P. falciparum malaria prevalence among blood donors in Bamako, Mali

Risk of transfusion-associated malaria in sub-Saharan Africa: The case of Mali

INTRODUCTION

Malaria is a health threat in sub-Saharan Africa, where Plasmodium is not tested in blood bags. Our objective was to determine the prevalence of plasmodial carriage in blood bags and the associated factors, and the involvement of these bags in the occurrence of malaria in recipients.

METHODS

From 1st April to 30th November, 2020, we conducted a prospective cross-sectional study of 348 blood bags stored at 4°C in Bamako. Using SPSS 21.0 software, statistical analyses were performed using a binary logistic regression model with a significance threshold of p < 0.05 and the odds ratio (OR) framed by its 95% confidence interval (CI).

RESULTS

During this period, 348 blood bags were transfused into 108/152 hospitalised patients, generating a transfusion frequency of 71.1%, with a prevalence of plasmodial carriage of 22%. Among the 54 initially malaria-negative recipients, all 20 (37%) who received malaria-positive blood bags and slept under long-acting insecticide-treated nets (LLINs) developed malaria. We recorded 33.3% deaths. Donor age ≤ 34 years (p = 0.011; OR = 2.55[CI.95% = 1.25-5.23]), replacement donation (p = 0.000; OR = 0.04[CI.95% = 0.0-0.19]) and not regular use of LLINs by donors (p = 0.048; OR = 0.53[CI.95% = 0.29-1]) were factors associated with plasmodial carriage of blood bags. CD4 count<200 cells/mm3 (p = 0.002; OR = 0.2[CI.95% = 0.10-0.52]), severe anaemia (p = 0.034; OR = 0.26[CI.95% = 0.10-0.90]) and decompensated anaemia (p = 0.034; OR = 3.88[CI.95% = 1.11-13.56]) were factors independently associated with recipient death.

CONCLUSION

The prevalence of plasmodial carriage among blood donors is increasing in Mali. Transfusion malaria is a reality to be feared, with the risk increasing with the level of malaria endemicity of the blood donor.

Sub-national tailoring of seasonal malaria chemoprevention in Mali based on malaria surveillance and rainfall data

Background

In malaria endemic countries, seasonal malaria chemoprevention (SMC) interventions are performed during the high malaria transmission in accordance with epidemiological surveillance data. In this study we propose a predictive approach for tailoring the timing and number of cycles of SMC in all health districts of Mali based on sub-national epidemiological surveillance and rainfall data. Our primary objective was to select the best of two approaches for predicting the onset of the high transmission season at the operational scale. Our secondary objective was to evaluate the number of malaria cases, hospitalisations and deaths in children under 5 years of age that would be prevented annually and the additional cost that would be incurred using the best approach.

Methods

For each of the 75 health districts of Mali over the study period (2014–2019), we determined (1) the onset of the rainy season period based on weekly rainfall data; (ii) the onset and duration of the high transmission season using change point analysis of weekly incidence data; and (iii) the lag between the onset of the rainy season and the onset of the high transmission. Two approaches for predicting the onset of the high transmission season in 2019 were evaluated.

Results

In the study period (2014–2019), the onset of the rainy season ranged from week (W) 17 (W17; April) to W34 (August). The onset of the high transmission season ranged from W25 (June) to W40 (September). The lag between these two events ranged from 5 to 12 weeks. The duration of the high transmission season ranged from 3 to 6 months. The best of the two approaches predicted the onset of the high transmission season in 2019 to be in June in two districts, in July in 46 districts, in August in 21 districts and in September in six districts. Using our proposed approach would prevent 43,819 cases, 1943 hospitalisations and 70 deaths in children under 5 years of age annually for a minimal additional cost. Our analysis shows that the number of cycles of SMC should be changed in 36 health districts.

Conclusion

Adapting the timing of SMC interventions using our proposed approach could improve the prevention of malaria cases and decrease hospitalisations and deaths. Future studies should be conducted to validate this approach.

Graphical Abstract

Zika Virus Circulation in Mali

The circulation of Zika virus (ZIKV) in Mali has not been clearly characterized. Therefore, we conducted a serologic survey of 793 asymptomatic volunteers >15 years of age (2016), and 637 blood donors (2013) to assess the seroprevalence of ZIKV infection in 2 ecoclimatic regions of Mali, tropical savannah and warm semiarid region, using ELISA and seroneutralization assays. The overall seroprevalence was ≈12% and increased with age, with no statistical difference between male and female participants. In the warm semiarid study sites we detected immunological markers of an outbreak that occurred in the late 1990s in 18% (95% CI 13%-23%) of participants. In tropical savannah sites, we estimated a low rate of endemic transmission, with 2.5% (95% CI 2.0%-3.1%) of population infected by ZIKV annually. These data demonstrate the circulation of ZIKV in Mali and provide evidence of a previously unidentified outbreak that occurred in the late 1990s.

Transfusional Malaria and Associated Factors at the National Blood Transfusion Center of Niamey-Niger

SUMMARY

Problem. Transfusional malaria is an accidental transmission of Plasmodium via a blood transfusion. Its magnitude is underestimated and very little data on the assessment of this risk are available in Niger.

OBJECTIVE

This study aimed to determine the prevalence of plasmodial infection of blood bags at the National Blood Transfusion Center of Niamey (NBTC).

METHODOLOGY

A cross-sectional study to diagnose Plasmodium infection by microscopy and Rapid Diagnostic Test (RDT) was carried out during the rainy season (September to November 2015). Blood grouping was performed by the BETH-VINCENT technique.

RESULTS

One thousand three hundred and fifty-seven (1357) blood bags were collected. One hundred and fifty-seven (11.6%) of the donors were infected with Plasmodium by microscopy and 2.4% (9/369) by rapid diagnostic test. All infections were with P. falciparum (100%). The mean parasite density was 197 parasites/μL (SD=281; [80: 2000]). There were no significant differences in infection prevalence between the ABO blood groups (p = 0.3) or the rhesus positivity (p=08). There is also no significant difference in temporal (p = 0.1) and spatial (p = 0.6) distribution.

CONCLUSION

The transmission of transfusional malaria during the rainy season is a fact in Niger. Such risks were independent of the ABO blood type and positivity for the rhesus antigen. Pretransfusion diagnosis or posttransfusion therapy should be instituted to prevent it.

Evaluation of automated malaria diagnosis using the Sysmex XN-30 analyser in a clinical setting

BACKGROUND

Early and accurate diagnosis of malaria is a critical aspect of efforts to control the disease, and several diagnostic tools are available. Microscopic assessment of a peripheral blood smear enables direct visualization of parasites in infected red blood cells and is the clinical diagnostic gold standard. However, it is subjective and requires a high level of skill. Numerous indirect detection methods are in use, but are not ideal since surrogate markers of infection are measured. This study describes the first clinical performance evaluation of the automated Sysmex XN-30 analyser, which utilizes fluorescence flow cytometry to directly detect and quantitate parasite-infected red blood cells.

RESULTS

Residual EDTA blood samples from suspected malaria cases referred for routine diagnosis were analysed on the XN-30. Parasitaemia was reported as a percentage, as well as absolute numbers of infected red blood cells, and scattergrams provided a visual image of the parasitized red blood cell clusters. The results reported by the XN-30 correlated with microscopy and the analyser demonstrated 100% sensitivity and specificity. Measurements were reproducible and storage of samples at room temperature did not affect the parameters. Several Plasmodium species were detected, including Plasmodium falciparum, Plasmodium vivax and Plasmodium ovale. The XN-30 also identified the transmissible gametocytes as a separate cluster on the scattergrams. Abnormal red blood cell indices (low haemoglobin and raised reticulocyte counts), haemoglobinopathies and thrombocytopenia did not interfere with the detection of parasites. The XN-30 also generated a concurrent full blood count for each sample.

CONCLUSIONS

The novel technology of the Sysmex XN-30 provides a robust, rapid, automated and accurate platform for diagnosing malaria in a clinical setting. The objective enumeration of red blood cells infected with Plasmodium species makes it suitable for global use and allows monitoring of the parasite load once therapy has been initiated, thereby providing an early marker of drug resistance. The automated generation of a full blood count for each sample provides an opportunity for detecting unsuspected cases. Asymptomatic carriers can also be identified, which will be useful in blood transfusion centres, and will enable treatment of these individuals to prevent the spread of the disease.