الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Bancroftian filariasis (BF) is a human disease caused by infection with the parasite W. bancrofti. It falls among the leading causes of permanent and long-term disability as it causes severe clinical manifestations including elephantiasis and hydrocoele. BF has been endemic in Egypt for centuries, mostly in the Nile Delta region. Diagnosis of this disease depends on parasitological, clinically physical, ultrasound, immunological and molecular methods. According to the clinical as well as parasitological diagnosis, it is agreed that human population in an endemic area with BF is classified into chronic (CP), microfilaremic patients (MF) and endemic normals individuals (EN) who are residing in an endemic area but never develop infection. Immunological diagnosis included surveys for antibody levels against W. bancrofti or other animal filarial parasite derived antigens using enzyme-linked immunosorbent assay (ELISA). It also included immunochromatographic test (ICT) card which is based on an immobilized monoclonal antibody (MAB) specific for detecting a circulating parasite antigen in blood of infected individuals.
Since little is known on prevalence of animal filarial parasites in Egypt, our study aimed at isolating and identifying 2 local animal filarial parasites known as Setaria equina, from the peritoneal cavity of equines, and Onchocerca armillata, from the aortic arches of female bovines and determining their seasonal prevalence. Significant prevalences for S. equina and O. armillata were recorded in the Spring and Summer when compared to Summer and winter, respectively. The study also aimed to determine the extent of cross reaction between epitopes in different antigenic preparations from those parasites and IgG in sera of Egyptian CP, MF and EN in comparison to non-endemic normals (NEN) who has never been residing in an endemic area for the disease by ELISA.
Both soluble and detergent extracted antigens were prepared from both sexes of S. equina adult worms. However, surface and excretory-secretory antigens were prepared from female worms only. Two different fractions from both sexes of adult O. armillata worm were used. Generally, CP sera showed the highest IgG reactivity against all adult worm crude antigens from both parasites in comparison to MF and EN. The highest IgG prevalence (100%) was recorded among CP sera against the crude surface antigen of S. equina. This gives such antigen a potential for differentiating CP from others. Using a crude soluble antigen from S. equina microfilariae (mf), fewer positive IgG reactions were recorded among CP. Correlation analysis of IgG levels among CP sera against all antigen preparations from both parasites revealed that the highest correlation was observed against two O. armillata antigen fractions. For MF patients, the highest correlation for IgG reactivity was recorded between one of the O. armillata prepared fractions and soluble antigen from female S. equine worms. For EN sera, the highest correlation for IgG reactivity was observed between the soluble antigens prepared from each of female and male S. equina worms.
Electrophoresis of different crude antigens followed by coomassie staining revealed remarkable differences in their protein profiles. In immunoblots, recognition of common molecular weight proteins in the crude preparations by the IgG was observed using pooled sera of CP, MF and EN. In addition, the 100% positive IgG reactivity in CP sera against the surface antigen of female S. equine by ELISA corresponded to recognition of a 27.8 kDa using pooled of the same sera. Immunoblots of soluble mf antigen using pooled CP sera revealed recognition of 24 and 60 kDa peptides that could be associated with amicrofriaremia and/or protective immunity against mf. Developing the immunoblots of excretory-secretory antigen using pooled MF or CP sera resulted in recognition of a common 200 kDa protein. This represents a cross-reactive epitope between S. equina and W. bancrofti of possible diagnostic potential.
Implantation of S. equina gravid female worms in the peritoneal cavity of white albino rat resulted in successful infection as measured by appearance of blood mf by time. When serum from S. equina infected rat was applied to ICT card which is coated with MAB AD 12.1 specific for W. bancrofti antigen, cross reaction was evident and the same result was obtained upon using heat shock protein prepared from the female S. equina, worm excretory-secretory antigen
The present study aimed to describe the morphology of different areas of both O. armillata worm sexes except the posterior end of the female worm using scanning electron microscopy. Results demonstrated difference in morphology of the cephalic papillae and cuticular striations between the male and female worms. In O. armillata, the copulatory papillae of male worm that are of taxonomic importance, showed a characteristic distribution than other Onchocerca species.
As the control and elimination of filariasis in Egypt was dependent on mass treatment by diethylcarbamazine citrate (DEC) which is known as a successful macro- and microfilaricidal drug, our work also focused on studying the in vitro and in vivo mode of action of the drug on S.equina. The mode of action of DEC on S. equina adult worms was studied by direct incubation of worms with known concentration of DEC for 8 hrs. Results revealed a reduction in the mf counts and worm motility after DEC treatment in comparison to untreated worms.
Transmission electron microscopy was also used to observe possible ultrastructural alterations in both male and female S.equina worms after DEC treatment. In female worms, damage of the muscle filaments of body wall, uterine wall and coiled embryos was evident. In male worms, vacuolization in the muscle cells of body wall, epithelial cells of vas deferens and spermatozoa was also evident. In vitro incubation of S. equina mf with DEC for 2 days did not show any direct effect. However, the in vivo effect in MF white albino rats showed a significant decrease in blood mf count at 45 min and 5 hrs post-treatment. Examination of liver, lung, kidney and spleen sections from infected treated and infected saline given animals by light microscopy at the same three time points indicated an efficacious role for those organs in lysis and elimination of the parasite larvae from the circulation after treatment. Although the cellular adherence to mf was evident in both of liver and lung at 5 hrs, it was only evident in spleen at 8 hrs post-treatment. Lysis of mf was mostly prominent at the later time points after treatment (5 and 8 hrs) in liver and lung but only at 5 and 8 hrs for Kidney and spleen, respectively.