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

<i>Cryptosporidium</i> 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 <i>Cryptosporidium</i>. The Philippines, renowned for its rich biodiversity, is home to diverse bat species, providing a unique ecological setting to investigate <i>Cryptosporidium</i> infection dynamics. Understanding the prevalence and genetic diversity of <i>Cryptosporidium</i> 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 <i>Cryptosporidium</i> 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 <i>Cryptosporidium</i>, 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 <i>Cryptosporidium parvum</i> (intestinal <i>Cryptosporidium</i>) and <i>Cryptosporidium</i> sp. (gastric <i>Cryptosporidium</i>). Phylogenetic analysis of the 18S rRNA gene revealed that intestinal and gastric <i>Cryptosporidium</i> spp. form two distinct clades. Intestinal <i>Cryptosporidium</i> includes <i>C. parvum</i>, <i>C. hominis</i>, and most bat genotypes, while gastric <i>Cryptosporidium</i>, such as <i>C. andersoni</i> and <i>C. serpentis</i>, is typically found in reptiles and cattle. An unidentified <i>Cryptosporidium</i> species was also detected in one sample, whose sequence matched that of <i>Cryptosporidium</i> previously isolated from a human patient with diarrhea. Nine other samples exhibited genotypes related to <i>C. parvum</i>, indicating a potential for transmission to humans. The remaining three samples exhibited <i>Cryptosporidium</i> 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 <i>Cryptosporidium</i> and highlight the diversity of <i>Cryptosporidium</i> species in Philippine bats.