Schistosoma mansoni infection is associated with a reduced course of asthma.
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).


CONCLUSIONS
Our results suggest that S mansoni infection is associated with a milder course of asthma.
Servico de Imunologia do Hospital Universitário Prof Edgar Santos, Salvador, Bahia; Instituto de Saude Coletiva, Salvador, Bahia, Brazil.
Manoel
M
Medeiros
Joanemile P
JP
Figueiredo
Maria C
MC
Almeida
Maria Analia
MA
Matos
Maria I
MI
Araújo
Alvaro A
AA
Cruz
Ajax M
AM
Atta
Marco Antonio V
MA
Rego
Amélia R
AR
de Jesus
Ernesto A
EA
Taketomi
Edgar M
EM
Carvalho
D000293:Adolescent; D000909:Antibodies, Helminth / Q000097:blood; D001249:Asthma / Q000517:prevention & control*; D005260:Female; D006636:Histamine Release; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D016753:Interleukin-10 / Q000096:biosynthesis; D008297:Male; D012555:Schistosomiasis mansoni / Q000276:immunology*; D012882:Skin Tests
D000909:Antibodies, Helminth; D016753:Interleukin-10; D007073:Immunoglobulin E