| 1. |
- Barber, I., et al.
(författare)
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Effects of experimental Schistocephalus solidus infections on growth, morphology and sexual development of female three-spined sticklebacks, Gasterosteus aculeatus
- 2003
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 126, s. 359-367
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Tidskriftsartikel (refereegranskat)abstract
- The use of naturally infected hosts in studies attempting to identify parasite-induced changes in host biology is problematical because it does not eliminate the possibility that infection may be a consequence, rather than a cause, of host trait variation. In addition, uncontrolled concomitant infections may confound results. In this study we experimentally infected individual laboratory-bred female three-spined sticklebacks Gasterosteus aculeatus L. with the pseudophyllidean cestode Schistocephalus solidus [Muller], and compared the morphology and growth patterns of infected females with sham-exposed controls over a 16-week period. Fish were fed a ration of 8% body weight per day. Non-invasive image analysis techniques allowed the growth of individual plerocercoids to be tracked in vivo throughout the course of infection, and patterns of host and parasite growth were determined. Females that developed infections diverged morphometrically from unexposed control females and exposed-uninfected females at 6 weeks post-infection, with the width of the body at the pectoral fins giving the earliest indication of infection success. When including the plerocercoid, infected females gained weight more quickly than controls, but when plerocercoid weight was removed this trend was reversed. There was no effect of infection on the increase in fish length. Plerocercoids grew at different rates in individual hosts, and exhibited measurable sustained weight increases of up to 10% per day. Final estimates of plerocercoid weight from morphometric analysis prior to autopsy were accurate to within +/-17% of actual plerocercoid weight. At autopsy, infected female sticklebacks had significantly lower perivisceral fat reserves but had developed significantly larger ovaries than controls. The results are discussed in relation to previous studies examining natural infections, and the value of utilizing experimental infections to examine ecological aspects of host-parasite interactions is discussed.
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| 2. |
- Bensch, Staffan, et al.
(författare)
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Low prevalence of Haemoproteus infections in Chiffchaffs.
- 2012
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Ingår i: Parasitology. - 1469-8161. ; 139, s. 302-309
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Tidskriftsartikel (refereegranskat)abstract
- SUMMARY: Parasite prevalence is an important variable in many evolutionary and ecological studies. In birds, haemosporidian blood parasites have been in focus of many comparative analyses. Because low prevalence is difficult to estimate precisely and that studies finding low prevalence are more likely to remain unpublished, our knowledge of parasite prevalence is biased towards highly infected taxa. Species with naturally low levels of infection are nonetheless interesting as they may provide models for studying the evolution of pathogen resistance. In the present study we show that the prevalence of Haemoproteus parasites is markedly lower in several taxa within the widely distributed chiffchaff species-complex compared to other species within the genus Phylloscopus. Since chiffchaffs, P. collybita, commonly coexists in the same habitat as congeners frequently infected with Haemoproteus parasites, immediate ecological variables like abundance of vectors can hardly explain this difference. Some of the parasites infecting coexisting congeners are broad host generalists leaving it enigmatic why chiffchaffs are almost free of Haemoproteus infections. We propose that detailed infection experiments are needed to illuminate whether chiffchaffs possess a genetic immunity against Haemoproteus parasites or if other more subtle ecological processes, like anti-vector behaviour, play a role in its generally low level of infestation.
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| 3. |
- Billker, Oliver, et al.
(författare)
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Determination of mosquito bloodmeal pH in situ by ion-selective microelectrode measurement : implications for the regulation of malarial gametogenesis
- 2000
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Ingår i: Parasitology. - : Cambridge University Press (CUP). - 0031-1820 .- 1469-8161. ; 120, s. 547-551
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Tidskriftsartikel (refereegranskat)abstract
- Malarial gametocytes circulate in the peripheral blood of the vertebrate host as developmentally arrested intra-erythrocytic cells, which only resume development into gametes when ingested into the bloodmeal of the female mosquito vector. The ensuing development encompasses sexual reproduction and mediates parasite transmission to the insect. In vitro the induction of gametogenesis requires a drop in temperature and either a pH increase from physiological blood pH (ca pH 7.4) to about pH 8.0, or the presence of a gametocyte-activating factor recently identified as xanthurenic acid (XA). However, it is unclear whether either the pH increase or XA act as natural triggers in the mosquito bloodmeal. We here use pH-sensitive microelectrodes to determine bloodmeal pH in intact mosquitoes. Measurements taken in the first 30 min after ingestion, when malarial gametogenesis is induced in vivo, revealed small pH increases from 7.40 (mouse blood) to 7.52 in Aedes aegypti and to 7.58 in Anophĕles stephensi. However, bloodmeal pH was clearly suboptimal if compared to values required to induce gametogenesis in vitro. Xanthurenic acid is shown to extend the pH-range of exflagellation in vitro in a dose-dependent manner to values that we have observed in the bloodmeal, suggesting that in vivo malarial gametogenesis could be further regulated by both these factors.
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| 4. |
- Billker, Oliver, et al.
(författare)
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The roles of temperature, pH and mosquito factors as triggers of male and female gametogenesis of Plasmodium berghei in vitro
- 1997
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Ingår i: Parasitology. - : Cambridge University Press. - 0031-1820 .- 1469-8161. ; 115, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Developmentally arrested malarial gametocytes undergo gamete formation in the mosquito midgut immediately after ingestion of the infected bloodmeal. In the rodent malaria parasite Plasmodium berghei male gametogenesis (exflagellation) can be induced in vitro by a temperature decrease (from 39 degrees C in the vertebrate host to 20 degrees C) and a concomitant pH increase (from 7.3 in mouse blood to 8.0). We report the presence of additional Gametocyte Activating Factor(s) (GAF) present in Anopheles stephensi tissue extracts, which induce both male and female gametogenesis at the otherwise nonpermissive pH of 7.3 in vitro but are unable to overcome the low temperature requirement. All constituent cellular events of microgametogeneis studied here are induced by the same triggers in vitro. A temperature decrease is also required for exflagellation in the mosquito midgut. The possible role of GAF as a second obligatory natural trigger of gametogenesis is discussed.
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| 5. |
- Björkman, Camilla, et al.
(författare)
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Cryptosporidium infections in suckler herd beef calves
- 2015
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 142, s. 1108-1114
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Tidskriftsartikel (refereegranskat)abstract
- A study was carried out to investigate how common Cryptosporidium infections are in beef calves in Swedish suckler herds and to explore which species and subtypes that occur. We further aimed at identifying factors associated with shedding of Cryptosporidium oocysts in this type of calf management. The study was conducted in two regions in Sweden and included 30 herds. Faecal samples were collected from calves younger than 3 months. A brief clinical examination was done and a questionnaire was used to collect data on management routines. Faeces were cleaned and concentrated and oocysts identified by epifuorescence microscopy. Cryptosporidium positive samples were analyzed at the 18S rRNA and GP60 genes to determine species and Cryptosporidium parvum subtype, respectively. Logistic regression was used to identify factors associated with infection. Oocysts were detected in 122 (36·7%) calves from 29 (97%) herds, at 400 to 2·4 × 107 OPG. The youngest positive calves were only 1 and 2 days old. There was no association between age and Cryptosporidium infection. Cryptosporidium bovis, C. ryanae, C. parvum and C. ubiquitum were identified, with C. bovis being the major species. Two C. parvum subtypes, IIaA16G1R1 and IIdA27G1 were identified. Routines for cleaning calf pens and number of cows in calving pens were associated with infection.
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| 6. |
- Björkman, Camilla
(författare)
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Endogenous and exogenous transplacental transmission of Neospora caninum - how the route of transmission impacts on epidemiology and control of disease
- 2009
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 136, s. 1895-1900
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Forskningsöversikt (refereegranskat)abstract
- Vertical transmission of the protozoan parasite, Neospora caninum is highly efficient and can take two forms - endogenous transplacental transmission resulting from activation of the quiescent bradyzoite stage during pregnancy or exogenous transplacental transmission resulting from ingestion of oocysts during pregnancy. Calves born carrying infection derived from either endogenous or exogenous transplacental transmission are capable of infecting their offspring when they start to breed. This review considers firstly the frequency with which exogenous and endogenous transmission occur, secondly the role of the immune response in controlling N. caninum infection and thirdly how the parasite persists in an immune-competent host and is re-activated during pregnancy.
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| 7. |
- Dolnik, O. V., et al.
(författare)
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Isospora hypoleucae sp n. (Apicomplexa: Eimeriidae), a new coccidian parasite found in the Pied Flycatcher (Ficedula hypoleuca)
- 2009
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Ingår i: Parasitology. - 1469-8161. ; 136:8, s. 841-845
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Tidskriftsartikel (refereegranskat)abstract
- A new Coccidia species is reported from the natural population of Pied Flycatcher (Ficedula hypoleuca) in northern Germany. Sporulated oocysts were found in faeces from 6 of 8 sampled adults. The spherical oocysts of the new Isopora species have a brownish, smooth, bi-layered wall. Average size of sporulated oocysts was 19.4 x 19.3 mu m (17.5-22.8 mu m x 17.5-22.8 mu m) with a shape index (length/width) of 1.0. The sporulated oocysts have no micropyle or residuum, but enclose several small polar granules that often cluster into 2-3 dumbbell-shaped formations. Sporocytes are slightly elongated, rounded at the end opposite the Stieda body, 15.3 mu m x 9.2 mu m in size (13.8-16.1 mu m x 8.5-10.3 mu m), and have a shape index of 1.7 (1.6-1.8). The Stieda body has a prominent knob-like chip, whereas the substieda body is absent. Sporocysts contain a small compact sporocyst residuum and 4 sporozoites. COI haplotypes identical to those isolated from faecal oocysts were PCR amplified from the blood of 13-day-old nestlings, suggesting that the newly described species has extra-intestinal stages in blood. This represents the first description of a new avian Isospora species supported by molecular sequence data front the same oocysts that are described morphologically.
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| 8. |
- Dubiec, Anna, et al.
(författare)
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Differential prevalence and diversity of haemosporidian parasites in two sympatric closely related nonmigratory passerines
- 2016
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 143:10, s. 1320-1329
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Tidskriftsartikel (refereegranskat)abstract
- Haemosporidian parasites infecting birds show distinct heterogeneity in their distribution among host species. However, despite numerous studies on the prevalence and diversity of parasite communities across species, very little is known on patterns of differences between them. Such data is lacking because up to date the majority of studies explored the patterns of variation in infections in different years, different time of sampling within a year or a breeding cycle, different study sites or was based on a small sample size, all of which may affect the estimates of prevalence and parasite diversity. Here, the prevalence, richness and diversity of haemosporidian parasites from the genera Plasmodium and Haemoproteus were studied in two closely related non-migratory hole-nesting passerines: Great Tits and Blue Tits. Birds were sampled in sympatrically breeding populations during two seasons at the same stage of their breeding cycle - late nestling care. Great Tits were more prevalently infected with Plasmodium and Haemoproteus parasites (97.1 vs 71.2%), harboured a higher proportion of multiple infections (26.2 vs 3.2%) and had a more diverse parasite community (11 vs 5 parasite lineages) than Blue Tits. Observed differences between two host species are discussed with reference to their breeding densities and immunological and behavioural characteristics.
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| 9. |
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| 10. |
- Garcia-Longoria, Luz, et al.
(författare)
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Detecting transmission areas of malaria parasites in a migratory bird species.
- 2015
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Ingår i: Parasitology. - 1469-8161. ; 142:9, s. 1215-1220
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Tidskriftsartikel (refereegranskat)abstract
- The identification of the regions where vector-borne diseases are transmitted is essential to study transmission patterns and to recognize future changes in environmental conditions that may potentially influence the transmission areas. SGS1, one of the lineages of Plasmodium relictum, is known to have active transmission in tropical Africa and temperate regions of Europe. Nuclear sequence data from isolates infected with SGS1 (based on merozoite surface protein 1 (MSP1) allelic diversity) have provided new insights on the distribution and transmission areas of these allelic variants. For example, MSP1 alleles transmitted in Africa differ from those transmitted in Europe, suggesting the existence of two populations of SGS1 lineages. However, no study has analysed the distribution of African and European transmitted alleles in Afro-Palearctic migratory birds. With this aim, we used a highly variable molecular marker to investigate whether juvenile house martins become infected in Europe before their first migration to Africa. We explored the MSP1 allelic diversity of P. relictum in adult and juvenile house martins. We found that juveniles were infected with SGS1 during their first weeks of life, confirming active transmission of SGS1 to house martins in Europe. Moreover, we found that all the juveniles and most of adults were infected with one European transmitted MSP1 allele, whereas two adult birds were infected with two African transmitted MSP1 alleles. These findings suggest that house martins are exposed to different strains of P. relictum in their winter and breeding quarters.
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| 11. |
- Haag, Karen Luisa, et al.
(författare)
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Cytological and molecular description of Hamiltosporidium tvaerminnensis gen. et sp nov., a microsporidian parasite of Daphnia magna, and establishment of Hamiltosporidium magnivora comb. nov.
- 2011
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Ingår i: Parasitology. - 1469-8161. ; 138:4, s. 447-462
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Tidskriftsartikel (refereegranskat)abstract
- We describe the new microsporidium Hamiltosporidium tvaerminnensis gen. et sp. nov. with an emphasis on its ultrastructural characteristics and phylogenetic position as inferred from the sequence data of SSU rDNA, alpha-and beta-tubulin. This parasite was previously identified as Octosporea bayeri Jirovec, 1936 and has become a model system to study the ecology, epidemiology, evolution and genomics of microsporidia - host interactions. Here, we present evidence that shows its differences from O. bayeri. Hamiltosporidium tvaerminnensis exclusively infects the adipose tissue, the ovaries and the hypodermis of Daphnia magna and is found only in host populations located in coastal rock pool populations in Finland and Sweden. Merogonial stages of H. tvaerminnensis have isolated nuclei; merozoites are formed by binary fission or by the cleaving of a plasmodium with a small number of nuclei. A sporogonial plasmodium with isolated nuclei yields 8 sporoblasts. Elongated spores are generated by the most finger-like plasmodia. The mature spores are polymorphic in shape and size. Most spores are pyriform (4.9-5.6x2.2-2.3 mu m) and have their polar filament arranged in 12-13 coils. A second, elongated spore type (6.8-12.0x1.6-2.1 mu m) is rod-shaped with blunt ends and measures 6.8-12.0x1.6-2.1 mu m. The envelope of the sporophorous vesicle is thin and fragile, formed at the beginning of the sporogony. Cytological and molecular comparisons with Flabelliforma magnivora, a parasite infecting the same tissues in the same host species, reveal that these two species are very closely related, yet distinct. Moreover, both cytological and molecular data indicate that these species are quite distant from F. montana, the type species of the genus Flabelliforma. We therefore propose that F. magnivora also be placed in Hamiltosporidium gen. nov.
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| 12. |
- Hellgren, Olof, et al.
(författare)
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De novo synthesis of thiamine (vitamin B1) is the ancestral state in Plasmodium parasites – evidence from avian haemosporidians
- 2017
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Ingår i: Parasitology. - : Cambridge University Press (CUP). - 0031-1820 .- 1469-8161. ; 145:8, s. 1084-1089
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Tidskriftsartikel (refereegranskat)abstract
- Parasites often have reduced genomes as their own genes become redundant when utilizing their host as a source of metabolites, thus losing their own de novo production of metabolites. Primate malaria parasites can synthesize vitamin B1 (thiamine) de novo but rodent malaria and other genome-sequenced apicomplexans cannot, as the three essential genes responsible for this pathway are absent in their genomes. The unique presence of functional thiamine synthesis genes in primate malaria parasites and their sequence similarities to bacterial orthologues, have led to speculations that this pathway was horizontally acquired from bacteria. Here we show that the genes essential for the de novo synthesis of thiamine are found also in avian Plasmodium species. Importantly, they are also present in species phylogenetically basal to all mammalian and avian Plasmodium parasites, i.e. Haemoproteus. Furthermore, we found that these genes are expressed during the blood stage of the avian malaria infection, indicating that this metabolic pathway is actively transcribed. We conclude that the ability to synthesize thiamine is widespread among haemosporidians, with a recent loss in the rodent malaria species.
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| 13. |
- Henriksson, J, et al.
(författare)
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Chromosomal size variation in Trypanosoma cruzi is mainly progressive andis evolutionarily informative
- 2002
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 124:Pt3, s. 277-286
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Tidskriftsartikel (refereegranskat)abstract
- The evolutionary significance of chromosome size polymorphism was explored in a representative panel of 26 Trypanosoma cruzi stocks. We tested a progressive model (aCSDI) assuming that the larger the size difference between homologous chromosomes, the more divergent the parasites are. This was contrasted with a non-progressive model (Jaccard's distance), in which any chromosome size difference has the same weight. ACSDI-based dendrograms were very similar to those built-up from multilocus enzyme electrophoresis (MLEE) and random amplified polymorphic DNA (RAPD) data: structuring in 2 major lineages (T. cruzi I and T. cruz II) and 5 small subdivisions within T. cruzi II was identical, and branching was very similar. Furthermore, a significant correlation (P < 0.001) was observed between aCSDI and phenetic distances calculated from MLEE and RAPD data. In contrast, analysis of chromosome size polymorphism with Jaccard's distance generated dendrograms with relatively long branches, causing most branching points to cluster close together, which generates statistically uncertain branching points. Our results thus support a model of progressive chromosome size-variation and show that despite an extensive polymorphism, chromosomal sizes constitute valuable characters for evolutionary analyses. Furthermore, our data are consistent with the clonal evolution model previously proposed for T. cruzi.
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| 14. |
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| 15. |
- Höglund, Johan
(författare)
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Distribution of large lungworms (Nematoda: Dictyocaulidae) in free-roaming populations of red deer Cervus elaphus (L.) with the description of Dictyocaulus skrjabini n. sp.
- 2023
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 150, s. 956-966
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Tidskriftsartikel (refereegranskat)abstract
- Lungworms of the genus Dictyocaulus are causative agents of parasitic bronchitis in domestic and wild ungulates. This study investigates the distribution, morphology and genetic diversity of D. cervi and a new lungworm species, Dictyocaulus skrjabini n. sp. infecting red deer Cervus elaphus, fallow deer Dama dama and moose Alces alces in Poland and Sweden. The study was conducted on 167 red deer from Poland and on the DNA of lungworms derived from 7 fallow deer, 4 red deer and 2 moose collected in Sweden. The prevalence of D. cervi and D. skrjabini n. sp. in dissected red deer in Poland was 31.1% and 7.2%, respectively. Moreover, D. skrjabini n. sp. was confirmed molecularly in 7 isolates of fallow deer lungworms and 1 isolate of red deer lungworms from Sweden. Dictyocaulus skrjabini n. sp. was established based on combination of their distinct molecular and morphological features; these included the length of cephalic vesicle, buccal capsule (BC), buccal capsule wall (BCW), distance from anterior extremity to the nerve ring, the width of head, oesophagus, cephalic vesicle, BC and BCW, as well as the dimensions of reproductive organs of male and female. Additionally, molecular analyses revealed 0.9% nucleotide sequence divergence for 1,605 bp SSU rDNA, and 16.5-17.3% nucleotide sequence divergence for 642 bp mitochondrial cytB between D. skrjabini n. sp. and D. cervi, respectively, and 18.7-19% between D. skrjabini n. sp. and D. eckerti, which translates into 18.2-18.7% amino acid sequence divergence between D. skrjabini n. sp. and both lungworms.
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| 16. |
- Jazin, Elena, et al.
(författare)
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Trypanosoma cruzi exoantigen is a member of a 160 kDa gene family
- 1995
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 110:Pt1, s. 61-69
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Tidskriftsartikel (refereegranskat)abstract
- During the chronic stage of Chagas disease a 160 kDa antigen appears in the blood of patients and remains detectable many years after the onset of the disease. This antigen is secreted by the trypomastigote form of the parasite while it is undetectable in the epimastigote form. We report here that the chronic 160 kDa exoantigen is encoded by a gene family (CEA 160 family). We describe the cloning and partial nucleotide sequence of a gene (CEA 160-1) belonging to the CEA160 family. Comparison of the gene sequence with other sequences present in the databases revealed homologies with several Trypanosoma cruzi surface antigens. Highest amino acid identity (59%) was with members of a family containing epitopes that mimic nervous tissues (Van Voorhis et al. 1993). Another related group (18-22% amino acid identity) comprises proteins of 85 or 160 kDa sharing an amino acid motif that is conserved among bacterial neuraminidases (Fouts et al. 1991; Pollevick et al. 1991; Kahn et al. 1991; Takle & Cross, 1991; Franco et al. 1993). The amino acid identities with the different antigens were not homogeneously distributed. Regions of higher identity (40-60%) were grouped in the central region of each protein.
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| 17. |
- Khan, Aisha, et al.
(författare)
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Epidemiological and Pathological Characteristics of Cutaneous Leishmaniasis from Baluchistan Province of Pakistan
- 2021
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Ingår i: Parasitology. - : Cambridge University Press. - 0031-1820 .- 1469-8161. ; 148:5, s. 591-597
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Tidskriftsartikel (refereegranskat)abstract
- Cutaneous Leishmaniasis (CL) is considered a neglected tropical disease which in Pakistan can now be considered as growing public health problem. The exact figures on the magnitude of disease are lacking both at national and regional level and only a few health centers are available for diagnosis of CL. The present study was designed to identify the epidemiology of CL infection from August 2018 to December 2019 and to assess clinical aspects of CL in Baluchistan Province of Pakistan. A total of 4072 clinically suspected CL cases were analysed statistically. The highest number of CL cases were reported in May, followed by April, January and then July, February, and June and lowest number of cases were observed in March and November. The highest prevalence rate was found in males where 38% of reported cases were aged 0-9 years. The majority (24.4%) of lesions were found on the hands followed by the face in which cheeks, ears and nose were the effected organs. About 50% of the participants have single lesion while 14% of the participants had two and nearly 3% of the participants have six lesions. The atypical clinical presentations were observed in Baluchistan and common unusual presentations were lupus erythematosus. The study findings suggest that more epidemiological studies and health education campaigns are needed for the population awareness regarding CL in Baluchistan. It is recommended that risk factors should be evaluated to establish the control and management strategies to prevent disease at individual and community level.
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| 18. |
- Krizanauskiene, Asta, et al.
(författare)
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Molecular phylogenetic and morphological analysis of haemosporidian parasites (Haemosporida) in a naturally infected European songbird, the blackcap Sylvia atricapilla, with description of Haemoproteus pallidulus sp. nov
- 2010
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Ingår i: Parasitology. - 1469-8161. ; 137:2, s. 217-227
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Tidskriftsartikel (refereegranskat)abstract
- The blackcap (Sylvia atricapilla) is a common Palearctic migratory warbler, and haemosporidian parasites are common in this species. However, genetic and phenotypic diversity of haemosporidians in warblers has been insufficiently investigated and poorly linked. We addressed this issue by combining molecular and microscopy data for detection of pigment-forming haemosporidians of the genera Haemoproteus and Plasmodium. Blood samples from 498 blackcaps were collected at 7 different sites in Europe and investigated for these parasites by polymerase chain reaction (PCR)-based techniques and microscopic examination. In all, 56% of the birds were infected by at least 1 out of 25 distinct mitochondrial cytochrome b (cyt b) gene lineages of these haemosporidians. It is concluded that the blackcap is infected not only with blackcap specific haemosporidians, but also with Haemoproteus majoris, which is a host generalist and common in birds belonging to the Paridae. Haemoproteus pallidulus sp. nov. is described based on morphology of its blood stages and segments of the cyt b and dihydrofolate reductase/thymidylate synthase (DHFR-TS) genes. This study provides evidence that genetic diversity of haemosporidian parasites might be positively correlated with migratory strategies of their avian hosts; it also contributes to the value of both microscopy and molecular diagnostics of avian blood parasites.
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| 19. |
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| 20. |
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| 21. |
- McMillan, P. J, et al.
(författare)
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Differential inhibition of high and low Mr thioredoxin reductases of parasites by organotelluriums supports the concept that low Mr thioredoxin reductases are good drug targets
- 2009
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 136:1, s. 27-33
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Tidskriftsartikel (refereegranskat)abstract
- Thioredoxin reductase (TrxR), a NADPH-dependent disulfide oxidoreductase, is vital in numerous cellular processes including defence against reactive oxygen species, cell proliferation and signal transduction. TrxRs occur in 2 forms, a high M-r enzyme characterized by those of mammals, the malaria parasite Plasmodium falciparum and some worms, and a low M-r form is present in bacteria, fungi, plants and some protozoan parasites. Our hypothesis is that the differences between the forms can be exploited in the development of selective inhibitors. In this study, cyclodextrin- and sulfonic acid-derived organotelluriums known to inhibit mammalian TrxR were investigated for their relative efficacy against P. falciparum TrxR (PfTrxR), a high M-r enzyme, and Trichomonas vaginalis TrxR (TvTrxR), a low M-r form of TrxR. The results suggest that selective inhibition of low M-r TrxRs is a feasible goal.
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| 22. |
- Miller, Andrea, et al.
(författare)
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Transmission ecology of taeniid larval cestodes in rodents in Sweden, a low endemic area for Echinococcus multilocularis
- 2017
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 144, s. 1041-1051
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Tidskriftsartikel (refereegranskat)abstract
- Although local prevalence of Echinococcus multilocularis may be high, this zoonotic parasite has an overall low prevalence in foxes and rodents in Sweden. To better understand opportunities for E. multilocularis transmission in the Swedish environment, the aim of this study was to investigate other taeniid cestodes and to relate observed patterns to E. multilocularis. Cestode parasites were examined in fox feces and rodents caught in different habitats from four regions of Sweden. Arvicola amphibius and Microtus agrestis were parasitized with Versteria mustelae, Hydatigera taeniaeformis s.l., and E. multilocularis, whereas Myodes glareolus and Apodemus spp. were parasitized with V. mustelae, Taenia polyacantha, H. taeniaeformis s.l., and Mesocestoides spp. Rodents caught in field habitat (Ar. amphibius, Mi. agrestis) were more likely (OR 10, 95% CI 5-19) to be parasitized than rodents caught in forest habitat (My. glareolus, Apodemus spp.). The parasite preference for each rodent species was present regardless of the type of background contamination from fox feces. These results further support the importance of both ecological barriers and individual species susceptibility in parasite transmission, and indicate that future monitoring for E. multilocularis in the Swedish environment should focus in field habitats where Mi. agrestis and Ar. amphibius are abundant.
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| 23. |
- Muhammad, Asghar, et al.
(författare)
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Primary peak and chronic malaria infection levels are correlated in experimentally infected great reed warblers.
- 2012
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Ingår i: Parasitology. - 1469-8161. ; 139:10, s. 1246-1252
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Tidskriftsartikel (refereegranskat)abstract
- SUMMARY Malaria parasites often manage to maintain an infection for several months or years in their vertebrate hosts. In humans, rodents and birds, most of the fitness costs associated with malaria infections are in the short initial primary (high parasitaemia) phase of the infection, whereas the chronic phase (low parasitaemia) is more benign to the host. In wild birds, malaria parasites have mainly been studied during the chronic phase of the infection. This is because the initial primary phase of infection is short in duration and infected birds with severe disease symptoms tend to hide in sheltered places and are thus rarely caught and sampled. We therefore wanted to investigate the relationship between the parasitaemia during the primary and chronic phases of the infection using an experimental infection approach. We found a significant positive correlation between parasitaemia in the primary peak and the subsequent chronic phase of infection when we experimentally infected great reed warblers (Acrocephalus arundinaceus) with Plasmodium ashfordi. The reason for this association remains to be understood, but might arise from individual variation in exoerythrocytic parasite reservoirs in hosts, parasite antigenic diversity and/or host genetics. Our results suggest that the chronic phase parasitaemia can be used to qualitatively infer the parasitaemia of the preceding and more severe primary phase, which is a very important finding for studies of avian malaria in wild populations.
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| 24. |
- Neto, Julio, et al.
(författare)
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Prevalence and diversity of Plasmodium and Haemoproteus parasites in the globally-threatened Aquatic Warbler Acrocephalus paludicola.
- 2015
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Ingår i: Parasitology. - 1469-8161. ; 142:9, s. 1183-1189
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Tidskriftsartikel (refereegranskat)abstract
- The diversity and prevalence of malaria parasites of the genera Plasmodium and Haemoproteus were determined in the globally-threatened Aquatic Warbler Acrocephalus paludicola. Birds were sampled during migration in Portugal and at the wintering quarters in Senegal and parasites were detected using molecular methods. Only three generalist parasite lineages (Plasmodium) were found. There were no significant differences in the prevalence of parasites between sexes in Europe, but adults had higher prevalence than first-year birds, and birds in Europe had higher prevalence than those captured in Africa. When comparing with other Acrocephalus species and taking sample size into account, Aquatic Warblers had the lowest prevalence and, together with another threatened species, the Seychelles Warbler Acrocephalus sechellensis, the lowest diversity of malaria parasites. We hypothesize that the low diversity of parasites and absence of specialist lineages of Aquatic Warblers are caused by its small population size and fragmented distribution. Furthermore, Aquatic Warblers' extreme habitat specialization may decrease their exposure to malaria parasites, but other explanations such as high mortality (which would constraint the sampling of infected birds) or, in contrast, very efficient immunological system in clearing the infections cannot be ruled out. This study contributes to explain variation in prevalence and diversity of malaria parasites among hosts.
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| 25. |
- Perez-Tris, Javier, et al.
(författare)
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Diagnosing genetically diverse avian malarial infections using mixed-sequence analysis and TA-cloning
- 2005
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Ingår i: Parasitology. - 1469-8161. ; 131:1, s. 15-23
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Tidskriftsartikel (refereegranskat)abstract
- Birds harbouring several malarial parasites are common in the wild, and resolving such multiple infections is important for our understanding of host-parasite relationships. We propose a simple and reasonably accurate method for detecting and resolving multiple infections, based on the analysis of parasite cytochrome b DNA sequences: genetically mixed infections are first identified by double nucleotide peaks on sequence electropherograms, and later retrieved by TA-cloning. We applied this method to wild birds, and to experimentally created mixes with varying proportion of two parasites (Plasmodium spp. and Haemoproteus spp.). In general, the method was very efficient in detecting and resolving multiple infections, but some problems were encountered. Several multiple infections were erroneously scored as simple, either because one of the parasite lineages was a better target for the primers used, or because it was much more abundant in the mix. On the other hand, single nucleotide substitutions and template switching during PCR produced artificial sequences in some clones. We discuss the utility of the method, and propose a framework for its use when screening for genetically diverse avian malarial parasites.
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| 26. |
- Rock, Sebastian L., et al.
(författare)
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Effects of parasitic freshwater mussels on their host fishes : a review
- 2022
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Ingår i: Parasitology. - : Cambridge University Press. - 0031-1820 .- 1469-8161. ; 149:14, s. 1958-1975
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Tidskriftsartikel (refereegranskat)abstract
- Freshwater mussels in the order Unionida are highly adapted to parasitize fish for the primary purpose of dispersal. The parasitic larval stage affixes itself to the gills or fins of the host where it becomes encysted in the tissue, eventually excysting to develop into a free-living adult. Research on the parasitic interactions between unionids and their host fishes has garnered attention recently due to the increase in worldwide preservation efforts surrounding this highly endangered and ecologically significant order. With the exception of heavy infestation events, these mussels cause minor effects to their hosts, typically only observable effect in combination with other stressors. Moreover, the range of effect intensities on the host varies greatly with the species involved in the interaction, an effect that may arise from different evolutionary strategies between long- and short-infesting mussels; a distinction not typically made in conservation practices. Lower growth and reduced osmotic potential in infested hosts are commonly observed and correlated to infestation load. These effects are typically also associated with increases in metabolic rate and behaviour indicative of stress. Host fish seem to compensate for this through a combination of rapid wound healing in the parasitized areas and higher ventilation rates. The findings are heavily biased towards Margaritifera margaritifera, a unique mussel not well suited for cross-species generalizations. Furthermore, the small body of molecular and genetic studies should be expanded as many conclusions are drawn from studies on the ultimate effects of glochidiosis rather than proximate studies on the underlying mechanisms.
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| 27. |
- Sandholt, Arnar K. S., et al.
(författare)
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Dual RNA-Seq transcriptome analysis of chicken macrophage-like cells (HD11) infected in vitro with Eimeria tenella
- 2021
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Ingår i: Parasitology. - : Cambridge University Press. - 0031-1820 .- 1469-8161. ; 148:6, s. 712-725
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Tidskriftsartikel (refereegranskat)abstract
- The study aimed to monitor parasite and host gene expression during the early stages of Eimeria tenella infection of chicken cells using dual RNA-Seq analysis. For this, we used chicken macrophage-like cell line HD11 cultures infected in vitro with purified E. tenella sporozoites. Cultures were harvested between 2 and 72 h post-infection and mRNA was extracted and sequenced. Dual RNA-Seq analysis showed clear patterns of altered expression for both parasite and host genes during infection. For example, genes in the chicken immune system showed upregulation early (2-4 h), a strong downregulation of genes across the immune system at 24 h and a repetition of early patterns at 72 h, indicating that invasion by a second generation of parasites was occurring. The observed downregulation may be due to immune self-regulation or to immune evasive mechanisms exerted by E. tenella. Results also suggested pathogen recognition receptors involved in E. tenella innate recognition, MRC2, TLR15 and NLRC5 and showed distinct chemokine and cytokine induction patterns. Moreover, the expression of several functional categories of Eimeria genes, such as rhoptry kinase genes and microneme genes, were also examined, showing distinctive differences which were expressed in sporozoites and merozoites.
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| 28. |
- Tarbiat, Behdad, et al.
(författare)
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Evaluation of benzimidazole resistance status in Ascaridia galli
- 2017
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 144, s. 1338-1345
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Tidskriftsartikel (refereegranskat)abstract
- Susceptability of Ascaridia galli to benzimidazole (BZ) was investigated using faecal egg count reduction test (FECRT), in ovo larval development test (LDT) and genetic markers (mutations at codons 167, 198 and 200 of beta-tubulin gene). Six flocks (F1-F6) of a commercial laying hen farm with different number of exposure to BZ were recruited. The FECR was calculated by analyzing individual faeces (F1, F2, F4 and F5) before and 10 days after treatment. The LDT was performed on parasite eggs from pooled samples from F1 to F6 and LC50 and LC99 were calculated. DNA was extracted from 120 worms and sequenced for beta-tubulin gene. In all flocks, the FECRs were above 95% (lower CI above 90%). No significant difference was observed (p > 0.05) among obtained LC50 (F1/F4 and F2/F5 vs F3/F6) in the LDT. However, LC50 and LC99 were higher than suggested values for declaration of resistance in other nematode species. No variation was observed in codon positions involved in BZ resistance. Overall, our results indicated lack of evidence of resistance to BZ in A. galli. More research is needed to confirm these results and to further optimize the existing tools for detection and monitoring of anthelmintic resistance in A. galli.
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| 29. |
- Vasemägi, Anti
(författare)
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Know your enemy - transcriptome of myxozoan Tetracapsuloides bryosalmonae reveals potential drug targets against proliferative kidney disease in salmonids
- 2021
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 148, s. 726-739
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Tidskriftsartikel (refereegranskat)abstract
- The myxozoan Tetracapsuloides bryosalmonae is a widely spread endoparasite that causes proliferative kidney disease (PKD) in salmonid fish. We developed an in silico pipeline to separate transcripts of T. bryosalmonae from the kidney tissue of its natural vertebrate host, brown trout (Salmo trutta). After stringent filtering, we constructed a partial transcriptome assembly T. bryosalmonae, comprising 3427 transcripts. Based on homology-restricted searches of the assembled parasite transcriptome and Atlantic salmon (Salmo salar) proteome, we identified four protein targets (Endoglycoceramidase, Legumain-like protease, Carbonic anhydrase 2, Pancreatic lipase-related protein 2) for the development of anti-parasitic drugs against T. bryosalmonae. Earlier work of these proteins on parasitic protists and helminths suggests that the identified anti-parasitic drug targets represent promising chemotherapeutic candidates also against T. bryosalmonae, and strengthen the view that the known inhibitors can be effective in evolutionarily distant organisms. In addition, we identified differentially expressed T. bryosalmonae genes between moderately and severely infected fish, indicating an increased abundance of T. bryosalmonae sporogonic stages in fish with low parasite load. In conclusion, this study paves the way for future genomic research in T. bryosalmonae and represents an important step towards the development of effective drugs against PKD.
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| 30. |
- Yadav, Manisha, et al.
(författare)
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Nitric oxide radicals in leucocytes and vaginal washes of Trichomonas vaginalis -infected symptomatic and asymptomatic women
- 2006
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Ingår i: Parasitology. - 1469-8161. ; 132:Pt 3, s. 339-343
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Tidskriftsartikel (refereegranskat)abstract
- The clinical spectrum of Trichomonas vaginalis infection varies from asymptomatic to mild, moderate or severe vaginitis. Nitric oxide and other reactive nitrogen radicals produced by immune effector cells are important cytotoxic and cytostatic mediators against several microorganisms including parasites. In the present study, inducible nitric oxide synthase (iNOS) and reactive nitrogen intermediates (RNI) were determined in leucocyte cultures (stimulated with T. vaginalis in vitro) and vaginal washes (VWs) of 22 symptomatic and 20 asymptomatic T. vaginalis-infected and 20 healthy women by immunoblotting and Griess method respectively. The iNOS protein was detected in leucocytes and VWs of all the symptomatic and asymptomatic women, but was not detected in any of the samples from healthy women. Mean iNOS protein band intensity was significantly higher in leucocytes as compared to VWs (P<0.001) of both symptomatic and asymptomatic women and was also higher in leucocytes of asymptomatic as compared to symptomatic women (P<0.05). Mean RNI concentration was also significantly higher in leucocytes (P<0.01) and VWs (P<0.05) of asymptomatic as compared to symptomatic women, and was also higher in samples of infected as compared to healthy women (P<0.001). These results suggest that reactive nitrogen radicals may have a role in limiting T. vaginalis infection in asymptomatic women.
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