University of Tabriz Journal of Zoonotic Diseases 2476-535X 10 1 2026 01 01 Prevalence and zoonotic implications of Dirofilariasis in shelter dogs in Gilan province, Iran 1106 1113 21043 10.22034/jzd.2026.21043 EN Bahar Ghanbari Department of Parasitology, Faculty of veterinary Medicine, University of Tehran, Tehran, Iran Seyed Hossein Hosseini Department of parasitology, faculty of veterinary medicine, University of Tehran, Tehran, Iran Shahram Jamshidi Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran Fateme Jalousian Department of parasitology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran Niloofar Mosavat Department of internal medicine, faculty of veterinary medicine, University of Tehran, Tehran, Iran Fatemeh Manshori Ghayshghorshagh Department of parasitology, faculty of veterinary medicine, University of Tehran, Tehran, Iran Journal Article 2025 11 11 Dirofilariasis, caused by <em>Dirofilaria immitis</em> (<em>D. immitis</em>), is a zoonotic disease. Iran is an endemic country, and shelter dogs are particularly susceptible due to limited veterinary care, high-density housing, and increased exposure to mosquito vectors. This study aimed to determine the prevalence of <em>D. immitis</em> in shelter dogs in Gilan province, northern Iran, using a combined parasitological and molecular approach. A total of 271 blood samples were collected from shelter dogs across seven cities in Gilan province. All samples were initially screened for microfilariae using the modified Knott's test. Subsequently, they were analyzed by a species-specific PCR targeting the 155 bp partial sequence of the ITS1 gene of <em>D. immitis</em>, with the beta-actin gene amplified as an internal control. The modified Knott's test identified microfilariae in 32 dogs (11.80% prevalence), while PCR analysis detected <em>D. immitis</em> DNA in 143 dogs, corresponding to a significantly higher prevalence of 52.8%. Measurements taken with Axiovision software (v4.1) yielded average microfilarial dimensions of 301.89 µm in length (±13.351) and 6.392 µm in width (±0.5). This discrepancy highlights a substantial number of occult (amicrofilaremic) infections, and the hyper endemic status of <em>D. immitis</em> in shelter dogs in Gilan province. Within the shelter environment, the high-density housing of susceptible dogs creates an amplification hotspot. In Gilan province, the hyperendemicity is likely driven by environmental and entomological factors. These findings necessitate the development of integrated control strategies, including routine molecular screening, preventive chemotherapy, and formal shelter management protocols, to mitigate animal suffering and reduce zoonotic risk. https://jzd.tabrizu.ac.ir/article_21043_0766a71b8601ce4e206cd035fb5b6bbc.pdf