Mapping environmental suitability for P ythium insidiosum under current and future climate conditions

Pythium insidiosum is an aquatic oomycete causing pythiosis, a serious disease in humans and animals, particularly dogs and horses. Treatment is limited and often requires surgery, leading to substantial health and economic impacts. In Thailand, infections occur mainly in rural areas with frequent environmental exposure and limited healthcare. Despite its importance, the environmental drivers of the persistence of the organism remain poorly understood. This study assessed the current environmental suitability for P. insidiosum and examined changes through 2100 under different climate scenarios. A two-step modeling approach was used, incorporating confirmed occurrence records and key environmental variables. The highest suitability was found in the irrigated lowlands, particularly in the Chao Phraya Basin. Under higher-emission scenarios, suitable areas expanded into parts of northeastern and eastern Thailand, while the upland regions consistently showed low suitability. These findings highlight uneven future risk and support the need for coordinated One Health surveillance.