Babesia microti (apicomplexa: piroplasmida): electron microscope detection in salivary glands of the tick vector Ixodes ricinus (Ixodoidea: Ixodidae).
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[Babesia choloepi n. sp. (Apicomplexa, Piroplasmida), a parasite of the two-toed sloth, Choloepus didactylus (Linnaeus, 1758) (Xenarthra, Bradypodidae), in French Guiana].
A two-toed sloth (Choloepus didactylus) from French Guiana showed an erythrocytic parasite morphologically related to the Babesiidae family, and described as Babesia choloepi. It is the first Babesia species described in the Edentata order.
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Epizootiologic instability of bovine populations against Babesia bovis (Piroplasmida:Babesiidae) in the region of Poas, Costa Rica.
In Poás (Costa Rica), more than 78% of the cattle population is susceptible to Babesia bovis (Babes, 1888) which indicates that care should be taken during animal movement to avoid tick exposure. Seroprevalence is less than 22%; the frequency distribution of antibody titers is presented. Significant differences (p < 0.05) were observed in the distribution of seropositive animals between ecological zones. Lower mountain rain forest and lower mountain wet forest presented higher risk for seropositivity. Based on the serological characteristics of the herds and the frequency of clinical cases, it is suggested that the cattle situation in the area is epidemiologically unstable for B. bovis.
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Babesia microti (Piroplasmida: Babesiidae) in nymphal Ixodes ricinus (Acari: Ixodidae) in the Czech Republic.
A total of 350 nymphs of the common tick Ixodes ricinus (Linnaeus, 1758) were collected in an endemic focus of Lyme borreliosis (South Moravia, Czech Republic) and examined for the presence of the protozoan Babesia microti (França, 1909) by polymerase chain reaction (PCR), using primers specific for the B. microti gene encoding small subunit rRNA. The assay revealed five positive pools (out of 70 pools examined); the corresponding prevalence rate was about 1.5%. Sequence analysis of the PCR products confirmed their 100% homology with that of B. microti. The study represents the first evidence of B. microti in ixodid ticks in the Czech Republic.
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[Ultrafine structure of Nuttallia musculi Muratov, 1966 (Piroplasmida)].
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Babesia mephitis sp. N. (Protozoa: Piroplasmida), a hematozoan parasite of the striped skunk, Mephitis mephitis.
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[Invasiveness and developmental forms of 3 Babesia species and piroplasmids (Piroplasmida) in the eggs of ixodid ticks].
The paper presents the materials on the identification and study of the developmental forms and morphology of B. colchica and P. bigeminum in eggs of Hyalomma anatolicum. The description of developmental forms of B. colchica in eggs of Boophilus calcaratus is given for the first time. P. bigeminum and P. beliceri were detected in eggs of B. calcaratus and H. anatolicum from the first day of egg production up to the emergence of larvae while B. colchica was found beginning from the 4th-5th day of egg production up to the 5th-7th day before larvae emergence. The invasion rate of eggs of B. colchica is considerably smaller than that of B. bigeminum and P. beliceri. In piroplasmids and babesians there were observed sigar--like, roundish, amoebapear-, rod-shaped and oval forms. Some indivisuals of piroplasmids had projections of cytoplasm of different size. Individuals of B. colchica are smaller than those of P. bigeminum and P. beliceri that enables an easy differentiation of babesians from piroplasmids.
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Molecular characterization of haemoparasites infecting bats (Microchiroptera) in Cornwall, UK.
The presence of haemoparasites from the Order Piroplasmida and the genera Bartonella and Trypanosoma was assessed in the blood of 60 bats, belonging to 7 species, inhabiting sites across Cornwall in southwest England. DNA extracted from macerated heart tissue was incorporated into taxon-specific polymerase chain reactions (PCRs) and amplification products were sequenced as a means of identifying, or assigning an identity, to detected haemoparasites. A Piroplasmida species was detected in 6 Pipistrellus spp., whereas Bartonella infections were detected in 5 bats belonging to 4 different species. Trypanosoma dionisii was detected in 1 Pipistrellus spp. Phylogenetic inference from alignment of a partial 18S rRNA-encoding gene sequence of the pipistrelle-associated Piroplasmida species with homologous sequences available for other members of the Order indicated that this organism was unique but specifically related to members of the genus Babesia, a phylogeny that would be in keeping with the organism being Babesia vesperuginis. Alignment of partial citrate synthase gene sequences from the bat-associated bartonellae revealed 5 distinct genotypes that were probably derived from 2 distinct Bartonella species. The study demonstrates the utility of molecular methods for detecting haemoparasites in dead bats and provides, for the first time, tangible identities for bat-associated Babesia and Bartonella species.
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Prevalence of theileriosis in Red Hartebeest (Alcelaphus buselaphus caama) in Namibia.
A total of 23 blood samples from Red Hartebeest and 28 ticks of the subspecies Rhipicephalus evertsi were collected in Namibia during the summer 2003. For a Piroplasmida species, Theileria sp 95.7% of blood and 50.0% of tick samples (all R. e. mimeticus, none of R. e. evertsi were carrying the pathogen) were PCR positive. Sequencing showed infection from a re-emerging mild species of Theileria phylogenetically different from other African Theileria species such as Theileria parva, T. buffeli, T. annulata, T. taurotragi or T. mutans.
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Ticks (Ixodidae) from passerine birds in the Carpathian region.
Birds have been found to be a reservoir host of borrelia. In order to assess the situation in Slovakia ticks were collected from a total of 3057 mist-netted, ringed and released passerine birds in two locations at 500 m (in 2001) and 1000 m (in 2003) above sea level in the Bukovské Vrchy Hills, part of the Carpathian region in the north-east of Slovakia. A total of 75 birds of 16 species were infested with subadult ticks of Ixodes ricinus species (prevalence of parasitization 5%). Sixty-two larvae from 31 birds of 9 species and 80 nymphs from 52 birds of 15 species were found. The highest intensity of parasitization was observed on blackbirds Turdus merula, song thrushes T. philomelos and dunnocks Prunella modularis. Six Ixodes ricinus adult ticks were found on humans working with birds, and one I. ricinus female tick on their dog. In ticks, the presence of Rickettsia sp., Coxiella burnetii, Borrelia burgdorferi sensu lato and members of the Anaplasmataceae and Piroplasmidae, were investigated by polymerase chain reaction, followed by sequence analysis. Rickettsia sp. was found in 1 nymph from the European robin Erithacus rubecula, in 3 adult ticks (1 male, 2 females) from humans and in the tick from the dog. The closely related Ehrlichia- like species "Schotti variant" was detected in 1 nymph from the song thrush. Borrelia afzelii was identified in 1 male and B. garinii in 1 female tick collected on humans. Ixodes ricinus was found to be the vector of a wide spectrum of tick-borne pathogens in a mountainous area of the Carpathians. Because of the low yield of ticks and pathogens the importance of birds as reservoir hosts is still poorly understood.
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Babesia microti: prevalence in wild rodents and Ixodes ricinus ticks from the Mazury Lakes District of North-Eastern Poland.
Infections of Babesia microti (Apicomplexa, Piroplasmida), a common erythroparasitic protozoon of Holarctic rodents, are not widely acknowledged in Poland. The presence of this parasite in various species of wild rodents has been well documented throughout the northern temperate zone of North America, Europe, and Eurasia. However, human babesiosis attributable to infection with B. microti has been reported only from the north-eastern and upper midwestern United States and Japan. We recently carried out an epizootiological survey investigating the prevalence of B. microti both in the tick Ixodes ricinus and in wild rodents in North-Eastern Poland. Blood samples were collected from a total of 483 animals comprising three species: Apodemus flavicollis, Microtus arvalis, and Microtus oeconomus trapped at Urwitałt near Mikołajki in the Mazury Lakes District. Questing adult I. ricinus ticks were collected in the study sites by blanket dragging of vegetation in heterogeneous, deciduous woodland, and, in addition, rodents were carefully examined for feeding larvae and nymphs. Altogether, B. microti was detected in 9 out of 1513 I. ricinus ticks (0.6%) examined by PCR. This included 163 adults (92 females and 71 males), 50 nymphs, and 1300 larvae 3%, 8%, and 0% of which were PCR-positive, respectively. Of 85 A. flavicollis, 374 M. arvalis and 24 M. oeconomus, 1%, 12.8%, and 42% were parasitaemic, respectively, as determined by microscopic examination of blood smears stained with Giemsa. B. microti DNA, extracted from 53 M. arvalis and 5 M. oeconomus and examined by nested PCR, targeting a piroplasm-specific portion of the 18S ribosomal DNA, revealed 72% and 40%, respectively, to be PCR positive. Sequence analysis showed that all PCR-positive samples had rDNA sequences identical (100% homology) to that of the Munich B. microti strain isolated from Mus musculus. The results of this study indicate that the B. microti commonly encountered among Microtus spp. rodents is probably not a zoonotic strain and, therefore, that it is most unlikely to represent a risk to public health in the Mazury Lakes District of North-Eastern Poland.
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What is Babesia microti?
Babesia microti (Apicomplexa: Piroplasmida) has historically been considered a common parasite of Holarctic rodents. However, human babesiosis due to this species has generally been limited to the northeastern seaboard of the United States and Minnesota and Wisconsin. The absence of reports of B. microti babesiosis from sites where the agent is enzootic, such as in western Europe, remains unexplained. Previous work focusing on the 18S rDNA demonstrates little sequence diversity among samples from allopatric host populations across a wide geographical area. It may be that genetic diversity is underestimated due to sample size or the gene analysed. Accordingly, we collected blood or spleen samples from American or Eurasian animals with parasites that were morphologically consistent with B. microti, amplified the 18S rDNA and beta-tubulin gene, and conducted phylogenetic analysis. Surprisingly, what was considered to be 'B. microti' by microscopy appears to be a diverse species complex. We identify 3 distinct clades within this complex, including parasites from non-rodent hosts. Rodent parasites comprise 2 clades, one representing zoonotic isolates, and the other apparently maintained in microtine rodents, and therefore their morphological detection within animals from a site does not necessarily imply a risk to public health.
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Distribution and phenology of ixodid ticks in southern Zambia.
Distribution data for epidemiologically important ticks (Acari: Ixodidae) in the Southern Province of Zambia, one of the main cattle areas of the country, are presented. Boophilus microplus (Canestrini) was not recorded in southern Zambia, whereas Boophilus decoloratus (Koch) is present throughout the area. New distribution patterns for less economically important ixodid ticks are also discussed. Southern Zambia is a transition zone because it is the most northern area in Africa where mixed Rhipicephalus appendiculatus Neumann and Rhipicephalus zambeziensis Walker, Norval & Corwin populations were reported. Although a second generation of adult R. appendiculatus/R. zamnbeziensis was encountered, simulations indicated that this phenomenon is very rare in southern Zambia, mainly because of the colder temperatures during the early dry season and lower rainfall. These simulations were supported by a development trial under experimental conditions. Tick body size measurements showed that southern Zambian ticks are larger than eastern Zambian R. appendiculatus. It is hypothesized that body size is related to diapausing intensity in this species. The epidemiological consequences are that a different approach to control Theileria parva (Theiler) (Piroplasmida: Theileriidae) and other tick-borne diseases is needed in southern Zambia, compared to the one adopted in eastern Zambia.
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Enzootic Babesia microti in Maine.
Human babesiosis in the northeastern United States caused by Babesia microti (Apicomplexa: Piroplasmida) is mainly reported from coastal New England sites, where deer ticks (Ixodes dammini) are common. However, the piroplasm has been detected in microtine rodents elsewhere in association with I. angustus or other nidicolous ticks, suggesting that the agent is widely distributed but zoonotically significant only where a human-biting "bridge" vector is present. To determine whether this piroplasm may be enzootic in areas where I. dammini is absent, we surveyed small mammals collected from 2 sites in Maine, where I. angustus or I. muris is common but I. dammini is not. Of 43 chipmunks, voles, deer mice, and shrews examined, 3 (6.9, 95% confidence interval 0 to 14.5) were parasitemic, as determined by blood smear or polymerase chain reaction targeting a piroplasm-specific portion of the 18S ribosomal DNA gene. Phylogenetic analysis of the sequenced amplification products demonstrates the presence of 2 forms of B. microti. We conclude that B. microti may be enzootic in the absence of I. dammini but that human risk relates to dense infestations of this human-biting tick.
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Genotypic status of Babesia microti within the piroplasms.
For resolution of the controversial taxonomic status of Babesia microti in relation to other Babesia and Theileria spp. a phylogenetic analysis of an American and a German B. microti strain was performed on the basis of sequences of the small-subunit rRNA gene (rDNA) using distance-matrix, maximum-parsimony, and maximum-likelihood algorithms. Both B. microti isolates clearly separated from a group containing other Babesia spp. as well as from a second group consisting of Theileria spp. Interestingly, the B. microti isolates clustered in a monophyletic group together with other piroplasm species of unclear taxonomic status, B. rodhaini, and a recently described small canine piroplasm species. These results support the existence of a third taxonomic entity of equal rank besides the Babesiidae and Theileriidae.
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An organelle-like small subunit ribosomal RNA gene from Babesia bovis: nucleotide sequence, secondary structure of the transcript and preliminary phylogenetic analysis.
Investigations aimed at identifying the mitochondrial genome of Babesia bovis using the polymerase chain reaction (PCR) have established the existence of an organelle-like small subunit ribosomal RNA (SSU rRNA) gene in the parasite. The sequence, compiled from three main PCR products, was 1448 bp in length (including the primer regions), had a 73% A+T content and showed significant similarity (68% sequence identity) to the "organellar" SSU rRNA gene from Plasmodium falciparum. The proposed secondary structure of the transcript showed several features which were consistent with a eubacterial origin for the organelle-like gene. The presence of putative binding sites for streptomycin and tetracycline also supported an "organellar" location for the gene and suggested that the SSU rRNA transcript is functional in protein synthesis because tetracycline has anti-babesial activity. Phylogenetic analyses based on the conserved regions of the SSU-like rRNA genes from a wide variety of organisms showed only a weak association of the babesial sequence with its mitochondrial homologues and an even weaker association with the corresponding genes of plastid origin. The origin of this organelle-like gene in B. bovis therefore remains unresolved, as is the case for its homologue from P. falciparum.
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Development and evaluation of a PCR assay for the detection of Cytauxzoon felis DNA in feline blood samples.
Cytauxzoonosis is an emerging tick borne infectious disease of domestic cats in the United States, caused by the organism Cytauxzoon felis (C. felis). In naturally infected domestic cats the disease is almost always fatal. Currently there are no commercially available molecular or serologic tests to facilitate the antemortem diagnosis of C. felis infection. Clinical and pathological diagnosis of cytauxzoonosis is based on microscopic identification of parasites in tissues or on blood smears. We have developed and evaluated the sensitivity and specificity of a polymerase chain reaction (PCR) based assay for the diagnosis of C. felis infections in feline blood samples. The assay is sensitive enough to detect one copy of a cloned fragment of the C. felis 18S rRNA gene. This PCR assay can be used for the rapid clinical diagnosis of cytauxzoonosis and for epidemiological studies that will better define the geographic distribution of C. felis infection in cats.
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New data on epizootiology and genetics of piroplasms based on sequences of small ribosomal subunit and cytochrome b genes.
As a continuation of our studies on molecular epizootiology of piroplasmosis in Spain and other countries, we present in this contribution the finding of new hosts for some piroplasms, as well as information on their 18S rRNA gene sequences. Genetic data were complemented with sequences of apocytochrome b gene (whenever possible). The following conclusions were drawn from these molecular studies: Theileria annulata is capable of infecting dogs, since it was diagnosed in a symptomatic animal. According to cytochrome b sequences, isolates from cows and dog present slight differences. The same isolates showed, however, identical sequence in the 18S rRNA gene. This exemplifies well the usefulness of the mitochondrial gene for examining infra-specific variation. Babesia bovis is an occasional parasite of equines, since it was detected in two symptomatic horses. We found evidence of genetic polymorphism occurring in the 18S rRNA gene of Spanish T. equi-like and B. ovis isolates. B. bennetti from Spanish seagull is loosely related to B. ovis, and might represent a genetically distinct branch of babesids. A partial sequence of a cytochrome b pseudogene was obtained for the first time in Babesia canis rossi from South Africa. The pseudogene is distantly related to B. bigemina cytochrome b gene. These new findings confirm the ability of some piroplasms to infect multiple hosts, as well as the existence of a relatively wide genetic polymorphisms with respect to the cytochrome b gene. On the other hand, the existence of mtDNA-like pseudogenes of possible nuclear location in piroplasms is interesting due to their possible impact on molecular phylogeny studies.
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