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From the time of the discovery of Trichinella larvae in 1835 until the middle of the next century it was commonly assumed that all trichinellosis was caused by a single species Trichinella spiralis. This species is an intracellular parasite in both a larva and an adult stage. The L1 larvae live in a modified skeletal muscles. The adult worms occupy a membrane-bound portion of columnar epitelium, living as intramulticellular parasite. More than century later T. spiralis have been reported from more than 150 different naturally or experimentally infected hosts and demonstrated worldwide distribution in domestic and/or sylvatic animals. Up to date, Trichinella genus comprised eight species (T. spiralis, T. nativa, T. britovi, T. murrelli, T. nelsoni, T. pseudospiralis, T. papuae and T. zimbabwensisi) and three additional genotypic variants that have not yet to be taxonomically defined (T6, T8, T9). Molecular markers revealed that Trichinella T6 is related to T. nativa, Trichinella T8 related to T. britovi. Two main clades are recognized in the genus Trichinella: the first encapsulated in host muscle tissue and the second-non-encapsulated. In this paper the history of Trichinella spp. discovery, their life cycle, taxonomy and phylogeny have been reviewed.
The experiment was carried out on sheep and lambs inoculated orally with 10 000 mc P. fasciolaemorpha. Some of the animals were given intramuscular injections of the somatic antigen from adult flukes together with complete Freund’s adjuwant against parasitic infection. Changes in the percentage of T lymphocytes were examined. A slight increase in the number of T lymphocytes was observed in infected animals but stronger reaction was found in lambs. In adult sheep the average intensity of infection was 27.89% compared with only 9.41% in lambs. Statistically significant high levels of lymphocytes also occurred in infected animals after intramuscular immunization up to the and of the prepatent phase of infection. This increase took place more rapidly and was higher in comparison with nonimmunized hosts. In immunized animals the average intensity was lower: 7.33% in sheep and 3.85% in lambs.
Immune response of rats exposed to 4000 L1 T. spiralis and treated with P. granulosum was measured. Intraperitoneal injection of propionibacteria results in an increase of percentage of T lymphocytes and an activation of neutrophils. The inhibition of macrophage migration was observed till 5 DAI. In infected rats, after P. granulosum intraperitoneal injection, an increase of specific IgG₁ antibody level was not observed. The reduction of the number of muscle larvae depended on the time of P. granulosum injection after infection with T. spiralis.
Faecal nematode egg counts and IgG activity to Haemonchus contortus were followed in naturally infected Polish Wrzosówka ewes. The egg counts were overdis- persed; most individuals had relatively low egg counts but a small proportion had high counts. Egg production followed a different pattern each grazing season. Larvae cultured from eggs in 1996 were predominantly H. contortus and Trichostrongylus spp. In 1997 the recoveries were largely Trichostrongylus spp. In 1998, larval recoveries were mainly Trichostrongylus spp. and Teladorsagia spp. There were no discernible patterns in the composition of the nematode population within each grazing season. Egg counts in different months were moderately repeatable, indicating that animals tended to maintain their rankings over time. The repeatabilities rose during the grazing season but declined with increasing intervals between sample dates. IgG activity against a somatic extract of adult H. contortus was higher than activity against a preparation from excretory/secretory antigens but the two responses were very strongly correlated. The repeatability of IgG activity at monthly intervals was higher than the repeatability of faecal egg counts. Animals with higher than average IgG activity had significantly lower than average egg counts but only in the last two years of the study. A combination of egg counts and antibody responses may be better at identifying resistant animals than either method used in isolation, but more research is necessary to determine why the association between antibody and egg counts varies in different years.
The association between faecal egg counts and serum IgG response against somatic (SAg) and two excretory/secretory antigens (ESAg-4h, ESAg-24h) obtained from adult Haemonchus contortus was monitored over one season in young Polish Wrzosówka ewes naturally infected with gastrointestinal nematodes. There was a considerable variation in faecal egg counts and in the proportion of larvae from each species recovered from faeces at different months. Very similar IgG responses against the three antigen preparations were observed; the differences among months were significant. The distribution of antibody among young ewes was unimodal and positively skewed. The repeatabilities of IgG responses against SAg and ESAg-24h were all positive and statistically significant, although repeatabilities against ESAg-4h were of border line significance. The correlation coefficients among IgG responses tended to increase in the second half of season. There was a significant association between increased IgG responses to somatic antigens and reduced faecal egg counts. The combination of antibody responses against different antigen preparations of H. contortus and faecal egg counts appear better at identifying resistant Polish Wrzosówka sheep than either method used in isolation.
A longitudinal study in young Polish Wrzosówka ewes, naturally infected with gastrointestinal nematodes, was carried out to examine the association between parasite-specific IgG antibody and faecal egg counts. IgG activity varied among the young ewes in each sampling month. The highest individual values were measured in the second half of the each season, when the overall means were highest. The distribution of IgG activity among individuals was unimodal with a positive skew. This study appears the first to examine the distribution, among animals and over time, of IgG responses to natural mixed infection. Serum IgG responses were repeatable and significantly associated with reduced nematode faecal egg counts. A combination of faecal egg counts and IgG responses can be used to identify animals with increased resistance to nematode infection in this breed of sheep.
Three species of oribatid mites: Scheloribates latipes, Pergalumna nervosa and Ceratozetes sp. were experimentally infected with Moniezia expansa eggs or oncospheres. The intermediate hosts were kept under constant laboratory conditions at 27°C and 80% relative humidity. Three species of oribatid mites became infected and completely developed cestode cysticercoids were found. The early part of life cycle of M. expansa was studied in S. latipes. The mites were examined on 20th, 24th and 29th day after cestode oncosphera invasion. A fully fonned cysticercoid of M. expansa was observed on 29th day after infection. The mean of intensity of infection was 1-5 cysticercoides per mite. The infected and living oribatid mites could be kept under laboratory conditions for 7 months. The cysticercoides which had been recovered from S. latipes after this time were able to infect sheep.
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