Automated detection of malaria by means of the haematology analyser CoulterR GEN.STM

Prognostic value of cellular population data in patients with COVID-19

Background and aims

Beckman Coulter hematology analysers identify leukocytes by their volume (V), conductivity (C) and scatter (S) of a laser beam at different angles. Each leukocyte sub-population [neutrophils (NE), lymphocytes (LY), monocytes (MO)] is characterized by the mean (MN) and the standard deviation (SD) of 7 measurements called "cellular population data" (@CPD), corresponding to morphological analysis of the leukocytes. As severe forms of infections to SARS-CoV-2 are characterized by a functional activation of mononuclear cells, leading to a cytokine storm, we evaluated whether CPD variations are correlated to the inflammation state, oxygen requirement and lung damage and whether CPD analysis could be useful for a triage of patients with COVID-19 in the Emergency Department (ED) and could help to identify patients with a high risk of worsening.

Materials and method

The CPD of 825 consecutive patients with proven COVID-19 presenting to the ED were recorded and compared to classical biochemical parameters, the need for hospitalization in the ward or ICU, the need for oxygen, or lung injury on CT-scan.

Results

40 of the 42 CPD were significantly modified in COVID-19 patients in comparison to 245 controls. @MN-V-MO and @SD-V-MO were highly correlated with C-reactive protein, procalcitonin, ferritin and D-dimers. SD-UMALS-LY > 21.45 and > 23.92 identified, respectively, patients with critical lung injuries (>75%) and requiring tracheal intubation. @SD-V-MO > 25.03 and @SD-V-NE > 19.4 identified patients required immediate ICU admission, whereas a @MN-V-MO < 183 suggested that the patient could be immediately discharged. Using logistic regression, the combination of 8 CPD with platelet and basophil counts and the existence of diabetes or obesity could identify patients requiring ICU after a first stay in conventional wards (area under the curve = 0.843).

Conclusion

CPD analysis constitutes an easy and inexpensive tool for triage and prognosis of COVID-19 patients in the ED.

The utility of basic blood counts, WBC histogram and C-reactive protein in detecting malaria

Background

Hematology analyzers display abnormal parameters during malaria infection providing insightful information for suspecting and assessing malaria infection. The goal of this study is to demonstrate the potential of a three-part differential hematology analyzer to assess malaria, provide information about the parasitemia, and discuss the importance of combining C-reactive protein (CRP) with hematology parameters to obtain further information about the malaria infection.

Methods

The present study shows the results of a case–control study during the monsoon season of years 2018 and 2019 in Mumbai, India. The study considers 1008 non-malaria febrile cases, 209 P. vivax and 31 P. falciparum positive malaria samples, five cases of mixed P. vivax and P. falciparum infection, and three co-infection cases of P. vivax and dengue. Raw data from the three-part analyzer LC-667G CRP (HORIBA) and the corresponding microscopic findings (golden standard for diagnosis of malaria) were obtained for each sample.

Results

The medians of platelet counts (PLT) were 102.5, 109.0, and 223.0 × 10³/µL, while CRP medians were 67.4, 81.4 and 10.4 mg/L in P. vivax, P. falciparum and control groups respectively (p < 0.001 in Mann–Whitney U tests between malaria and control groups). Compared with negative samples, platelets counting less than 161.5 × 10³/µL were observed on malaria patients (OR 19.12, 95% CI 11.89–30.75). Especially in P. vivax cases, an abnormal peak was frequently observed in the white blood cells (WBC) histogram around the 37fL channel. The events counted around that channel showed a linear correlation with the counting of red blood cells infected predominantly with larger parasitic forms. Parameters like CRP (rs = 0.325, p < 0.001), WBC (rs = 0.285, p < 0.001) and PLT (rs = − 0.303, p < 0.001) were correlated with the parasitemia of P. vivax samples. Between the malaria and dengue groups, the highest area under the receiver operating characteristic curve was observed on CRP (0.867, CRP ≥ 26.85 mg/L).

Conclusions

A three-part differential hematology analyzer has the potential to not only trigger malaria diagnosis confirmation but also assess the severity of the infection when CRP is considered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06704-5.

Application of Sysmex XN-Series Automated Haematology Analyser in the Rapid Detection of Malaria

Malaria, an important parasitic disease worldwide, still has diagnostic challenges in the laboratory. Many studies have been conducted on the detection ability of haematology analysers for malaria. We evaluated the Sysmex XN-series analyser as a tool for detection of malaria by analysing the leukocyte cell population data (LCPD), scattergrams and associated Flow Cytometry Standard (FCS) data from both the WNR (white cell nucleated) and WDF (white cell differential) channels. 1281 clinically suspected cases of malaria were screened for malaria by peripheral blood smear examination and were run in the Sysmex XN-1000 for analysis of haematological parameter data, LCPD, all the scattergrams and FCS data. 1281 clinically suspected cases of malaria were screened for malaria by peripheral blood smear examination and were run in the Sysmex XN-1000 for analysis of haematological parameter data, LCPD, all the scattergrams and FCS data. 48 cases had malarial parasite on microscopy; of which, 41 cases were of Plasmodium vivax, 6 cases of Plasmodium falciparum and 1 case of mixed infection. 46 malaria-positive samples showed certain patterns of clusters in the scattergrams of both WDF and WNR channels. A case with only a few ring forms of P. vivax and another with very low parasite load having only gametocyte of P. falciparum didn't show the distinctive cluster. The most distinctive clusters for all other cases were seen in WNR (SFL-SSC) and WNR (SSC-FSC) scattergrams. FCS data for the same were analysed to gate for those events. The gated events correlated (Spearman ρ = 0.77, p < 0.01) with the parasite load of the patients. By observing the scattergrams and different parameters in the Sysmex XN-series analyser, malaria can be detected from the analyser itself.

AutomatedPlasmodiumdetection by the Sysmex XN hematology analyzer

Background

Malaria is a potentially severe disease affecting nearly 200 million people per year. Early detection of the parasite even in unsuspected patients remains the challenging aim for effective patient care. Automated complete blood counts that are usually performed for any febrile patient might represent a tool to ascertain malaria infection.

Aims

To evaluate the ability of the new generation of the Sysmex hematology analyzer (XN-series) to detect malaria.

Methods

We retrospectively studied 100 blood samples performed with the recent Sysmex XN analyzer that were positive forPlasmodiumand explored its ability to detect the parasite. 100 samples from patients uninfected by malaria were used as control group.

Results

Specific abnormalities such as additional events in the mature neutrophil/eosinophil area of the white blood cells differential (WDF) scattergram were noted for 1.1% ofPlasmodium falciparumsamples and 56.2% of otherPlasmodiumspecies samples. Mature parasite stages (schizonts or gametocytes) were observed on blood smears among those samples. WDF scattergrams were able to detect 80.0% (12/15) ofPlasmodiummature stages. Furthermore, the differential in white blood counts between WDF and white cell nucleated (WNR) channels was a predictive signal ofPlasmodiummature stages in 73.3% (11/15) of samples and may be explained by a differential destruction of particles with the analyzer reagent.

Conclusion

Associated to thrombocytopaenia, a Sysmex XNPlasmodiumpattern may represent a useful warning forPlasmodiumdetection in unsuspected patients, particularly when mature parasite stages are present.

Evaluation of the LH780 hematology analyzer for detection and therapeutic monitoring of malaria: Cross-reactivity with nucleated RBCs

We evaluated the diagnostic usefulness of the LH780 Coulter blood cell counter for detection and therapeutic monitoring of malaria including cross-reactivity with nucleated RBC (NRBC) samples. A total of 405 patients (43 patients with Plasmodium vivax malaria and the control group of 120 healthy subjects, 111 patients with fever, and 131 patients with NRBCs) were analyzed with routine CBC using the LH780. We analyzed the CBC results according to three selected parameters: an abnormal peak in the WBC histogram before 35fL, the presence of red dots in the nonwhite cell zone of 2D WBC Diff Dataplot, and platelet-related flags suggesting platelet clumps or giant platelets. Of the 43 malaria samples collected at diagnosis, an abnormal peak (≥2.2mm) was present in 93.0% (95% confidential interval (CI), 80.9-98.5%). Of all samples, 97.7% (95% CI, 87.7-99.9%) exhibited red dots, and platelet-related flags were observed in 81.4% (95% CI, 66.6-91.6%). The specificity of these three selected parameters was 83.1% (95% CI, 78.9-86.9%), 77.3% (95% CI, 72.7-81.6%), and 90.1% (95% CI, 86.5-92.9%), respectively. The abnormal peak (≥2.2mm) showed moderate correlation with parasite level (r=0.79). The three selected LH780 parameters were useful for identifying malaria in healthy subjects and febrile patients, but unsatisfactory for discriminating malaria in NRBC samples. The parameters showed a substantial proportion of false positives in the NRBC group, ranging from 26.7% to 49.6%. Therefore, microscopic confirmation will be necessary for application of these parameters for malaria screening and treatment monitoring.

Cell population data in neonates: differences by age group and associations with perinatal factors

INTRODUCTION

Cell population data (CPD) describe physical parameters of white blood cell subpopulations and are reported to be of some value in the diagnosis of sepsis in neonates. Before using the CPD for diagnosing sepsis, the baseline features of the CPD distribution in healthy neonates should be clarified. The aim of this study was to compare the CPD distributions of healthy neonates and other age groups and to identify perinatal factors that are associated with changes in the CPD distribution of healthy neonates.

METHODS

The CPD distribution of 69 samples from term neonates was compared with adolescents and adults. The CPD distribution of 163 samples from healthy neonates was analyzed in association with perinatal factors, including gestational age, chronologic age, birthweight, delivery mode, premature rupture of membranes, diabetes, and pregnancy-induced hypertension.

RESULTS

The CPD distribution for term neonates was significantly different from those in adolescents and adults. The mean lymphocyte volume showed a negative correlation with gestational age at birth (r = -0.305; P < 0.01). The mean neutrophil volume was smaller in the cesarean section group than in the normal delivery group. The small for gestational age (SGA) group had smaller mean neutrophil volume and mean monocyte volume than the appropriate for gestational age group.

CONCLUSION

The CPD distribution of healthy neonates differed from those of adolescents or adults, and the differences were associated with gestational age, delivery mode, and being SGA.

Advances in malaria diagnosis

Malaria is a leading cause of mortality worldwide and accurate diagnostic testing for malaria can potentially save an estimated 100,000 lives annually. New technologies have the potential to circumvent limitations of the traditional diagnostic method, light microscopy, which is labor intensive and requires considerable technician expertise. Immunochromatographic tests, which are easy to use in field conditions and relatively inexpensive, offer a potential solution to the problem of malaria overtreatment in resource-poor endemic countries. Assays based on the PCR are highly sensitive, can be used for unambiguous species identification and, thus, may increasingly complement or even replace light microscopy in developed countries. Experimental diagnostics using flow cytometry and mass spectrometry are currently under investigation for high-throughput screening.

Abnormal WBC scattergram: a clue to the diagnosis of malaria

OBJECTIVE

Malaria is highly prevalent and endemic in tropical countries and carries a significant health burden. The detection of malaria by light microscopy of Giemsa-stained smears is the gold standard. There are many hematological abnormalities associated with malaria like anemia, thrombocytopenia, and leucopenia; however, none of these abnormalities are specific. The present study was undertaken to assess the utility of WBC scattergram in predicting the diagnosis of malaria.

METHODS

In this study all cases diagnosed as Plasmodium vivax/Plasmodium falciparum infection on peripheral smear examination were included. Their complete blood counts and WBC scattergrams obtained from XT2000i were critically evaluated. Accordingly, sensitivity, specificity, positive predictive value (PPV), and negative predictive value of detection of malaria by abnormal WBC scattergram with and without abnormal blood counts were also calculated.

RESULTS

A total of 2251 ethylendiaminetetraacetic acid samples were run on XT2000i hematology autoanalyzer. Out of these 148 cases of malaria were diagnosed on peripheral smear (128 P. vivax and 20 P. falciparum). While analyzing the WBC scattergrams, 233 cases including 124 (83.8%) malaria cases showed different abnormalities. Sensitivity and PPV for the diagnosis of malaria by abnormal WBC scattergram were 83.78 and 53.20%, respectively. This had increased to 98.60 and 57.25%, respectively, when cytopenias were included.

DISCUSSION

Sysmex XT-2000i is capable of detecting specific abnormalities in WBC scattergram in patients with malaria. Therefore, the presence of an abnormal WBC scattergram with thrombocytopenia in a febrile patient helps the pathologist to clinch the diagnosis of malaria.

Sensitive detection and accurate monitoring of Plasmodium vivax parasites on routine complete blood count using automatic blood cell analyzer (DxH800(TM))

INTRODUCTION

Plasmodium vivax malaria is one of the most important infectious diseases plaguing humanity and causes significant mortality and morbidity worldwide. The gold standard of P. vivax malaria diagnosis is the microscopy of blood smears. Although microscopy is a rapid, cost-effective, and readily applicable method, it has many disadvantages, including low sensitivity, specificity, and precision. Therefore, there is a clear need for an effective screening test for P. vivax malaria detection both in high-prevalence areas and developed countries.

METHODS

A total of 1761 complete blood count (CBC) samples generated by the automated hematology analyzer (DxH 800™; Beckman Coulter Inc., Miami, FL, USA) were retrospectively analyzed. The sample pool contained 123 samples from 52 P. vivax malaria patients and 1504 nonmalarial samples including 509 patients with leukopenia (white blood cell <2000/μL) and 134 normal subjects.

RESULTS

The P. vivax malaria samples exhibited easily recognizable typical malaria signals on the nucleated red blood cell (nRBC) plots (sensitivity 100%) in DxH 800™. All 1504 samples without P. vivax infection were negative for malaria signal (specificity 100%). The size of P. vivax malaria signals correlated roughly with the parasite burden.

CONCLUSION

DxH800™ provides very sensitive and specific, easily recognizable P. vivax malaria signals on routine CBC without need for the additional reagents or special procedures.

Automated haematology analysis to diagnose malaria

For more than a decade, flow cytometry-based automated haematology analysers have been studied for malaria diagnosis. Although current haematology analysers are not specifically designed to detect malaria-related abnormalities, most studies have found sensitivities that comply with WHO malaria-diagnostic guidelines, i.e. ≥ 95% in samples with > 100 parasites/μl. Establishing a correct and early malaria diagnosis is a prerequisite for an adequate treatment and to minimizing adverse outcomes. Expert light microscopy remains the 'gold standard' for malaria diagnosis in most clinical settings. However, it requires an explicit request from clinicians and has variable accuracy. Malaria diagnosis with flow cytometry-based haematology analysers could become an important adjuvant diagnostic tool in the routine laboratory work-up of febrile patients in or returning from malaria-endemic regions. Haematology analysers so far studied for malaria diagnosis are the Cell-Dyn^®, Coulter^® GEN·S and LH 750, and the Sysmex XE-2100^® analysers. For Cell-Dyn analysers, abnormal depolarization events mainly in the lobularity/granularity and other scatter-plots, and various reticulocyte abnormalities have shown overall sensitivities and specificities of 49% to 97% and 61% to 100%, respectively. For the Coulter analysers, a 'malaria factor' using the monocyte and lymphocyte size standard deviations obtained by impedance detection has shown overall sensitivities and specificities of 82% to 98% and 72% to 94%, respectively. For the XE-2100, abnormal patterns in the DIFF, WBC/BASO, and RET-EXT scatter-plots, and pseudoeosinophilia and other abnormal haematological variables have been described, and multivariate diagnostic models have been designed with overall sensitivities and specificities of 86% to 97% and 81% to 98%, respectively. The accuracy for malaria diagnosis may vary according to species, parasite load, immunity and clinical context where the method is applied. Future developments in new haematology analysers such as considerably simplified, robust and inexpensive devices for malaria detection fitted with an automatically generated alert could improve the detection capacity of these instruments and potentially expand their clinical utility in malaria diagnosis.

Design of malaria diagnostic criteria for the Sysmex XE-2100 hematology analyzer

Thick film, the standard diagnostic procedure for malaria, is not always ordered promptly. A failsafe diagnostic strategy using an XE-2100 analyzer is proposed, and for this strategy, malaria diagnostic models for the XE-2100 were developed and tested for accuracy. Two hundred eighty-one samples were distributed into Plasmodium vivax, P. falciparum, and acute febrile syndrome groups for model construction. Model validation was performed using 60% of malaria cases and a composite control group of samples from AFS and healthy participants from endemic and non-endemic regions. For P. vivax, two observer-dependent models (accuracy = 95.3-96.9%), one non-observer-dependent model using built-in variables (accuracy = 94.7%), and one non-observer-dependent model using new and built-in variables (accuracy = 96.8%) were developed. For P. falciparum, two non-observer-dependent models (accuracies = 85% and 89%) were developed. These models could be used by health personnel or be integrated as a malaria alarm for the XE-2100 to prompt early malaria microscopic diagnosis.

[Evaluation of usefulness of the panel test composed of malaria non-specific tests as a surrogate marker]

BACKGROUND

Although malaria-specific antibody or antigen test is useful for the diagnosis of malaria infection, its cost-effectiveness has to be concerned in the area where malaria prevalence is very low. We created a panel test composed of malaria non-specific parameters, namely hematology autoanalyzer-derived results with or without addition of HDL-cholesterol data, and evaluated its usefulness in comparison with malaria-specific antibody test.

METHODS

For 395 patients tested for malaria smear, the hematology parameters such as platelet count, NRBC (%) and VCS (volume, conductivity, scattering) parameters of WBC, and HDL-cholesterol data were analyzed. Statistical significance of each parameter and that of panel test with or without addition of HDL-cholesterol were evaluated.

RESULTS

Malaria antibody test showed sensitivity of 97.1% and specificity of 99.1%. Each parameter of platelet count, NRBC (%), D parameter and HDL-cholesterol showed sensitivity of 86.8%, 41.2%, 81.8%, and 70.6%, and specificity of 85.9%, 96.3%, 72.3%, and 81.7%, respectively. Panel test without including HDL-cholesterol showed sensitivity of 91.2% and specificity of 81.6%, and that including HDL-cholesterol showed sensitivity of 91.2% and specificity of 86.2%.

CONCLUSIONS

The malaria non-specific panel test composed of hematology autoanalyzer-derived parameters showed relatively good, but slightly lower sensitivity than that of malaria-specific antibody test. It might be used as a screening test for the diagnosis of malaria infection, and addition of HDL cholesterol improved little the usefulness of the panel test.