الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Schistosomiasis remains a truly neglected tropical disease and an important public
health problem in many countries. It was suggested that an alarming 201.5 million cases of
schistosomiasis may occur in Africa alone and that over 90% of all schistosomiasis cases
are found in underdeveloped areas of Africa.
The control of schistosomiasis in human depends mainly on treatment with the drug
praziquantel (PZQ). Although PZQ is the cornerstone of current schistosomiasis control
programs, there is some evidence of developing resistance. This highlights the need to find
other alternatives including vaccination. However, none of the vaccines tested before
proved to be effective. Thus, there is a persistent need to find ways to increase the efficacy
of vaccination.
In the present study, we tested cercarial transformation fluid antigen (CTF) singly
and in combination with crude cercarial antigen (CCA) as immunizing agent against
experimental schistosomiasis mansoni.
The study was performed on 96 male Swiss strain Albino mice. The mice were
divided into two main groups: control and experimental and each was subdivided into three
subgroups.
Control group included non-infected control mice (subgroup Ia), infected control
mice (subgroup Ib) and adjuvant infected control mice (subgroup Ic). While
experimental group included; mice receiving CTF (subgroup IIa), mice receiving CCA
(subgroup IIb) and mice receiving combined antigens (subgroup IIc). Mice of the
experimental group and subgroup Ic followed the same schedule of immunization and
infection. They received two separate doses of the vaccines one week apart. Then they
were infected two weeks after the second dose of the vaccination by tail immersion
technique with 100 freshly shed cercariae.
At the end of the experimental study, 45 days post-infection, mice of each subgroup
were sacrificed. The following studies were done: parasitological, biochemical and
immunological. The parasitological studies included estimation of adult worms load,
counting of Schistosoma mansoni ova in liver and intestine, estimation of the size of the
hepatic granulomata and ultrastructural study by scanning electron microscopic
examination. Biochemical study included measurement of liver enzymes (AST, ALT).
In addition, immunological study included measurement of CD4+ T-lymphocytes by flow
cytometry. The results were tabulated and statistical analysis was performed.
Results of all studied parameters were in favour of combined antigens given to
subgroup IIc. The mean adult worm load reduction was the highest in mice receiving
combined antigens (subgroup IIc) as it showed 62.12% reduction. It was 26.47% and
43.75% in mice receiving CTF (subgroup IIa) and mice receiving CCA (subgroup IIb)
respectively when compared to infected control subgroup (subgroup Ib). The percentage
of reduction of liver tissue egg count was 26.47% in subgroup IIa, 60.28% in subgroup IIb
and 77.93% in subgroup IIc. While percentage of reduction of intestinal tissue egg count
was 28.69%, 76.50% and 87.26% in subgroups IIa, IIb and IIc respectively. Regarding the
granuloma size, the highest reduction was recorded in subgroup IIc followed by subgroups