Determining the prevalence of giardiasis and intestinal parasitism in pre-school children from the Instituto Colombiano de Bienestar Familiar (ICBF). Three serial faecal samples were collected from 328 children following informed consent from their legal guardians. Microscopic and macroscopic tests were made using 1% Lugol, 0.83% saline solution, saline-eosin solution and Kato Katz and Ritchie's test as a confirming test. Positive samples were preserved in saline formol solution. Pathogen parasites had the following prevalence frequencies: 2.4% for Ascaris lumbricoides, 0.6% for Hymenolepsis nana, 2.1% for Trichuris trichura, 6.1% for Blastocystis hominis and 13% for Giardia lamblia. The results of this work showed low helminth frequency compared to that for protozoa; control strategies using single doses of Albendazol are therefore not useful. The most prevalent pathogen parasite was Giardia lamblia in children from the ICBF in Armenia. Periodic surveillance of parasites in children is thereby recommended. The prevalence of Giardia lamblia was not statistically related to the children's nutritional state. Most Giardia-infected children were asymptomatic.

Two zoonotic protozoan pathogens, Giardia duodenalis and Toxoplasma gondii, are important causes of waterborne infections in the Quindío region in Colombia. No previous data exist on how contamination occurs at the source for drinking water consumed by the human population in this region. Our aim was to describe the frequency of G. duodenalis and T. gondii DNA in 11 sampling points during a five-month period in water and adjacent soil at the Quindío River basin (Andean region in the central western part of Colombia). The study employed nested PCR for T. gondii, using the B1 gene as the amplification target, and single-round PCR for G. duodenalis assemblage A and assemblage B, amplifying the gdh gene, followed by DNA sequencing. In 50 soil samples, 28% (14/50) were positive for T. gondii. For G. duodenalis, distribution was in equal parts for assemblage A (8%; 4/50) and assemblage B (8%, 4/50). Genotyping of T. gondii sequences showed two soil samples with type I strain, another two samples of soil with type III strain, but most samples were of unidentified strains. In water samples, T. gondii was detected in 9.1% (5/55), G. duodenalis assemblage A in 34.5% (19/55), and G. duodenalis assemblage B in 12.7% (7/55). T. gondii DNA positivity was associated with lower soil temperature (p = 0.0239). Presence of G. duodenalis and T. gondii was evidenced in soil and water samples in the Quindío River basin, indicating soil as the potential source of contamination for the river that it is destined for human consumption. Monitoring these protozoa in drinking water is necessary to prevent public health risks in human populations.