Schistosoma mansoni infection is associated with a reduced course of asthma1
Received 17 August 2002; received in revised form 5 January 2003; accepted 10 January 2003.
Background:
Helminthic infections decrease skin reactivity to indoor allergens, but data on whether they influence asthma severity are lacking.
Objective:
This study evaluated the course of asthma in patients with and without Schistosoma mansoni infection.
Methods:
Asthmatic subjects were enrolled from 3 low-socioeconomic areas: a rural area endemic for schistosomiasis (group 1) in addition to a rural area (group 2) and a slum area (group 3), both of which were not endemic for schistosomiasis. A questionnaire on the basis of the International Study of Asthma and Allergies in Childhood study was applied in these 3 areas, and from each area, 21 age- and sex-matched asthmatic subjects were selected for a prospective 1-year study. Pulmonary function tests, skin prick tests with indoor allergens, stool examinations, and serum evaluations were performed in these subjects. Every 3 months, the subjects were evaluated for asthma exacerbation through physical examination, and a questionnaire regarding asthma symptoms and use of antiasthma medicine was administered.
Results:
The prevalence of S mansoni infection was greater in group 1 compared with in groups 2 and 3 (P<.0001), whereas the frequency of other helminth and protozoa infections was similar among the 3 groups. The frequency of positive skin test responses to indoor allergens was less (19.0%) in group 1 subjects relative to those in group 2 (76.2%) and group 3 (57.1%; P<.001). The frequencies of symptoms, use of antiasthma drugs, and pulmonary abnormal findings at physical examination were less in group 1 subjects than in group 2 and 3 subjects (P=.0001).
Conclusion:
Our results suggest that S mansoni infection is associated with a milder course of asthma.
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aServico de Immunologia do Hospital Universitário Prof Edgar Santos, Salvador, Bahia, Brazil
bInstituto de Saude Coletiva, Salvador, Bahia, Brazil
cDepartmento de Analises Clinicas e Toxicologicas, Universidade Federal da Bahia, Salvador, Bahia, Brazil
dEscola Baiana de Medicina e Saude Publica, Salvador, Bahia, Brazil
eDepartamento de Immunologia, Microbiologia e Parasitologia, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil
Reprint requests: Manoel Medeiros, Jr, MD, Serviço de Imunologia, Hospital Universitário Prof Edgar Santos. Rua João das Botas, s/n-5° andar-Canela, CEP 40110.160 Salvador-Bahia, Brazil.
1 Supported by the Fundação de Apoio a Pesquisa do Estado da Bahia (FAPESB) and Conselho Nacional de Pesquisa (CNPq) through Instituto de Investigação em Imunologia (iii). Edgar M. Carvalho is Senior Investigator of CNPq.
ABSTRACT