Asymptomatic carriage of diarrhoea-causing enteric protist parasites in the general population is poorly understood, particularly in medium- to high-income countries. This molecular epidemiological survey investigates the presence, molecular diversity, and household transmission of
Giardia duodenalis,
Cryptosporidium spp.,
Blastocystis sp., and
Enterocystozoon bieneusi in schoolchildren aged 2–13 years (
n = 74) and their legal guardians (
n = 6) in Madrid, Spain. Enteroparasite detection and genotyping was conducted in stool samples by molecular (PCR and Sanger sequencing) methods. Potential associations linked to infections were investigated through epidemiological questionnaires.
Giardia duodenalis was the most prevalent enteric parasite found (14%, 95% CI: 7.1–23), followed by
Blastocystis sp. (10%, 95% CI: 6.2–22) and
Cryptosporidium spp. (3.8%, 95% CI: 0.78–11). None of the participants tested positive for
E. bieneusi. Sequence analyses revealed the presence of
G. duodenalis assemblage B, sub-assemblage BIV in a single child. The three
Cryptosporidium isolates obtained were assigned to
C. hominis, two of them belonging to the
gp60 subtype IbA10G2. Four
Blastocystis subtypes were identified including ST2 (38%, 3/8), ST3 (25%, 2/8), ST4 (25%, 2/8), and ST8 (12%, 1/8). All
G. duodenalis and
Cryptosporidium isolates were detected in children only.
Blastocystis ST3 and ST4 were circulating in members of the same household.
Blastocystis carriage rates increased with the age of the participants. Presence of diarrhoea-causing enteric protists was common in apparently healthy children.
Full article
