<i>Cryptosporidium hominis</i> n. sp. (Apicomplexa: Cryptosporidiidae) from <i>Homo sapiens</i>

TLDR

The study describes the structure and infectivity of oocysts from a newly identified human Cryptosporidium species. The oocysts are morphologically similar to *C. parvum* but are fully sporulated, lack sporocysts, measure 4.4–5.9 µm, are non‑infectious to several mammals yet infect neonatal gnotobiotic pigs, exhibit distinct pathogenicity and growth patterns, and genetic analysis confirms the organism as a separate species, *C.

Abstract

ABSTRACT. The structure and infectivity of the oocysts of a new species of Cryptosporidium from the feces of humans are described. Oocysts are structurally indistinguishable from those of Cryptosporidium parvum . Oocysts of the new species are passed fully sporulated, lack sporocysts, and measure 4.4–5.4 μm (mean = 4.86) × 4.4–5.9 μm (mean = 5.2μm) with a length to width ratio 1.0–1.09 (mean 1.07) (n = 100). Oocysts were not infectious for ARC Swiss mice, nude mice, Wistar rat pups, puppies, kittens or calves, but were infectious to neonatal gnotobiotic pigs. Pathogenicity studies in the gnotobiotic pig model revealed significant differences in parasite‐associated lesion distribution (P = 0.005 to P = 0.02) and intensity of infection (P = 0.04) between C. parvitm and this newly described species from humans. In vitro cultivation studies have also revealed growth differences between the two species. Multi‐locus analysis of numerous unlinked loci, including a preliminary sequence scan of the entire genome demonstrated this species to be distinct from C. parvum and also demonstrated a lack of recombination, providing further support for its species status. Based on biological and molecular data, this Cryptosporidium infecting the intestine of humans is proposed to be a new species Ciyptosporidium hominis n. sp.