Molecular characterization and zoonotic risk assessment of Cryptosporidium spp. in Philippine bats

Cryptosporidium is a genus of parasitic protozoa known to cause diarrheal disease that impacts both humans and animals through infection of various vertebrate species. Bats are recognized as reservoirs for zoonotic pathogens, including Cryptosporidium. The Philippines, renowned for its rich biodiversity, is home to diverse bat species, providing a unique ecological setting to investigate Cryptosporidium infection dynamics. Understanding the prevalence and genetic diversity of Cryptosporidium in Philippine bats is crucial for assessing their potential role in zoonotic disease transmission and associated public health risks. We investigated the prevalence and genotypic diversity of Cryptosporidium in bats in the Philippines. From January 2019 to March 2024, a total of 569 bats were captured and analyzed, with 14 of the bat samples testing positive for the 18 s rRNA gene of Cryptosporidium, yielding an overall infection rate of 2.46 %. One sample exhibited co-infection, with 18 s rRNA sequence analysis indicating mixed infection with a species closely related to Cryptosporidium parvum (intestinal Cryptosporidium) and Cryptosporidium sp. (gastric Cryptosporidium). Phylogenetic analysis of the 18S rRNA gene revealed that intestinal and gastric Cryptosporidium spp. form two distinct clades. Intestinal Cryptosporidium includes C. parvum, C. hominis, and most bat genotypes, while gastric Cryptosporidium, such as C. andersoni and C. serpentis, is typically found in reptiles and cattle. An unidentified Cryptosporidium species was also detected in one sample, whose sequence matched that of Cryptosporidium previously isolated from a human patient with diarrhea. Nine other samples exhibited genotypes related to C. parvum, indicating a potential for transmission to humans. The remaining three samples exhibited Cryptosporidium bat genotypes II and VI, which have previously been detected in Philippine bats. Our findings underscore the role of bats in the Philippines as potential reservoirs for Cryptosporidium and highlight the diversity of Cryptosporidium species in Philippine bats.