الفهرس 
Collection of metacercariaeOnly 14 pages are availabe for public view
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Abstract
Fascioliasis, due to Fmciola gzgantica, is of a considerable economic importance to the livestock industry in Egypt. Mammalian hosts vary in their response to infection with fascioliasis and their ability to acquire resistance to challenge infections. Rabbits, like rats and cattle, are highly susceptible to infection and consistently exhibit significant resistance to reinfection. Flukes from a primary infection survive as long as the natural life of the rabbit. The study aimed to investigate: - 1- The course of infection during the patent period. 2- The effect of host sensitization wtih thymus and bone marrow cells on the nature of infection. 3- The influence of natural immunodepression (host’s pregnancy and lactation) on the infection pattern and host’s immune response. At postmortems, worm recovery and effectivencess of infection were studied. Bile, liver and mucosal extracts were collected. Total serum proteins as well as protein contents of biles, liver and mucosal extracts were estimated employing the biwet reaction. Antibodies were estimated in antisera, biles, liver and mucosal extracts with haemagglutinating & precipitating tests. Total 1gA and 1gM were evaluated by radal immunodiffusion test. Summary 193 The following results were obtained:- 1- During the primary infection, the percentage of infection varied from 2- 8% in liver parenchyma and 4.7-6.7% in bile ducts. Flukes were found in liver parenchyma from week 4 peakng at week 8 postinfection, thereafter, the flukes migrated to the bile ducts from the 9th WAI. During immunization, the mean number of flukes, decreased to one and the percentage of infection was 2% in rabbits sensitized with 12x103 thymus cells giving a protection of 56.5%. In rabbits sensitized with 12x1 03 bone marrow cells, the mean number of flukes decreased to a mean of 0.3 with 0.7% effectiveness of infection and the magnitude of worm reduction was 87%; During lactation and pregnancy an increased prevalence of infection occurred. The highest fluke burden was noticed in lactating rabbits (mean 3 and 6% effectivenes of infection). Ln pregnant rabbits the mean fluke burden was 2.7 and the percentage of infection was 5.3%. 2- Serum and mucosal hyperproteinemia occurred in rabbits of the three experiments. Liver proteins decreased during primary infection and increased accordmg to the present schedule of sensitization and infection. During pregnancy and lactation no differences of liver proteins were observed in infected rabbits. Hyperproteinemia in biles occurred only in the infected pregnant and lactating rabbits. 3- Precipitating antibodes were detected in the sera of primary infected rabbits 6 WAI against adult antigen and metacercarial antigen and 9,10 WAI against adult excretory-secretory products. In liver these antibodies were detected at the 6& and 8th WAI against somatic adult and metacercarial antigens. Ad&tionally mucosal precipitins appeared at 6& and 8th WAI against somatic adult antigen and metacercarial antigen. During cell transfer, pregnancy and lactation infection did not elicit precipitanting antibodies.