Genetic Diversity of Strongyloides stercoralis with Attention to Clinical Features in Patients Originated from Three Endemic Provinces in the North and South of Iran

Background: Strongyloides stercoralis is one of the neglected tropical diseases. We aimed to verify the genetic diversity of S. stercoralis with attention to clinical features of the infection in patients using the Cox1 gene and DNA sequencing. Methods: Using parasitological methods, S. stercoralis was isolated from stool samples of patients who had been referred to Tehran University of Medical Sciences, Tehran, Iran. The patients originated from three endemic provinces of Iran including Guilan and Mazandaran in the north and Khouzestan in the south of Iran. After recording the clinical symptoms of the patients, DNA extraction of the isolates, PCR, and sequencing of the Cox1 gene region were performed. The gene sequences were analyzed by Chromas, Bio edit, and Dna SP 6.0, and phylogenetic analysis using MEGA 7. Results: Overall 10 isolates of S. stercoralis were collected from patients 55 to 73 years old. Among the patients, gastrointestinal, respiratory, and cutaneous clinical symptoms were the most common, respectively. Ten isolates were classified into 4 haplotypes, 2 of which were specific to this study. Haplotypes 2 and 3 were placed in a subclade with haplotypes including isolates from dogs in Cambodia. Haplotype 4 which is hereby introduced in the world for the first time included an isolate from a patient with hyper-infection syndrome and disseminated strongyloidiasis. Conclusion: The Cox1 gene showed genetic diversity for S. stercoralis isolates. Accordingly, no significant genetic difference was observed between the sequences from patients with hyper-infection and non-hyper-infection. The only isolate from a patient with disseminated and hyper-infection strongyloidiasis was genetically different from all other isolates in the present study.