Non-atopic asthma is associated with helminth infections and bronchiolitis in poor children

¹ Paediatric Pulmonary Research Laboratory, Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
² WHO Collaborating Centre for Research on Children's Environmental Health, Curtin University of Technology, Perth, Australia; and Centre for Child Health Research, University of Western Australia, Perth, Australia
³ Dept of Epidemiology, University of Ulm, Ulm, Germany

^* To whom correspondence should be addressed. E-mail: rstein{at}pucrs.br.

	Abstract

Asthma is common in urban centers in Latin America, but atopic asthma may not be the main phenotype among children. Helminth infections are highly prevalent in poor populations and we hypothesized that they attenuate allergic asthma, while other factors are related to the expression of a non-atopic wheeze/asthma phenotype.

A total of 1982 children aged 10.1 (0.76) years (SD) from Southern Brazil completed asthma questionnaires and 1011 were evaluated for intestinal parasites and atopy with skin-prick tests (SPTs).

Wheeze in the previous 12 months was reported by 25.6% and 9.3% had current asthma; 13% were SPT-positive and 19.1% were positive for any helminthes. Most children with either wheeze or asthma were SPT-negative; however, severe wheeze was more prevalent amongst the atopic minority. Helminth infections were inversely associated with positive SPTs. Bronchiolitis before the age of two was the major independent risk factor for asthma at age 10; high-load Ascaris infection, family history of asthma, and positive SPTs were also asthma risk factors.

Most asthma and wheeze are of the non-atopic phenotype suggesting that some helminthes may exert an attenuating effect on the expression of the atopic portion of the disease while viral bronchiolitis predisposes more specifically to recurrent airway symptoms.

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