Risk factors for acute asthma in tropical America: a case–control study in the City of Esmeraldas, Ecuador

Abstract

BackgroundDespite the high asthma rates described in Latin America, asthma risk factors in poor urban settings are not well established. We investigated risk factors for acute asthma among Ecuadorian children.MethodsA matched case–control study was carried out in a public hospital serving a coastal city. Children with acute asthma were age‐ and sex‐matched to non‐asthmatics. A questionnaire was administered, and blood, as well as stool, and nasopharyngeal swabs were collected.ResultsSixty cases and 119 controls aged 5–15 were evaluated. High proportions of cases were atopic with population‐attributable fractions for atopy of 68.5% for sIgE and 57.2% for SPT. Acute asthma risk increased with greater titers of mite IgE (3.51–50 kU/l vs. <0.70kU/l – OR 4.56, 95% CI 1.48–14.06, p = 0.008; >50kU/l vs. <0.70kU/l – OR 41.98, 95% CI: 8.97–196.39, p < 0.001). Asthma risk was significantly independently associated with bronchiolitis (adj. OR: 38.9, 95% CI 3.26–465), parental educational level (adj. OR 1.26, 95% CI: 1.08–1.46), and presence of sIgE (adj. OR: 36.7, 95% CI: 4.00–337), while a reduced risk was associated with current contact with pets (adj. OR: 0.07, 95% CI: 0.01–0.56). Rhinovirus infection was more frequent in cases (cases 35.6% vs. controls 7.8%, p = 0.002). None of the cases were on maintenance therapy with inhaled corticosteroids and most relied on emergency department for control.ConclusionsA high proportion of children presenting to a public hospital with acute asthma were allergic to mite, particularly at high IgE titer. Poor asthma control resulted in overuse of emergency care.

Soil‐transmitted helminth parasites and allergy: Observations from Ecuador

“…Alternatively, the association between anti‐ Ascaris IgE and wheeze could be explained by cross‐reactivity between IgE epitopes of parasites and aeroallergens . Mite atopy appeared to explain a greater proportion of wheeze in urban compared to rural schoolchildren and in a population of asthmatics with a low prevalence of STH, the association between anti‐ Ascaris IgE and acute asthma disappeared after controlling for mite IgE . This is in contrast to a previous rural study that showed that controlling for mite IgE did not affect the association between anti‐ Ascaris IgE and wheeze .…”

“…Numerous studies have measured the associations between anti‐ Ascaris IgE and asthma symptoms, generally showing strong positive associations with wheeze, asthma and bronchial hyper‐reactivity . In cross‐sectional studies in Ecuador, we have observed strong associations between anti‐ Ascaris IgE and wheeze symptoms among schoolchildren living in rural and urban areas of Esmeraldas Province . Among rural schoolchildren, the presence of anti‐ Ascaris IgE explained approximately 50% of wheeze symptoms and 30% of wheeze and asthma in the City of Esmeraldas.…”

“…Among rural schoolchildren, the presence of anti‐ Ascaris IgE explained approximately 50% of wheeze symptoms and 30% of wheeze and asthma in the City of Esmeraldas. In the case of the latter, only 4% had positive stool samples for STH while 49% had anti‐ Ascaris IgE . The presence of anti‐ Ascaris IgE was associated with IgE sensitization to aeroallergens, an effect that might be mediated by a higher degree of atopy among wheezy/asthmatic children exposed to ascariasis or by a direct effect on airways reactivity caused by inflammation consequent to the host response to the presence of Ascaris larvae migrating through the lungs .…”

“…Map of Ecuador showing locations where studies of soil‐transmitted helminth infections and allergy were done. Studies were done in tropical and sub‐tropical regions of: Esmeraldas Province in the City of Esmeraldas, the Districts of Quininde, and Eloy Alfaro and San Lorenzo; Pichincha Province in the Districts of Pedro Vicente Maldonado, Puerto Quito and San Miguel de los Bancos; and Manabi Province in the District of Pedernales…”

Caracterización de los niños menores de cinco años con sospecha de enfermedades alérgicas

“…18,19,20 No obstante, y aunque está claramente establecido su impacto negativo, 21 la exposición pasiva a humo de tabaco no se correlacionó con la presencia de sínto-mas respiratorios. El tabaquismo de los adultos se ha implicado como un claro inductor de tos y sibilancias en los niños, ya que induce estrés oxidativo y afecta el crecimiento normal de la vía aérea; además, la respuesta al tratamiento antiinfl amatorio es menor en los pacientes expuestos.…”