The protozoan parasite Giardia intestinalis and the pathogenic bacterium Helicobacter pylori are well known for their high prevalences in human hosts world-wide. The prevalence of both organisms is known to peak in densely populated, low resource settings and children are infected early in life. Different Giardia genotypes/assemblages have been associated with different symptoms and H. pylori with induction of cancer. Despite this, little data is available from sub-Saharan Africa with regards to the prevalence of different G. intestinalis assemblages and their potential association with H. pylori infections.
Fecal samples from 427 apparently healthy children, 0-12 years of age, living in urban Kampala, Uganda were analyzed for the presence of H. pylori and G. intestinalis. G. intestinalis was found in 86 (20.1%) out of the children and children age 1<5 years had the highest rates of colonization. No significant association was found in the studied population with regards to the presence of Giardia and gender, type of toilet, source of drinking-water or type of housing. H. pylori was found in 189 (44.3%) out of the 427 children and there was a 3-fold higher risk of concomitant G. intestinalis and H. pylori infections compared to non-concomitant G. intestinalis infection, OR = 2.9 (1.7-4.8). A panel of 45 G. intestinalis positive samples was further analyzed using multi-locus genotyping (MLG) on the β-giardin (bg), glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) loci, combined with assemblage-specific analyses. Giardia MLG analysis yielded a total of five assemblage A, 25 assemblage B, and four mixed assemblage infections. The assemblage B isolates were highly genetically variable and a significant association was found between Giardia assemblage B and H. pylori infection, OR=5.0 (1.9- 16).
This study shows that Giardia assemblage B dominates in children in Kampala, Uganda and that Giardia-infected children have a 3-fold higher risk of being infected by H. pylori. The data also suggests that assemblage B Giardia may be more closely associated with H. pylori infection.