الفهرس 
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Abstract
This study was initiated to evaluate and compare two DNA based techniques (conventional PCR and real-time PCR) with traditional parasitological investigations for detection of Trypanosoma evansi and follow up the infection in experimentally infected mice. Pathological alterations in different tissues obtained from mice throughout the course of infection were recorded.
Seventy three females’ mice and seventy three males’ mice were used for this purpose. In experiment I, 21 females and 21 males were inoculated by 104 trypanosomes, and 5 mice from each group were kept as non infected control. In experiment II, 42 females and 42 males were inoculated with 102 parasites and 5 mice in each group were kept as non infected control. In both, prepatent periods were followed up daily from the first day post inoculation (DPI) to the peaking of parasitemia by DME, GSBS, PCR and real-time PCR then twice weekly till the end.
Results revealed higher sensitivities of PCR and real-time PCR using both TBR1/2 and TeRoTat1.2 primer sets than direct microscopy in early determination of prepatent periods as early as 24 hours post infection, while direct microscopy revealed prepatent period of 3 and 5 days in experiment I and II respectively.
Using direct microscopy, following up the course of infection revealed three waves of parasitemia alternative with three waves of parasite disappearance from blood. Molecular techniques could clearly detect T. evansi in chronic stages of low parasitemia (waves of parasite disappearance) throughout the course of infection. By testing field samples, real-time PCR was more reliable in detecting and quantifying very low parasitemia in clinical blood samples rather than PCR.
Histopathological examination revealed that T. evansi induced destructive irreversible damage of mice vital organs (kidneys, liver, spleen, brain and testes) especially in chronic infection and lead to death of animals with a progression of the disease. Moreover, animal fertility was reduced in the form of degenerative changes in testes and seminiferous tubules.
In conclusion, real time PCR can be considered more suitable for screening of newly introduced animals to exclude carriers and detect early infected animals for saving free herds.