First Molecular Detection of Echinococcus granulosus Sensu Stricto in Dogs from Istanbul’s Anatolian Side: A Multi-methodological Approach

Acta Parasitologica (2026) 71:94 https://doi.org/10.1007/s11686-026-01283-4 ORIGINAL ARTICLE First Molecular Detection of Echinococcus granulosus Sensu Stricto in Dogs from Istanbul’s Anatolian Side: A Multi-methodological Approach Mesut Akil1 · Mehmet Karakus2 · Sena Erkinay3 · Mehmet Aykur4 · Hakki Seckin Cetin5 · Muhammet Karakavuk6 · Tuncer Ozekinci7 · Esra Kocoglu7 Received: 18 December 2025 / Accepted: 9 April 2026 © The Author(s) 2026 Abstract Purpose Cystic echinococcosis (CE) is a zoonotic disease caused by the larval stage of Echinococcus granulosus sensu lato (s.l.). Istanbul’s large stray dog population represents a significant risk for human CE transmission. However, prevalence and genotype studies about E. granulosus s.l. in dogs remain limited. This study aimed to determine the presence and genotypes of E. granulosus s.l. in stray dogs on the Anatolian side of Istanbul using microscopy, Copro-Enzyme-Linked Immunosorbent Assay (Copro-ELISA), and molecular diagnostic methods. Methods Fecal samples (n = 110) were collected from stray dogs in seven districts. Samples were examined using modified formalin–ethyl acetate sedimentation (mFEAS). Coproantigens were detected using a commercial ELISA kit. Genomic DNA was extracted for PCR targeting the mitochondrial CO1 gene, and positive amplicons were sequenced and evaluated phylogenetically. Results Microscopy revealed Taeniid-type eggs in 2 samples (1.8%) and these were confirmed molecularly. Copro-ELISA detected 7 positive samples (6.4%); however, none of these were confirmed by molecular and microscopy. Sequencing analysis revealed E. granulosus sensu stricto (s.s.) (G1 genotype) in 2 dogs from Sultanbeyli and Beykoz. Phylogenetic analysis demonstrated both isolates clustered within the E. granulosus s.s. (G1–G3) clade. Conclusions This study provides the first molecular confirmation of E. granulosus s.s. in stray dogs on Istanbul’s Anatolian side, showing active zoonotic transmission potential in this highly populated region. The discrepancy between Copro-ELISA and molecular/microscopic findings highlights the requirement for multi-methodological approach. Continuing prevalence studies and molecular surveillance within a One Health framework are essential to reduce the public health threat posed by CE. Keywords Echinococcus granulosus · Dogs · Copro-ELISA · Copro-PCR · Genotype · Istanbul Mesut Akil 1 Department of Parasitology, Faculty of Medicine, Istanbul Medeniyet University, 34700 Istanbul, Uskudar, Turkey 2 Department of Medical Microbiology, Hamidiye Faculty of Medicine, University of Health Sciences, Istanbul, Turkey 3 Department of Parasitology, Veterinary Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey 4 Department of Parasitology, Faculty of Medicine, Tokat Gaziosmanpasa University, Tokat, Turkey 5 ParsLab Veterinary Laboratory, Umraniye, Istanbul, Turkey 6 Odemis Vocational School, Ege University, Izmir, Turkey 7 Department of Medical Microbiology, Faculty of Medicine, Istanbul Medeniyet University, Istanbul, Turkey Introduction Cystic echinococcosis (CE) is an important zoonotic disease caused by the larval stage of Echinococcus granulosus sensu lato (s.l.), which is a cryptic species complex [1]. This disease continues to pose serious health risks to both animals and humans; notably, recent epidemiological data highlight its persistent public health impact and distribution across Europe [2]. CE is more common in areas where the dog population and livestock farming are widespread. Therefore, it causes a considerable economic burden on the livestock industry and public healthcare sector [3]. According to its global impact, the World Health Organization 13 94 Page 2 of 10 listed CE as one of the most important food-borne parasitic diseases in 2014 [4]. Carnivores, particularly dogs, play a role as a definitive host in the domestic life cycle of E. granulosus s.l [5]. Additionally, a sylvatic cycle exists involving various wild canids such as dingoes and wolves serve as definitive hosts, while wild ungulates (moose, elk, red deer, and wild boar), and various marsupials, such as kangaroos, act as intermediate hosts. And this cycle varies by region, as observed in the Australian sylvatic cycle or the Northern form in North America and Eurasia [6, 7]. In both domestic and sylvatic life cycles, adult parasites are located in small intestine of definitive hosts, and the eggs of the parasite are spread to the environment via feces, contaminating soil, water, and food sources. Intermediate hosts, including livestock (sheep, cattle, and goat etc.), wild ungulates and humans can become infected by ingesting these eggs from contaminated sources [8]. Humans are accidental intermediate hosts. Once the infection is acquired from dogs, hydatid cysts develop primarily in the liver, secondarily in the lungs and then in other organs. Therefore, transmission risk is especially high in endemic areas with large stray dog populations, where the domestic cycle is actively maintained [3, 9]. Molecular studies have revealed that E. granulosus s.l. is a cryptic species complex including distinct genotypes and species with varying geographic distributions, host specificity, and pathogenicity. Within this complex, E. granulosus sensu stricto (s.s) (G1–G3) is recognized as the primary cause of cystic echinococcosis in human [10]. Phylogenetic studies have also identified other genotypes of the complex including E. equinus (G4), E. ortleppi (G5), E. canadensis (G6-G10) and E. felidis [5, 11]. In endemic regions, such as many parts of Türkiye, the large and growing stray dog population plays significant role in transmission of E. granulosus s.l. In molecular studies investigating genotypes of E. granulosus s.l. in Türkiye, the G1-G3, G4, G6, and G7 genotypes were identified in livestock animals, while the G1-G3, G4, G6, and G7 genotypes were detected in humans [12, 13]. The studies in dogs have also revealed the presence of G1-G3, G4, G5 and G6/G7 genotypes [14]. Despite these findings, data on the prevalence and genotype diversity of E. granulosus s.l. in dogs remains limited, particularly studies using advanced molecular approaches [8, 15]. Diagnosing Echinococcus infections in dogs is a crucial step for understanding the epidemiology and planning effective control programs. There are several diagnostic methods for the infection in dogs, each with advantages and disadvantages. Direct microscopy of dog feces is commonly used to investigate the presence of eggs or adult forms of the parasite. Although supplementary methods like flotation and sedimentation techniques can help in the detection of 13 Acta Parasitologica (2026) 71:94 parasitic structures, enhancing the sensitivity of technique, it is limited by its inability to differentiate from Taeniid-type eggs [16, 17]. The detection of E. granulosus s.l. antigens in feces using Copro-Enzyme-Linked Immunosorbent Assay (Copro-ELISA) provides (...truncated)