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E Schein

Publications and source records attributed to E Schein.

72 records · Page 4Linked to original sources
PubMed1979

On the life cycle of Theileria velifera (Uilenberg, 1964) in the gut and the haemolymph of the tick vector Amblyomma variegatum (Fabriciu, 1794).

The development of Theileria velifera in the gut and the haemolymph of the tick vector Amblyomma variegatum is described. Between days three and eight after repletion various sexual stages are present in the gut of the nymphs. Zygotes were detected in the gut on day 14, while undifferentiated kinetes first appeared on day 15. In the haemolymph, differentiated kinetes were observed from day 16 after repletion onwards. Zygotes and kinetes were also found after the moult, in the adult tick, for a prolonged period of time. The results of this study show that the developmental stages of T. velifera in the gut and haemolymph are characteristic of the genus Theileria.

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PubMed1979

Electron microscopical studies on the development of Babesia canis (Sporozoa) in the salivary glands of the vector tick Dermacentor reticulatus.

The formation of sporozoites of Babesia canis was studied by light- and electron microscopy in the salivary gland cells of adult female ticks from the 2nd day after attachment until 1 day after detachment. It was found that this process was initiated by the binary division of kinetes that had already entered or entered during the period examined. During division the kinetes (15 X 2.5 microns) lost their typical organelles, reduced their three-layered pellicle to a single membrane and became spherical. After nuclear division and a further time-lag cell division occurred, giving rise to two cells in which this process was repeated. After numerous binary divisions the parasites acquired more and more closely the shape of the later infectious, pyriform sporozoite. These sporozoites measured about 2.5 X 1.5 microns and also had a three-layered pellicle, with rhoptries and a few micronemes, but never contained "spherical bodies". The formation process needed about 2--3 days so that the transmission to the dog could be carried out while the tick engorges and this is probably the stimulation for the development. Finally the cytological features of this sporozoite formation were compared to those in the Theileria species studied by our group.

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PubMed1978

[Light microscopic studies on the development of Theileria annulata (Dschunkowsky and Luhs, 1904) in Hyalomma anatolicum excavatum (Koch, 1844). II. The development in haemolymph and salivary glands (author's transl)].

Fully differentiated kinetes, average length 17.6 micrometer, appeared in the haemolymph of engorged nymphs usually 17 to 20 days after repletion. Kinetes were observed at first in the salivary glands on day 18 after repletion. The kinetes then transformed into fission bodies of about 10 micrometer in diameter, mainly in type III alveoli and less frequently in type II alveoli. The fission bodies grew up to a size of about 20 micrometer after several divisions of their nucleus. At this time the ticks moulted and no further development occurred until activation. Shortly before infestation the salivary glands began to proliferate, and rapid growth of the fission bodies was observed, especially in young ticks where development of 'infective particles' ('sporozoites') was concluded within two days. Development in feeding adult ticks apparently occurred in four major steps: (1) Division of primary fission bodies (sporonts) into numerous secondary fission bodies ('primary sporoblasts'), (2) division of secondary fission bodies into tertiary fission bodies ('secondary sporoblasts'), (3) production of particles ('sporozoites') by tertiary fission bodies and release of particles into the saliva, and (4) degeneration of fission bodies and their host cell but further release of particles. The host cell was stimulated to giant growth, thus its diameter increased, on average, from 15 to 110 micrometer. Heavy infections resulting from parasitaemias of greater than 40% caused disease and mortality in the tick population. Development was much retarded by aging. In ticks starved for six months 'sporozoites' did not develop before day five to seven of infestation. 'Sporozoites' did not develop before day five to seven of infestation. 'Sporozoites' may not develop at all in six to nine month old female ticks during the infestation period. The significance of the described developmental stages of T. annulata was discussed and a sexual generation postualted. The hypothetic development of T. annulata in its tick vector was illustrated.

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PubMed1978

Electron microscopic studies on the development of kinetes of Theileria parva Theiler, 1904 in the gut of the vector ticks Rhipicephalus appendiculatus Neumann, 1901.

The development of motile stages, called kinetes, from a stationary stage (regarded as zygote) has been followed in Theileria parva by means of electron miscroscopy. This process started after moult of the tick nymphs which had sucked on highly infected calves, i.e. about 20 days after repletion (a.r.) of the ticks. The transformation took place by formation of a growing protrusion (= anlage) into an inner, enlarging vacuole. During this process the limiting membrane of the enlarging vacuole serves as the outer membrane of the developing motile stage, whereas the two inner ones as well as the subpellicular microtubules are newly formed. This transformation proceeds rapidly, so that on the 25th day a.r. most of the kinetes have already left the gut cells and started penetration into the salivary gland cells. On the way to the salivary glands nuclear divisions occurred within the kinetes. The steps of the transformation described were compared to those in T. annulata and to ookinete formation in haemosporidia.

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PubMed1977

Electron microscopic studies of the development of kinetes in Theileria annulata Dschunkowsky & Luhs, 1904 (Sporozoa, Piroplasmea).

Gamogony of Theileria annulata Dschunkowsky & Luhs occurs within the intestine of nymphs of the tick Hyalomma anatolicum excavatum Koch. After the 5th day post repletionem (p.r.) of the ticks spherical and ovoid parasites were found within the intestinal cells. These stages were thought to represent fertilized macrogametes. These underwent a transformation process leading ultimately to the differentiation of a motile stage, the kinete, which leaves the intestinal cells on the 14th-17th day p.r. and penetrates the alveoles of the salivary glands. The transformation of the stationary into a motile stage takes place by formation of a growing protrusion (= anlage) into an inner, enlarging vacuole. During this process the limiting membrane of the vacuole serves as the outer membrane of the developing motile stage, whereas the 2 inner membranes of its pellicle are newly formed. The steps of this differentiation in T. annulata are compared to the process of ookinete formation in haemosporina.

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PubMed1976

[Electron microscope studies on developmental stages of Theileria parva (Theiler, 1904) in the intestine of the tick Hyalomma anatolicum excavatum (Koch, 1844) (author's transl)].

The developmental stages of Theileria parva within the intestine of ticks were studied by electron microscopy. On the 2nd-4th day post repletionem (p.r.) the intestine of the ticks contained numerous stages, which were very similar to microgamonts and microgametes of haemosporidia. From these results it seemed likely that gamogony of Theileria parva takes place in the intestine of ticks, too. The microgamont-like stages were spear-head-like; they measured about 10.5 mum in length with a maximum diameter of about 2.1 mum in their middle region. These parasites, which were limited by a unit membrane, had a stiletto-like apex, several flagellar-like protrusions of about 3 mum in length and mostly two slender posterior protrusions. The stiletto-like structure was electron-dense and measured about 2.0 mum in length; at its base it appeared spongy consisting of coiled, fibrillar elements of about 20 nm in diameter. Up to 4 flagellar-like protrusions were found in cross sections originating near the base of the stiletto-like structure. At most, up to six microtubules were seen within these protrusions, which, however, at their free ends usually contained only two microtubules. Near the base of the stiletto-like structure two groups of additional microtubules began. One group ran beneath a third of the peripheral margin to the posterior cell pole. The other group was bundle-like arranged. In cross sections through the posterior slender protrusions of the parasite about 10 microtubules appeared in an irregular pattern. The slender posterior protrusions had nearly double dimensions of the flagellar-like protrusions.

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PubMed1975

[Light microscopic studies on the development of Theileria annulata (Dschunkowsky and Luhs, 1904) in Hyalomma anatolicum excavatum (Koch, 1844). I. The development in the gut of engorged nymphs (author's transl)].

A laboratory strain of H. a. excavatum was selected on high susceptibility for T. annulata through several generations. Giemsa-stained smears and wet smears of gut and gut content were studied. After engorgement of erythrocytic stages of T. annulata by the nymphs the following development was observed: 1. Erythrocytic merozoites developed to slender, spindleshaped "microgamonts" in the gut 24 to 96 hours after repletion (p. repl.). Spherical stages with a conspicuous spike developed at the same time and earlier. The "microgamonts" then form up to 4 nuclei and several flagella-like appendices. Filiform "microgametes" obviously develop from the "microgamonts". In addition, spherical stages, i.e. "macrogametes", occur. 2. Spherical "zygotes" with a vacuole-like center appear in the epithelial cells of the gut from day 5 p. repl. These "zygotes" increase steadily in size and then stain more intensely up to day 12 p. repl. 3. From day 12 p. repl. the spherical "Zygotes" change to elongate forms by a continuing process of folding. Finally, from day 13 p. repl., they extend to clubshaped kinetes. These kinetes move actively by gliding within the gut cells and from day 17 p. repl. in the haemolymph. It could not be decided yet whether these kinetes are oo- or sporokinetes.

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PubMed1975

[Electron microscope studies on development stages of Theileria annulata (Dschunkowsky, Luhs, 1904) in the intestine and haemolymph of Hyalomma anatolicum excavatum (Koch, 1844) (author's transl)].

For the first time developmental stages of Theileria within the intestine and haemolymph of ticks were studied by electron microscopy. On the 1st-6th day post repletionem the intestine of the ticks contained humerous tages, which were very similar to microgamonts and microgametes of haemosporidia. Later, on the 14th-19th day p.r. ookinete-like stages ere found in the haemolymph of ticks. From these results it seemed likely that gamogony of Theileria takes place in the intestine of ticks. In more detail: The microgamont-like stages were spindle-shaped; they measured about 8-12 mu in length with a diameter of about. 08 mu in their middle region...

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PubMedDate not supplied

[Liver fluke infection and sarcoptic mange in red foxes in Berlin].

396 red foxes originating from the city of Berlin were examined for opisthorchiid liver flukes and clinical sarcoptic mange between January 1997 and March 1998. Out of 232 (= 58.6%) foxes positive for opisthorchiid flukes 221 animals harboured Metorchis bilis and 70 were infected with Opisthorchis felineus. Pseudamphistomum truncatum was found only in 8 foxes. M. bilis occurred as mono-infection in 154 animals. M. bilis in combination with O. felineus was found in 61 cases. Pure Opisthorchis infection as well as other fluke combinations were found in a small number of animals only. 85 (= 21.5%) foxes showed clinical sarcoptic mange. Liver fluke positive foxes showed a higher mange prevalence than uninfected animals. However, significant associations between flukes and manage were only found when comparing uninfected foxes with those having the highest worm burden. The association of liver flukes and mange could be established for adult female foxes by a significant Odds Ratio of 4.3.

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PubMedDate not supplied

[The subspecies specificity of Babesia canis].

The large Babesia species of dogs, Babesia canis, is transmitted by different ticks. Dermacentor reticulatus, Rhipicephalus sanguineus and haemaphysalis leachi are the known main vectors. Four B. canis isolates of different geographic origin were investigated for their transmission specificity and pathogenicity in infection trials. R. sanguineus ticks exclusively transmitted the Babesia isolate from Egypt. D. reticulatus was the vector for isolates from Hungary and France. Transmission of an South-African isolate was only possible by H. laechi. The B. canis isolates differed markedly in their pathogenicity. The South-African isolate was highly pathogenic and resulted in nearly complete mortality. Infections with the isolate from Hungary transmitted by D. reticulatus, also resulted in severe clinical disease which often ended fatal without treatment with an anti-Babesia drug. Clinical disease also resulted from infections with the French isolate while the isolate from Egypt was largely non-pathogenic. Challenge trials for investigations of cross-immunity demonstrated immunogenic differences between the individual isolates. The degree of immunogenicity appeared to be related to the pathogenicity of the Babesia isolates. Serological investigations revealed that antigen of the isolate from Hungary in ELISA reacted markedly higher than the other three antigens. Due to their vector specificity B. canis classification into three groups is possible: B. canis canis transmitted by D. reticulatus, B. canis vogeli transmitted by R. sanguineus and B. canis rossi transmitted by H. laechi.

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