Rivers are important freshwater sources. They provide water for domestic and recreational use and serve as ecological sites for various microorganisms. Free-living amoebae are considered naturally occurring organisms in freshwater. However, their prevalence can suggest the water quality at a given source. Forty-five surface water samples from nine different sites were collected from the Marikina River. Samples were processed and cultured in non-nutrient agar (NNA) lawned with Escherichia coli, and were observed for 14 days using a light microscope. Thirty-six (80%) samples yielded a positive amoebic growth. Further molecular testing confirmed the presence of Acanthamoeba spp. using specific primer sets, JDP1 and JDP2. The current results of this study have shown a remarkable jump in the detection rate for free-living amoebae (FLAs). The continued deterioration of the Marikina River due to several human and non-human factors may have been the reason for this phenomenon. River clean-up, resettlement programs, and strict implementation of laws on waste disposal should be considered to rehabilitate the Marikina River.

河流是重要的淡水来源。它们提供生活用水和娱乐用水，并作为各种微生物的生态场所。自由生活的变形虫被认为是淡水中自然存在的生物。然而，它们的流行程度可以表明特定水源的水质。从马里基纳河采集了来自 9 个不同地点的 45 个地表水样本。样品在铺有大肠杆菌的非营养琼脂（NNA）中进行处理和培养，并使用光学显微镜观察 14 天。三十六个 (80%) 样本显示出阿米巴原虫阳性生长。进一步的分子测试证实了棘阿米巴属的存在。使用特定引物组 JDP1 和 JDP2。这项研究的当前结果表明，自由生活的变形虫（FLA）的检出率显着提高。由于多种人为和非人为因素，马里基纳河的持续恶化可能是造成这一现象的原因。应考虑河流清理、重新安置计划和严格执行废物处理法律来恢复马里基纳河。