Giardia duodenalis assemblage, clinical presentation and markers of intestinal inflammation in Brazilian children

Abstract

SummaryData on the relationship between the two genotypes of Giardia duodenalis that infect humans, assemblages A and B, their clinical presentation and intestinal inflammation are limited. We analyzed 108 stool samples previously collected for a diarrhoeal study among Brazilian children, representing 71 infections in 47 children. Assemblage B was most prevalent, accounting for 43/58 (74.1%) infections, while assemblage A accounted for 9/58 (15.5%) infections and 6/58 (10.3%) infections were mixed (contained both assemblage A and B). There was no significant difference in diarrhoeal symptoms experienced during assemblage A, B or mixed infections. Children with assemblage B demonstrated greater variability in G. duodenalis cyst shedding but at an overall greater level (n = 43, mean 3.6 × 10 5 , range 5.3 × 10 2 -2.5 × 10 6 cysts/ml) than children infected with assemblage A (n = 9, mean 1.4 × 10 5 , range 1.5 × 10 4 -4.6 × 10 5 cysts/ml; P = 0.009). Children with mixed infections shed more cysts (mean 8.3 × 10 5 , range 3.1 × 10 4 -2.8 × 10 6 cysts/ml) than children with assemblage A or B alone (P = 0.069 and P = 0.046 respectively). This higher rate of cyst shedding in children with assemblage B may propagate its spread, accounting for its increased incidence. Additionally, second and third infections had decreasing faecal lactoferrin, suggesting some protection against severity, albeit not against infection, by prior infection. Authors' contributions: AAML, RLG, AK and OYB designed the study protocol; RDN, AK and OYB carried out the clinical assessment; AK carried out and EH designed and carried out the quantitative PCR of Giardia; AK, RCP, OYB, CLS and RDN carried out the analysis and interpretation of these data; AK, OYB, RDN and CLS drafted the manuscript. All authors read and approved the final manuscript. AK and RLG are guarantors of the paper.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Conflicts of interest: None declared.Ethical approval: The study protocol and informed consent were approved by the human investigations committees of the Federal

Giardia duodenalis: NEW INSIGHTS ON AN ANCIENT PARASITE

“…Similar results were observed in Bangladesh, Spain and Portugal, with a significant association between genotype A and symptomatic infection being reported [104,107]. Unlike the above mentioned studies, some reports have not found a correlation between genotype and clinical presentation of giardiasis [102].…”

“…Several studies have suggested that the variability of symptoms of giardiasis would be mediated by the host immune response. A longitudinal study in endemic areas of Brazil indicated that individuals previously infected with Giardia were less prone to symptomatic reinfection than individuals who were never exposed to the parasite [102]. Our research group has observed that the frequency of symptomatic giardiasis in schoolchildren in the province of Buenos Aires diminished as age increased [47,48].…”

Epidemiological, parasitological and molecular aspects of Giardia duodenalis infection in children attending public daycare centers in southeastern Brazil

“…29 Several studies have been conducted using 18S rRNA markers. However, although it is an excellent marker, gdh has higher variability and allows for the subtyping within assemblages.…”

Genotipos de Giardia duodenalis en niños de las guarderías del Instituto Colombiano de Bienestar Familiar y de caninos en Ibagué, Tolima, Colombia

“…Durante nuestro estudio no se tuvo en cuenta la sintomatología del paciente, por lo cual no se pudo hacer una correlación entre el genotipo y las manifestaciones clínicas, como sí lo han hecho otros autores (36,37).…”