Zeitschrift fur Parasitenkunde (Berlin, Germany)最新文献

The ultrastructure of Toxocara canis eggs is described before and after exposure to microwaves. The morphology of normal eggs is compared to that of eggs from other helminths. Following treatment, the complete disorganization of the surface structure of the shell and the loss of much turgidity of the egg are observed. The destruction of the internal structure is most marked in the center of the egg and is associated with the disappearance of some layers of the shell. In addition, there is substantial damage to the synthesis apparatus (ribosomes, endoplasmic reticulum, lipid cisternae). An explanation based on the specific action of microwaves and micro-overheating is proposed, and the prophylactic use of this technique is considered.

Thirty adult donkeys from Burkina Faso were necropsied and their gastro-intestinal worm burdens counted and determined. The strongylids were the most abundant species with a prevalence of 100% for Strongylus vulgaris. Four species of Strongylus, two of Triodontophorus and six of the Cyathostominae were recovered. All of the animals were also infested with habronematid nematodes, but oxyurid and ascaridid nematodes were found in low numbers. In addition to the nematodes, the paramphistomid trematode Gastrodiscus aegyptiacus and the anoplocephalid cestode Anoplocephala magna occurred in varying numbers. Faecal egg-counts from 131 donkeys ranged between 100 and 9,200 for strongylid eggs.

Fifty-eight specimens of cyathocotylid flukes were collected from dogs fed on the fish Clarias lazera: 10 Duboisia, 27 Mesostephanus appendiculatus; and 21 Prosostephanus industrius. This is the first time that these genera have been identified as parasites of C. lazera. The danger of human infection with these trematodes by means of C. lazera and other commercially important fish is stressed.

Muscle cysts from rodents (Mastomys natalensis, Mus musculus, Rattus norvegicus, Meriones unguiculatus, Phodopus sungorus) experimentally infected with Sarcocystis dirumpens were examined by light and electron microscopy. The corrugated primary wall showed a pattern of densely arranged invaginations surrounded by minute bleb-like evaginations. True protrusions were absent. The length of the blebs and the thickness of the primary wall varied insignificantly but not remarkable host-dependent morphological differences could be noticed between the cyst wall structures 60-418 days p.i. In the mature parts of the cysts merozoites and metrocytes showed typical apicomplexan features of fine structure and mode of multiplication (endodyogeny). In the tips of the cysts large metrocytes simultaneously formed more than two daughter cells (at least up to 12) by endopolygeny.

Eleven of 15 ferrets experimentally infected with Brugia malayi became amicrofilaremic after a brief patency; only four ferrets remained patent after 6 months of infection and two of these ferrets developed a high, persistent microfilaremia. Blastogenic responses of peripheral blood lymphocytes to antigens of microfilariae (mf), assayed in vitro, demonstrated an antigen sensitivity at prepatent, patent and postpatent periods of infection. Lymphocytes from ferrets with high microfilaremia had elevated background responses in culture which were directly correlated with the number of circulating mf. This background response was attributed to antigenic stimulation by mf present in the lymphocyte cultures; addition of mf to cultures of lymphocytes from postpatent ferrets induced responses equivalent to those observed in microfilaremic ferrets. Lymphocyte responses to the mitogen, concanavalin A, did not differ significantly among microfilaremic, amicrofilaremic and uninfected ferrets. Antibody in IgG to antigens of mf measured by ELISA and by immunoblots from SDS-PAGE showed similar patterns of response in ferrets which became amicrofilaremic and in the few ferrets which remained microfilaremic. prausnitz-Kustner tests demonstrated no consistent differences in titers to microfilarial antigens between patent and amicrofilaremic ferrets. The results suggest a high level of immune responsiveness to antigens of mf in infected ferrets with no evidence of immunosuppression associated with prolonged microfilaremia or of major changes in immune responses with development of amicrofilaremic infections.

Blood and bone marrow eosinophilia was assessed in nonpermissive (guinea pigs) and permissive (rats) hosts following the pulmonary arterial transfers of live or dead young adult worms of Angiostrongylus cantonensis. Guinea pigs showed a marked eosinophilic response to live worms but only a slight response to dead worms. Neither IgE nor haemagglutinating antibodies correlated with the induction of this eosinophilia. In contrast, the rat responded to neither form of the young adult worm. When the guinea pig and the rat were injected with whole worm extract (WWE) of the young adult worms either by an osmotic mini-pump connected to the jugular vein or by intermittent intravenous injections, the former animal showed blood eosinophilia but the latter failed to do so. Guinea pigs also developed blood eosinophilia after continuous exposure to the excretory and secretory products of the young adult worms, administered by the mini-pump. Eosinophil responses to WWE could be induced both in athymic CD-1 (ICR) nude mice and in its heterozygous litter mates, suggesting that T cell-independent mechanism(s) could be involved in the induction of blood eosinophilia in the nonpermissive, mouse host. These data clearly indicate that the eosinophilia-inducing factor(s) and the mechanism of eosinophilia are different in permissive and nonpermissive hosts.

The infectivity of Encephalitozoon cuniculi grown in cell cultures was determined in cultured cells and in wild and domestic rabbits. The ratio of the total to tissue culture viable count was 1,300 (median of seven determinations). The mean ratio of intact spore count to total count, as determined by electron microscopy was 0.12. Although variation between infectivity experiments was large, the median animal infective dose contained 51 FFU (cell culture focus-forming units) for wild rabbits (Oryctolagus cuniculus) and 40 FFU for domestic rabbits. These two infectivities were not statistically different.

In human infection with Schistosoma mansoni from Beni-Suef, the eggs were encountered more frequently in the urine of patients than in infection with S. mansoni from Giza, where eggs were passed into the stool. A comparative study of the two strains of S. mansoni from Beni-Suef and Giza has been carried out in golden hamster. Consistent strain differences were observed. The Beni-Suef strain proved to have lower worm recovery and different egg distribution patterns in tissues of infected hamsters. Worms of both sexes of this strain were larger in size and required a longer period to reach maturity. Hence, the prepatent period was prolonged. Significant differences between the two strains were also noted in the number of eggs per worm. A lower mortality rate and a longer survival time were encountered in hamsters infected with the Beni-Suef strain.

In a study of the immune response of the rat to infection with the nematode Strongyloidis ratti, the antigens of the infective larval stage (L3) and of the parasitic, parthenogenetic female (Fp) were investigated. From both the larvae and the adult females, one metabolic (exoantigen) and two somatic antigens were extracted. Of the two somatic antigens, one was soluble and obtainable by physical means while the other was separated by chemical means from the tegument of the parasite. Humoral responses to the various antigens were evaluated by immunodiffusion and ELISA techniques, while the overall immune response was assayed by the worm burden in the immunized and subsequently infected rats. Agar-gel double diffusion yielded precipitin bands only with larval somatic antigens. ELISA proved positive at a titer of 20,000 with larval metabolic antigen and sera of rats immunized against either larval metabolic or somatic antigens. By 20 days post challenge infection, however, this titer diminished to 4000. In vivo studies of worm burden in rats immunized with the various antigens and then exposed to the live L3 of the nematode showed that there were significantly fewer adult worms in the rats immunized with larval somatic antigen and adult metabolic antigen than in those immunized with adult somatic antigen or larval metabolic antigen.