Infrared spectroscopy combined with chemometrics in transflectance mode: An alternative approach in the photodiagnosis of COVID-19 using saliva.

The Coronavirus Disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has required the search for sensitive, rapid, specific, and lower-cost diagnostic methods to meet the high demand. The gold standard method of laboratory diagnosis is real-time reverse transcription polymerase chain reaction (RT-PCR). However, this method is costly and results can take time. In the literature, several studies have already described the potential of Fourier transform infrared spectroscopy (FTIR) as a tool in the biomedical field, including the diagnosis of viral infections, while being fast and inexpensive. In view of this, the objective of this study was to develop an FTIR model for the diagnosis of COVID-19. For this analysis, all private clients who had performed a face-to-face collection at the Univates Clinical Analysis Laboratory (LAC Univates) within a period of six months were invited to participate. Data from clients who agreed to participate in the study were collected, as well as nasopharyngeal secretions and a saliva sample. For the development of models, the RT-PCR result of nasopharyngeal secretions was used as a reference method. Absorptions with high discrimination (p < 0.001) between GI (28 patients, RT-PCR test positive to SARS-CoV-2 virus) and GII (173 patients who did not have the virus detected in the test) were most relevant at 3512 cm-1, 3385 cm-1 and 1321 cm-1 after 2nd derivative data transformation. To carry out the diagnostic modeling, chemometrics via FTIR and Discriminant Analysis of Orthogonal Partial Least Squares (OPLS-DA) by salivary transflectance mode with one latent variable and one orthogonal signal correction component were used. The model generated predictions with 100 % sensitivity, specificity and accuracy. With the proposed model, in a single application of an individual's saliva in the FTIR equipment, results related to the detection of SARS-CoV-2 can be obtained in a few minutes of spectral evaluation.

Associations between house dust mites and prevalence of asthma and allergic rhinitis among school-age adolescents in the south of Brazil / Associações entre ácaros da poeira domiciliar e prevalência de asma e rinite alérgica em adolescentes em idade escolar no sul do Brasil

Background: Allergic reactions resulting from exposure to environmental allergens are responsible for problems such as asthma and allergic rhinitis. House dust mites (HDMs) are one of the most important causes of allergic sensitization and a major source of allergens worldwide. Objective: To investigate associations between the presence of HDMs in the homes of adolescents aged 13 to 14 years and the prevalence of respiratory problems using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Methods: A total of 103 adolescents from the city of Lajeado, south of Brazil, participated in the ISAAC Protocol, and 10 homes were sampled for dust collection. Results: Regarding the medical history of asthma and rhinitis, a prevalence of 14.7% of asthma was found, and 68.9% of the adolescents have already had rhinitis. The investigation of active asthma and rhinitis showed that 5.15% of adolescents had symptoms of asthma and 39.14% had symptoms of allergic rhinitis. Premature birth, low birth weight and smoking mother were shown to be risk factors for the development of asthma and allergic rhinitis. HDMs were mostly found on the carpet (46.80%), followed by bed (34.04%) and sofa (14.89%); curtains had the fewest mites (4.25%). Dermatophagoides pteronyssinus (46.0%) and Dermatophagoides farinae (31.91%) were the most frequently found species. Conclusion: The homes of adolescents with respiratory problems had a large number of HDMs.

Introdução: As reações alérgicas resultantes da exposição a alérgenos ambientais são responsáveis por problemas como asma e rinite alérgica. Os ácaros conhecidos como ácaros da poeira domiciliar (HDMs) são uma das causas mais importantes de sensibilização alérgica e representam uma das fontes de alérgenos mais importantes do mundo. Objetivo: O presente estudo tenta encontrar uma relação entre a presença de HDMs nas residências de adolescentes de 13 a 14 anos e a prevalência de problemas respiratórios, usando o questionário ISAAC (International Study of Asthma and Allergies in Childhood). Método: Participaram do Protocolo ISAAC 103 adolescentes da cidade de Lajeado (RS), dez domicílios foram amostrados para coleta de poeira. Resultados: Em relação à história clínica de asma e rinite, foi encontrada prevalência de 14,7% de asma, sendo que 68,9% dos adolescentes já apresentaram rinite. A investigação de asma e rinite ativa mostrou que 5,15% dos adolescentes apresentaram sintomas de asma e 39,14% apresentaram sintomas de rinite alérgica. Nascimento prematuro, baixo peso ao nascer e mãe fumante demonstraram ser fatores de risco para o desenvolvimento de asma e rinite alérgica. O local onde foi encontrado o maior número de ácaros foi tapete (46,80%), seguido de cama (34,04%), sofá (14,89%); cortina foi o local com menor número de ácaros encontrados (4,25%). Dermatophagoides pteronyssinus (46,0%) e Dermatophagoides farinae (31,91%) foram as espécies mais encontradas na poeira. Conclusão: As residências de adolescentes com problemas respiratórios apresentaram um maior número de HDMs.