Quality control of blood smears prepared on transparent methanol: an alternative method for the microscopic diagnosis of malaria

摘要

Background: Malaria is one of the leading causes of infant mortality in the Democratic Republic of Congo. A retrospective study examining 100 negative blood smear slides after methanol fixation was conducted at the National Malaria Control Program (NMCP) at Kinshasa. The objective of the study was to control the quality of Giemsa-stained negative slides fixation methods on the sensitivity and specificity of the two diagnostic methods.Methods: The methanol solution was used prior to Giemsa staining to fix the smear preparations. Thick and thin blood smears were prepared using the conventional method on slides. Staining was performed using Giemsa staining for thick and thin smears.Results: Of the 100 slides received for reading for malaria parasitic stage; 100 slides had been reported negative. Laboratory diagnosis by microscopic examination after methanol fixation of blood smears showed that 60 slides of the 100 slides were positive. Microscopic images of parasites and blood cells in a thick non-methanolic blood film were prepared on glass slides and fixed with methanol. The absence of methanol fixation showed a lower apparent prevalence than that fixed with methanol fixation. Previous information on the sensitivity and specificity of the diagnostic methods was available on malaria in the Democratic Republic of the Congo.Conclusion: The preparation of thin and thick blood smears in the methanol binding makes it possible to identify the false negatives of certain slides for the microscopic diagnosis of malaria. It is reasonable to predict the applicability of methanol in relevant situations such as the training of qualified professionals for the microscopic diagnosis of malaria and the preparation of positive samples for the assessment of skills (quality control) of professionals and services involved in the diagnosis of malaria.