Epidemiological surveillance of waterborne diseases among displaced populations: A cross-sectional study.

Armed conflict and forced displacement in the Gaza Strip have severely disrupted access to safe water and sanitation, increasing the risk of waterborne diseases. This study aimed to assess the prevalence of waterborne illness symptoms and evaluate water quality, sanitation conditions, and associated risk factors among internally displaced persons (IDPs) in Gaza. A cross-sectional survey was conducted from March 16 to July 2, 2025, involving 1,200 displaced individuals residing in temporary shelters across five governorates. Data were collected on self-reported symptoms, water sources, sanitation access, and hygiene practices. In addition, 240 household water samples (20%) were microbiologically tested for fecal coliforms and Escherichia coli. Logistic regression was used to identify factors associated with reported illness. Among participants, 31.5% reported symptoms consistent with waterborne illness, with the highest prevalence among children under five years (38.3%). Only 27.5% accessed piped or humanitarian water, whereas 61.2% relied on trucked water from unregulated vendors. Shared sanitation was common, with 45.4% using latrines shared by ≥5 families, and 31.7% lacking soap. Microbiological testing showed that 74.2% of water samples exceeded WHO thresholds for fecal coliforms and 62.5% tested positive for E. coli, with significantly higher contamination in water from unregulated vendors (p < 0.001). In adjusted models, use of untreated water (aOR 2.31), shared sanitation (aOR 1.89), and lack of soap (aOR 1.77) were independently associated with increased odds of illness. Displaced populations in Gaza face a high burden of waterborne illness, primarily driven by unsafe water sources, overcrowded sanitation, and poor hygiene. These findings underscore the urgent need for integrated WASH interventions and strengthened disease surveillance to prevent outbreaks and protect vulnerable populations in conflict-affected settings.