دراسة تصنيفية وجزيئية لبعض الطفيليات من مضائف مختلفة في محافظة النجف الأشرف

Rp-Taxonomic and Molecular Study of Some Parasites from Different Hosts in Al-Najaf governorate.pdf

This study was conducted in Al-Najaf governorate, covering the central district of the governorate, Al-Kufa, Al-Abbasiya, Al-Manathira, and Al-Mishkhab districts, in addition to Al-Hira and Al-Qadisiyya sub-districts and their surrounding rural areas, the Veterinary Hospital in the governorate, veterinary dispensaries, private veterinary clinics, poultry and bird markets, and the municipal slaughterhouse in the city center, during the period from 1/3/2024 to 1/10/2024. Parasites were obtained from their hosts through the Veterinary Hospital, dispensaries, private clinics, poultry and bird markets, and grazing areas of sheep and cattle in the governorate, in order to isolate and identify some infectious endoparasites and ectoparasites affecting hosts such as wild pigeons, domestic chickens, cattle, and sheep. The aim of this study was a diagnostic and descriptive morphological investigation using both light and electron microscopy, in addition to molecular genetic analysis of a group of parasites of veterinary and medical importance.
Using a simple light microscope, several parasites were obtained. The endoparasites, which live inside the host’s body and usually inhabit different parts such as the intestine and lungs, included: Ascaridia galli and Raillietina cesticillus, both isolated from domestic chickens (Gallus gallus domesticus) and inhabiting the intestines and gizzard; and the tapeworm Moniezia expansa, isolated from the intestines of sheep (Ovis aries). The ectoparasites, which inhabit the external surface of the host and cause serious diseases to the animals they infest, included larvae of the New World screwworm Cochliomyia hominivorax (NWS), isolated from sheep (Ovis aries), and the hard tick Amblyomma integrum, isolated from cattle (Bos taurus).
A total of 145 samples were collected from different hosts and geographic locations in Al-Najaf governorate. Worms were preserved for molecular examination. Samples were subjected to morphological examination using the light microscope and the scanning electron microscope to determine precise diagnostic characteristics. Twenty nematodes (Ascaridia galli) were isolated from the intestines of domestic chickens (Gallus gallus domesticus); 16 tapeworms (Moniezia expansa) from the intestines of sheep (Ovis aries) at the municipal slaughterhouse in Al-Najaf under veterinary supervision; 18 cestodes (Raillietina cesticillus) from the intestines of domestic chickens (Gallus gallus domesticus); 30 larvae of Cochliomyia hominivorax from sheep (Ovis aries) collected from the Veterinary Hospital, Al-Kufa, Al-Abbasiya, and Al-Manathira; and 20 ticks (Amblyomma integrum) from cattle (Bos taurus) in the rural areas of Al-Manathira, Al-Hira, and other host-grazing sites. All samples were preserved in 10% formalin.
After parasite isolation and grouping, molecular identification was carried out using Conventional Polymerase Chain Reaction (PCR), and the results were revealed by gel electrophoresis to confirm species-level identification. Specific primers were used for each species: the ITS1 region for Ascaridia galli; the 18S rDNA region for Raillietina cesticillus; the CO1 gene region for Moniezia expansa; the ITS2 region for the larvae of Cochliomyia hominivorax; and the primers LCO1490 and HCO2198 for Amblyomma integrum.
Subsequently, morphological features of Ascaridia galli, Raillietina cesticillus, Amblyomma integrum, and Cochliomyia hominivorax were studied using the scanning electron microscope after being molecularly identified in the present study. Moniezia expansa was molecularly confirmed, but the scolex was not obtained for electron microscopic examination. For nematodes and cestodes, the scolex, mature proglottids, gravid proglottids, and both anterior and posterior regions were examined. Other worms and ectoparasites were identified according to the standard taxonomic keys specific to each species.
The results confirmed host infection with these parasites. The combination of morphological examination using light and electron microscopy with molecular analysis provided high diagnostic accuracy at the species level. The present study offered important insights into the biodiversity of parasites, their host specificity, and their potential zoonotic transmission. These findings contribute to enhancing the epidemiological understanding of parasitic infections and support the development of effective control strategies in both veterinary and public health sectors.
Based on genetic analysis, a phylogenetic tree was constructed for all study sequences. Results revealed: Ascaridia galli with 80% similarity, Raillietina cesticillus with 99%, Raillietina saudiae with 99%, Moniezia expansa with 98%, Cochliomyia hominivorax with 97%, and Amblyomma integrum with 85% similarity to isolates deposited in the NCBI GenBank from different regions of the world. Importantly, this study recorded for the first time in Al-Najaf governorate the isolation of Ascaridia galli from the intestines of domestic chickens (Gallus gallus domesticus), with its sequence deposited in NCBI GenBank under accession number PV703757.1