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At least 991 records · Page 55Linked to original sources
PubMed1991

Epidemiological observations on theileriosis following field immunisation using infection and treatment.

Thirty-seven high grade cattle were immunised against Corridor disease (Theileria parva lawrencei infection) on a farm with a history of heavy and often lethal theilerial challenge. Nineteen cattle were immunised by treating with two doses of long-acting oxytetracyclines given at 20 mg/kg on days 0 and 4 after sporozoite stabilate inoculation, while the other 18 were treated with naphthoquinone buparvaquone, given as a single dose of 2.5 mg/kg simultaneously with stabilate inoculation. All the cattle underwent subclinical theilerial reactions with all but two developing high antibody titres on the IFAT test against T. parva schizont antigen by day 35 after the immunisation. Both buparvaquone and long-acting oxytetracycline appeared equally effective in the immunisation. To date, 26 months later, only two cases of theileriosis parasitologically characteristic of T. p. parva have been reported in the immunised cattle. Following the two cases, investigations showed that when uninfected Rhipicephalus appendiculatus nymphal ticks were deliberately fed on healthy resident cattle on the farm, the resultant adult ticks transmitted acute and lethal theilerial infections to five out of five susceptible cattle. The resultant infections were parasitologically characteristic of T. p. parva infections. Furthermore, the monoclonal antibody profiles of schizont infected cell lines from these infections appeared to be characteristic of T. p. parva. It was thus concluded that resident cattle on the farm could be a potential source of T.p. parva infection which had broken through the immunity of T.p. lawrencei immunised cattle and could constitute a reservoir of theilerial infection for ticks and hence to susceptible stock on the farm.

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PubMed1976

Application of the indirect fluorescent antibody test for diagnosis of Theileria hirci infection of sheep: using cell culture schizont antigen.

The indirect fluorescent antibody test was applied for detection of circulating antibodies in sheep as a result of Theileria hirci infections. A schizont antigen was prepared from an in vitro culture suspension of lymphoid cells infected with T. hirci macroschizonts. The peak antibody titre of 1/8, 192 was reached 24 days after the initial antibody rise in the sheep experimentally infected by means of Hyalomma anatolicum anatolicum ticks.

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PubMed2005

Formation of a parasitophorous vacuole in a nonadequate experimental host: electron microscopical and X-ray microanalytical study.

An unusual mechanism of formation of a parasitophorous vacuole as a result of interaction between an invasive stage of a parasite (merozoites of a protozoon, Mattesia dispora) and defense response of an insect host, Galleria mellonella is reported. The entire ontogenesis of parasitophorous vacuole can be divided into five morphologically clearly discernible stages. They differed, e.g., in the contents and distribution of elements at subcellular level, as determined by direct in situ elemental analysis of single organelles (electron microprobe X-ray analysis). The method was used in conjunction with electron microscopy to investigate the relationship between the host and the parasite.

Animals↗
PubMed2002

Scratching the sporocyst surface: characterisation of European Aggregata species by atomic force microscopy.

The application of atomic force microscopy to the understanding of surface structure and atomic-scale measurements on the sporocyst of European Aggregata species, intracellular coccidia of the cephalopods Octopus vulgaris and Sepia officinalis, is presented here. Using the roughness mean surface (RMS) as an index, we reveal texture to be a key parameter for characterisation of the sporocyst surface properties, which resolve the historical synonymy within the European Aggregatidae. Roughness measurements from RMS algorithms may also be an important diagnostic taxonomic character for the differentiation of Aggregata species in the future.

Algorithms↗
PubMed2002

Prime-boost: the way forward for recombinant vaccines against apicomplexan parasites. A Theileria perspective.

A good CD8+ response is required for immunity to many intracellular pathogens. Traditional antigen delivery using isolated sub-units or killed pathogens and adjuvant stimulates strong antibody responses but weak T-cell reactivity. Attenuated vaccines are usually more effective. The prime-boost delivery system based on immunisation with a naked DNA antigen-gene construct followed by boosting with an attenuated vaccinia virus expressing the same antigen is proving to be a powerful way to stimulate antigen-specific CD8 responses. Success using single epitopes is possible in malaria and we believe this approach holds much promise for other apicomplexan parasites such as Theileria spp.

Animals↗
PubMed2003

Schizogonic stages of Haemoproteus from Wenyon's Baghdad sparrows are also found in Passer domesticus biblicus in Israel.

Schizont bodies reminiscent of those described by Wenyon from Baghdad sparrows were found in the liver and lungs of an Israeli house sparrow ( Passer domesticus biblicusHartert 1904) infected with Haemoproteus passeris Kruse, 1890. All observed schizonts were composed of packed assemblages of walled compartments, each holding a differentiating schizogonic body. The schizogonic bodies in the various compartments demonstrated sequential stages in the differentiation process from a compact multinucleate cytoplasmic mass to massive formation of multiple merozoites. Young non-differentiated schizont assemblages reached 0.2 x 0.25 mm in size and the fully differentiated ones, containing merozoites, were double or triple that. Among species of Haemopterus, division to compartmented and single-plasmodium schizonts could not be associated with any recognized generic or infrageneric division. Moreover, in some species of Haemoproteus, both types of schizogony co-existed.

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PubMed2004

Blood monocyte alteration caused by a hematozoan infection in the lizard Ameiva ameiva (Reptilia: Teiidae).

Although hematozoa have been described from many different host species, little is known about the infection and its relationship to the physiology of the host. We studied a hematozoan, regarded as a species of Lainsonia Landau, 1973 (Lankestereliidae), which infects the monocytes of the lizard Ameiva ameiva. The infected animals show a huge monocytosis and morphological changes in the monocytes. Ultrastructurally, the parasite has an apical complex, dense bodies, electron lucent structures, plasma membrane projections and folding which may be involved with nutrition. The parasite occupies a parasitophorous vacuole (PV) exhibiting high electron density at its membrane. Mitochondria and the Golgi complex of the monocytes were concentrated around the PV, and the cytoplasm was totally occupied by a vimentin type of intermediate filament radiating from (or to) the cytosolic surface of the PV. Vimentin was identified by diameter measurement, immunofluorescence and immunoelectron microscopy. These observations indicate that this infection alters the physiological state of the host and suggest that this parasite has the ability to modify monocyte vimentin assembly.

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PubMed2004

Double gametocyte infections in apicomplexan parasites of birds and reptiles.

The simultaneous occurrence of male and female gametocytes inside a single host blood cell has been suggested to enhance apicomplexan transmission ["double gametocyte infection (DGI) hypothesis"]. We did a bibliographic search and a direct screen of blood smears from wild birds and reptiles to answer, for the first time, how common are these infections in the wild. Taking these two approaches together, we report here cases of DGIs in Plasmodium, Haemoproteus, Leucocytozoon and Hepatozoon, and cases of male-female DGIs in Haemoproteus of birds and reptiles and in Leucocytozoon of birds. Thus, we suggest that DGIs and male female DGIs are more widespread than previously thought, opening a new research avenue on apicomplexan transmission.

Animals↗
PubMed2004

Prevalence and intensity of haemogregarinid blood parasites in a population of the Iberian rock lizard, Lacerta monticola.

The study of the effect of parasites on their host populations is essential for understanding their role in host population dynamics and ecology. We describe the general field population biology of haemogregarines in the Iberian rock lizard, Lacerta monticola, examining the factors that determine the prevalence and intensity of infection. Prevalence and infection intensity were higher in adults than in juvenile lizards. The prevalence rate was higher in larger lizards, probably because they were also older and had been more often in contact with parasites during their lifetime. During the mating season, the intensity of parasite infection was greater in males than in females, probably due to immunosuppressive effects of testosterone. The parasite load had a negative effect on the body condition during the reproductive season. The results suggest that the interactions between parasites and hosts are not stable in this lizard population.

Animals↗
PubMed2007

Susceptibility to infection by a haemogregarine parasite and the impact of infection in the Australian sleepy lizard Tiliqua rugosa.

The Hamilton and Zuk hypothesis on haemoparasite-mediated sexual selection and certain studies of fitness are based on the assumption that blood parasite infections are detrimental to their hosts. However, there are few reports that have demonstrated harmful effects of endemic blood parasites on fitness in wild populations, and it has even been suggested that they may be non-pathogenic. In this paper, we show that individuals of the Australian sleepy lizard (Tiliqua rugosa) have smaller home ranges when they are infected with the haemogregarine blood parasite Hemolivia mariae than when no infection can be detected. An apparently contradictory result was that lizards with larger home ranges were more susceptible to infection under experimental exposure to Hemolivia. We propose that lizards sacrifice defence against pathogens by increased activity, perhaps associated with maintaining home ranges and mating opportunities. As a consequence, they gain higher parasite loads, which in turn inhibit their activity. In this case, the parasite-host interaction may act as a buffer of lizard activity.

Animals↗
PubMed2001

Role of chicken serum in inhibiting Leucocytozoon caulleryi development in Culicoides arakawae infected by membrane-feeding of infective blood meals.

Leucocytozoon caulleryi, the most important pathogen of leucocytozoonsis in several Asian countries, is transmitted by Culicoides arakawae. Although the vector blood meal factors that influence the infectivity of L. caulleryi remain poorly understood, the factors in infected chicken serum remain vital. C. arakawae blood-fed through a membrane were used in this experiment to examine the influence of serum factors on L. caulleryi development. Experimental results indicate that C. arakawae were successfully blood-fed through a chicken-egg-shell membrane and the serum factors in infected chicks significantly affected L. caulleryi sporogony. The inhibition effect of serum factors calculated from sporozoite averages was 53.6% +/- 2.2%. The serum factors, including transmission-blocking antibody, require further detailed study.

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