OBJECTIVE: This study aimed to explore the association between asthma and atopy in a cohort of children living in a large urban center in Brazil. Atopy was defined by the presence of allergen-specific IgE in serum or by a positive skin prick test. METHODS: In a sample of 1 445 Brazilian children, the association between the prevalence of asthma, skin prick test positivity, and allergen-specific IgE in serum was investigated. RESULTS: The prevalence of asthma was 22.6%. The presence of serum allergen-specific IgE was frequent in asthmatics and nonasthmatics, and the prevalence of asthma increased only with levels of allergen-specific IgE > 3.5 kilounits/L. The proportion of asthma attributable to atopy was estimated to be 24.5% when atopy was defined by the presence of allergen-specific IgE. With a given level of specific IgE, no association between skin test reactivity and asthma was observed. Skin prick tests were less sensitive than specific IgE for detection of atopy. CONCLUSIONS: Most asthma cases in an urban underprivileged setting in Brazil were not attributable to atopy. This observation has important implications for understanding the risk factors for the asthma epidemic in Latin America

OBJETIVO: Explorar la relación entre el asma y la atopia en una cohorte de niños que viven en un gran centro urbano de Brasil. En este estudio, se considera atopia la detección de IgE sérica específica de algún alérgeno o un resultado positivo a la prueba de punción cutánea. MÉTODOS: Se estudió la relación entre la prevalencia del asma, el resultado positivo a la prueba de punción cutánea y la detección de IgE sérica específica de algún alérgeno en una muestra de 1 445 niños brasileños. RESULTADOS: El asma registró una prevalencia de 22,6%. La presencia de IgE séricas específicas de alérgenos fue frecuente tanto en los asmáticos como en los no asmáticos, y la prevalencia del asma fue mayor solo cuando el valor detectado de la IgE específica del alérgeno era > 3,5 kilounidades/litro. Se calculó que la atopia definida como la detección de IgE específicas de alérgenos es responsable de 24,5% de los casos de asma. No se observó ninguna relación entre la reactividad a la prueba de punción cutánea y el asma en función de los valores de IgE específicas. La prueba de punción cutánea es menos sensible que la detección de IgE específicas en lo que respecta al diagnóstico de atopia. CONCLUSIONES: La mayoría de los casos de asma que se registran en entornos urbanos desfavorecidos de Brasil no son atribuibles a atopia. Esta observación tiene implicaciones importantes en lo que respecta a la comprensión de los factores de riesgo que predisponen a la epidemia de asma en América Latina

Two well-defined synthetic peptides TcD and PEP2 were used in a sero-epidemiological study for the detection of Trypanosoma cruzi infections in an indigenous group in the Amazon region of Ecuador. Of the 18 communities studied along the Río Napo, province of Napo, 15 (83.3%) were found to be positive for T. cruzi infection. Of the 1,011 individuals examined 61 (6.03%) resulted positive. A prevalence of infection of 4.8% was found in children aged 1-5 years. The prevalence of infection increased with age, with adults 50 years or older showing a maximum prevalence of 18.8%. Autochthonous transmission of T. cruzi is present among this isolated indigenous population

The prevalence of onchocerciasis infection was determined in communities on 7 rivers located in the northern area of the cantón San Lorenzo, province of Esmeraldas. Diagnosis of the infection was obtained by skin biopsies and recombinant-antigen based-serology. No evidence of infection was detected in 9 communities studied along the Río Mataje, which forms the frontier between Ecuador and Colombia, nor in 10 adjacent communities located on 5 interior rivers. Evidence for Onchocerca volvulus infection was found in 4 communities on the Río Tululví with the following prevalence: La Boca (3.5% by biopsy and 3.9% by serology), Guayabal (9.1% by both biopsy and serology), La Ceiva (51.5% by biopsy and 53% by serology), and Salidero (4% by biopsy and 7.7% by serology). A few individuals in these communities were seropositive for O. volvulus in the absence of detectable dermal microfilariae: these might harbor very light or prepatent infections. No clinical disease attributable to onchocerciasis was found. The infected communities will be included in the ivermectin-based National Control Program for the disease, with no evidence of the infection having extended north of the Ecuadorian-colombian border

Trends in prevalence rates of onchocercal ocular lesions were examined over the period 1980 to 1990 using data from two cross-sectional surveys. There was evidence for increasing prevalence of anterior chamber microfilariae, iridocyclitis, optic atrophy, and chorioretinopathy. Large increases in prevalence, in particular, were seen for posterior segment lesions: optic atrophy increased from 2.7% to 6.4% and chorioretinopathy from 8.8% to 35.6%. Greatest increases in these lesions were seen in the Chachi which was attributed to the large increases in prevalence of microfilariae in the anterior chamber particularly in those aged 30 years or greater. The study findings suggest that ocular onchocerciasis is evolving in parallel with the well documented parasitological changes.