Dados do Trabalho

Título

Useful of Dried Blood Spot for Serological Screening for Chagas Disease

Introdução

The absence of a screening policy for Chagas disease means that many cases of the disease go undiagnosed. This impacts the administration of antiparasitic treatment and the development of a therapeutic and follow-up plan for these patients. The relative complexity of laboratory procedures in diagnosing Chagas disease infection hampers the implementation of population screening policies to determine the disease's prevalence. Therefore, facilitating access to diagnosis is crucial for identifying the disease.

Objetivo (s)

The use of filter paper collection allows community health agents, especially in rural areas, to obtain a small amount of blood for disease screening.  

Material e Métodos

Using the Wiener 4.0 and Euroimmun tests for Chagas, we detected IgG against T. cruzi in matched serum in dried blood spots (DBS) collected from 723 patients living in an endemic area in Minas Gerais state. All individuals signed the Free and Informed Consent Form (TCLE) for the project approved at CEP UNIMONTES, MG, number 5.467.411

Resultados e Conclusão

A total of 506 samples tested positive for Chagas using two different serological tests. The agreement statistic for the DBS/serum proportion for detecting antibodies against T. cruzi was 0.7692 for the Wiener kit and 0.7381 for Euroimmun, considering an S/CO (Signal/Cut off). Comparing DBS tests in Wiener and Euroimmun, the agreement was 0.9654 in negative serum samples and 0.5517 in positive ones. The sensitivity of the kits using DBS was 90.9% for Wiener and 93.0% for Euroimmun, while the specificity was 97.7% and 94.2% for Wiener and Euroimmun, respectively. Overall, the median S/CO values for DBS negative in seropositive samples were lower than those for serum (2.63 versus 4.82) with the Wiener kit. These findings were not related to the quality of DBS collected samples. Despite having lower sensitivity compared to serological tests, DBS may be a simple and reliable method for detecting IgG against T. cruzi when blood sampling via venipuncture is not feasible. The use of  two DBS assays could be an alternative to reduce the false-positive rates observed. The lower relative sensitivity compared to the reference method may be improved by considering S/CO values from at least two different kits or using a more sensitive methodology such as chemiluminescence. Regardless, DBS should be considered for Chagas disease screening purposes.

Palavras Chave

Chagas disease; diagnosis; Serology: Dried Blood Spot