Environmental and Epidemiological Factors Influencing Schistosomiasis Transmission Among Ruminants in Municipalities Around Naujan Lake, Oriental Mindoro, Philippines

Abstract

This study aimed to map endemic areas of Schistosomiasis, identify snail sites, evaluate epidemiological factors, and raise awareness of public and animal health risks. Research was conducted around Naujan Lake, Oriental Mindoro using Formalin Ethylene Acetate Sedimentation Digestion (FEA-SD) technique and direct microscopy on ruminant feces and Oncomelania hupensis quadrasi (Katsurada 1904) snails. High-risk areas were identified in Socorro and Pola, where carabaos were found to significantly contribute to Schistosomiasis transmission by defecating near snail habitats, perpetuating the parasite’s life cycle. Intermediate host snails were found in 34 snail-positive sites across the municipalities. High disease prevalence in these areas was associated with favorable environmental conditions: water pH of 7.51–7.61, humidity of 75.33–76.29%, water temperature of 23.55–26.19°C, and air temperature of 31.47–32.80°C. A significant negative correlation between ruminant infection rates and environmental variables was observed. Using multiple regression, Schistosomiasis prevalence (Pₛₕᵢₛₜₒₘᵢₐₛᵢₛ) was predicted with 93% accuracy through the equation: Pₛₕᵢₛₜₒₘᵢₐₛᵢₛ = 5.85013(SF) – 0.08091(WTEMP) – 0.09910(ATEMP), where SF = presence of Schistosomes in feces, WTEMP = water temperature, ATEMP = air temperature. These findings emphasize the strong influence of environmental conditions on disease proliferation. The study recommends systematic monitoring of snail sites and environmental parameters to support control programs. Local policies must consider replacing carabaos with mechanized tools in endemic areas to break transmission cycles. For enhanced surveillance and accurate detection, advanced diagnostic techniques such as enzyme-linked immunosorbent assay (ELISA) or reverse transcription polymerase chain reaction (RT-PCR) should be employed in both human and animal populations within endemic zones.