Emergence and spread of Aedes albopictus in northern Iran with risk assessment and habitat hotspot analysis in Mazandaran Province.

Diverse ecosystems, trade and travel create favorable conditions for the spread and establishment of invasive Aedes species in different geographical areas and the diseases they transmit. To maximize the effect of vector control and preventive interventions, it is crucial to detect the presence of invasive Aedes mosquitoes through entomological surveillance and map their larval habitats, hence, this study aimed to search for invasive Aedes mosquitoes as well as identify potential larval habitats and assess the risk of invasive Aedes dispersal in Mazandaran Province. This study was conducted in Mazandaran Province, characterized by diverse ecosystems favorable for mosquito breeding. “Enhanced surveillance efforts” to identify invasive Aedes mosquitoes were conducted from early 2024 through mid-August 2025. Sampling methods include ovitraping, larval collection, and Human Landing Catches (HLC), conducted biweekly across selected counties. In the summer of the same year, an exploratory field study was conducted to identify potential larval habitats of invasive Aedes mosquitoes. Environmental parameters, along with demographic data, were recorded to assess their impact on potential larval habitat abundance. Descriptive statistics, chi-square, cluster analysis (K-means algorithm), Getis-Ord Gi, Geographically Weighted Regression (GWR), and Generalized Estimating Equations (GEE) were applied using SPSS version 25 and ArcGIS version 10.5 for data analysis. Aedes albopictus was first identified at a Hotel in Ramsar County in western Mazandaran on July 8, 2024. Subsequent detections were made at 26 sites in Ramsar and 23 sites in Tonekabon, among others. A total of 80 potential larval habitat types were identified, with disposable plastic containers being the most abundant (2271, 28.2% of total). The highest abundance of potential habitats was noted in Chalus, followed by Babolsar and Amol. Risk assessment categorized counties into three clusters based on the environmental conditions, habitat diversity and risk levels. Nur County exhibited low risk, while Amol, Babolsar, Fereydunkenar and Mahmoodabad were classified as moderate risk. Chalus, Ramsar, Tonekabon, Abbasabad, and Nowshahr counties showed a high risk profile. Spatial clustering analysis using the Getis-Ord Gi* statistic identified three out of ten cities as significant hotspots for potential Ae. albopictus larval habitats, with Z-scores ranging from 0.086 to 0.220 (p < 0.05). Apart from reporting the first record of Aedes albopictus in Mazandaran, Iran, this study provides critical insights into the spatial distribution of invasive Aedes habitats, highlighting areas of high risk and informing targeted vector control interventions. The findings contribute to public health strategies aimed at mitigating the spread of mosquito-borne diseases in northern Iran as well as contingency measures for vector control in the case of epidemics.