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PubMed1994

Phylogeny and evolution of the piroplasms.

Small subunit ribosomal RNA (srRNA) genes of three Theileria species, one Cytauxzoon and four Babesia species were amplified using the polymerase chain reaction (PCR), cloned and sequenced. Our sequences were aligned with srRNA sequences previously published for eight species of Apicomplexa, one ciliate and one dinoflagellate, the last two being included as free-living outgroup species. Phylogenetic relationships between the organisms were inferred by four independent methods of phylogenetic tree construction using the ciliate Oxytricha nova to root the trees. Our trees fail to show a consensus branching order. They do, however, clearly indicate that the theilerias form a monophyletic taxon derived from a paraphyletic group which includes the species B. equi, C. felis and B. rodhaini. The distance trees indicate that the babesias sensu stricto (B. canis, B. caballi, B. bigemina and B. bovis) form another monophyletic taxon which diverged before the theilerias separated from the above-mentioned paraphyletic group. The parsimony and maximum likelihood trees suggest that the babesias and theilerias are sister taxa, both of which were derived from the paraphyletic group.

Algorithms↗

PubMed1994

Codon usage and bias among individual genes of the coccidia and piroplasms.

Codon usage has been analysed in individual gene sequences, derived from a variety of parasitic protozoa in the class Sporozoa of the phylum Apicomplexa using metric multidimensional scaling. The two groups of codon usage patterns detected reflect the two main subgroups of organisms studied (the coccidia and the piroplasms), and it is the pattern of usage of synonymous codons that has the largest influence on overall codon usage in the individual genes, rather than being the pattern of amino acid composition of the gene product. The magnitude of the codon usage bias in the sequences was determined using three commonly used indices-NC, GC3S and B. In general, although relatively low levels of codon usage bias were detected in these gene sequences, codon usage bias does explain at least some of the codon usage patterns observed. Codon usage bias was observed to be dependent on the overall base composition of the genes analysed, which in turn was reflected in the types of codons that were either over- or under-represented in the nucleotide sequences. In keeping with observations on prokaryotic organisms, it is speculated that the codon usage patterns detected in these parasitic protozoa are the result of directional mutation pressure on the base composition of the genomic DNA.

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PubMedDate not supplied

Phylogeny of adeleid blood parasites with a partial systematic revision of the haemogregarine complex.

The phylogenetic relationships of taxa representative of blood parasitic adeleids were investigated in a cladistic analysis. Two phylogenetic analyses were performed. Monophyly of species of Haemogregarina (sensu lato) of some marine fishes with species of Haemogregarina (sensu stricto) was not supported in either analysis. A new genus, Desseria n.g., was created to accommodate these species. The historical burden placed on the genus Haemogregarina Danilewsky, 1885 as a repository for poorly known and inadequately described species is partially relieved through taxonomic revisions involving the genera Haemogregarina, and Desseria n.g.

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PubMed1992

A redescription of schizogony of Cytauxzoon felis in the domestic cat.

Cytauxzoon felis is a protozoan parasite that is transmitted by Dermacentor variabilis ticks and causes a uniformly fatal disease in domestic cats. In order to study schizogony and merozoite formation, D. variabilis nymphs were allowed to feed on domestic cats experimentally infected with C. felis, after which the molted adult ticks were fed on susceptible cats. Lung and liver tissues were collected from the cats during clinical cytauxzoonosis and were fixed for light and transmission electron microscopy. Some stages of parasite development were evident with light microscopy, but specific events associated with merogony could be documented only with electron microscopy. Schizogony was observed in endothelial macrophages of all tissues examined. The parasite appeared first as a multinucleated syncytium in which nuclear proliferation was evident. As the parasite syncytium developed, it became an increasingly elaborate labyrinth with extensive branches that were interconnected by thin processes of parasite cytoplasm. Organelles, including mitochondria and rhoptries, became apparent. Merozoite formation seemed to occur by rapid sequential fission along the margins of the multinucleated sporont in the cytoplasm of the host cell. As the sporont became smaller, merozoites were produced in a rosette-like configuration from the remaining parasite mass. Merozoites entered erythrocytes directly by endocytosis, without apparent injury to these cells. The sequence of events associated with merozoite formation in Cytauxzoon felis described herein differs from the previous description for this species and appears to be analogous to that described for the genus Theileria.

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PubMed1999

Detection of enzootic babesiosis in baboons (Papio cynocephalus) and phylogenetic evidence supporting synonymy of the genera Entopolypoides and Babesia.

Blood smear evaluation of two baboons (Papio cynocephalus) experiencing acute hemolytic crises following experimental stem cell transplantation revealed numerous intraerythrocytic organisms typical of the genus Babesia. Both animals had received whole-blood transfusions from two baboon donors, one of which was subsequently found to display rare trophozoites of Entopolypoides macaci. An investigation was then undertaken to determine the prevalence of hematozoa in baboons held in our primate colony and to determine the relationship, if any, between the involved species. Analysis of thick and thin blood films from 65 healthy baboons (23 originating from our breeding facility, 26 originating from an out-of-state breeding facility, and 16 imported from Africa) for hematozoa revealed rare E. macaci parasites in 31%, with respective prevalences of 39, 35, and 12%. Phylogenetic analysis of nuclear small-subunit rRNA gene sequences amplified from peripheral blood of a baboon chronically infected with E. macaci demonstrated this parasite to be most closely related to Babesia microti (97.9% sequence similarity); sera from infected animals did not react in indirect fluorescent-antibody tests with Babesia microti antigen, however, suggesting that they represent different species. These results support an emerging view that the genus Entopolypoides Mayer 1933 is synonymous with that of the genus Babesia Starcovici 1893 and that the morphological variation noted among intracellular forms is a function of alteration in host immune status. The presence of an underrecognized, but highly enzootic, Babesia sp. in baboons may result in substantial, unanticipated impact on research programs. The similarity of this parasite to the known human pathogen B. microti may also pose risks to humans undergoing xenotransplantation, mandating effective screening of donor animals.

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PubMed2006

Polyphasic taxonomy.

Several organisms from a number of prokaryotic and eukaryotic groups have presented problems for systematists for a long time. Both phenotypic and genotypic methods for sorting out these relationships have been employed. There are limitations with each method when taken alone. Since the purpose of systematics is to determine the correct genealogical relationships among biological organisms, it is necessary to use all available means to arrive at consensus associations, and polyphasic taxonomy, which takes into consideration both methods, is a rational approach. In this short article, we provide a number of examples where polyphasic taxonomy is serving as the means of arriving at the desired consensus.

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PubMed2005

Polymerase chain reaction detection of Cytauxzoon felis from field-collected ticks and sequence analysis of the small subunit and internal transcribed spacer 1 region of the ribosomal RNA gene.

Cytauxzoon felis produces a disease in domestic cats in the Midwest (U.S.A.), which often leads to a fatal outcome. Although the clinical disease process is well described, there are still many unanswered questions about this organism. For example, it is unknown whether species of ticks other than Dermacentor variabilis can serve as vectors for transmission. With recent reports of surviving cats from limited geographic areas, another relevant question is the potential for genetically less virulent organism strains. This study evaluated 352 individual or pooled tick samples (1,362 total ticks) for the presence of C. felis small subunit ribosomal RNA and internal transcribed spacer 1 (ITS-1) region genes using a polymerase chain reaction (PCR). These ticks were collected from dogs and cats in several Missouri counties, including 10 from cats diagnosed with cytauxzoonosis. Only 3 positive C. felis samples were identified in Amblyomma americanum nymphs, and there was very limited genetic variation noted in both genes. The small number of positive samples did not allow the study to determine which PCR analysis was more sensitive. This is the first known report of ITS-1 gene identification and sequencing for C. felis. It is also the first published investigation of genetic variation in C. felis.

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PubMed2005

A new species of Cytauxzoon from Pallas' cats caught in Mongolia and comments on the systematics and taxonomy of piroplasmids.

DNA was extracted and the 18S ribosomal RNA gene was amplified and sequenced from the blood of 2 Pallas' cats (Otocolobus manul) infected with small intraerythrocytic piroplasms. Sequences of the parasite were found to be identical with that of a previously reported Cytauxzoon-like piroplasm from a Pallas' cat. Phylogenetic analyses of the parasite DNA sequences obtained from the 3 Pallas' cats to other piroplasms revealed a sister group relationship to C. felis. The mean corrected percent sequence divergence between the Pallas' cat parasite and C. felis was 1.490%, which is greater than that for most other piroplasms in which species status has been accepted. On the basis of the sequence variation, we propose to name the Pallas' cat parasite C. manul. Phylogenetic analyses of C. manul also revealed a close relationship with the Spanish Cytauxzoon-like isolate because they exhibited only 0.389% sequence divergence, yet these sequences exhibit a mean of 1.690% sequence divergence from the New World isolate of C. felis. Our phylogenetic analyses also revealed several taxonomic problems that have impeded the development of a classification that accurately reflects evolutionary history of piroplasms. As currently arranged, Babesia and Theileria are paraphyletic taxa and are in need of reorganization.

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PubMedDate not supplied

Cats surviving natural infection with Cytauxzoon felis: 18 cases (1997-1998).

Eighteen cats surviving natural infection with Cytauxzoon felis were identified. All cats came from a limited geographic area in northwestern Arkansas and northeastern Oklahoma. Clinical signs in most cats were similar to those described for cytauxzoonosis; however, 4 cats were asymptomatic. All cases were initially diagnosed by microscopic identification of signet ring-shaped piroplasms in erythrocytes of peripheral blood smears. Four of 4 cats tested had detectable serum antibodies to C felis. Four different cats were positive by polymerase chain reaction (PCR). Partial sequencing of the PCR product from 1 cat revealed >99% homology with the reported sequence of C felis. Repeated examination of blood smears from 12 cats revealed that the erythroparasitemia was generally persistent for the duration of follow-up (3-154 days). Survival did not seem dependent on treatment, as only 1 cat was treated with a drug with potential antiprotozoal activity (imidocarb dipropionate), and 4 cats received no treatment. The findings of this study may indicate the existence of a less virulent strain of C felis.

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PubMed2006

Cytauxzoon felis infection in cats in the mid-Atlantic states: 34 cases (1998-2004).

OBJECTIVE: To describe the demographic and clinical characteristics of feline cytauxzoonosis in the mid-Atlantic states and compare the Cytauxzoon felis 18S rRNA gene sequences from affected cats with sequences reported from affected cats in other regions. DESIGN: Retrospective case series. ANIMALS: 34 cats with C. felis infection. PROCEDURE: Medical records of cats in which C. felis infection was diagnosed from May 1998 through June 2004 were reviewed; data collected included signalment, month of diagnosis, geographic location, clinicopathologic abnormalities, medical treatments, outcome, and necropsy findings when applicable. Cytauxzoon felis DNA was amplified, cloned, and sequenced from 4 of these cats and compared with previously reported C. felis DNA sequences. RESULTS: Of 34 C. felis-infected cats, 28 resided in North Carolina, 3 resided in South Carolina, and 3 resided in Virginia; in 32 cats, a diagnosis of C. felis infection was made in April through September. Pancytopenia and icterus were the most common clinicopathologic abnormalities. Thirty-two cats either died or were euthanatized, and 2 cats survived. At 5 veterinary hospitals, multiple cases were identified, and 4 multicat households had > 1 cat infected with C. felis. The 18S rRNA gene sequences characterized in organisms obtained from 4 cats were nearly identical to C. felis DNA sequences reported from other US regions. CONCLUSIONS AND CLINICAL RELEVANCE: Data indicate that veterinarians in the mid-Atlantic region of the United States should consider C. felis infection in cats that become ill with fever, icterus, and pancytopenia or bicytopenia, especially in the spring and summer months.

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PubMedDate not supplied

Feline cytauxzoonosis: a case report and literature review.

A 5.5-year-old Siamese presented for evaluation of a three-day history of anorexia and lethargy. Upon physical examination, the cat was depressed, dehydrated, pyrexic, had injected conjunctiva and sclera, pale mucous membranes, and a grade II/VI systolic heart murmur. Thoracic radiographs revealed moderate to severe, diffuse, bronchointerstitial pulmonary changes with enlarged and tortuous pulmonary vessels. With continued hospitalization, the cat became dyspneic and died. The postmortem cytopathological examination of the liver, spleen, and lung impressions revealed reticuloendothelial cell infection with Cytauxzoon felis.

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PubMed1999

Hematologic effects of cytauxzoonosis in Florida panthers and Texas cougars in Florida.

Cytauxzoon felis is a long-recognized hemoparasite of free-ranging Florida panthers (Puma concolor coryi), but its prevalence and effect on the population has not been assessed. Red blood cell indices and white blood cell counts were compared between infected and noninfected Florida panthers and Texas cougars (Puma concolor stanleyana) from 1983-1997 in Florida (USA). The prevalence of cytauxzoonosis for both populations was 39% (11/28) for Texas cougars, 35% for Florida panthers (22/63) and 36% overall. Thirteen hematologic parameters were compared between C. felis positive and negative panthers and cougars. Florida panthers had significantly lower mean cell hemoglobin count (MCHC) and higher white blood cell (WBC), neutrophil, monocyte and eosinophil counts (P < or = 0.05) than Texas cougars. Infected Florida panthers had significantly lower mean cell hemoglobin (MCH) and monocyte counts and higher neutrophil and eosinophil counts than infected Texas cougars. Although statistically significant differences were measured for hematologic parameters in C. felis positive panthers and cougars, biologically significant differences were not likely because values were generally within expected reference ranges for healthy animals. Cytauxzoonosis does not appear to have a negative effect on the hematologic parameters of chronically infected panthers and cougars. Potential transient changes during initial infection were not evaluated.

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PubMed2002

Fatal cytauxzoonosis in a free-ranging bobcat (Lynx rufus).

In September 2000, a free-ranging bobcat (Lynx rufus) cub was presented to the Kansas State University Veterinary Teaching Hospital (Manhattan, Kansas, USA) in a moribund state with signs of severe anemia and respiratory difficulty. The cub was euthanized. Gross necropsy findings included multifocal atelectasis, splenomegaly, and pericardial effusion. Microscopic examination revealed subacute pulmonary thrombosis, mild vasculitis in the brain, and large schizont-filled macrophages within blood vessels of all tissues examined. The organisms were typical of the developmental stages of Cytauxzoon felis. Cytauxzoonosis is considered to be a persistent, subclinical infection in the bobcat; however, this cub had lesions consistent with those seen in fatal infections in domestic cats. This case of fatal C. felis infection indicates that some free-ranging bobcats may die of cytauxzoonosis.

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PubMed2003

An intraerythrocytic small piroplasm in wild-caught Pallas's cats (Otocolobus manul) from Mongolia.

During the quarantine examination of four Pallas's cats (Otocolobus manul) imported from Mongolia in October and December 2000, intraerythrocytic piroplasms were detected on Wright-Giemsa stained blood films that were morphologically indistinguishable from other small piroplasms of felids. Further characterization of this unknown organism via polymerase chain reaction amplification, sequencing of a portion of the 18S nuclear small subunit rRNA gene, and comparisons with orthologous sequences from other piroplasms, revealed similarity to Cytauxzoon felis. This is the first report of naturally occurring erythroparasitemia in Pallas's cats and the first documented case of naturally occurring piroplasm infections in a free-ranging felid from Mongolia.

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PubMed2006

Molecular detection and characterization of Cytauxzoon felis and a Babesia species in cougars from Florida.

Piroplasms, morphologically indistinguishable from Cytauxzoon felis, previously were detected in 36% of cougars in Florida. We utilized a nested 18S rRNA assay, which amplifies DNA from all piroplasms, to screen blood samples collected from 41 cougars from Florida (39 native Florida panthers [Puma concolor coryi] and two translocated Texas cougars [P. c. stanleyana]) from 1989-2005. Thirty-nine of the 41 cougars (95%) were positive for piroplasms; however, sequence analysis and restriction enzyme digestion revealed that only five were positive for C. felis. Samples from 32 cougars were positive for a Babesia sp. Two cougars were co-infected with both C. felis and the Babesia sp. Phylogenetic analysis of 18S rRNA gene sequence indicated that the Florida panther Babesia sp. was most closely related to a Babesia sp. reported from Ixodes ovatus from Japan, Babesia divergens, and Babesia odocoilei. This study indicates that Florida panthers harbor two distinct piroplasms, C. felis and a Babesia sp., and that some individuals are infected with both organisms. The infectivity and pathogenicity of this Babesia sp. for domestic cats is unknown. This represents the first report of a feline Babesia sp. in North America.

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PubMed1999

Administration of diminazene aceturate or imidocarb dipropionate for treatment of cytauxzoonosis in cats.

Bobcats (Lynx rufus) are the reservoir hosts for Cytauxzoon felis, the causative agent of cytauxzoonosis. Cytauxzoonosis is a highly fatal tickborne blood protozoal disease of domestic and exotic cats. Treatment of clinically affected cats has generally been unrewarding. In our report, 6 of 7 cats had signs of illness and laboratory findings indicative of cytauxzoonosis and were successfully treated with 2 i.m. injections of diminazene aceturate or imidocarb dipropionate (2 mg/kg [0.9 mg/lb] of body weight, each). One cat died after the first injection of diminazene. Additional treatment with isotonic fluids i.v. and heparin s.c. were used as supportive care for dehydration and disseminated intravascular coagulation that were detected by laboratory testing between diminazene or imidocarb treatments. Atropine was effective in recovery and preventing adverse reactions associated with imidocarb treatment of 1 cat.

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PubMed1995

Survival of a domestic cat with naturally acquired cytauxzoonosis.

A cat with acute onset of febrile systemic illness was determined to be infected with Cytauxzoon felis. The diagnosis was made on the basis of cytologic morphology of erythroparasites seen in blood smears and results of microfluorometric immunoassay for serum antibody directed against C felis-parasitized RBC. Treatment consisted of parenteral administration of fluids and antibiotics. The cat recovered within 2 weeks. Circulating erythroparasites were not detected on blood smears from samples collected during follow-up examinations. However, high serum antibody titer persisted for at least 15 weeks after infection. The cat continued to be free of clinical disease 2.5 years after the initial diagnosis. Whether C felis infection persists in this cat has yet to be determined. This case indicates that some domestic cats can recover from naturally acquired cytauxzoonosis.

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PubMed1994

Cytauxzoonosis in cats: eight cases (1985-1992).

Cytauxzoonosis is a rapidly and highly fatal disease in cats that is caused by the protozoan Cytauxzoon felis, which may be transmitted by Ixodid ticks (Dermacentor variabilis) from parasitemic bobcats (Lynx rufus). During an 8-year period, cytauxzoonosis was diagnosed in 8 cats, 7 cats within 14 months. Risk factors for these cats were warm weather, access to a wooded environment, and exposure to ticks. The most consistent clinical signs were acute lethargy, anorexia, decreased response to external stimuli (depression), icterus, dehydration, and capillary refill time > 2 seconds. Pertinent clinicopathologic findings were normocytic normochromic anemia, leukopenia, and thrombocytopenia; high serum concentrations of total bilirubin and glucose, low serum concentrations of albumin and potassium, high serum alanine transaminase activity; and, bilirubinuria. Confirmation of cytauxzoonosis was made by cytologic or histologic identification of the C felis organism. Splenic, lymph node, and bone marrow aspirates can provide an antemortem diagnosis when the number of parasitized erythrocytes is low on blood smears. Supportive treatment of 6 cats was temporarily palliative in some, but all 8 cats either died (3) or were euthanatized (5) when they became moribund. Survival time from observed onset of illness to death was < 5 days. Necropsy of 4 cats revealed predominately pulmonary involvement with venous congestion. Histologic examination revealed venous occlusion by parasitized mononuclear phagocytes in all tissue specimens, but only minimal inflammatory infiltrates.

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