Molecular Identification and Drug Susceptibility of Cryptosporidium Species in HIV-Positive Patients in Kaduna State

Molecular species identification of Cryptosporidium is critical for understanding transmission pathways and clinical prognosis, given that C. hominis and C. parvum have distinct epidemiological and clinical profiles in immunocompromised individuals. This study performed molecular identification and drug susceptibility characterisation of Cryptosporidium isolates from HIV-positive patients in Kaduna State, Northwest Nigeria. Stool samples from 180 HIV-positive patients with confirmed diarrhoea were screened by modified Ziehl-Neelsen staining, and positive samples underwent DNA extraction for PCR amplification of the 18S rRNA gene. Amplicons were sequenced and subjected to phylogenetic analysis for species and subtype assignment. Nitazoxanide minimum inhibitory concentrations were determined using in vitro drug susceptibility assays on viable oocysts. Cryptosporidium was detected in 24.4 percent of diarrhoea patients. C. hominis IbA10G2 was the predominant subtype at 61.4 percent of sequenced isolates, followed by C. parvum IIa and IId subtypes. Phylogenetic analysis confirmed human anthroponotic transmission pathways as dominant. In vitro nitazoxanide susceptibility was reduced in three isolates from patients who had previously received nitazoxanide therapy. These findings provide the first molecular subtyping data for Cryptosporidium from Northwest Nigeria and highlight the need for HIV care protocols to incorporate species-differentiated treatment approaches. Keywords: Cryptosporidium, molecular identification, HIV, drug susceptibility, Kaduna State.