene revealed that distinct haplotypes are present in hawks of these genera. Haplotypes present in Buteo spp. are not found in Accipiter spp., and there is a 10.9% sequence divergence between the 2 lineage clades. In addition, Leucocytozoon sp. from Accipiter spp. from Europe group more closely with parasites found in Accipiter spp. from California than the same California Accipiter species do with their sympatric Buteo spp. Similarly, a Leucocytozoon haplotype from a Common Buzzard (Buteo buteo) from Kazakhstan forms a monophyletic lineage with a parasite from B. jamaicensis from California. These results suggest that Leucocytozoon toddi is most likely a group of cryptic species, with 1 species infecting Buteo spp. and 1 or more species, or subspecies, infecting Accipiter spp.

Characterization of toxoplasma gondii isolates in free-range chickens from amazon, brazil

Abstract: The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 50 free-range chickens (Gallus domesticus) from Amazon, Brazil, was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and found in 33 (66%) chickens with titers of 1:5 in 3, 1:10 in 2, 1:20 in 1, 1:40 in 1, 1:80 in 2, 1:160 in 5, 1:200 in 9, 1:400 in 5, 1:800 in 2, 1:1,600 in 2, and 1:3,200 or higher in 1. Hearts and brains of 33 seropositive chickens were bioassayed individually in mice. Tissues from 17 seronegative chickens were pooled and fed to 2 T. gondii-free cats. Feces of cats were examined for oocysts, but none was found. Toxoplasma gondii was isolated from 24 chickens with MAT titers of 1:5 or higher. Genotyping of these 24 T. gondii isolates by polymorphisms at the SAG2 locus indicated that 14 were type I, and 10 were type III; the absence of type II strains from Brazil was confirmed. Fifty percent of the infected mice died of toxoplasmosis, irrespective of the genotype.

Human thelaziosis--a neglected parasitic disease of the eye.

Abstract: The oriental eyeworm, Thelazia callipaeda (Spirurida, Thelaziidae), infects a range of definitive hosts, such as dogs, cats, foxes, rabbits, and humans This parasite usually lives under the nictitating membrane of the eye, where the adult females release first-stage larvae into the lachrymal secretions; these larvae are subsequently ingested by the intermediate arthropod host within which they develop to the infective, third-stage larvae The latter larvae are then deposited into the eyes of the definitive host Recently, T callipaeda has been reported to infect dogs, foxes, and/or cats in Europe (Italy, France, and Germany) Human thelaziosis (HT) is considered to be an underestimated parasitic disease, whose prevalence appears to have increased in poor socioeconomic settings in many Asian countries, including China In humans, the disease can be subclinical or symptomatic, exhibiting epiphora, conjunctivitis, keratitis, excessive lachrymation, corneal opacity, and/or ulcers Knowledge about HT is presently fragmentary and mainly limited to clinical case reports This article provides a background on the parasite and its life cycle, reviews cases of human thelaziosis, summarizes key aspects regarding the diagnosis of thelaziosis, and proposes future research and methods of control of the disease in humans, particularly in Asia

An approach to revealing blood fluke life cycles, taxonomy, and diversity: provision of key reference data including dna sequence from single life cycle stages

Abstract: Revealing diversity among extant blood flukes, and the patterns of relationships among them, has been hindered by the difficulty of determining if specimens described from different life cycle stages, hosts, geographic localities, and times represent the same or different species. Persistent collection of all available life cycle stages and provision of exact collection localities, host identification, reference DNA sequences for the parasite, and voucher specimens eventually will provide the framework needed to piece together individual life cycles and facilitate reconciliation with classical taxonomic descriptions, including those based on single life cycle stages. It also provides a means to document unique or rare species that might only ever be recovered from a single life cycle stage. With an emphasis on the value of new information from field collections of any available life cycle stages, here we provide data for several blood fluke cercariae from freshwater snails from Kenya, Uganda, and Australia. Similar data are provided for adult worms of Macrobilharzia macrobilharzia and miracidia of Bivitellobilharzia nairi. Some schistosome and sanguinicolid cercariae that we recovered have peculiar morphological features, and our phylogenetic analyses (18S and 28S rDNA and mtDNA CO1) suggest that 2 of the new schistosome specimens likely represent previously unknown lineages. Our results also provide new insights into 2 of the 4 remaining schistosome genera yet to be extensively characterized with respect to their position in molecular phylogenies, Macrobilharzia and Bivitellobilharzia. The accessibility of each life cycle stage is likely to vary dramatically from one parasite species to the next, and our examples validate the potential usefulness of information gleaned from even one such stage, whatever it might be.

The occurrence of Lepeophtheirus salmonis and Caligus clemensi (Copepoda: Caligidae) on three-spine stickleback Gasterosteus aculeatus in coastal British Columbia.

Abstract: Infections with sea lice species belonging to Lepeophtheirus and Caligus are reported from examinations of 1,309 three-spine sticklebacks collected in coastal British Columbia. Over 97% of the 19,960 Lepeophtheirus specimens and nearly 96% of the 2,340 Caligus specimens were in the copepodid and chalimus developmental stages. The parasites were identified as Lepeophtheirus salmonis and Caligus clemensi based on morphology of adult stages. Between 1,763 and 1,766 base pairs (bp) of 18S rDNA from adult specimens collected from sticklebacks and salmon differed from the GenBank L. salmonis reference sequence by a single bp and were distinct from those of 2 other Lepeophtheirus species. A 530-bp region of 18S rDNA from chalimus stages of Lepeophtheirus obtained from sticklebacks and salmon was identical to that of the L. salmonis reference sequence. The three-spine stickleback is a new host record for L. salmonis. The prevalence of L. salmonis was 83.6% and that of C. clemensi was 42.8%. The intensities of these infections were 18.3 and 4.2, respectively. There was no significant relationship between sea lice abundance and stickleback condition factor. Significant spatial and temporal variations both in abundance of sea lice and surface seawater salinities were measured. The abundance of both sea lice species was lowest in zones in which surface seawater salinity was also lowest. Sticklebacks appear to serve as temporary hosts, suggesting a role of this host in the epizootiology of L. salmonis. The stickleback may be a useful sentinel species with which to monitor spatial and temporal changes in the abundance of L. salmonis and C. clemensi.

Involvement of manayunkia speciosa (annelida: polychaeta: sabellidae) in the life cycle of parvicapsula minibicornis, a myxozoan parasite of pacific salmon

Abstract: A coelomic myxozoan infection was detected in freshwater polychaetes, Manayunkia speciosa from the Klamath River, Oregon/California, a site enzootic for the myxozoan parasites Ceratomyxa shasta and Parvicapsula minibicornis. The tetractinomyxon type actinospores had a near-spherical spore body 7.9 × 7.1 μm, with 3 spherical, protruding polar capsules, no valve cell processes, and a binucleate sporoplasm. Parvicapsula minibicornis-specific primers Parvi1f and Parvi2r amplified DNA from infected polychaetes in a polymerase chain reaction (PCR) assay. The small subunit 18S rRNA gene of the spores was sequenced (GenBank DQ231038) and was a 99.7% match with the sequence for P. minibicornis myxospore stage in GenBank (AF201375). Chinook salmon (Oncorhynchus tshawytscha) exposed to a dose of 1,000 actinospores per fish tested PCR positive for P. minibicornis at 14 wk postinfection and presporogonic stages were detected in the kidney tubules by histology at 20 wk. This life cycle is 1 of only about 30 known from ...

Species affinity and infracommunity ordination of helminths of leptodactylus chaquensis (anura: leptodactylidae) in two contrasting environments from northeastern argentina

Abstract: One hundred seventy-two frogs (Leptodactylus chaquensis) were collected from November 2002 to November 2003, in agricultural (n = 132) and nonagricultural (n = 40) areas. Both sites are near the city of Corrientes, Argentina. The main goals of this study were as follows: (1) to determine the helminth parasite community in agricultural and nonagricultural habitats; (2) to analyze the relationships between helminth parasites and site of infection, frog body size, and gender; (3) to identify and examine covariation and association of helminth communities; and (4) to determine the mean richness and diversity of parasite communities. The helminth compound community of this amphibian species consisted of 24 species: 19 in agricultural habitats and 18 in nonagricultural habitats. The mean richness, mean diversity, and evenness of helminths were significantly different between the habitats (P < 0.05). The body size of the host was the important factor in determining parasite richness. Both habitats exhibited differences in community ordination. The helminth species in the 2 habitats exhibited the same interspecific relationships, although differences were observed in the intensity of infection.

Genetic differentiation in eastern European and western Asian populations of the liver fluke, Fasciola hepatica, as revealed by mitochondrial nad1 and cox1 genes.

Abstract: Partial sequences of mitochondrial genes nad1 (316 bp) and cox1 (429 bp) were analyzed to estimate the variability of the liver fluke samples collected in 20 localities in Russia, Belarus, Ukraine, Bulgaria, Armenia, Azerbaijan, Georgia, Turkey, Turkmenistan, and China. The sequences had 4.1% (nad1) and 2.3% (cox1) of variable sites, and 13 and 10 haplotypes were identified among nad1 and cox1 genes, respectively. Spatial analysis of genetic and nucleotide diversity indicated little or no structuring of genetic variation between hosts or regions. The analysis of distribution of both separate and combined (nad1 + cox1) haplotypes revealed the existence of 2 well-defined lineages with 2 main haplotypes and a number of shared divergent haplotypes. Our study showed that the first lineage included the main N1-C1 haplotype, which was found in Australia, China, Georgia, Turkey, Armenia, Azerbaijan, and in all European populations (from Russia, Belarus, Ukraine, Bulgaria). The second lineage was found in all European populations and in populations from Armenia and Azerbaijan. It was suggested that one of the lineages (I) has an Asian origin. The possible source of mtDNA variability and associations between lineage divergence of parasite and its definitive hosts (cattle and sheep) are discussed.

Malaria and helminth co-infection in children living in a malaria endemic setting of mount cameroon and predictors of anemia

Abstract: A study was carried out with 425 children aged 0–14 yr residing in Bolifamba, Cameroon, to investigate the effect of Plasmodium falciparum malaria and intestinal helminth coinfection on anemia and to identify significant predictors of anemia in the community. Blood was collected by finger prick to determine malaria parasitemia and packed cell volume (PCV). The Kato-Katz technique was used to assess the prevalence and egg load of intestinal helminths. The prevalence of P. falciparum malaria, intestinal helminth infections, and coinfection was 64.2%, 38.3%, and 24.7%, respectively. Coinfections in which heavy helminth loads were detected had corresponding high mean P. falciparum parasite loads >5,000/μl compared with coinfections involving light helminth burden. The overall prevalence of anemia was 30.8%. Anemia prevalence increased significantly with P. falciparum parasite load >5,000/μl compared with lower densities (χ2 = 6.734, P = 0.034). Anemia prevalence was significantly higher in febrile children co...

Effect of Haemoproteus belopolskyi (Haemosporida: Haemoproteidae) on Body Mass of the Blackcap Sylvia atricapilla

Abstract: The effect of initial Haemoproteus belopolskyi infection on the weight of its natural host, the blackcap Sylvia atricapilla, was investigated. Fourteen blackcap nestlings were taken at the age of 4–5 days and raised by hand in the laboratory. They were free of blood parasites. Seven 20- to 21-day-old nestlings were infected experimentally by inoculation in their pectoral muscle with approximately 45 sporozoites, which had developed in the experimentally infected biting midge Culicoides impunctatus. Seven nestlings were used as negative controls. Parasitemia developed in 6 inoculated nestlings, with a prepatent period of 11–12 days. No infections were detected in the controls during this study. The weight of experimentally infected and control birds was measured 2 days before parasitemia became patent and for a 45-day period after patency. Blood smears were prepared from all birds on the days when they were weighed. When compared with controls, there was a significant weight loss of experimentally infected...

Multilocus microsatellite analysis reveals extensive genetic diversity in Neospora caninum.

Abstract: Neospora caninum is a world-wide parasite that causes neuromuscular disorders in dogs and bovine abortion. Biological diversity among isolates has been proved in both in vivo and in vitro studies. In contrast, little is known about the genetic diversity of this parasite. Microsatellite sequence analysis constitutes a suitable tool that has been used for the genetic analysis of other apicomplexan parasites. In this report, we describe the identification and analysis of 13 microsatellite loci from N. caninum DNA sequences deposited in public databases, which were evaluated with the use of 9 isolates grown in vitro. One microsatellite was monomorphic, and the remaining 12 loci exhibited 3 to 9 separate alleles. Multilocus analysis showed that each of the 9 isolates investigated here displayed a unique profile and revealed no association between the genetic similarity and host or geographic origin. The multilocus analysis approach described here might nevertheless provide the powerful tool needed to study the genetic complexity of N. caninum and the molecular epidemiology of neosporosis.

Blood parasites of nearctic–neotropical migrant passerine birds during spring trans-gulf migration: impact on host body condition

Abstract: To test the hypothesis that migrants infected with blood parasites arrive on the northern coast of the Gulf of Mexico in poorer condition than uninfected birds, we examined 1,705 migrant passerine birds representing 54 species of 11 families from 2 Gulf Coast sites for blood parasites. Three hundred and sixty (21.1%) were infected with 1 or more species of 4 genera of blood parasites. The prevalence of parasites was as follows: Haemoproteus spp. (11.7%), Plasmodium spp. (6.7%), Leucocytozoon spp. (1.3%), and Trypanosoma spp. (1.2%). Both prevalence and density of Haemoproteus spp. infection varied among species. We found no relationship of gender or age with the prevalence of Haemoproteus spp. infection or Plasmodium spp. infection, with the exception of the orchard oriole (Icterus spurius) for which older birds were more likely to be infected with Haemoproteus spp. than younger birds. We also found that scarlet tanagers and summer tanagers infected with species of Haemoproteus have lower fat scores than ...

Status of corynosoma (acanthocephala: polymorphidae) based on anatomical, ecological, and phylogenetic evidence, with the erection of pseudocorynosoma n. gen

Abstract: The possession of genital spines has been considered as a key taxonomic trait to differentiate Corynosoma from other genera of the Polymorphidae. However, Corynosoma currently consists of 2 groups of species with clear ecological and morphological divergences: the “marine” group (with ca. 30 species) infects mammals and piscivorous birds in the marine realm, whereas the “freshwater” group (with ca. 7 species) infects waterfowl in continental waters. Species from these groups differ in shape of body and neck, trunk spination, lemnisci length and shape, testes arrangement, and number and shape of cement glands. We tested whether species from these 2 groups formed a monophyletic assemblage based on a phylogenetic analysis by using 15 morphological characters. We also included species of Andracantha, Polymorphus, and Hexaglandula with which potential taxonomic conflicts could most likely arise. We obtained 108 equally most parsimonious trees of 32 steps, with a consistency index (CI) = 0.59, and a retention i...

Environmental factors influencing trematode prevalence in grey tree frog (hyla versicolor) tadpoles in southern ontario

Abstract: The emergence or increased prevalence of various parasites may be linked to alterations in host—parasite interactions caused by environmental changes. We investigated prevalence of trematode infections in grey tree frog (Hyla versicolor) tadpoles from ponds in nonagricultural settings versus ponds adjacent to cornfields in southern Ontario. We found that agricultural activity was a significant factor in determining the percentage of tadpoles infected by 1 or more trematodes from 1 or more species (combined trematode infection). However, we found no associations between combined trematode infection and forest cover; pond size; road density; and measures of water quality, such as nitrate level and the presence of the herbicide atrazine. Although combined trematode prevalence was associated only with agricultural activity, prevalence of Alaria species showed a positive association with forest cover. This latter result probably reflects the importance of habitat suitability for the canid definitive hosts of t...

Resistance-induced changes in triclabendazole transport in fasciola hepatica: ivermectin reversal effect

Abstract: Triclabendazole (TCBZ) and albendazole (ABZ) are flukicidal benzimidazole compounds extensively used in veterinary medicine. Although TCBZ has excellent activity against mature and immature stages of the liver fluke, Fasciola hepatica, ABZ action is restricted to flukes older than 12 wk. The intensive use of TCBZ has resulted in the development of resistance. To gain insight into the mechanisms of resistance to TCBZ, the ex vivo diffusion of TCBZ, TCBZ sulfoxide (TCBZSO, the active metabolite of TCBZ), and ABZ into TCBZ-susceptible and -resistant adult flukes was compared. TCBZ-susceptible (Cullompton) and -resistant (Sligo) flukes were incubated in Krebs-Ringer Tris buffer with either TCBZ, TCBZSO, or ABZ (5 nmol/ ml) for 90 min. Drug/metabolite concentrations were quantified by high-performance liquid chromatography. All the assayed molecules penetrated through the tegument of both susceptible and resistant flukes. However, significantly lower concentrations of TCBZ and TCBZSO were recovered within the TCBZ-resistant flukes. In contrast, ABZ entrance into the susceptible and resistant flukes was equivalent. The influx/efflux balance for TCBZ, TCBZSO, and ABZ in susceptible and resistant flukes in the presence or absence of a substrate (ivermectin) of the drug transporter P-glycoprotein was assessed. The ivermectin-induced modulation of P-glycoprotein activity decreased TCBZ efflux from the resistant flukes. Higher concentrations of TCBZ and TCBZSO were recovered from the resistant liver flukes in the presence of ivermectin. Thus, an altered influx/efflux mechanism may account for the development of resistance to TCBZ in F. hepatica.

Effects of high-pressure processing on Toxoplasma gondii tissue cysts in ground pork

Abstract: Ingestion of Toxoplasma gondii tissue cysts can result in severe disease in immunocompromised individuals and pregnant women. Treatment of meat and meat products to eliminate viable T. gondii tissue cysts would provide a means to protect consumers. In this study, we examined the effects of high-pressure processing (HPP) on ground pork containing viable tissue cysts of the VEG strain of T. gondii. Ground pork containing tissue cysts was exposed to 400, 300, 200, 100, or 0 MPa treatment for 30, 60, or 90 sec in a commercial HPP unit. The HPP-treated ground pork was subjected to acid-pepsin digestion and bioassayed in mice. The results of the mouse bioassay revealed that none of the mice inoculated with tissue cysts exposed to 400 or 300 MPa became infected, whereas all mice inoculated with tissue cysts exposed to 200, 100, or 0 MPa became infected with T. gondii regardless of exposure time. Results indicate that HPP treatment of ground pork with 300 MPa of pressure will render tissue cysts of T. gondii nonviable and make pork safe for human consumption.

Neospora caninum-like oocysts observed in feces of free-ranging red foxes (Vulpes vulpes) and coyotes (Canis latrans).

Abstract: The aim of this study was to examine the feces of free-ranging foxes and coyotes for the presence of Neospora caninum oocysts. Feces were collected from 271 foxes and 185 coyotes in the Canadian province of Prince Edward Island, processed by sucrose flotation, and examined by light microscopy for the presence of coccidian oocysts. In 2 fox and 2 coyote samples, oocysts morphologically and morphometrically similar to oocysts of N. caninum were observed. DNA was extracted from these samples and subjected to nested polymerase chain reaction (PCR) using primers to the N. caninum-specific Nc5 genomic sequence. Through DNA sequencing, alignment of the sequences of at least 3 clones from each isolate to sequences deposited in GenBank revealed 95-99% similarity to the Nc5 sequence of N. caninum. PCR using primers specific for Hammondia heydorni failed to yield an amplification product from these DNA samples.

Biological studies and molecular characterization of a cryptosporidium isolate from ostriches (struthio camelus)

Abstract: There are many reports of cryptosporidial infection in ostriches, but none with molecular characterization of the isolates. A study was undertaken for the characterization of a Brazilian Cryptosporidium sp. ostrich isolate by using molecular phylogenetic analysis of fragments of the 18S ribosomal DNA, heat-shock protein (hsp) 70 coding gene, and actin coding gene. Biological studies were accomplished by the experimental inoculation of chickens via oral or intratracheal routes with fresh ostrich Cryptosporidium sp. oocysts. Molecular analysis of nucleotide sequences of the 3 genes by using neighbor-joining and parsimony methods grouped the ostrich isolate as a sister taxon of Cryptosporidium baileyi and showed that the ostrich isolate is genetically distinct from all other known Cryptosporidium species or genotypes. None of the inoculated chickens developed infection as determined by mucosal smears, histology, and fecal screening for oocysts. Although biological and molecular studies indicate that the ostrich Cryptosporidium is a new species, further studies regarding morphological, biological, and molecular characteristics of other ostrich isolates are required to confirm the species status of the ostrich Cryptosporidium.

Systematics and emerging infectious diseases: from management to solution.

Abstract: The crisis of emerging infectious disease stems from the absence of comprehensive taxonomic inventories of the world's parasites, which includes the world's pathogens. Recent technological developments raise hopes that the global inventory of species, including potential pathogens, can be accomplished in a timely and cost-effective manner. The phylogenetics revolution initiated by systematists provides a means by which information about pathogen transmission dynamics can be placed in a predictive framework. Increasingly, that information is widely available in digital form on the internet. Systematic biology is well positioned to play a crucial role in efforts to be proactive in the arena of emerging parasitic and infectious diseases.

Infection by trypanosomes in marsupials and rodents associated with human dwellings in ecuador

Abstract: Small mammals trapped in domestic and peridomestic environments of rural Ecuador were screened for trypanosome infection by direct microscopy and hemoculture. Identification of species of trypanosomes was then performed by morphological characteristics and by polymerase chain reaction (PCR) assays. Of 194 animals collected, 15 were positive for infection (7.73%). Eight (4.12%) were infected with Trypanosoma cruzi (1 of 33 Didelphis marsupialis; 7 of 61 Rattus rattus). Eleven R. rattus (18.03%) harbored T. lewisi, 5 of which presented mixed infections with T. cruzi. Additionally, 1 of 3 Oryzomys xanthaeolus was infected with T. rangeli. No trypanosome infection was detected in Philander opossum (n = 1), Mus musculus (n = 79), Rattus norvegicus (n = 8), Akodon orophilus (n = 4), Sigmodon peruanus (n = 3), or Proechimys decumanus (n = 2). Many of the isolates belong to T. cruzi, the causative agent of Chagas disease, and R. rattus had the highest prevalence. Because of its abundance in the study areas, this ...

Seroprevalence of Toxoplasma gondii Antibodies in Cats and Pigs From Rural Western Amazon, Brazil

Abstract: Antibodies to Toxoplasma gondii were assayed in sera of 63 cats and 80 pigs from 71 farms located at Rondonia State, Western Amazon, Brazil, by the modified agglutination test (MAT) and the indirect immunofluorescent antibody test (IFAT). Antibodies (MAT ≥ 1: 25) were found in 55 of 63 cats (87.3%) with titers of 1:25 in 2, 1:50 in 2, 1:100 in 7, 1:200 in 1, 1:400 in 2, 1:800 in 9, 1:1,600 in 6, and 1:3,200 or higher in 26 cats. By IFAT, antibodies were found in 55 cats (87.3%) with titers of 1:25 in 2, 1:50 in 1, 1:100 in 4, 1:200 in 4, 1: 400 in 1, 1:800 in 13, 1:1,600 in 12, and 1:3,200 or higher in 18 cats. In pig sera, by MAT, antibodies were found in 30 of 80 pigs (37.5%) with titers of 1:25 in 2, 1:50 in 3, 1:100 in 2, 1:200 in 8, 1:400 in 3, 1:800 in 5, 1:1,600 in 3, and 1:3,200 or higher in 4 pigs. By using the IFAT (titers ≥ 1:64), antibodies were found in 35 (43.7%) pigs. The ingestion of undercooked tissues of infected pigs can be a source of T. gondii infection for humans and cats. However, t...

Subtype Analysis of Cryptosporidium Isolates From Children in Uganda

Abstract: Cryptosporidium hominis and Cryptosporidium parvum isolates from children in Uganda were characterized by DNA sequence analysis of the GP60 gene. Eight alleles were identified, 4 C. hominis and 4 C. parvum, of which 3 represent new C. parvum families. The data show that it is highly likely that the route of transmission is anthroponotic.

Effects of atrazine on cercarial longevity, activity, and infectivity

Abstract: Susceptibility of free-living infective stages of parasites to contaminants is relatively understudied compared with independent effects on measures of host health or immunity, but may be important in affecting prevalence and intensity of parasite infections. We investigated whether atrazine, an herbicide commonly used in North America, affected the cercariae of 4 different species of digenetic trematodes, and found that effects of atrazine concentration on mortality and activity of cercariae varied among species. Mortality of Echinostoma trivolvis increased in a 200 μg/L atrazine solution, and a species of Alaria showed both decreased activity and increased mortality. We also examined whether the ability of E. trivolvis to infect the second intermediate host, larval amphibians, was compromised by atrazine exposure. Longevity and prevalence of E. trivolvis cercariae was affected at 200 μg/L atrazine, whereas intensity of infection in Rana clamitans tadpoles was reduced at both 20 μg/L and 200 μg/L atrazin...

Spermiogenesis and spermatozoon ultrastructure of the cranial digenean troglotrema acutum (leuckart, 1842)

Abstract: Ultrastructure of spermiogenesis and the main characters of the mature spermatozoon of Troglotrema acutum are described by means of transmission electron microscopy. Specimens were obtained from the nasolacrimal sinuses of an American mink (Mustela vison). Spermiogenesis in T. acutum follows the general pattern of digeneans. The zone of differentiation is a conical-shaped area bordered by cortical microtubules and delimited at its base by a ring of arched membranes. This area contains 2 centrioles associated with striated rootlets and an intercentriolar body between them. The centrioles develop 2 free flagella that grow ortogonally to the median cytoplasmic process. The posterior flagellar rotation and proximodistal fusion of the free flagella with the median cytoplasmic process originate the spermatozoon. The mature spermatozoon of T. acutum is characterized by the presence of 2 axonemes of different lengths presenting the 9+‘1’ trepaxonematan pattern, 2 bundles of parallel cortical microtubules, 2 mitoc...