Quantitative Buffy Coat Test Research Articles

Comparative evaluation of traditional and molecular diagnostic methods for malaria: An analysis of performance.

As we edge closer to the eradication of malaria, several methods for detecting Plasmodium species have been developed, including peripheral blood smear examination (PBS), rapid diagnostic tests (RDTs), serological evaluations, fluorescent microscopy, polymerase chain reactions (PCRs), fluorescent in situ hybridization, and flow cytometry. The suitability of these tools for routine diagnosis requires evaluation, considering both their diagnostic accuracy and cost-effectiveness. Our study compared four diagnostic techniques for malaria: PBS, quantitative buffy coat (QBC), RDT, and PCR. We used PCR as the benchmark standard and statistically assessed the performance of PBS, QBC, and RDT against PCR in detecting malaria. Adopting a prospective observational approach, we collected blood samples from 117 patients exhibiting the symptoms suggestive of malaria. The findings from our study showed that PBS had a positivity rate of 93.4%, with a 95% confidence interval (CI) of 0.881-0.987, indicating reliable results for a similar population. The QBC assay demonstrated an elevated positivity rate of 96.7% with a solid 95% CI of 0.930-1.000. Although the RDT had a slightly lower rate of 92.4%, it still delivered dependable results, presenting a significant 95% CI of 0.868-0.980, ensuring a robust diagnostic performance compared to PCR. PCR is a reliable test when the identification of the specific species is inconclusive. Conversely, the commonly used PBS occasionally overlooks positive malaria cases due to the specialized skills needed for accurate reading. The cost-effective RDT is feasible for field operations without the need for expert knowledge. However, it fails to differentiate between old and new infections. Meanwhile, the QBC test, known for its sensitivity and speed, can be consistently employed for malaria diagnosis in a tertiary care settings.

Genetic diversity of Indian Plasmodium vivax isolates based on the analysis of PvMSP3β polymorphic marker.

Background:Malaria is one of the major communicable diseases in India and worldwide. PvMSP3β is a highly polymorphic gene due to its large insertions and deletions in the central alanine-rich region, which, in turn, makes it a valuable marker for population genetic analysis. Very few studies are available from India about the genetic diversity of Plasmodium vivax based on PvMSP3β gene, and hence, this study was designed to understand the molecular diversity of the P. vivax malaria parasite. The accumulating epidemiological data provide insights into the circulating genetic variants of P. vivax in India, and ultimately benefits the vaccine development.Materials and Methods:A total of 268 samples confirmed to be positive by microscopy, rapid diagnostic test, and quantitative buffy coat test were collected from four different regions of India (Puducherry, Mangaluru, Jodhpur, and Cuttack) in the present study. Polymerase chain reaction (PCR)-based diagnosis was carried out to confirm the P. vivax monoinfection, and only the mono-infected samples were subjected to PvMSP3β gene amplification and further restriction fragment length polymorphism (RFLP) to determine suballeles.Results:Based on the size of the amplified fragment, the PvMSP3β gene was apportioned into two major types, namely Type A genotype (1.6–2 Kb) was predominantly present in 148 isolates and Type B (1–1.5 Kb) was observed in 110 isolates. The percentage of mixed infections by PCR was 3.73%. All the PCR products were subjected to RFLP to categorize into suballeles and we detected 39 suballeles (A1–A39) in Type A, and 23 suballeles (B1–B23) in Type B genotype. A high degree of diversity was observed among the isolates collected from Mangaluru region when compared to isolates collected from other regions.Conclusion:The present study showed a high degree of genetic diversity of PvMSP3β gene among the isolates collected from various parts of India. High polymorphism in PvMSP3β gene makes it a promising marker for epidemiological and vaccine development studies.

Variation in common serum lipid parameters in patients with malaria: A 1-year cross-sectional study

Background: Variations in serum lipid parameters are commonly and ubiquitously reported in patients with malaria. Different host cell lipid-dependent processes have been observed in the life cycle of the malarial parasite Plasmodium. Aim: The present study was undertaken to assess the serum lipid profile in patients with malaria. Materials and Methods: This 1-year cross-sectional study was conducted from January 2013 to December 2013 at the Department of Medicine. A total of 50 adult patients with positive-smear and quantitative buffy coat test for malaria, as well as with clinical features of malarial infection, were investigated for serum lipid profile changes. Patients on lipid-lowering drugs were excluded from the study. Fasting lipid profile estimation was performed using fully-automated Siemens Dimension Clinical Chemistry System for total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides. Data were analyzed using the independent sample t-test and one-way ANOVA. Results: Majority (86%) of the patients were positive for Plasmodium vivax. Thrombocytopenia was observed in 64% of the patients. Serum lipid profile estimation in these patients revealed that 60% of the patients had low total cholesterol levels (100–150 mg/dL), 56% of patients had low-LDL levels ( 150 mg/dL). Interestingly, patients with low-LDL cholesterol level had low-platelet count (51.25 ± 29.67;P = 0.035). Conclusion: Patients with malaria infections may have lipid parameters alteration in terms of hypocholesterolemia, low-HDL and -LDL levels, and hypertriglyceridemia.

A COMPARISON OF RAPID DIAGNOSTIC TESTING (BY PLASMODIUM LACTATE DEHYDROGENASE), AND QUANTITATIVE BUFFY COAT TECHNIQUE IN MALARIA DIAGNOSIS IN CHILDREN.

Background:The World Health Organization (WHO) considers early and rapid diagnosis as one of the strategies to control malaria. This study compared the performance of Quantitative Buffy Coat (QBC) test and the Plasmodium lactate dehydrogenase (pLDH) rapid diagnostic test (RDT) with microscopy as the gold standard.Materials and Methods:The study involved children ages 0-5 years who presented with a history of fever at the University College Hospital, Ibadan, Nigeria. Blood was collected from each patient and used for RDT, QBC and Giemsa-stained blood films for malaria parasites (MP). Results of QBC and RDT were compared with microscopy results for the diagnosis of malaria.Results:A total of 370 cases (194 boys and 176 girls) were studied giving a male: female ratio of 1.1:1. Of the 370 cases tested using Giemsa-stained thick blood films for MP, 78 (21 %) were positive. For the QBC test, 78 (21%) of the cases were positive with sensitivity, specificity, positive and negative predictive values of 70.5 %, 92.1%, 70.5 % and 92.1 % respectively. Seventy-six (20%) of the cases were positive by RDT with sensitivity, specificity, positive and negative predictive values of 84.2 %, 95.2 %, 82.1 %, and 95.9 % respectively. There was no significant difference in the sensitivity of QBC compared with the RDT.Conclusion:Both the QBC and the pfLDH (RDT) performed reasonably well in this study Malaria rapid diagnostic tests are recommended in malaria endemic clinical settings to avoid unnecessary antimalarial treatment.List of Abbreviations: AO: Acridine orange, AIDS: Acquired immunodeficiency syndrome, ACT: Artemisinin-based combination therapy, CM:Cerebral malaria, BCP:Benzothiocarboxypurine, DDT:Dichloro-diphenyl-trichloroethane, DNA:DeoxyriboNucleic Acid, ELAM-1: Endothelial leukocyte adhesion molecule, G6PD: Glucose-6-Phosphate Dehydrogenase, HIV: Human immuno deficiency virus, HRP 2: Histidine Rich Protein 2, ICAM -1: Inter cellular adhesion molecule1, ICER: Incremental cost effectiveness ratio, IL-1: Interleukin -1, IFN-g: Interferon-gamma, IgG: Immunoglobulin G, MP: Malaria parasite, NADP: Oxidised Nicotinamide Adenine Dinucleotide Phosphate, NADPH: Reduced Nicotinamide Adenine Dinucleotide Phosphate, PCV: Packed Cell Volume (haematocrit), P. falciparum: Plasmodium falciparum, PLDH: Plasmodium lactate dehydrogenase, PCR: Polymerase Chain Reaction, PPV: Positive predictive value, QBC: Quantitative Buffy Coat examination, TNF: Tumour necrosis factor, NPV: Negative predictive value, RDT: Rapid diagnostic test, SP: Sulphadoxine -Pyrimethamine, SMA: Severe malarial anaemia, UM: Uncomplicated malaria, USA:United States of America, VCAM-1: Vascular cell adhesion molecule, WBC: White Blood Cell, WHO: World Health Organization.

English

BACKGROUND: Malaria is the most important protozoan disease in India. The mortality and morbidity associated with this disease is considerably high whereas only limited diagnostic modalities are available in India. AIMS: To compare the conventional peripheral smear examination with Quantitative buffy coat (QBC) and rapid antigen detection kits. MATERIALS & METHODS: In the present study a total of 200 patients with clinically suspected malaria are screened with various techniques including conventional peripheral smear examinations with Giemsa, Leishman and JSB stain and newer modalities like Quantitative buffy coat testing and rapid antigen detection kits detecting PLDH. RESULTS: Among all these methodologies QBC test has shown highest sensitivity and antigen detection kit showed least sensitivity in the diagnosis of malaria.

Sensitivity of Parasitological Tests in Imported Plasmodium vivax Malaria in Adults and Impact of Chemoprophylaxis and Attack Type

Plasmodium vivax is the second most common species among cases of imported malaria diagnosed in Europe. The objective of this study is to describe the sensitivity of the parasitological tests in imported P. vivax malaria, and the impact of chemoprophylaxis and attack type (primary infection or relapse). A retrospective study included the imported vivax malaria cases admitted in a French military hospital between 2001 and 2013. The reference diagnosis method was microscopy corrected by polymerase chain reaction (PCR). Thin and thick blood films examination, quantitative buffy coat (QBC) test, and a rapid diagnostic test (RDT) had been systematically performed. PCR had been carried out for ambiguous profiles. Eighty-nine cases recorded from 78 patients were included, 65 of them having recently traveled to French Guyana. Forty-two patients had properly followed chemoprophylaxis. Forty-six cases were primary infections while 43 were relapses. The sensitivity was 91% for the thin blood smear, 96% for the concentration techniques (Giemsa thick blood smear and QBC test), and 76% for the RDT. The combination of the three conventional tools has an imperfect sensitivity, both for the positive diagnosis of malaria (96%) and for the diagnosis of vivax species (80%). In 4% of the cases, the positive diagnosis was established only by the PCR. The species identification was established in 20% by the PCR. The sensibility of thin blood smear and of RDT decreased significantly with full compliance of chemoprophylaxis or primary infection, whereas the decrease of sensibility of concentration techniques was not significant. This study illustrates the difficulties encountered in vivax malaria diagnosis, especially in patients who properly followed chemoprophylaxis or with primary infection due to a lower parasitemia. It underlines the lack of sensitivity of RDT for P. vivax and emphasizes the need for systematically combining various diagnosis methods.

Performance of the Now Malaria rapid diagnostic test with returned travellers: a 2-year retrospective study in a French teaching hospital

Malaria caused by Plasmodium falciparum remains the major life-threatening parasitic infection in the world. The number of cases in non-endemic countries continues to increase, and it is important that misdiagnosis of malaria should not occur, especially in non-immune travellers, because of the high risk of a fatal outcome. In a retrospective study of 399 sera, the Now Malaria rapid test was compared with the quantitative buffy coat (QBC) test and microbiological examination of thin blood films. Compared with the QBC test and thin blood films, the Now Malaria test had sensitivity and specificity values of 96.4% and 97%, respectively, for the detection of pure P. falciparum infection. A negative predictive value of 99.4% allows this test to be included in diagnostic strategies for patients presenting with clinical suspicion of malaria. Two false-negative results were associated with low levels of parasitaemia in the specimens. Thus, use of the Now Malaria test alone to detect P. falciparum infection in non-endemic countries could lead to misdiagnosis of malaria. This rapid diagnostic test should therefore be performed in association with another prompt traditional method such as examination of thin blood films.