Automated measurement of malaria parasitaemia among asymptomatic blood donors in Malawi using the Sysmex XN-31 analyser: could such data be used to complement national malaria surveillance in real time?

BACKGROUND: The recent worldwide increase in malaria cases highlights the need for renewed efforts to eliminate malaria. The World Health Organization advocates that malaria surveillance becomes a core intervention. Current methods to estimate the malaria burden rely on clinical malaria case reports and surveys of asymptomatic parasite infection mainly from children < 5 years. In this study the hypothesis was that screening blood donors for malaria parasites would provide real-time information on the asymptomatic reservoir of parasites in the adult population and mirror other surveillance data. METHODS: This study was conducted in Malawi, a high malaria burden country, at the Malawi Blood Transfusion Service, which collects blood units at donation sites countrywide. A secondary analysis was conducted on data obtained from a prior Sysmex XN-31 analyser malaria diagnostic evaluation study utilizing residual donor blood samples. XN-31 malaria results, donor age, sex, geographical location, and collection date, were analysed using standard statistical methods. RESULTS: The malaria parasite prevalence in blood donors was 11.6% (614/5281 samples) increasing seasonally from December (8.6%) to April (18.3%). The median age was 21 years and 45.9% of donors were from urban areas, which showed a lower prevalence compared to non-urban regions. The Central administrative region had the highest and the Northern region the lowest malaria parasite prevalence. The donors were predominantly male (80.2%), 13.1% of whom had malaria parasites, which was significantly higher (p < 0.0001) than for female donors (7.4%). Multivariable logistic regression analysis showed that age, location, and collection month were significant predictors of malaria positivity in males, whereas in females only location was significant. There was no gender difference in parasite density nor gametocyte carriage. CONCLUSIONS: This study demonstrates the powerful utility of screening blood donors for malaria parasites using the XN-31, which not only improves the safety of blood transfusion, but provides valuable complementary surveillance data for malaria control, especially targeting males, who are generally excluded from periodic household surveys. Blood donations are sourced countrywide, year-round, and thus provide dynamic, real-time information on the malaria burden. Furthermore, the XN-31 identifies the asymptomatic human reservoir of infectious gametocytes, which must be targeted to eliminate malaria.

A method comparison study of the high throughput automated HISCL® SARS-CoV-2 antigen assay using nasopharyngeal swab samples from symptomatic and asymptomatic subjects against conventional RT-PCR.

Our study aim was to evaluate the performance of the automated Sysmex HISCL® severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen assay against reverse-transcription polymerase chain reaction (RT-PCR). We tested 277 remnant frozen nasopharyngeal swab samples, stored in universal transport medium (UTM), yielding a sensitivity of 94.9% against historical RT-PCR results with cycle threshold (Ct ) < 30, and a sensitivity of 76.7% for Ct < 35, and specificity of 100% (all Ct values) confirming compatibility of UTM-diluted samples with the assay system. Thereafter, we prospectively collected 141 nasopharyngeal swab samples in UTM from healthcare workers and 1369 paired swabs (400 UTM; 969 dry) from individuals at a public health testing center, with the first swab (UTM) reserved for RT-PCR, yielding a positivity rate of 4.6%. HISCL assay performance using UTM swabs was superior to dry swabs, with a sensitivity of 100% (95% confidence interval [CI] 71.5%-100%) at Ct < 30 versus 92.3% (95%CI 81.5%-97.9%), and a specificity of 99.3% (95% CI 98.1-99.89) against 83.3% (95%CI 80.7%-85.6%). We conclude that this antigen assay is suitable for high throughput facilities where the primary indication for testing is to rule out infection with low RT-PCR Ct values (proxy for high viral loads) to curb viral spread.

Evaluation of the Sysmex XN-31 automated analyser for blood donor malaria screening at Malawi Blood Transfusion Services.

BACKGROUND AND OBJECTIVES: Balancing blood supply safety and sufficiency is challenging in malaria-endemic countries where the risk of transfusion-transmitted malaria (TTM) is ever-present. In support of reducing this risk, our study aimed at evaluating the performance of the Sysmex XN-31 analyser in blood donor malaria screening, as compared with current practice in Malawi. MATERIALS AND METHODS: This prospective observational study was conducted on remnant venous donor blood samples collected at Malawi Blood Transfusion Service donation sites countrywide for routine blood-borne pathogen screening. XN-31 results were compared with routine thick smear malaria microscopy, using expert microscopy (phase 1 and 2) plus qualitative malaria polymerase chain reaction (PCR) (phase 2) to adjudicate discrepancies. RESULTS: XN-31 detected malaria in 614 (11.6%) of 5281 study samples compared with 341 (6.5%) for routine microscopy. Of the 273 discrepant samples, 60 smears (phase 1) could not be retrieved for expert microscopic review. Expert microscopy confirmed the XN-31 positivity in 78.8% (149/189) and 91.7% (22/24) of discrepant samples in phase 1 (n = 4416) and phase 2 (n = 975), respectively, with two cases requiring PCR testing, confirming one each as positive and negative, giving sensitivities of 100% and 75% and specificities of 99.9% and 100%, respectively, for XN-31 and routine microscopy. CONCLUSION: The automated Sysmex XN-31 analyser's high sensitivity and specificity, ability to detect all Plasmodium species and high throughput with rapid turnaround-time, overcomes many of the limitations of currently available diagnostic tests, making it well-suited for malaria screening of donated blood in malaria-endemic countries in support of TTM risk reduction.

A novel haemocytometric COVID-19 prognostic score developed and validated in an observational multicentre European hospital-based study.

COVID-19 induces haemocytometric changes. Complete blood count changes, including new cell activation parameters, from 982 confirmed COVID-19 adult patients from 11 European hospitals were retrospectively analysed for distinctive patterns based on age, gender, clinical severity, symptom duration, and hospital days. The observed haemocytometric patterns formed the basis to develop a multi-haemocytometric-parameter prognostic score to predict, during the first three days after presentation, which patients will recover without ventilation or deteriorate within a two-week timeframe, needing intensive care or with fatal outcome. The prognostic score, with ROC curve AUC at baseline of 0.753 (95% CI 0.723-0.781) increasing to 0.875 (95% CI 0.806-0.926) on day 3, was superior to any individual parameter at distinguishing between clinical severity. Findings were confirmed in a validation cohort. Aim is that the score and haemocytometry results are simultaneously provided by analyser software, enabling wide applicability of the score as haemocytometry is commonly requested in COVID-19 patients.

Immature platelet fraction levels in a variety of bone marrow pathologies in South African HIV-positive patients with thrombocytopenia.

OBJECTIVES: Thrombocytopenia is common in HIV-infected individuals and often requires a diagnostic bone marrow examination. Interpretation may, however, be limited due to the multifactorial nature of HIV-associated thrombocytopenia and the difficulty in assessing megakaryocyte function morphologically. The immature platelet fraction (IPF) is a parameter which reportedly reflects megakaryocyte activity, with an IPF >7.7% suggesting increased platelet production. The aim of this study was to correlate the IPF with the bone marrow findings as well as other clinical variables of interest in South African patients with HIV-associated thrombocytopenia. METHODS: Seventy-eight HIV-positive patients with thrombocytopenia were enrolled from the Charlotte Maxeke Johannesburg Academic Hospital. The IPF levels were measured using a Sysmex XE-5000 haematology analyzer and were correlated with bone marrow and other findings. RESULTS: The median IPF was 7.6%, ranging from 1.3 to 44%. It was raised in 78% of patients with immune thrombocytopenia (ITP) (median = 16.3%) and low in 79% of patients with hypocellular marrow (median = 6.5%). Surprisingly, it was highly variable among patients with malignant marrow infiltration and mycobacterial infection of the bone marrow (BMTB) (median = 8.4 and 7.1%, respectively). Multivariate linear regression analysis confirmed a significant independent inverse relationship between the IPF and hypocellular marrow (P < 0.0001), a marginally significant positive association with ITP (P = 0.059), and the absence of any relationship with malignant infiltration or BMTB. The IPF had a significant inverse association with the platelet count (P = 0.0006), but was unrelated to the CD4 count and exposure to anti-retroviral therapy. Unexpectedly, it showed a significant positive association with the HIV viral load (P = 0.005). We speculate this to reflect increased megakaryocyte activity in compensation for accelerated platelet clearance due to HIV-driven platelet activation. CONCLUSION: This study investigates the role of the IPF in HIV-associated thrombocytopenia, and emphasizes the limitations of morphological analysis in determining megakaryocyte function.

The BEST study--a prospective study to compare business class versus economy class air travel as a cause of thrombosis.

BACKGROUND: As many as 10% of airline passengers travelling without prophylaxis for long distances may develop a venous thrombosis. There is, however, no evidence that economy class travellers are at increased risk of thrombosis. OBJECTIVES: A suitably powered prospective study, based on the incidence of deep-vein thrombosis (DVT) reported in previous studies on long-haul flights, was designed to determine the incidence of positive venous duplex scans and D-dimer elevations in low and intermediate-risk passengers, comparing passengers travelling in business and economy class. PATIENTS/METHODS: Eight hundred and ninety-nine passengers were recruited (180 travelling business class and 719 travelling economy). D-dimers were measured before and after the flight. A value greater than 500 ng/ml was accepted as abnormal. A thrombophilia screen was conducted which included the factor V Leiden mutation, the prothombin 20210A mutation, protein C and S levels, antithrombin levels, and anticardiolipin antibodies immunoglobulin G (IgG) and immunoglobulin M (IgM). On arrival, lower limb compression ultrasonography of the deep veins was performed. Logistical regression analysis was used to determine the risk factors related to abnormally high D-dimer levels. RESULTS: Only 434 subjects had a full venous duplex scan performed. None had ultrasonic evidence of venous thrombosis. Nine passengers tested at departure had elevated D-dimer levels and these volunteers were excluded from further study. Seventy-four of the 899 passengers had raised D-dimers on arrival. Twenty-two of 180 business class passengers (12%) developed elevated D-dimers compared with 52 of 719 economy class passengers (7%). There was no significant association between elevation of D-dimers and the class flown (odds ratio (OR) 0.61, p = 0.109). The factor V Leiden mutation, factor VIII levels and the use of aspirin were, however, associated with raised D-dimers (OR 3.36, p = 0.024; OR 1.01, p = 0.014; and OR 2.04, p = 0.038, respectively). Five hundred and five passengers were contacted within 6 months and none reported any symptoms of a clinical thrombosis or pulmonary embolus. CONCLUSION: The incidence of ultrasonically proven DVT is much lower than previously reported. However, more than 10% of all passengers developed raised D-dimers, which were unrelated to the class flown. A rise in D-dimers is associated with an inherent risk of thrombosis and/or thrombophilia, demonstrates activation of both the coagulation and fibrinolytic systems during long-haul flights, and may indicate the development of small thrombi.