First report of biological contaminants in household water in the Philippines and long-term viability of Acanthamoeba species in one-year-old household water sediment

This study aimed to detect biological contaminants, specifically Cryptosporidium, Cyclospora, Giardia, and FLAs, in Metro Manila, Philippines' household water samples. Eighty household water samples comprising 40 unfiltered water/water filter scrapings (F0) and 40 filtered water samples (F1) were filtered through a 1.2 μm-pore glass microfiber filter. F0 samples demonstrated Cryptosporidium, Cyclospora, and Giardia spp. (oo)cysts through Modified Kinyoun's staining. Non-nutrient agar culture and DNA sequencing identified Acanthamoeba genotype T4, Acanthamoeba polyphaga, and Vermamoeba vermiformis. Incidental findings of suspected Trichostrongylus species larvae and fungi (Cubamyces flavidus and Candida parapsilosis) were also identified. A significant discovery was the long-term viability of Acanthamoeba lenticulata in household water sediment, stored unpreserved for one year at room temperature. All F1 samples were negative for the target biological contaminants. These biological contaminants are a risk to human health and can cause gastrointestinal and extra-intestinal infections with morbid to mortal outcomes. The age of filters ranged from 0.5 to 48 months, demonstrating prolonged use beyond a water filter's life span. The reported biological contaminants are evidence of the poor state of water quality in the main metropolis of the Philippines and highlight the urgent need for immediate action from all government and private sector stakeholders.