BackgroundSmear microscopy is used to assess the patient's infectiousness at the time of initial diagnosis of pulmonary tuberculosis. However, its limited sensitivity and specificity highlights the need for new diagnostic strategies. The aim of our study was to assess the diagnostic accuracy of GX Ct value as a predictor of smear status and its usefulness to quantify mycobacterial load.MethodsAll GX-positive sputum samples during a seven-year period were included in the study. Correlations among Ct values, smear status and TTD on liquid culture were calculated. An optimal Ct value for ruling in infectious patients was established. Clinical and radiological variables were also analyzed.ResultsSixty-eight samples from 65 patients were included. Ct value and TTD yielded a positive correlation (ρ = 0.714; p < 0.05), while Ct and smear grade yielded an inverse correlation (r = −0.71). An optimal Ct value for ruling in smear positive patients was established at 21.1 cycles (90.5% sensitivity, 61% specificity, 81% PPV and 78% NPV).ConclusionsOur study confirms the value of GX Ct levels for quantifying mycobacterial load and demonstrates the added value of Ct as a predictor of positive smear status, especially at Ct values below 21.

Using S/CO ≥ 3.80, the ARCHITECT Chagas could be used as a single test for diagnosis of chronic CD in Bolivian immigrants. Patients with S/CO between 0.80 and 3.80 would require additional testing.

Background The emergence and spread of anti-malarial resistance continues to hinder malaria control. Plasmodium falciparum, the species that causes most human malaria cases and most deaths, has shown resistance to almost all known anti-malarials. This anti-malarial resistance arises from the development and subsequent expansion of Single Nucleotide Polymorphisms (SNPs) in specific parasite genes. A quick and cheap tool for the detection of drug resistance can be crucial and very useful for use in hospitals and in malaria control programmes. It has been demonstrated in different contexts that genotyping by Kompetitive Allele Specific PCR (KASP), is a simple, fast and economical method that allows a high-precision biallelic characterization of SNPs, hence its possible utility in the study of resistance in P. falciparum. Methods Three SNPs involved in most cases of resistance to the most widespread anti-malarial treatments have been analysed by PCR plus sequencing and by KASP (C580Y of the Kelch13 gene, Y86N of the Pfmdr1 gene and M133I of the Pfcytb gene). A total of 113 P. falciparum positive samples and 24 negative samples, previously analysed by PCR and sequencing, were selected for this assay. Likewise, the samples were genotyped for the MSP-1 and MSP-2 genes, and the Multiplicity of Infection (MOI) and parasitaemia were measured to observe their possible influence on the KASP method. Results The KASP results showed the same expected mutations and wild type genotypes as the reference method, with few exceptions that correlated with very low parasitaemia samples. In addition, two cases of heterozygotes that had not been detected by sequencing were found. No correlation was found between the MOI or parasitaemia and the KASP values of the sample. The reproducibility of the technique shows no oscillations between repetitions in any of the three SNPs analysed. Conclusions The KASP assays developed in this study were efficient and versatile for the determination of the Plasmodium genotypes related to resistance. The method is simple, fast, reproducible with low cost in personnel, material and equipment and scalable, being able to core KASP arrays, including numerous SNPs, to complete the main pattern of mutations associated to P. falciparum resistance.

The NIE-ELISA is more specific than the CrAg-ELISA, but its low sensitivity limits its use in S. stercoralis screening. New diagnostic tests are needed for the diagnosis of S. stercoralis.

Background The importance of submicroscopic malaria infections in high-transmission areas could contribute to maintain the parasite cycle. Regarding non-endemic areas, its importance remains barely understood because parasitaemia in these afebrile patients is usually below the detection limits for microscopy, hence molecular techniques are often needed for its diagnosis. In addition to this, the lack of standardized protocols for the screening of submicroscopic malaria in immigrants from endemic areas may underestimate the infection with Plasmodium spp. The aim of this study was to assess the prevalence of submicroscopic malaria in afebrile immigrants living in a non-endemic area. Methods A prospective, observational, multicentre study was conducted. Afebrile immigrants were included, microscopic observation of Giemsa-stained thin and thick blood smears, and two different molecular techniques detecting Plasmodium spp. were performed. Patients with submicroscopic malaria were defined as patients with negative blood smears and detection of DNA of Plasmodium spp. with one or both molecular techniques. Demographic, clinical, analytical and microbiological features were recorded and univariate analysis by subgroups was carried out with STATA v15. Results A total of 244 afebrile immigrants were included in the study. Of them, 14 had a submicroscopic malaria infection, yielding a prevalence of 5.7% (95% confidence interval 3.45–9.40). In 71.4% of the positive PCR/negative microscopy cases, Plasmodium falciparum alone was the main detected species (10 out of the 14 patients) and in 4 cases (28.6%) Plasmodium vivax or Plasmodium ovale were detected. One patient had a mixed infection including three different species. Conclusions The prevalence of submicroscopic malaria in afebrile immigrants was similar to that previously described in Spain. Plasmodium vivax and P . ovale were detected in almost a third of the submicroscopic infections. Screening protocols for afebrile immigrants with molecular techniques could be useful for a proper management of these patients. Electronic supplementary material The online version of this article (10.1186/s12936-019-2870-3) contains supplementary material, which is available to authorized users.

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