Multi-spatial contamination of environmental aquatic matrices with Cryptosporidium: a climate, health, and regulatory framework for the Philippines

Background: Cryptosporidium is a waterborne global pathogen causing diarrhea primarily in infants and immunocompromised individuals. The Philippines is a tropical country susceptible to the influences of climate change and water crises. To date, the country has no existing epidemiologic data, regulation, or strategy for monitoring Cryptosporidium in freshwater systems. We, therefore, endeavored to provide evidence on the multi-spatial contamination of Cryptosporidium in environmental aquatic matrices using low-cost, user-friendly, and sustainable strategies and submit implications on the presence of Cryptosporidium in freshwater systems in a climate, health, and regulatory framework. Results: Here, we present the microscopic detection of Cryptosporidium oocysts in low-volume (50 mL) environmental samples of surface water (SW), sediments (BW), and substrate-associated biofilm (SAB) and in 1 L bulk SW investigated by PCR. The multi-spatial distribution of Cryptosporidium oocysts in the low-volume (50 ml) aquatic matrices based on microscopy was highest at 69% (20/29) in SW and lowest at 50% (13/26) in BW. Immunofluorescence technique provided the highest microscopic positivity rate with 59% (17/29), 38% (10/26), and 50% (10/20) detection in SW, BW, and SAB, respectively. The detection and identification of Cryptosporidium in 1 L bulk SW by PCR and sequence analysis was recorded in total at 21% (6/29) in sampling sites where the differential identification of C. parvum, C. hominis, and Cryptosporidium spp. was 7% (2/29), 10% (3/29), and 3% (1/29), respectively. Conclusions: We report the microscopical and first molecular epidemiologic data of Cryptosporidium from the most significant environmental freshwater systems in the Philippines. The presence of the two main human and animal pathogenic species C. parvum and C. hominis from the largest lakes and major water reservoirs in the country calls for sustainable solutions in safeguarding the quality of freshwater resources in a climate, health, and regulatory approach.