Sara LARKI, Alireza ALBORZ, Abbas ZEINAL

Evaluation of larval culture and conventional PCR methods for the detection of Strongylus vulgaris in equines of Iran

Strongylus vulgaris (S. vulgaris) is known as the equine’s most pathogenic nematode due to the extraintestinal migration in mesenteric arterial vessels. Since a few kinds of S. vulgaris can threat the animals’ health and working efficiency, high precision and early detection of strongylid nematodes is essential. Traditionally, the larval coproculture method was used frequently for identification of strongylid species.The technique of larval culture is costly, time consuming, and does not have sufficient accuracy and reliability. Here, we critically evaluated the polymerase chain reaction (PCR) with larval culture methods for the detection of S. vulgaris eggs in fecal samples. To this aim, fresh fecal samples were obtained from 42 horses and 71 donkeys in different provinces of Iran. All samples containing strongyle form eggs were individually cultured and third–stage (L3 ) S. vulgaris larvae were harvested from Baermann apparatus. The collected strongyle form eggs were individually kept in ethanol for molecular study. The L3 strongyle larvae were identified by morphological characteristics. The genomic DNA of strongyle eggs extracted and the second internal transcribed spacer (ITS-2) region was amplified using PCR technique. Then, the phylogenetic tree was drawn based on sequenced products. The results showed that the shedding eggs of strongylid nematodes were observed in 85%, 27.58%, and 50% of the donkeys in Chaharmahal and Bakhtiari, Isfahan, and Khuzestan provinces and 12% of the horses in the Khuzestan province. Also, S. vulgaris was identified in 10 (8.85%) and 11 (9.73%) of the donkeys by larval culture and PCR methods, respectively. Phylogenetic analysis showed the Iranian S. vulgaris isolates found in clusters in other countries, and isolates of this parasite have recorded. Molecular findings of the PCR method are closer to the realistic values of S. vulgaris infection and detect a higher rate of positive samples. So, it can be applied for large scale screening programs of equine population

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