Prevalence and risk factors for Giardia duodenalis infection among children: A case study in Portugal

<p>Abstract</p> <p>Background</p> <p><it>Giardia duodenalis </it>is a widespread parasite of mammalian species, including humans. The prevalence of this parasite in children residing in Portugal is currently unknown. This study intended to estimate <it>G. duodenalis </it>infection prevalence and identify possible associated risk factors in a healthy paediatric population living in the District of the Portuguese capital, Lisbon.</p> <p>Methods</p> <p>Between February 2002 and October 2008, 844 children were randomly selected at healthcare centres while attending the national vaccination program. A stool sample and a questionnaire with socio-demographic data were collected from each child. <it>Giardia </it>infection was diagnosed by direct examination of stools and antigen detection by ELISA.</p> <p>Results</p> <p>The population studied revealed a gender distribution of 52.8% male and 47.2% female. Age distribution was 47.4% between 0-5 years and 52.6% between 6-15 years.</p> <p>The prevalence of <it>Giardia </it>infection was 1.9% (16/844) when estimated by direct examination and increased to 6.8% (57/844) when ELISA results were added. The prevalence was higher among children aged 0-5 years (7.8%), than among older children (5.8%), and was similar among genders (6.9% in boys and 6.5% in girls). The following population-variables were shown to be associated risk factors for <it>G. duodenalis </it>infection: mother's educational level (odds ratio (OR)= 4.49; confidence interval (CI): 1.20-16.84), father's educational level (OR = 12.26; CI: 4.08-36.82), presence of <it>Helicobacter pylori </it>infection (OR = 1.82; CI: 1.05-3.15), living in houses with own drainage system (OR = 0.10; CI: 0.02-0.64) and reported household pet contact, especially with dogs (OR = 0.53; CI: 0.31-0.93).</p> <p>Conclusion</p> <p>The prevalence of giardiasis in asymptomatic children residing in the region of Lisbon is high. Several risk factors were associated with <it>Giardia </it>prevalence and highlight the importance of parents' education and sanitation conditions in the children's well being. The association between <it>G. duodenalis </it>and <it>H. pylori </it>seems an important issue deserving further investigation in order to promote prevention or treatment strategies.</p