الفهرس 
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Abstract
In Egypt, the greatest impediment to poultry production is the diseases. The domestic birds are raised traditionally in villages without any veterinary care, thereby exposure to parasitic infections is expected. Therefore, the records of intestinal helminth parasites described in this study are important. This is attributed to the great value of poultry production in Egypt.
The prevalence of intestinal helminth parasites in different domestic birds including pigeons (Columba livia domestica), chickens (Gallus gallus domesticus), ducks (Anas platyrhynchos domesticus) and white chickens, were conducted throughout the period between April 2015 and June 2017.
A total of 553 domestic birds were collected and the intestinal tracts were examined for helminth infection. The collected cestodes and nematodes were prepared for light, and scanning electron microscopy. As well as DNA was extracted for molecular studies.
Eight species of helminth parasites were recorded: three nematode species; Ascaridia galli, A. columbae and Heterakis gallinarum and five species of cestodes; Raillietina echinobothrida, R. tetragona, R. sp., Cotugnia digonopora and Choanotaenia infundibulum.
The total prevalence of infections in domestic chicken was 14.39%. All seasons are represented by single cestode infections with a percentage of 4.41%, 17.07% and 5.5% in summer, fall and spring seasons respectively. On the other hand, single nematode infection was 2.94%, 2.43% and 5.5% in summer, fall and spring seasons respectively. However, In white chickens, 130 examined samples were clear from any intestinal helminth infections.
In pigeons, the total prevalence of infections was 24.79%. The single cestode infections were 10.6% and 25.9% in summer and fall seasons respectively. While the single nematode infection was 2.66% and 4.54% in summer and fall seasons respectively.
Within 45 examined samples, 4 ducks (30.7%) samples were positive with single nematode infections in winter season and only 1 (5.2%) sample was found positive with single cestode infection in the summer season.
In this study, the morphological characterizations of the recovered intestinal helminth parasites were described by the mean of the light and scanning electron microscopy.
Different molecular techniques (RAPD-PCR, SSCP-PCR and LSSP-PRC) were used to generate polymorphic DNA fingerprints of Ascaridia, Raillietina and Choanotaenia species.
There are some bands with a faint appearance and others with high intensity. The five, six and four arbitrary primers for Ascaridia, Raillietina and Choanotaeina species respectively amplified different classes of bands; polymorphic and monomorphic. The number of these amplified bands was different for each locality analyzed.
In Ascaridia species, the total amplified DNA fragments generated by all primers were 26-33 for Ascaridia columbae, 35-37 for A. galli (from chicken) and 26-38 for A. galli (from duck).The highest similarity coefficient (SC) was among isolates of chicken (78%), followed by duck isolates (72%) and then pigeon isolates (67%). Also, the mean range of SC between different isolates was 68% for A. galli (from chicken) & A. columbae, 70% for A. galli (from chicken) & A. galli (from duck) and 60% for A. galli (from duck) & A. columbae. SSCP data confirmed that A. galli and A. columbae may be closely related to each other by generating nearly the same pattern of bands.
In Raillietina species, the total amplified DNA fragments generated by all primers were 22 for Raillietina sp., 27-32 for R. echinobothrida and 32-35 for R. tetragona. The highest SCs were between R. sp & R. echinobothrida (70%), and R. sp & R. tetragona (70%). While the lowest SC was between R. echinobothrida and R. tetragona (62%). On the other hand, the genetic relationship within individuals of the same species were (67%) for R. echinobothrida and (72%) for R. tetragona. Consequently, the SSCP data confirmed that the three species are closely related to each other by having the nearly identical pattern of bands.
In Choanotaenia infundibulum, the total amplified DNA fragments generated by all primers were 33-44 for chicken isolates, 24-34 for pigeon isolates and 24 for duck isolate. The mean range of SCs within individuals in the same isolate was 82% among isolates of pigeon followed by 78 % among chicken isolates. Also, the most related isolates are chickens and pigeons (69%). While LSSP-PCR data revealed an intra-specific polymorphism in the amplified genomic fragments.
Conclusion
In conclusion, the prevalence of helminth infections of domestic chicken, pigeon and duck were relatively low in comparison with previous studies all over the world.
The variations in results and percentage in the present study with the previous studies (even higher or lower) and the presence of other reported species of cestodes or nematodes in other countries may be due to abundance and presence of intermediate hosts (such as ants, cockroaches, beetles, earthworms, and some molluscs), the host species and its feeding habits, climate factors such as temperature and geographical factors in Egypt.
In the present study, no trematode infections were recorded, this may be due to the natural habitat of domestic birds lacking the presence of intermediate hosts.
Also, no helminth infections were recorded in white chickens from Egypt, this may be due to medications systems, high veterinary and hygienic care.
The studied morphological characters of the recorded helminths have been confirmed using scanning electron microscopy (SEM) which is an invaluable method that may define some unclear morphological aspects for helminths identifications.
RAPD-PCR, SSCP-PCR and LSSP-PCR techniques have been proved to be the most reliable techniques in the identification of species and in detecting the intra-specific genetic variations between closely related and similar parasites of the same species.
This work strongly suggested that helminthiasis is a serious problem in domestic birds in Egypt and adequate control strategies need to be devised.