IntroductionAngiogenic factors such as angiopoietin 1 (Ang-1) and angiopoietin 2 (Ang-2) are biomarkers produced during activation and dysfunction of the vascular endothelium in several infectious diseases. The aim of this study was to determine the serum levels of Ang-1 and Ang-2 and to establish their relationship with the main indicators of worst-case prognosis in patients with P. vivax malaria.MethodsThis is a retrospective case-control study nested within a cohort of symptomatic malaria patients. A potentially severe case was defined as a patient that presented at least one of the main indicators of the worst-case prognosis for falciparum malaria, as established by the World Health Organization. Ang-2 and Ang-1 and the Ang-2/Ang-1 ratio were used to analyze the role of angiopoietins as biomarkers in signaling potentially severe vivax malaria. ROC curves were generated to identify a cut-off point discriminating between the angiopoietin concentrations that were most strongly associated with potential infection severity.ResultsThe serum levels of Ang-2 and the Ang-2/Ang-1 ratio were higher in the case group. In contrast, the serum levels of Ang-1 were lower in the cases than in the control patients. The blood count for platelets showed a positive correlation with Ang-1 and a negative correlation with Ang-2 and with the Ang-2/Ang-1 ratio. The area under the ROC curve (AUC) for serum angiopoietins, as an indicator of worst-case prognosis in a potentially severe P. vivax malarial infection, was larger in the subgroup of patients with platelet counts <75,000/µL.ConclusionThis study showed that patients with predictors of worst-case prognoses for P. vivax malaria have lower Ang-1 and higher Ang-2 serum levels (and higher values for the Ang-2/Ang-1 ratio) than controls. Elevated serum levels of Ang-2 and high values for the Ang-2/Ang-1 ratio may potentially be used as predictors of worst-case prognoses for P. vivax malaria, especially in patients with thrombocytopenia.

The polymerase chain reaction (PCR)-based methods for the diagnosis of malaria infection are expected to accurately identify submicroscopic parasite carriers. Although a significant number of PCR protocols have been described, few studies have addressed the performance of PCR amplification in cases of field samples with submicroscopic malaria infection. Here, the reproducibility of two well-established PCR protocols (nested-PCR and real-time PCR for the Plasmodium 18 small subunit rRNA gene) were evaluated in a panel of 34 blood field samples from individuals that are potential reservoirs of malaria infection, but were negative for malaria by optical microscopy. Regardless of the PCR protocol, a large variation between the PCR replicates was observed, leading to alternating positive and negative results in 38% (13 out of 34) of the samples. These findings were quite different from those obtained from the microscopy-positive patients or the unexposed individuals; the diagnosis of these individuals could be confirmed based on the high reproducibility and specificity of the PCR-based protocols. The limitation of PCR amplification was restricted to the field samples with very low levels of parasitaemia because titrations of the DNA templates were able to detect < 3 parasites/µL in the blood. In conclusion, conventional PCR protocols require careful interpretation in cases of submicroscopic malaria infection, as inconsistent and false-negative results can occur.

Introduction: Leprosy reactions, classified as type 1 and type 2 reactions, are acute clinical conditions of exacerbation of localized or systemic inflammatory response inpatients with leprosy. No laboratory biomarker is available to predict the emergence of these reactions. Neutrophil-to-lymphocyte ratio (NLR) is an accurate biomarker for diagnosis and prognosis of various inflammatory and neoplastic diseases.Objective: This study aimed to investigate the accuracy of the NLR in the diagnosis of leprosy reactions. Materials and methods: NLR was calculated for all patients and a receiver operating characteristic curve (ROC) were generated to identify the NLR cut-off point. Results: A total of 123 patients with leprosy were included, 98 with leprosy reactions of which 56 (45.5%) had type 1 and 42 (34.1%) with type 2. Mean NLR was higher among patients with reactions than among those without. It was also statistically higher among patients with type 2 reactions than in those with type 1 reactions. Receiver operating characteristic curves were generated to identify the NLR cut-off point. The area under the ROC curve was 0.794 for diagnosis of any leprosy reaction and 0.796 for the diagnosis of type 2 reaction. The NLR cutoff points for diagnosis of any leprosy reaction and for type 2 reaction were 2.75 (sensitivity 61.0%, specificity 92.0%, accuracy 77.0%) and 2.95 (sensitivity 81.0%, specificity 74.0%, accuracy 78.0%), respectively. Conclusion: These results suggest that NLR could be a potential biomarker for diagnosis of leprosy reaction and useful for discriminating patients with type 2 reactions from those with type 1 leprosy reactions.

Quantification of parasite density is an important component in the diagnosis of malaria infection. The accuracy of this estimation varies according to the method used. The aim of this study was to assess the agreement between the parasite density values obtained with the assumed value of 8,000 cells/μL and the automated WBC count. Moreover, the same comparative analysis was carried out for other assumed values of WBCs. The study was carried out in Brazil with 403 malaria patients who were infected in different endemic areas of the Brazilian Amazon. The use of a fixed WBC count of 8,000 cells/μL to quantify parasite density in malaria patients led to overestimated parasitemia and resulted in low reliability when compared to the automated WBC count. Assumed values ranging between 5,000 and 6,000 cells/μL, and 5,500 cells/μL in particular, showed higher reliability and more similar values of parasite density when compared between the 2 methods. The findings show that assumed WBC count of 5,500 cells/μL could lead to a more accurate estimation of parasite density for malaria patients in this endemic region.