Genetic diversity of Cryptosporidium isolates from human populations in an urban area of Northern Tunisia.

Cryptosporidium is an enteric parasite infecting a wide range of hosts. It has emerged as an important cause of chronic life-threatening diarrhea in humans worldwide. Several subtypes of Cryptosporidium sp. have been described to be responsible for several large outbreaks related to water contamination in developed countries. However, there is a lack of information in the genetic diversity of Cryptosporidium among human population especially in developing countries. The present study aimed to update and report the genetic diversity of human Cryptosporidium spp. at the subtype level in an urban area of Tunisia using the 18S rRNA and gp60 gene. Genotyping of 42 Cryptosporidium positive isolates from different human populations at the 18S rRNA locus has identified three Cryptosporidium species: C. hominis (n = 20), C. parvum (n = 19), C. meleagridis (n = 2) and a co-infection C. hominis/C. meleagridis (n = 1). The sub-genotyping of these isolates at the 60-kda glycoprotein (gp60) locus was possible in 40 cases. It showed the presence of three subtype families (IIa, IIb and IIc) within C. parvum, a single subtype family within C. hominis and C. meleagridis isolates (Ia and IIIb respectively). Several subtypes were implicated in different human populations with the dominance of IaA26G1R1, IIaA15G2R1, IIdA16G1R1, IIdA22G2R1 and IIIbA26G1R1 variant respectively for C. hominis, C. parvum and C. meleagridis. The distribution of Cryptosporidium isolates in urban area of Northern Tunisia was dominated by the anthroponotic transmission via C. hominis species and the IIc subtype of C. parvum. However, zoonotic transmission is still possible in this region via zoonotic subtypes of C. parvum (IIa and IId) and C. meleagridis (IIIb). Subtype diversity was higher in this area.