Risk Factors for Infectious Disease Emergence following the late October 2024 Valencia Floods (Eastern Iberian Peninsula, Spain)

On October 29, 2024, extreme weather struck the eastern part of the Iberian Peninsula, causing heavy rainfall that triggered ephemeral stream overflows and destructive flooding. These events affected 75 municipalities in Valencia province, including Valencia City, which is located on the banks of the Turia River. Regarding the direct impact on the population, the flooding caused about 237 fatalities based on official reports published by the governmental authorities.

The methodology applied in this research involved detecting risk factors that could trigger a public health crisis in flood-affected Valencia province, including the collection of disaster-related observations and information during post-event field surveys conducted by the authors shortly after the disaster.

Residential areas were inundated and underground urban spaces, including car parks and underpasses, were filled with water, locally reaching or exceeding 7 meters. Vehicles were swept away, blocking roads and underpasses. Heavy structural damage included building collapses and partial destruction of bridges due to intense stream erosion. Flood deposits and debris left extensive areas submerged for days.

Beyond the impact on infrastructure and the population, risk factors for infectious diseases emerged immediately after flooding. Disrupted clean water supply and contamination of drinking water by sewage and flood waste compromised water quality in Valencia City and increased the risk of gastrointestinal diseases.

Environmental changes, such as floodwater accumulation in underground urban spaces and sensitive habitats like the Albufera lagoon south of Valencia City, pose significant public health risks by creating breeding grounds for vectors, increasing the transmission of rodent- and mosquito-borne diseases and the likelihood of infectious disease outbreaks.

Flood waste management is a key risk factor for infectious disease emergence in flood-affected Valencia. Disaster responders faced risks from hazardous flood waste, inadequate personal protective equipment, and improper disposal sites within residential areas.

Efficient local and regional disease surveillance is vital for early warning and prevention of infectious diseases in flood-affected areas. Key measures include training for involved agencies, public education and awareness raising, and implementing structural and nonstructural actions to enhance climate resilience of infrastructure within a One Health framework.