High Diversity of Giardia duodenalis Assemblages and Sub-Assemblages in Asymptomatic School Children in Ibadan, Nigeria

Abstract

Giardia duodenalis is a significant contributor to the burden of diarrheal disease in sub-Saharan Africa. This study assesses the occurrence and molecular diversity of G. duodenalis and other intestinal parasites in apparently healthy children (n = 311) in Ibadan, Nigeria. Microscopy was used as a screening method and PCR and Sanger sequencing as confirmatory and genotyping methods, respectively. Haplotype analyses were performed to examine associations between genetic variants and epidemiological variables. At microscopy examination, G. duodenalis was the most prevalent parasite found (29.3%, 91/311; 95% CI: 24.3–34.7), followed by Entamoeba spp. (18.7%, 58/311; 14.5–23.4), Ascaris lumbricoides (1.3%, 4/311; 0.4–3.3), and Taenia sp. (0.3%, 1/311; 0.01–1.8). qPCR confirmed the presence of G. duodenalis in 76.9% (70/91) of the microscopy-positive samples. Of them, 65.9% (60/91) were successfully genotyped. Assemblage B (68.3%, 41/60) was more prevalent than assemblage A (28.3%, 17/60). Mixed A + B infections were identified in two samples (3.3%, 2/60). These facts, together with the absence of animal-adapted assemblages, suggest that human transmission of giardiasis was primarily anthroponotic. Efforts to control G. duodenalis (and other fecal-orally transmitted pathogens) should focus on providing safe drinking water and improving sanitation and personal hygiene practices.

Assemblages and Subassemblages of Giardia duodenalis in Rural Western, Kenya: Association with Sources, Signs, and Symptoms

“…Furthermore, studies in Mozambique demonstrated that assemblage B of the parasite accounted for 90% of giardiasis infection in children under five years of age [ 6 ]. Similar results were also obtained in asymptomatic Nigerian children 5 to 17 years old showing that assemblage B was more frequent than assemblage A infections [ 28 ]. The reasons as to why children appear to be more vulnerable to assemblage B infection include the fact that they are more active and thus likely to interact with contaminated environment and associated risk factors.…”

“…It is worthy to note that this study recruited both children (age ≥ 3 < 18 years) and adults referred to the clinical laboratory for stool analysis, as such the G. duodenalis genotypes were associated with gastrointestinal complaints and stool characteristics. Although sequencing techniques have been utilized in the molecular characterization of G. duodenalis genotypes [ 9 , 28 , 46 , 47 ], the current study used the frequently applied multilocus genotyping strategy based on the constitutively expressed genetic markers GDH and TPI [ 48 ]. Despite the current study showing a link of G. duodenalis assemblages A and B with human contact with cattle, goats, and poultry, the rates of giardiasis in these animals including abattoirs and sewage treatment plants were not determined.…”