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Submitted by Maria Creuza Silva (mariakreuza@yahoo.com.br) on 2015-06-11T17:27:14Z No. of bitstreams: 1 Mauricio Lima. 2014.pdf: 1013895 bytes, checksum: 049178f11b0a0acea7bc1bf41a3008c7 (MD5) Made available in DSpace on 2015-06-11T17:27:14Z (GMT). No. of bitstreams: 1 Mauricio Lima. 2014.pdf: 1013895 bytes, checksum: 049178f11b0a0acea7bc1bf41a3008c7 (MD5) Previous issue date: 2014-07 The ECUAVIDA birth cohort is studying the impact of exposures to soil-transmitted helminth (STH) parasites and early-life microbial exposures on the development of atopy, allergic diseases and immune responses in childhood. A total of 2404 newborns were recruited between 2006 and 2009 in a public hospital serving the rural district of Quininde, Esmeraldas Province, in a tropical region of coastal Ecuador. Detailed measurements were done around the time of the birth, at 7 and 13 months and at 2 and 3 years, and data collection is ongoing at 5 and 8 years. Data being collected include questionnaires for: sociodemographic, lifestyle, psychosocial (at 4-6 years only) and dietary (at 6-7 years only) factors; childhood morbidity and clinical outcomes; stool samples for parasites; blood samples for DNA, measurements of vaccine responses and other measures of immune function/inflammation; and anthropometrics. Allergen skin prick test reactivity is done from 2 years and measures of airway function and inflammation at 8 years. London

Submitted by Maria Creuza Silva (mariakreuza@yahoo.com.br) on 2015-06-09T13:13:28Z No. of bitstreams: 1 Mauricio Barreto 2014.pdf: 194088 bytes, checksum: 0a9d906576db3dbcd34d10b0249c4a7f (MD5) Made available in DSpace on 2015-06-09T13:13:28Z (GMT). No. of bitstreams: 1 Mauricio Barreto 2014.pdf: 194088 bytes, checksum: 0a9d906576db3dbcd34d10b0249c4a7f (MD5) Previous issue date: 2014 BACKGROUND: The association between atopy and asthma is attenuated in non-affluent populations, an effect that may be explained by childhood infections such as geohelminths. OBJECTIVE: To investigate the association between atopy and wheeze in schoolchildren living in urban and rural areas of Ecuador and examine the effects of geohelminths on this association. METHODS: We performed nested case-control studies among comparable populations of schoolchildren living in rural communities and urban neighbourhoods in the Province of Esmeraldas, Ecuador. We detected geohelminths in stool samples, measured recent wheeze and environmental exposures by parental questionnaire, and atopy by specific IgE (sIgE) and skin prick test (SPT) reactivity to aeroallergens. RESULTS: Atopy, particularly sIgE to house dust mite (HDM), was more strongly associated with recent wheeze in urban than rural schoolchildren: (urban, adj. OR 5.19, 95% CI 3.37-8.00, P < 0.0001; rural, adj. OR 1.81, 95%CI 1.09-2.99, P = 0.02; interaction, P < 0.001). The population fractions of wheeze attributable to atopy were approximately two-fold greater in urban schoolchildren: SPT to any allergen (urban 23.5% vs. rural 10.1%), SPT to HDM (urban 18.5% vs. rural 9.6%), and anti-HDM IgE (urban 26.5% vs. rural 10.5%), while anti-Ascaris IgE was related to wheeze in a high proportion of rural (49.7%) and urban (35.4%) children. The association between atopy and recent wheeze was attenuated by markers of geohelminth infections. CONCLUSIONS: Our data suggest that urban residence modifies the association between HDM atopy and recent wheeze, and this effect is explained partly by geohelminth infections. London

Submitted by Maria Creuza Silva (mariakreuza@yahoo.com.br) on 2015-06-09T13:13:28Z No. of bitstreams: 1 Mauricio Barreto 2014.pdf: 194088 bytes, checksum: 0a9d906576db3dbcd34d10b0249c4a7f (MD5) Made available in DSpace on 2015-06-09T13:13:28Z (GMT). No. of bitstreams: 1 Mauricio Barreto 2014.pdf: 194088 bytes, checksum: 0a9d906576db3dbcd34d10b0249c4a7f (MD5) Previous issue date: 2014 BACKGROUND: The association between atopy and asthma is attenuated in non-affluent populations, an effect that may be explained by childhood infections such as geohelminths. OBJECTIVE: To investigate the association between atopy and wheeze in schoolchildren living in urban and rural areas of Ecuador and examine the effects of geohelminths on this association. METHODS: We performed nested case-control studies among comparable populations of schoolchildren living in rural communities and urban neighbourhoods in the Province of Esmeraldas, Ecuador. We detected geohelminths in stool samples, measured recent wheeze and environmental exposures by parental questionnaire, and atopy by specific IgE (sIgE) and skin prick test (SPT) reactivity to aeroallergens. RESULTS: Atopy, particularly sIgE to house dust mite (HDM), was more strongly associated with recent wheeze in urban than rural schoolchildren: (urban, adj. OR 5.19, 95% CI 3.37-8.00, P < 0.0001; rural, adj. OR 1.81, 95%CI 1.09-2.99, P = 0.02; interaction, P < 0.001). The population fractions of wheeze attributable to atopy were approximately two-fold greater in urban schoolchildren: SPT to any allergen (urban 23.5% vs. rural 10.1%), SPT to HDM (urban 18.5% vs. rural 9.6%), and anti-HDM IgE (urban 26.5% vs. rural 10.5%), while anti-Ascaris IgE was related to wheeze in a high proportion of rural (49.7%) and urban (35.4%) children. The association between atopy and recent wheeze was attenuated by markers of geohelminth infections. CONCLUSIONS: Our data suggest that urban residence modifies the association between HDM atopy and recent wheeze, and this effect is explained partly by geohelminth infections. London

Rationale: IgE antibodies to the mammalian oligosaccharide galactose-α-1,3-galactose (α-gal) are common in the southeastern United States. These antibodies, which are induced by ectoparasitic ticks, can give rise to positive skin tests or serum assays with cat extract.

Submitted by Maria Creuza Silva (mariakreuza@yahoo.com.br) on 2011-09-21T14:10:21Z No. of bitstreams: 1 Per Inter 2011.1.pdf: 2091495 bytes, checksum: c79de44b83265cc0a1aca097cba43610 (MD5) Made available in DSpace on 2011-09-21T14:10:21Z (GMT). No. of bitstreams: 1 Per Inter 2011.1.pdf: 2091495 bytes, checksum: c79de44b83265cc0a1aca097cba43610 (MD5) Previous issue date: 2011 Background: Geohelminth infections are highly prevalent infectious diseases of childhood in many regions of the Tropics, and are associated with significant morbidity especially among pre-school and school-age children. There is growing concern that geohelminth infections, particularly exposures occurring during early life in utero through maternal infections or during infancy, may affect vaccine immunogenicity in populations among whom these infections are endemic. Further, the low prevalence of allergic disease in the rural Tropics has been attributed to the immune modulatory effects of these infections and there is concern that widespread use of anthelmintic treatment in high-risk groups may be associated with an increase in the prevalence of allergic diseases. Because the most widely used vaccines are administered during the first year of life and the antecedents of allergic disease are considered to occur in early childhood, the present study has been designed to investigate the impact of early exposures to geohelminths on the development of protective immunity to vaccines, allergic sensitization, and allergic disease. Methods/Design: A cohort of 2,403 neonates followed up to 8 years of age. Primary exposures are infections with geohelminth parasites during the last trimester of pregnancy and the first 2 years of life. Primary study outcomes are the development of protective immunity to common childhood vaccines (i.e. rotavirus, Haemophilus influenzae type B, Hepatitis B, tetanus toxoid, and oral poliovirus type 3) during the first 5 years of life, the development of eczema by 3 years of age, the development of allergen skin test reactivity at 5 years of age, and the development of asthma at 5 and 8 years of age. Potential immunological mechanisms by which geohelminth infections may affect the study outcomes will be investigated also. Discussion: The study will provide information on the potential effects of early exposures to geohelminths (during pregnancy and the first 2 years of life) on the development of vaccine immunity and allergy. The data will inform an ongoing debate of potential effects of geohelminths on child health and will contribute to policy decisions on new interventions designed to improve vaccine immunogenicity and protect against the development of allergic diseases. Londres

The synthesis of IgE by B cells occurs at a low rate compared with that of other antibodies, even in allergic subjects. One rate-limiting step is the class switch, by which B lymphocytes switch to produce immunoglobulin epsilon heavy chains rather than mu or gamma heavy chains. We propose an additional rate-limiting step: survival of the B lymphocyte after the switch to IgE. The hypothesis we present here is that the survival of the IgE-switched B cell is compromised, particularly in an active germinal center. Antigenic stimulation in the absence of a danger signal fails to induce a mature germinal center, which allows IgE-switched B cells to escape and mature into plasma cells. Antigenic stimulation in the presence of a danger signal (or under nonhygienic conditions) induces germinal centers, which eliminate IgE-switched B cells. Thus the essence of an allergen is antigenic stimulation in the absence of conditions that generate mature germinal centers. Because germinal centers are important for the generation of B-cell memory, the IgE immune response is characteristically poor in memory (but might be long lasting because of the generation of long-lived plasma cells). In addition to this direct route to IgE, typical for atopic sensitization, another type of T(H)2 response exists. On chronic allergen exposure with the concomitant induction of germinal centers, IgG4-switched B memory cells are induced that are slow to differentiate into plasma cells. These IgG4-switched B memory cells might occasionally undergo a secondary switch to IgE

Asthma is a common cause of emergency care attendance in low and middle-income countries (LMICs). While few prospective studies of predictors for emergency care attendance have been undertaken in high-income countries, none have been done in a LMIC.We followed a cohort of 5-15 year olds treated for asthma attacks in Emergency Rooms (ERs) of public health facilities in Esmeraldas City, Ecuador. We collected blood and nasal wash samples, and did spirometry and Fractional exhaled Nitric Oxide measurements. We explored potential predictors for recurrence of severe asthma attacks requiring emergency care over 6 months follow-up.We recruited 283 children of whom 264 (93%) were followed up for at least 6 months or until their next asthma attack. Almost half (46%) had a subsequent severe asthma attack requiring emergency care. Predictors of recurrence in adjusted analyses were (adj. OR; 95% CI) younger age (0.87 per year; 0.79-0.96), previous asthma diagnosis (2.2; 1.2-3.9), number of parenteral corticosteroid courses in previous year (1.3; 1.1-1.5), food triggers (2.0; 1.1-3.6), and eczema diagnosis (4.2; 1.02-17.6). A parsimonious Cox regression model included the first three predictors plus urban residence as a protective factor (adj. HR: 0.69; 0.50-0.95). Laboratory and lung function tests did not predict recurrence.Factors independently associated with recurrent emergency attendance for asthma attacks were identified in a low-resource LMIC setting. This study suggests a simple risk-assessment tool could potentialy be created for ERs in similar settings to identify higher risk children on whom limited resources might be better focussed.