Emergence of Cryptosporidium parvum IIc Subtype and Giardia duodenalis Assemblage E in AIDS Patients in Central China: Evidence for Neglected Transmission Dynamics

Zoonotic opportunistic enteric protozoa represent a significant global health threat to immunocompromised populations, especially individuals with human immunodeficiency virus (HIV). Despite China's severe HIV burden, molecular epidemiological data on enteric protozoa remain limited in this population. In this study, we investigated the occurrence and molecular characteristics of <i>Cryptosporidium</i> species, <i>Giardia duodenalis</i>, and <i>Enterocytozoon bieneusi</i> among 150 AIDS patients with severe immunodeficiency in Wuhan city, Hubei Province, China. The overall test-positive rate was 5.33% (8/150), comprising <i>Cryptosporidium</i> species (including <i>C. hominis</i>, <i>C. parvum,</i> and <i>C. meleagridis</i>) in 2.00% (3/150) and <i>G. duodenalis</i> (including assemblage A, B, and E) in 3.33% (5/150); <i>E. bieneusi</i> was not detected. Notably, this study reports the first identification of the <i>C. parvum</i> subtype IIcA5G3 in humans in China, certainly indicating possible cross-border transmission. Furthermore, the detection of <i>C. meleagridis</i> IIIbA22G1R1c provided additional molecular evidence for chicken-to-human transmission. The finding of <i>G. duodenalis</i> assemblage E highlights the underrecognized zoonotic spillover risks to immunocompromised populations. These findings emphasize the diversity of infectious reservoirs, and the need for enhanced national molecular surveillance of these neglected zoonotic enteric protozoa, alongside targeted interventions for vulnerable populations.