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

Data on the relationship between the two genotypes of Giardia duadenalis that infect humans, assemblages A and 13, their clinical presentation and intestinal inflammation are limited. We analyzed 108 stool samples previously collected for a diarrhoea( 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 x 10(5), range 5.3 x 10(2)-2.5 x 10(6) cysts/ml) than children infected with assemblage A (n = 9, mean 1.4 x 10(5), range 1.5 x 10(4)-4.6 x 10(5) cysts/mL; P = 0.009). Children with mixed infections shed more cysts (mean 8.3 x 10(5), range 3.1 x 10(4)-2.8 x 10(6) cysts /ml) than children with assemblage A or B atone (P = 0.069 and P = 0.046 respectively). This higher rate of cyst shedding in children with assemblage B may promote 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. (C) 2008 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.