Investigação dos fatores de risco para infecção por Toxoplasma Gondii e Helicobacter Pylori e possíveis associações destas infecções com asma e atopia.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Introduction: Toxoplasma gondii e Helicobacter pylori infections are endemic worldwide and characterized by chronic asymptomatic infections. Both infections are highly related with low socioeconomic status, lack of basic sanitation, hygiene e crowding condition. Moreover, it has been observed in industrialized countries a decrease in those infections prevalence, perhaps as consequence of hygiene improvement in these countries, thought out urbanization. Then, supported by hygiene hypothesis, some authors have studied the role of these infections in the modulation of atopy and allergic diseases. Methods: An ISAAC phase II questionnaire was applied to collect data on allergies and risk factors for these diseases in 1,445 children from Salvador, Bahia. Two definitions of asthma were used: (1) at least one wheezing episode in the last twelve months or (2) definition 1 plus other asthma symptoms. Skin prick test and serum IgE against different allergens were carried out to assess the children atopic status. IgG antibodies against T. gondii and H. pylori were determined by ELISA. Odds ratio values were obtained by bivariable and multivariable logistic regression to analyze associations between the outcomes (T. gondii and H. pylori infection; sensibilization and asthma). Results: anti-Toxoplasma gondii and anti-Helicobacter pylori IgG antibodies prevalence was 17.5% e 28.7, respectively. Among the studied variables, age, mother schooling, number of sibling, untreated water, paved road and others were pointed out as potential risk factors for those infections in our population. 22.1% of the studied children were asthmatics; 50.0% were positive for at least one specific IgE against any tested allergen, and 30.1% had SPT ≥3mm for at least one tested allergen. T. gondii infection showed an inverse association with IgE (OR=0,68 IC95%=0,50;0,93) and SPT ≥3mm (OR=0,62 CI95%=0,44;0,87). In other hand, H. pylori infection was inversely associated (OR=0,71 IC95%=0,51;0,98) with asthma. Conclusions: these results corroborate literature reports on the rule of low socioeconomic status in the determination of these infections, where the population living in poor sanitation conditions and lacking hygiene care, are more affected by these pathogens. Our results also agreed with the hygiene hypothesis which postulated that these infections protect their hosts against the development of Type I hypersensibility reactions and consequently against allergic diseases. Different immune mechanisms enrolled in the host defense against these infections may support these epidemiologic data, eg. a Th1/Th2 modulation, TLR activation associated with allergy protection, or a T regulatory response, able to suppress atopy and asthma on infected subjects.

ASSUNTO(S)

children imunologia toxoplasma gondii helicobacter pylori asthma asma toxoplasma gondii atopia crianças helicobacter pylori atopy

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