Genetic diversity of glutamate-rich protein (GLURP) in Plasmodium falciparum isolates from school-age children in Kinshasa, DRC

Malaria infections in school-age children further make it difficult to control the disease's spread. Moreover, the genetic diversity of glutamate-rich protein, potentially a candidate for vaccine development, has not yet been investigated in the Democratic Republic of Congo. Therefore, we aimed to assess the genetic diversity of the immunodominant C-terminal repetitive region (R2) of Plasmodium falciparum glutamate-rich protein gene (pfglurp) among school-age children living in Kinshasa, DRC. We conducted nested PCR targeting R2 of pfglurp and the amplicon were directly sequenced. We summarized the prevalence of mutations of bases and amino acids and indicated the amino acid repeat sequence in the R2 region by the unit code. We then statistically analyzed whether there was a relationship between the number of mutations in the pfglurp gene and attributes. In 221 samples, haplotype 1 was the most common (n = 137, 61.99%), with the same sequence as the 3D7 strain. Regarding the number of base mutations, it was higher in urban areas than rural areas (p = 0.0363). When genetic neutrality was tested using data from 171 samples of the single strain, Tajima's D was -1.857 (p = 0.0059). In addition, FST as the genetic distance between all attributes was very small and no significant difference was observed. This study clarified the genetic mutation status and relevant patient attributes among School-age children in the DRC. We found that urban areas are more likely to harbour pfglurp mutations. Future research needs to clarify the reason and mechanism involved.

A protocol and training guidelines for mosquito sampling in remote areas with limited power supply

Mosquito-borne diseases pose a significant threat in many Southeast Asian countries, particularly through the sylvatic cycle, which has a wildlife reservoir in forests and rural areas. Studying the composition and diversity of vectors and pathogen transmission is especially challenging in forests and rural areas due to their remoteness, limited accessibility, lack of power, and underdeveloped infrastructure. This study is based on the WHO mosquito sampling protocol, modifies technical details to support mosquito collection in difficult-to-access and resource-limited areas. Specifically, we describe the procedure for using rechargeable lithium batteries and solar panels to power the mosquito traps, demonstrate a workflow for processing and storing the mosquitoes in a -20 °C freezer, data management tools including microclimate data, and quality assurance processes to ensure the validity and reliability of the results. A pre- and post-test was utilized to measure participant knowledge levels. Additional research is needed to validate this protocol for monitoring vector-borne diseases in hard-to-reach areas within other countries and settings.

Biomolecular interactions between Plasmodium and human host: A basis of targeted antimalarial therapy

Malaria is one of the serious health concerns worldwide as it remains a clinical challenge due to the complex life cycle of the malaria parasite and the morphological changes it undergoes during infection. The malaria parasite multiplies rapidly and spreads in the population by changing its alternative hosts. These various morphological stages of the parasite in the human host cause clinical symptoms (anemia, fever, and coma). These symptoms arise due to the preprogrammed biology of the parasite in response to the human pathophysiological response. Thus, complete elimination becomes one of the major health challenges. Although malaria vaccine(s) are available in the market, they still contain to cause high morbidity and mortality. Therefore, an approach for eradication is needed through the exploration of novel molecular targets by tracking the epidemiological changes the parasite adopts. This review focuses on the various novel molecular targets.

A phase IIa, randomized, double-blind, safety, immunogenicity and efficacy trial of Plasmodium falciparum vaccine antigens merozoite surface protein 1 and RTS,S formulated with AS02 adjuvant in healthy, malaria-naïve adults

BACKGROUND

To improve the efficacy of Plasmodium falciparum malaria vaccine RTS,S/AS02, we conducted a study in 2001 in healthy, malaria-naïve adults administered RTS,S/AS02 in combination with FMP1, a recombinant merozoite surface-protein-1, C-terminal 42kD fragment.

METHODS

A double-blind Phase I/IIa study randomized N = 60 subjects 1:1:1:1 to one of four groups, N = 15/group, to evaluate safety, immunogenicity, and efficacy of intra-deltoid half-doses of RTS,S/AS02 and FMP1/AS02 administered in the contralateral (RTS,S + FMP1-separate) or same (RTS,S + FMP1-same) sites, or FMP1/AS02 alone (FMP1-alone), or RTS,S/AS02 alone (RTS,S-alone) on a 0-, 1-, 3-month schedule. Subjects receiving three doses of vaccine and non-immunized controls (N = 11) were infected with homologous P. falciparum 3D7 sporozoites by Controlled Human Malaria Infection (CHMI).

RESULTS

Subjects in all vaccination groups experienced mostly mild or moderate local and general adverse events that resolved within eight days. Anti-circumsporozoite antibody levels were lower when FMP1 and RTS,S were co-administered at the same site (35.0 µg/mL: 95 % CI 20.3-63), versus separate arms (57.4 µg/mL: 95 % CI 32.3-102) or RTS,S alone (62.0 µg/mL: 95 % CI: 37.8-101.8). RTS,S-specific lymphoproliferative responses and ex vivo ELISpot CSP-specific interferon-gamma (IFN-γ) responses were indistinguishable among groups receiving RTS,S/AS02. There was no difference in antibody to FMP1 among groups receiving FMP1/AS02. After CHMI, groups immunized with a RTS,S-containing regimen had ∼ 30 % sterile protection against parasitemia, and equivalent delays in time-to-parasitemia. The FMP1/AS02 alone group showed no sterile immunity or delay in parasitemia.

CONCLUSION

Co-administration of RTS,S and FMP1/AS02 reduced anti-RTS,S antibody, but did not affect tolerability, cellular immunity, or efficacy in a stringent CHMI model. Absence of efficacy or delay of patency in the sporozoite challenge model in the FMP1/AS02 group did not rule out efficacy of FMP1/AS02 in an endemic population. However, a Phase IIb trial of FMP1/AS02 in children in malaria-endemic Kenya did not demonstrate efficacy against natural infection.

CLINICALTRIALS

gov identifier: NCT01556945.

Molecular tools are crucial for malaria elimination

The eradication of Plasmodium parasites, responsible for malaria, is a daunting global public health task. It requires a comprehensive approach that addresses symptomatic, asymptomatic, and submicroscopic cases. Overcoming this challenge relies on harnessing the power of molecular diagnostic tools, as traditional methods like microscopy and rapid diagnostic tests fall short in detecting low parasitaemia, contributing to the persistence of malaria transmission. By precisely identifying patients of all types and effectively characterizing malaria parasites, molecular tools may emerge as indispensable allies in the pursuit of malaria elimination. Furthermore, molecular tools can also provide valuable insights into parasite diversity, drug resistance patterns, and transmission dynamics, aiding in the implementation of targeted interventions and surveillance strategies. In this review, we explore the significance of molecular tools in the pursuit of malaria elimination, shedding light on their key contributions and potential impact on public health.

Evaluation of different types of adjuvants in a malaria transmission-blocking vaccine

Adjuvants are critical components for vaccines, which enhance the strength and longevity of the antibody response and influence the types of immune response. Limited research has been conducted on the immunogenicity and protective efficacy of various adjuvants in malaria transmission-blocking vaccines (TBVs). In this study, we formulated a promising TBV candidate antigen, the P. berghei ookinete surface antigen PSOP25, with different types of adjuvants, including the TLR4 agonist monophosphoryl lipid A (MPLA), the TLR9 agonist cytosine phosphoguanosine oligodeoxynucleotides (CpG ODN 1826) (CpG), a saponin adjuvant QS-21, aluminum hydroxide (Alum), and two combination adjuvants MPLA + QS-21 and QS-21 + CpG. We demonstrated that adjuvanted vaccines results in elevated elicited antibody levels, increased proliferation of plasma cells, and efficient formation of germinal centers (GCs), leading to enhanced long-term protective immune responses. Furthermore, CpG group exhibited the most potent inhibition of ookinete formation and transmission-blocking activity. We found that the rPSOP25 with CpG adjuvant was more effective than MPLA, QS-21, MPLA + QS-21, QS-21 + CpG adjuvants in dendritic cells (DCs) activation and differentiation. Additionally, the CpG adjuvant elicited more rubust immune memory response than Alum adjuvant. CpG and QS-21 adjuvants could activate the Th1 response and promote the secretion of IFN-γ and TNF-α. PSOP25 induced a higher number of Tfh cells in splenocytes when combined with MPLA, CpG, and QS-21 + CpG; and there was no increase in these cell populations when PSOP25 was administered with Alum. In conclusion, CpG may confer enhanced efficacy for the rPSOP25 vaccine, as evidenced by the ability of the elicited antisera to induce protective immune responses and improved transmission-blocking activity.

Let it glow: genetically encoded fluorescent reporters in Plasmodium

The use of fluorescent proteins (FPs) in Plasmodium parasites has been key to understand the biology of this obligate intracellular protozoon. FPs like the green fluorescent protein (GFP) enabled to explore protein localization, promoter activity as well as dynamic processes like protein export and endocytosis. Furthermore, FP biosensors have provided detailed information on physiological parameters at the subcellular level, and fluorescent reporter lines greatly extended the malariology toolbox. Still, in order to achieve optimal results, it is crucial to know exactly the properties of the FP of choice and the genetic scenario in which it will be used. This review highlights advantages and disadvantages of available landing sites and promoters that have been successfully applied for the ectopic expression of FPs in Plasmodium berghei and Plasmodium falciparum. Furthermore, the properties of newly developed FPs beyond DsRed and EGFP, in the visualization of cells and cellular structures as well as in the sensing of small molecules are discussed.

Ageing of Plasmodium falciparum malaria sporozoites alters their motility, infectivity and reduces immune activation in vitro

BACKGROUND

Sporozoites (SPZ), the infective form of Plasmodium falciparum malaria, can be inoculated into the human host skin by Anopheline mosquitoes. These SPZ migrate at approximately 1 µm/s to find a blood vessel and travel to the liver where they infect hepatocytes and multiply. In the skin they are still low in number (50-100 SPZ) and vulnerable to immune attack by antibodies and skin macrophages. This is why whole SPZ and SPZ proteins are used as the basis for most malaria vaccines currently deployed and undergoing late clinical testing. Mosquitoes typically inoculate SPZ into a human host between 14 and 25 days after their previous infective blood meal. However, it is unknown whether residing time within the mosquito affects SPZ condition, infectivity or immunogenicity. This study aimed to unravel how the age of P. falciparum SPZ in salivary glands (14, 17, or 20 days post blood meal) affects their infectivity and the ensuing immune responses.

METHODS

SPZ numbers, viability by live/dead staining, motility using dedicated sporozoite motility orienting and organizing tool software (SMOOT), and infectivity of HC-04.j7 liver cells at 14, 17 and 20 days after mosquito feeding have been investigated. In vitro co-culture assays with SPZ stimulated monocyte-derived macrophages (MoMɸ) and CD8+ T-cells, analysed by flow cytometry, were used to investigate immune responses.

RESULTS

SPZ age did not result in different SPZ numbers or viability. However, a markedly different motility pattern, whereby motility decreased from 89% at day 14 to 80% at day 17 and 71% at day 20 was observed (p ≤ 0.0001). Similarly, infectivity of day 20 SPZ dropped to ~ 50% compared with day 14 SPZ (p = 0.004). MoMɸ were better able to take up day 14 SPZ than day 20 SPZ (from 7.6% to 4.1%, p = 0.03) and displayed an increased expression of pro-inflammatory CD80, IL-6 (p = 0.005), regulatory markers PDL1 (p = 0.02), IL-10 (p = 0.009) and cytokines upon phagocytosis of younger SPZ. Interestingly, co-culture of these cells with CD8+ T-cells revealed a decreased expression of activation marker CD137 and cytokine IFNγ compared to their day 20 counterparts. These findings suggest that older (day 17-20) P. falciparum SPZ are less infectious and have decreased immune regulatory potential.

CONCLUSION

Overall, this data is a first step in enhancing the understanding of how mosquito residing time affects P. falciparum SPZ and could impact the understanding of the P. falciparum infectious reservoir and the potency of whole SPZ vaccines.

Physical durability and insecticidal activity of long-lasting insecticidal nets in Cruzeiro do Sul, Brazil

Vector control is one of the principal strategies used for reducing malaria transmission. Long-lasting insecticidal bed nets (LLINs) are a key tool used to protect populations at risk of malaria, since they provide both physical and chemical barriers to prevent human-vector contact. This study aimed to assess the physical durability and insecticidal efficacy of LLINs distributed in Cruzeiro do Sul (CZS), Brazil, after 4 years of use. A total of 3000 LLINs (PermaNet 2.0) were distributed in high malaria risk areas of CZS in 2007. After 4 years of use, 27 'rectangular' LLINs and 28 'conical' LLINs were randomly selected for analysis. The evaluation of physical integrity was based on counting the number of holes and measuring their size and location on the nets. Insecticidal efficacy was evaluated by cone bioassays, and the amount of residual insecticide remaining on the surface of the LLINs was estimated using a colorimetric method. After 4 years of use, physical damage was highly prevalent on the rectangular LLINs, with a total of 473 holes detected across the 27 nets. The upper portion of the side panels sustained the greatest damage in rectangular LLINs. The overall mosquito mortality by cone bioassay was < 80% in 25/27 rectangular LLINs, with panel A (at the end of the rectangular bednet) presenting the highest mortality (54%). The overall mean insecticide concentration was 0.5 µg/sample, with the bednet roof containing the highest average concentration (0.61 µg/sample). On the conical LLINs, 547 holes were detected, with the bottom areas sustaining the greatest damage. The cone bioassay mortality was < 80% in 26/28 of the conical LLINs. The mean insecticide concentration was 0.3 µg/sample. After 4 years of use, the insecticidal efficacy of the LLINs was diminished to below acceptable thresholds.

Attitudes and perceptions towards developing a health educational video to enhance optimal uptake of malaria preventive therapy among pregnant women in Uganda: a qualitative study involving pregnant women, health workers, and Ministry of health officials

BACKGROUND

Malaria in pregnancy remains a major global public health problem. Intermittent prophylaxis treatment of malaria in pregnancy with Sulphadoxine-pyrimethamine and co-trimoxazole is efficacious for prevention of malaria in pregnancy HIV negative and positive women, respectively. However, uptake of the recommended doses of therapies has remained suboptimal in Uganda, majorly due to inadequate knowledge among pregnant women. Therefore, this study aimed to explore attitudes and perceptions towards developing an educational video for malaria preventive therapy.

METHODS

We conducted an exploratory study with qualitative methods among pregnant women attending antenatal care at Kisenyi Health Center IV (KHCIV), health workers from KHCIV, and officials from the Ministry of Health. The study was conducted at KHCIV from October 2022 to March 2023. Focus group discussions (FGD) were conducted among purposively selected pregnant women and key informant interviews (KII) among health workers and Ministry of Health officials. Data were analyzed using inductive and deductive thematic methods in atlas ti.8.

RESULTS

A total of five FGDs comprising of 7-10 pregnant women were conducted; and KIIs were conducted among four mid-wives, two obstetricians, and two Ministry of Health officials. Generally, all respondents mentioned a need for interventions to improve malaria preventive knowledge among pregnant women; were positive about developing an educative video for malaria preventive therapy in pregnancy; and suggested a short, concise, and edutaining video focusing both the benefits of taking and risks of not taking malaria preventive therapy. They proposed that women may be encouraged to view the video as soon as they conceive and throughout the pregnancy. It also was suggested that the video may be viewed on television sets in maternal and reproductive health clinics and homes, and on smart phones.

CONCLUSION

Pregnant women, health workers, and Ministry of Health officials were positive about the development of a short edutaining video on malaria preventive therapy that focuses on both benefits of taking and risks of not taking the malaria preventive therapy in pregnancy. This information guided the video development and therefore, in the development of health educative videos, client and stakeholder inputs may always be solicited.

Aspecific binding of anti-NK1.1 antibodies on myeloid cells in an experimental model for malaria-associated acute respiratory distress syndrome

BACKGROUND

Conventional natural killer (cNK) cells play an important role in the innate immune response by directly killing infected and malignant cells and by producing pro- and anti-inflammatory cytokines. Studies on their role in malaria and its complications have resulted in conflicting results.

METHODS

Using the commonly used anti-NK1.1 depletion antibodies (PK136) in an in-house optimized experimental model for malaria-associated acute respiratory distress syndrome (MA-ARDS), the role of cNK cells was investigated. Moreover, flow cytometry was performed to characterize different NK cell populations.

RESULTS

While cNK cells were found to be dispensable in the development of MA-ARDS, the appearance of a NK1.1+ cell population was observed in the lungs upon infection despite depletion with anti-NK1.1. Detailed characterization of the unknown population revealed that this population consisted of a mixture of monocytes and macrophages that bind the anti-NK1.1 antibody in an aspecific way. This aspecific binding may occur via Fcγ receptors, such as FcγR4. In contrast, in vivo depletion using anti-NK1.1 antibodies was proved to be specific for cNK cells.

CONCLUSION

cNK cells are dispensable in the development of experimental MA-ARDS. Moreover, careful flow cytometric analysis, with a critical mindset in relation to potential aspecific binding despite the use of commercially available Fc blocking reagents, is critical to avoid misinterpretation of the results.

Sanger sequencing and deconvolution of polyclonal infections: a quantitative approach to monitor drug-resistant Plasmodium falciparum

BACKGROUND

Anti-malarial drug resistance in Plasmodium falciparum is a major public health problem in malaria-endemic regions. Although various technical improvements in sequencing methods have been introduced to identify SNPs, the conventional approach with current tools does not discriminate mixed infections, and thus can be improved for more sensitive surveillance of anti-malarial resistance to better inform control strategies.

METHODS

We developed a computational approach for deconvolution of chromatograms generated by standard Sanger sequencing of PCR amplicons in order to quantify molecular marker variants of anti-malarial drug resistance genes [Plasmodium falciparum dihydropteorate synthase (Pfdhps) and P. falciparum dihydrofolate reductase (Pfdhfr)]. We validated this computational approach using mixtures of V1/S and FCR3 at varying proportions between 0 and 100%, then applied it to field samples collected in Doneguebougou, Mali in 2018. We determined the mean fraction of resistance alleles in individual samples, as well as the prevalence of infections carrying resistant parasites.

FINDINGS

We observed a highly significant correlation between the predicted and measured proportions of V1/S and FCR3 alleles in mixed laboratory samples (all p < 0.001). Among field samples, the mean fraction of resistant Pfdhps alleles was 4.7% 431V, 95.9% 436F/A, 49.9% 437G, 0.0% 540E, 1.2% 581G and 1.5% 613S/T; corresponding prevalences were 50.0%, 100%, 72.5%, 0.0%, 25.0%, and 12.5%, respectively. The mean fraction of resistant Pfdhfr alleles was 0.6% 16V, 11.1% 50R, 89.0% 51I, 98.3% 59R, 74.7% 108T/N, 8.6% 140L and 8.7% 164L; corresponding prevalences were 12.5%, 75.0%, 100%, 100%, 100%, 50.0%, and 28.6%, respectively. We identified two new point mutations on the Pfdhps gene at codons D484T and D545N.

INTERPRETATION

Computational deconvolution of sequencing chromatograms can discriminate varying proportions of antimalarial drug-sensitive versus -resistant alleles. This cost-effective and quantitative variant-sequencing approach will be useful for population-based surveys that characterize mixed infections at the individual level to survey known and unknown mutations in P. falciparum drug-resistance genes.

FUNDING

This work was supported by the Division of Intramural Research of the National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH). HM was supported by the African Postdoctoral Training Initiative (APTI) Fellowship program jointly managed by the US NIH, The African Academy of Sciences (AAS) and Bill & Melinda Gates Foundation (BMGF); Grant Reference Number: APTI-18-01.

Factors associated with the risk of malaria among children: analysis of 2021 Nigeria Malaria Indicator Survey

BACKGROUND

Malaria remains a burden globally, with the African region accounting for 94% of the overall disease burden and deaths in 2019. It is the major cause of morbidity and mortality among children in Nigeria. Though different environmental factors have been assessed to influence the distribution and transmission of malaria vectors, there is a shortage of information on how they may influence malaria transmission among under-fives in Nigeria.

METHODS

This study was based on the secondary data analysis of the Nigeria Malaria Indicator Survey 2021. The study sample comprised 10,645 women (aged 15-49) who delivered a child in the 2 years preceding the survey. The study was restricted to under-fives. Logistic regression was used to identify factors associated with the risk of malaria.

RESULTS

There was a positive association between the risk of malaria and heard/seen malaria messages in the last 6 months (AOR 1.39, 95% CI 1.19-1.62), houses with walls built using rudimentary materials (AOR = 1.38, 95% CI 1.04-1.83), at least 6 children living in the house (AOR 1.22, 95% CI 1.00-1.49), children being 1 or 2 years old was associated with increased odds (AOR 1.89, 95% CI 1.50-2.34 and AOR 1.89, 95% CI 1.52-2.36), children from households with only treated nets (AOR 1.23, 95% CI 1.04-1.46) and those from the North West or South East regions (AOR 1.50, 95% CI 1.10-2.05 and AOR 1.48, 95% CI 1.01-2.16), respectively. All other predictors were not associated with the risk of malaria.

CONCLUSION

The factors associated with the risk of malaria in this study included sleeping under treated mosquito nets, the age of the children, residing in the northwest and southeast regions, wall construction material, 6 children and above in the household and hearing/seen malaria messages in the last 6 months. Continuous health education and public health interventions, such as the provision of LLITNs, will reduce the risk of malaria and improve the health and well-being of children under 5 years of age.

Mapping malaria vectors and insecticide resistance in a high-endemic district of Haryana, India: implications for vector control strategies

BACKGROUND

Achieving effective control and elimination of malaria in endemic regions necessitates a comprehensive understanding of local mosquito species responsible for malaria transmission and their susceptibility to insecticides.

METHODS

The study was conducted in the highly malaria prone Ujina Primary Health Center of Nuh (Mewat) district of Haryana state of India. Monthly entomological surveys were carried out for adult mosquito collections via indoor resting collections, light trap collections, and pyrethrum spray collections. Larvae were also collected from different breeding sites prevalent in the region. Insecticide resistance bioassay, vector incrimination, blood meal analysis was done with the collected vector mosquitoes.

RESULTS

A total of 34,974 adult Anopheles mosquitoes were caught during the survey period, out of which Anopheles subpictus was predominant (54.7%). Among vectors, Anopheles stephensi was predominant (15.5%) followed by Anopheles culicifacies (10.1%). The Human Blood Index (HBI) in the case of An. culicifacies and An. stephensi was 6.66 and 9.09, respectively. Vector incrimination results revealed Plasmodium vivax positivity rate of 1.6% for An. culicifacies. Both the vector species were found resistant to DDT, malathion and deltamethrin.

CONCLUSION

The emergence of insecticide resistance in both vector species, compromises the effectiveness of commonly used public health insecticides. Consequently, the implementation of robust insecticide resistance management strategies becomes imperative. To effectively tackle the malaria transmission, a significant shift in vector control strategies is warranted, with careful consideration and adaptation to address specific challenges encountered in malaria elimination efforts.

Addressing low-density malaria infections in India and other endemic part of the world-the opportune time?

Shifting from high- to low-malaria transmission accompanies a higher proportion of asymptomatic low-density malaria infections (LDMI). Currently, several endemic countries, such as India, are experiencing this shift as it is striving to eliminate malaria. LDMI is a complex concept for which there are several important questions yet unanswered on its natural history, infectiousness, epidemiology, and pathological and clinical impact. India is on the right path to eliminating malaria, but it is facing the LDMI problem. A brief discussion on the concept and definitions of LDMI is beforehand presented. Also, an exhaustive review and critical analysis of the existing literature on LDMI in malaria-endemic areas, including India, are included in this review. Finally, we opine that addressing LDMI in India is ethically and pragmatically achievable, and a pool of sine qua non conditions is required to efficiently and sustainably eliminate malaria.

An optimised YOLOv4 deep learning model for efficient malarial cell detection in thin blood smear images

BACKGROUND

Malaria is a serious public health concern worldwide. Early and accurate diagnosis is essential for controlling the disease's spread and avoiding severe health complications. Manual examination of blood smear samples by skilled technicians is a time-consuming aspect of the conventional malaria diagnosis toolbox. Malaria persists in many parts of the world, emphasising the urgent need for sophisticated and automated diagnostic instruments to expedite the identification of infected cells, thereby facilitating timely treatment and reducing the risk of disease transmission. This study aims to introduce a more lightweight and quicker model-but with improved accuracy-for diagnosing malaria using a YOLOv4 (You Only Look Once v. 4) deep learning object detector.

METHODS

The YOLOv4 model is modified using direct layer pruning and backbone replacement. The primary objective of layer pruning is the removal and individual analysis of residual blocks within the C3, C4 and C5 (C3-C5) Res-block bodies of the backbone architecture's C3-C5 Res-block bodies. The CSP-DarkNet53 backbone is simultaneously replaced for enhanced feature extraction with a shallower ResNet50 network. The performance metrics of the models are compared and analysed.

RESULTS

The modified models outperform the original YOLOv4 model. The YOLOv4-RC3_4 model with residual blocks pruned from the C3 and C4 Res-block body achieves the highest mean accuracy precision (mAP) of 90.70%. This mAP is > 9% higher than that of the original model, saving approximately 22% of the billion floating point operations (B-FLOPS) and 23 MB in size. The findings indicate that the YOLOv4-RC3_4 model also performs better, with an increase of 9.27% in detecting the infected cells upon pruning the redundant layers from the C3 Res-block bodies of the CSP-DarkeNet53 backbone.

CONCLUSIONS

The results of this study highlight the use of the YOLOv4 model for detecting infected red blood cells. Pruning the residual blocks from the Res-block bodies helps to determine which Res-block bodies contribute the most and least, respectively, to the model's performance. Our method has the potential to revolutionise malaria diagnosis and pave the way for novel deep learning-based bioinformatics solutions. Developing an effective and automated process for diagnosing malaria will considerably contribute to global efforts to combat this debilitating disease. We have shown that removing undesirable residual blocks can reduce the size of the model and its computational complexity without compromising its precision.

Factors associated with the timely diagnosis of malaria and the utilization of types of healthcare facilities: a retrospective study in the Republic of Korea

Objectives

This study aimed to analyze trends in the timely diagnosis of malaria cases over the past 10 years in relation to the utilization of different types of healthcare facilities.

Methods

The study included 3,697 confirmed and suspected cases of malaria reported between January 1, 2013, and December 31, 2022, in the national integrative disease and healthcare management system. Some cases lacking a case report or with information missing from the case report were excluded from the analysis. A generalized linear model with a Poisson distribution was constructed to estimate rate ratios and 95% confidence intervals adjusted for other variables, such as distance.

Results

When cases involving diagnosis >5 days after symptom onset in confirmed patients (5DD) were examined according to the type of healthcare facility, the rate ratio of 5DD cases was found to be higher for public health facilities than for tertiary hospitals. Specifically, the rate ratio was higher when the diagnosis was established at a tertiary hospital, even after a participant had visited primary or secondary hospitals. In an analysis adjusted for the distance to each participant's healthcare facility, the results did not differ substantially from the results of the crude analysis.

Conclusion

It is imperative to improve the diagnostic capabilities of public facilities and raise awareness of malaria at primary healthcare facilities for effective prevention and control.

Characterization of drug resistance genes in Indian Plasmodium falciparum and Plasmodium vivax field isolates

One of the major challenges for malaria control and elimination is the spread and emergence of antimalarial drug resistance. Mutations in Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) field isolates for five drug resistance genes viz. crt, mdr1, dhps, dhfr and kelch known to confer resistance to choloroquine (CQ), sulfadoxine-pyrimethamine (SP) and artemisinin (ART) and its derivatives were analyzed. A total of 342 symptomatic isolates of P. falciparum (Pf) and P. vivax (Pv) from 1993 to 2014 were retrieved from malaria parasite repository at National Institute of Malaria Research (NIMR). Sample DNA was extracted from dried blood spots and various targeted single nucleotide polymorphisms (SNPs) associated with antimalarial drug resistance were analysed for these isolates. C72S (67.7%) and K76T (83.8%) mutations along with SVMNT haplotype (67.7%) predominated the study population for Pfcrt. The most prevalent SNPs were S108N (73.2%) and A437G (24.8%) and the most prevalent haplotypes were ACNRNI (51.9%) and SAKAA (74.5%) in Pfdhfr and Pfdhps respectively. Only two mutations in Pfmdr1, N86Y (26.31%) and Y184F (56.26%), were seen frequently in our study population. No mutations associated with Pfk13 were observed. For Pv, all the studied isolates showed two Pvdhps mutations, A383G and A553G, and two Pfdhfr mutations, S58R and S117N. Similarly, three mutations, viz. T958M, M908L and F1076L were found in Pvmdr1. No variations were observed in Pvcrt-o and Pvk12 genes. Overall, our study demonstrates an increase in mutations associated with SP resistance in both Pf and Pv, however, no single nucleotide polymorphisms (SNPs) associated with ART resistance have been observed for either species. Various SNPs associated with CQ resistance were seen in Pf; whereas only Pvmdr1 associated resistant SNPs were observed in Pv. Therefore, molecular characterization of drug resistance genes is essential for timely monitoring and prevention of malaria by identifying the circulating drug resistant parasites in the country.

Rapid diagnosis and prognosis of malaria infection using a microfluidic point-of-care immunoassay

Malaria is a major cause of illness and death worldwide. Rapid diagnostic tests are the most widely used tool for detecting malaria infection, however, they only provide binary results and lack the sensitivity needed to detect many asymptomatic infections. Molecular assays for quantifying malaria biomarkers offer higher detection sensitivity, however, they are time-consuming, and require expert training and expensive equipment, making them unsuitable for use in most of Africa. To address the need for simple, accurate and field-deployable malaria diagnostic tests, we have developed a microfluidic point-of-care (mPOC) immunoassay for rapid quantification of Plasmodium falciparum histidine-rich protein 2 (PfHRP2), a malaria parasite biomarker, in whole blood. This device features two diagnostic modes for detecting PfHRP2 at low (100's pg/mL) and high (1,000's ng/mL) concentrations, making it useful for multiple diagnostic applications, including the detection of asymptomatic infection, prediction of disease outcomes and diagnosis of cerebral malaria. Measurements of PfHRP2 in blood samples from malaria patients demonstrates that this platform offers similar accuracy as an ultra-sensitive PfHRP2 enzyme-linked immunosorbent assay (ELISA) test, while being 12× faster and simpler to use. This mPOC immunoassay can be deployed in rural health centers to assist clinicians in diagnosing and triaging malaria patients, ultimately improving patient outcomes.

Study protocol: improving response to malaria in the Amazon through identification of inter-community networks and human mobility in border regions of Ecuador, Peru and Brazil

INTRODUCTION

Understanding human mobility's role in malaria transmission is critical to successful control and elimination. However, common approaches to measuring mobility are ill-equipped for remote regions such as the Amazon. This study develops a network survey to quantify the effect of community connectivity and mobility on malaria transmission.

METHODS

We measure community connectivity across the study area using a respondent driven sampling design among key informants who are at least 18 years of age. 45 initial communities will be selected: 10 in Brazil, 10 in Ecuador and 25 in Peru. Participants will be recruited in each initial node and administered a survey to obtain data on each community's mobility patterns. Survey responses will be ranked and the 2-3 most connected communities will then be selected and surveyed. This process will be repeated for a third round of data collection. Community network matrices will be linked with each country's malaria surveillance system to test the effects of mobility on disease risk.

ETHICS AND DISSEMINATION

This study protocol has been approved by the institutional review boards of Duke University (USA), Universidad San Francisco de Quito (Ecuador), Universidad Peruana Cayetano Heredia (Peru) and Universidade Federal Minas Gerais (Brazil). Results will be disseminated in communities by the end of the study.

Activity refinement of aryl amino acetamides that target the P. falciparum STAR-related lipid transfer 1 protein

Malaria is a devastating disease that causes significant morbidity worldwide. The development of new antimalarial chemotypes is urgently needed because of the emergence of resistance to frontline therapies. Independent phenotypic screening campaigns against the Plasmodium asexual parasite, including our own, identified the aryl amino acetamide hit scaffold. In a prior study, we identified the STAR-related lipid transfer protein (PfSTART1) as the molecular target of this antimalarial chemotype. In this study, we combined structural elements from the different aryl acetamide hit subtypes and explored the structure-activity relationship. It was shown that the inclusion of an endocyclic nitrogen, to generate the tool compound WJM-715, improved aqueous solubility and modestly improved metabolic stability in rat hepatocytes. Metabolic stability in human liver microsomes remains a challenge for future development of the aryl acetamide class, which was underscored by modest systemic exposure and a short half-life in mice. The optimized aryl acetamide analogs were cross resistant to parasites with mutations in PfSTART1, but not to other drug-resistant mutations, and showed potent binding to recombinant PfSTART1 by biophysical analysis, further supporting PfSTART1 as the likely molecular target. The optimized aryl acetamide analogue, WJM-715 will be a useful tool for further investigating the druggability of PfSTART1 across the lifecycle of the malaria parasite.

Who was the first to visualize the malaria parasite?

Human malaria, an ancient tropical disease, is caused by infection with protozoan parasites belonging to the genus Plasmodium and is transmitted by female mosquitoes of the genus Anopheles. Our understanding of human malaria parasites began officially in 1880 with their discovery in the blood of malaria patients by Charles Louis Alphonse Lavéran (1845-1922), a French army officer working in Algeria. A claim for priority was made by Philipp Friedrich Hermann Klencke (1813-1881) in 1843, who wrote a chapter entitled: "Marvellous parallelism between the manifestations of vertigo and the presence of animalcule vacuoles in living blood." We should not lose sight of this old controversy, which is rarely mentioned in historical reviews on malaria.

Anopheles sacharovi in Italy: first record of the historical malaria vector after over 50 years

BACKGROUND

Anopheles sacharovi, a member of the Anopheles maculipennis complex, was a historical malaria vector in Italy, no longer found since the last report at the end of 1960s. In September 2022, within the Surveillance Project for the residual anophelism, a single specimen of An. maculipennis sensu lato collected in Lecce municipality (Apulia region) was molecularly identified as An. sacharovi. This record led to implement a targeted entomological survey in September 2023.

METHODS

Investigation was conducted in the areas around the first discovery, focusing on animal farms, riding stables and potential breeding sites. Adult and immature mosquitoes were collected, using active search or traps, in several natural and rural sites. Mosquitoes belonging to An. maculipennis complex were identified morphologically and molecularly by a home-made routine quantitative polymerase chain reaction (qPCR) assay, developed specifically for the rapid identification of An. labranchiae, and, when necessary, by amplification and sequencing of the ITS-2 molecular marker.

RESULTS

Out of the 11 sites investigated, 6 were positive for Anopheles presence. All 20 An. maculipennis s.l. (7 adults, 10 larvae and 3 pupae) collected in the areas were identified as An. sacharovi by ITS-2 sequencing.

CONCLUSIONS

The discovery of An. sacharovi, considered to have disappeared from Italy for over 50 years, has a strong health relevance and impact, highlighting an increase in the receptivity of the southern areas. As imported malaria cases in European countries are reported every year, the risk of Plasmodium introduction by gametocyte carriers among travellers from endemic countries should be taken into greater consideration. Our findings allow rethinking and building new models for the prediction and expansion of introduced malaria. Furthermore, to prevent the risk of reintroduction of the disease, the need to strengthen the surveillance of residual anophelism throughout the South should be considered.

Comparison of extraction methods in vitro Plasmodium falciparum: A 1H NMR and LC-MS joined approach

Malaria is a parasitic disease that remains a global concern and the subject of many studies. Metabolomics has emerged as an approach to better comprehend complex pathogens and discover possible drug targets, thus giving new insights that can aid in the development of antimalarial therapies. However, there is no standardized method to extract metabolites from in vitro Plasmodium falciparum intraerythrocytic parasites, the stage that causes malaria. Additionally, most methods are developed with either LC-MS or NMR analysis in mind, and have rarely been evaluated with both tools. In this work, three extraction methods frequently found in the literature were reproduced and samples were analyzed through both LC-MS and 1H NMR, and evaluated in order to reveal which is the most repeatable and consistent through an array of different tools, including chemometrics, peak detection and annotation. The most reliable method in this study proved to be a double extraction with methanol and methanol/water (80:20, v/v). Metabolomic studies in the field should move towards standardization of methodologies and the use of both LC-MS and 1H NMR in order to make data more comparable between studies and facilitate the achievement of biologically interpretable information.

Modelling spatiotemporal variation in under-five malaria risk in Ghana in 2016-2021

BACKGROUND

Ghana is among the top 10 highest malaria burden countries, with about 20,000 children dying annually, 25% of which were under five years. This study aimed to produce interactive web-based disease spatial maps and identify the high-burden malaria districts in Ghana.

METHODS

The study used 2016-2021 data extracted from the routine health service nationally representative and comprehensive District Health Information Management System II (DHIMS2) implemented by the Ghana Health Service. Bayesian geospatial modelling and interactive web-based spatial disease mapping methods were employed to quantify spatial variations and clustering in malaria risk across 260 districts. For each district, the study simultaneously mapped the observed malaria counts, district name, standardized incidence rate, and predicted relative risk and their associated standard errors using interactive web-based visualization methods.

RESULTS

A total of 32,659,240 malaria cases were reported among children < 5 years from 2016 to 2021. For every 10% increase in the number of children, malaria risk increased by 0.039 (log-mean 0.95, 95% credible interval = - 13.82-15.73) and for every 10% increase in the number of males, malaria risk decreased by 0.075, albeit not statistically significant (log-mean - 1.82, 95% credible interval = - 16.59-12.95). The study found substantial spatial and temporal differences in malaria risk across the 260 districts. The predicted national relative risk was 1.25 (95% credible interval = 1.23, 1.27). The malaria risk is relatively the same over the entire year. However, a slightly higher relative risk was recorded in 2019 while in 2021, residing in Keta, Abuakwa South, Jomoro, Ahafo Ano South East, Tain, Nanumba North, and Tatale Sanguli districts was associated with the highest malaria risk ranging from a relative risk of 3.00 to 4.83. The district-level spatial patterns of malaria risks changed over time.

CONCLUSION

This study identified high malaria risk districts in Ghana where urgent and targeted control efforts are required. Noticeable changes were also observed in malaria risk for certain districts over some periods in the study. The findings provide an effective, actionable tool to arm policymakers and programme managers in their efforts to reduce malaria risk and its associated morbidity and mortality in line with the Sustainable Development Goals (SDG) 3.2 for limited public health resource settings, where universal intervention across all districts is practically impossible.

Efficacy and safety of artemether-lumefantrine for the treatment of uncomplicated falciparum malaria in mainland Tanzania, 2019

BACKGROUND

Artemisinin-based combination therapy (ACT) has been a major contributor to the substantial reductions in global malaria morbidity and mortality over the last decade. In Tanzania, artemether-lumefantrine (AL) was introduced as the first-line treatment for uncomplicated Plasmodium falciparum malaria in 2006. The World Health Organization (WHO) recommends regular assessment and monitoring of the efficacy of the first-line treatment, specifically considering that artemisinin resistance has been confirmed in the Greater Mekong sub-region. This study's main aim was to assess the efficacy and safety of AL for treating uncomplicated P. falciparum malaria in Tanzania.

METHODS

This was a single-arm prospective antimalarial drug efficacy trial conducted in four of the eight National Malaria Control Programme (NMCP) sentinel sites in 2019. The trial was carried out in outpatient health facilities in Karume-Mwanza region, Ipinda-Mbeya region, Simbo-Tabora region, and Nagaga-Mtwara region. Children aged six months to 10 years with microscopy confirmed uncomplicated P. falciparum malaria who met the inclusion criteria were recruited based on the WHO protocol. The children received AL (a 6-dose regimen of AL twice daily for three days). Clinical and parasitological parameters were monitored during follow-up over 28 days to evaluate drug efficacy.

RESULTS

A total of 628 children were screened for uncomplicated malaria, and 349 (55.6%) were enrolled between May and September 2019. Of the enrolled children, 343 (98.3%) completed the 28-day follow-up or attained the treatment outcomes. There were no early treatment failures; recurrent infections during follow-up were common at two sites (Karume 29.5%; Simbo 18.2%). PCR-corrected adequate clinical and parasitological response (ACPR) by survival analysis to AL on day 28 of follow-up varied from 97.7% at Karume to 100% at Ipinda and Nagaga sites. The commonly reported adverse events were cough, skin pallor, and abdominal pain. The drug was well tolerated, and no serious adverse event was reported.

CONCLUSION

This study showed that AL had adequate efficacy and safety for the treatment of uncomplicated falciparum malaria in Tanzania in 2019. The high recurrent infections were mainly due to new infections, highlighting the potential role of introducing alternative artemisinin-based combinations that offer improved post-treatment prophylaxis, such as artesunate-amodiaquine (ASAQ).

Malaria cases in China acquired through international travel, 2013-2022

BACKGROUND

Despite the World Health Organisation certifying China malaria-free in 2021, the risk of local transmission caused by imported malaria cases remains a significant clinical and public health issue. It is necessary to present the changing trends of malaria in China and discuss the role of travel medicine services in consolidating malaria elimination.

METHODS

This study systematically reviewed articles and reports related to human malaria from 2013 to 2022 published in international and Chinese databases. Data on malaria (i.e. number of cases, Plasmodium spp., diagnostic method, country of acquisition, provinces with high risk of re-introduction and transmission) were collected and synthesised, then summarised using descriptive statistics.

RESULTS

Overall, 24 758 cases of malaria (>99.5% laboratory confirmed, > 99.2% imported, 0.5% fatal) were reported in China from 2013 to 2022, with a downward trend over the years (4128 cases in 2013 compared to 843 cases in 2022; χ2 trend p-value = 0.005). The last locally acquired case was reported in 2017. P. falciparum (65.5%) was the most common species identified, followed by P. vivax (20.9%) and P. ovale (10.0%). Two Pheidole knowlesi cases were also identified in 2014 and 2017 in returned travellers from Malaysia and Indonesia, respectively. The most common countries of malaria acquisition were Ghana, Angola, and Myanmar. P. vivax was mainly detected in returned travellers from Myanmar, while P. falciparum and P. ovale were detected in travellers from Sub-Saharan Africa. Imported cases were mainly reported in Yunnan, Jiangsu, Sichuan, Guangxi, Shandong, Zhejiang, and Henan provinces, where large numbers of Chinese people travel overseas for work.

CONCLUSION

Returned travellers from malaria-endemic countries pose a significant risk of malaria re-introduction to China. Travel medicine should be strengthened to improve the capacity and accessibility of both pre- and post-travel services, including malaria prophylaxis and prompt diagnosis of illness in returned travellers.

A formative cross-sectional study to assess caregiver's health-seeking behaviour and knowledge surrounding malaria, and understand the burden of malaria among children under-five in conflict-affected communities of Cameroon

BACKGROUND

Malaria remains a major global health problem often worsened by political instability and armed conflict. The purpose of the study was to explore community knowledge, attitudes and practices on malaria prevention, and to understand the burden of malaria and health-seeking behaviours of caregivers of children under-five in conflict-affected communities of the South West and Littoral Regions of Cameroon.

METHODS

A cross-sectional survey involving internally displaced persons (IDPS), host population, and their children under-five was conducted across 80 communities. The survey was conducted from May to June 2021. Participants were interviewed using a structured questionnaire. Malaria prevalence for children under-five was determined using rapid diagnostic tests (RDT) on blood samples. Association between variables and displacement status was measured using chi square test and multivariate logistic regression model was fitted to identify factors associated with adequate knowledge on malaria prevention.

RESULTS

A total of 2386 adults participated in the study and 1543 RDTs were conducted for children under-five. Adequate levels of knowledge and attitudes on malaria prevention was recorded among 1258 (52.9%) of the participants, with very strong evidence to suggest the level to be higher among the host (59.5%) compared to the IDPs (49.5%) and returnees (39.7%) (p < 0.001). Good practices towards malaria prevention was 43.3%, with very strong evidence indicating lower levels among IDPs (42.8%) and returnees (28.5%) compared to the host (49.4%) (p < 0.001). Malaria prevalence for children under-five was 54.0% and adequate health-seeking for suspected episodes of malaria was 53.0%, without any difference among IDPs (51.78%) and returnees (48.7%) compared to host populations (55.4%) (p = 0.154). Multivariate logistic regression model showed that there was quite strong evidence to suggest primary and secondary levels of education have higher odds of having correct knowledge of malaria prevention (adjusted odds ratio (AOR) 1.71, 95% confidence interval (CI): 1.11-2.64, p = 0.015 and AOR 1.80, 95% CI 1.15-2.82, p = 0.010 respectively). There was very strong evidence to suggest that owning a radio or a television was associated with greater odds of having a higher knowledge on malaria prevention (AOR 1.49, 95% CI 1.233-1.81, p = 0.000 and AOR 1.47, 95% CI 1.18-1.84, p = 0.001).

CONCLUSION

Over half of the population have correct knowledge and attitudes towards malaria prevention but gaps in complete knowledge remained. Some of the caregivers know the correct malaria preventive practices coupled with largely unsatisfactory treatment approaches and reflected by the high prevalence of malaria among their children. In order to effectively treat malaria, innovative strategies should target community participation.

The effect of physical barriers under a raised house on mosquito entry: an experimental study in rural Gambia

BACKGROUND

Anopheles gambiae, the major malaria mosquito in sub-Saharan Africa, feed largely indoors at night. Raising a house off the ground with no barriers underneath reduces mosquito-house entry. This experiment tested whether walling off the space under an elevated hut affects mosquito-hut entry.

METHODS

Four inhabited experimental huts, each of which could be moved up and down, were used in rural Gambia. Nightly collections of mosquitoes were made using light traps and temperature and carbon dioxide levels monitored indoors and outdoors using loggers. Each night, a reference hut was kept at ground level and three huts raised 2 m above the ground; with the space under the hut left open, walled with air-permeable walls or solid walls. Treatments were rotated every four nights using a randomized block design. The experiment was conducted for 32 nights. Primary measurements were mosquito numbers and indoor temperature in each hut.

RESULTS

A total of 1,259 female Anopheles gambiae sensu lato were collected in the hut at ground level, 655 in the hut with an open ground floor, 981 in the hut with air-permeable walls underneath and 873 in the hut with solid walls underneath. Multivariate analysis, adjusting for confounders, showed that a raised hut open underneath had 53% fewer mosquitoes (95% CI 47-58%), those with air-permeable walls underneath 24% fewer (95% CI 9-36%) and huts with solid walls underneath 31% fewer (95% CI 24-37%) compared with a hut on the ground. Similar results were found for Mansonia spp. and total number of female mosquitoes, but not for Culex mosquitoes where hut entry was unaffected by height or barriers. Indoor temperature and carbon dioxide levels were similar in all huts.

CONCLUSION

Raising a house 2 m from the ground reduces the entry of An. gambiae and Mansonia mosquitoes, but not Culex species. The protective effect of height is reduced if the space underneath the hut is walled off.

Efficacy and safety of artemether-lumefantrine for the treatment of uncomplicated falciparum malaria in mainland Tanzania, 2018

BACKGROUND

The use of artemisinin-based combination therapy (ACT) is recommended by the World Health Organization for the treatment of uncomplicated falciparum malaria. Artemether-lumefantrine (AL) is the most widely adopted first-line ACT for uncomplicated malaria in sub-Saharan Africa (SSA), including mainland Tanzania, where it was introduced in December 2006. The WHO recommends regular assessment to monitor the efficacy of the first-line treatment specifically considering that artemisinin partial resistance was reported in Greater Mekong sub-region and has been confirmed in East Africa (Rwanda and Uganda). The main aim of this study was to assess the efficacy and safety of AL for the treatment of uncomplicated falciparum malaria in mainland Tanzania.

METHODS

A single-arm prospective anti-malarial drug efficacy trial was conducted in Kibaha, Mlimba, Mkuzi, and Ujiji (in Pwani, Morogoro, Tanga, and Kigoma regions, respectively) in 2018. The sample size of 88 patients per site was determined based on WHO 2009 standard protocol. Participants were febrile patients (documented axillary temperature ≥ 37.5 °C and/or history of fever during the past 24 h) aged 6 months to 10 years. Patients received a 6-dose AL regimen by weight twice a day for 3 days. Clinical and parasitological parameters were monitored during 28 days of follow-up to evaluate the drug efficacy and safety.

RESULTS

A total of 653 children were screened for uncomplicated malaria and 349 (53.7%) were enrolled between April and August 2018. Of the enrolled children, 345 (98.9%) completed the 28 days of follow-up or attained the treatment outcomes. There were no early treatment failures, but recurrent infections were higher in Mkuzi (35.2%) and Ujiji (23%). By Kaplan-Meier analysis of polymerase chain reaction (PCR) uncorrected adequate clinical and parasitological response (ACPR) ranged from 63.4% in Mkuzi to 85.9% in Mlimba, while PCR-corrected ACPR on day 28 varied from 97.6% in Ujiji to 100% in Mlimba. The drug was well tolerated; the commonly reported adverse events were cough, runny nose, and abdominal pain. No serious adverse event was reported.

CONCLUSION

This study showed that AL had adequate efficacy and safety for the treatment of uncomplicated falciparum malaria. The high number of recurrent infections were mainly due to new infections, indicating the necessity of utilizing alternative artemisinin-based combinations, such as artesunate amodiaquine, which provide a significantly longer post-treatment prophylactic effect.

Usefulness of serial testing for the diagnosis of malaria in cases of fever upon return from travel

BACKGROUND

When malaria is suspected in case of fever after travel in endemic areas, the current recommendation is to repeat the malaria test at 24-hour intervals, with up to two additional tests, as long as the test result is negative. A retrospective analysis was conducted to investigate the appropriateness of this recommendation by determining the proportion of tests with negative result at first and subsequently with a positive one at second or third attempt.

METHODS

A retrospective study was conducted at the Centre for Primary Care and Public Health, Lausanne, covering a period of 15 years. All patients tested once for malaria were included. Testing included microscopy thick and thin films as well as malaria rapid diagnostic test used in combination. The main outcome measure was the proportion of patients with a first negative test result, subsequently positive on second or third test over the total patients with suspected malaria assessed. Demographic, travel, clinical, and laboratory variables were collected from patients' records to identify potential predictors of an initially negative and then positive test result.

RESULTS

Four thousand nine hundred seventy-two patients were included. Of those, 4557 (91.7%) had definitive negative test results, and 415 (8.3%) had a positive result on the first test [332/415 (80%) Plasmodium falciparum, 40/415 (9.6%) P. vivax, 21/415 (5.1%) P. ovale, 12/415 (2.9%) P. vivax/ovale, 9/415 (2.2%) P. malariae and 1/415 (0.2%) P. knowlesi], and 3/4972 (0.06%) had a positive result on the second test after a first negative result, 1/4972(0.02%) had a positive test result after 2 negative results, all with P. falciparum. One of the four patients that were positive after their initial negative test was pregnant. The very small number of patients with an initially negative test result and secondarily positive did not allow for risk factor analysis.

CONCLUSIONS

The current recommendation of serial malaria testing is not supported by the present study, a fortiori for those who do not present with a strong clinical or laboratory predictor of malaria.

Point of care devices for detection of Covid-19, malaria and dengue infections: A review

Need for affordable, rapid and user-friendly point of care (POC) devices are increasing exponentially for strengthening the health care system in primary care as well as for self- monitoring in routine analysis. In addition to routine analysis of glucose, Covid-19 type fast spreading, infectious diseases have created further push for exploring rapid, cost-effective and self-monitoring diagnostic devices. Successful implementation of self-monitoring devices for Covid -19 has been realized. However, not much success has been realized for malaria and dengue which are two fatal diseases that affect the population in underdeveloped and developing countries. To monitor the presence of parasites for these diseases, rapid, onsite monitoring devices are still being explored. In this review, we present a review of the research carried out on electrochemical POC devices for monitoring infectious diseases such as Covid-19, malaria and dengue.

Insights from structure-activity relationships and the binding mode of peptidic α-ketoamide inhibitors of the malaria drug target subtilisin-like SUB1

Plasmodium multi-resistance, including against artemisinin, seriously threatens malaria treatment and control. Hence, new drugs are urgently needed, ideally targeting different parasitic stages, which are not yet targeted by current drugs. The SUB1 protease is involved in both hepatic and blood stages due to its essential role in the egress of parasites from host cells, and, as potential new target, it would meet the above criteria. We report here the synthesis as well as the biological and structural evaluation of substrate-based α-ketoamide SUB1 pseudopeptidic inhibitors encompassing positions P4-P2'. By individually substituting each position of the reference compound 1 (MAM-117, Ac-Ile-Thr-Ala-AlaCO-Asp-Glu (Oall)-NH2), we better characterized the structural determinants for SUB1 binding. We first identified compound 8 with IC50 values of 50 and 570 nM against Pv- and PfSUB1, respectively (about 3.5-fold higher potency compared to 1). Compound 8 inhibited P. falciparum merozoite egress in culture by 37% at 100 μM. By increasing the overall hydrophobicity of the compounds, we could improve the PfSUB1 inhibition level and antiparasitic activity, as shown with compound 40 (IC50 values of 12 and 10 nM against Pv- and PfSUB1, respectively, IC50 value of 23 μM on P. falciparum merozoite egress). We also found that 8 was highly selective towards SUB1 over three mammalian serine peptidases, supporting the promising value of this compound. Finally, several crystal 3D-structures of SUB1-inhibitor complexes, including with 8, were solved at high resolution to decipher the binding mode of these compounds.

A case of severe Plasmodium ovale malaria with acute respiratory distress syndrome and splenic infarction in a male traveller presenting in Italy

BACKGROUND

Plasmodium ovale malaria is usually considered a tropical infectious disease associated with low morbidity and mortality. However, severe disease and death have previously been reported.

CASE PRESENTATION

A case of severe P. ovale malaria in a healthy Caucasian man with a triangle splenic infarction and clinical progression towards Acute Respiratory Distress Syndrome was reported despite a rapid response to oral chloroquine treatment with 24-h parasitaemia clearance.

CONCLUSION

Plasmodium ovale malaria is generally considered as a benign disease, with low parasitaemia. However, severe disease and death have occasionally been reported. It is important to be aware that occasionally it can progress to serious illness and death even in immunocompetent individuals.

Low long-lasting insecticidal net use in malaria elimination areas in Southern Ethiopia: results from community based cross-sectional study

BACKGROUND

Despite remarkable progress in malaria burden reduction, malaria continues to be a major public health problem globally. Ethiopia has been distributing long-lasting insecticidal nets (LLINs) for free and nationwide distribution was completed in 2016. However, evidence suggests that the utilization of LLINs varies from setting to setting and from time to time due to different factors, and up-to-date evidence is required for LLIN related decision-making. Hence, this study was designed to assess LLIN utilization and its determinants in the Southern Nations, Nationalities, and People's Region (SNNPR) of Ethiopia.

METHODS

A community-based cross-sectional study was conducted in Southern Ethiopia in 2019. Using multi-stage sampling, a total of 2466 households were included. The region was stratified based on the annual malaria index as high, moderate, low, and free strata. Cluster sampling was then applied to select households from high, moderate, and low strata. Data on LLIN ownership, utilization and different determinant factors were collected using household questionnaire. SurveyCTO was used to collect data and data was managed using Stata 15. Descriptive statistics and multilevel mixed-effects logistic regression were performed to identify the determinants of utilization of LLINs. Effect measures were reported using adjusted odds ratio (AOR) with 95% CI.

RESULTS

From a total of 2466 households, 48.7% of households had at least one LLIN. LLIN adequacy based on family size was 23% while it was15.7% based on universal access and 29.2% based on sleeping space. From 1202 households that possessed LLIN(s), 66.0% of households reported that they slept under LLIN the night preceding the survey. However, when the total population in all surveyed households were considered, only 22.9% of household members slept under LLIN the night preceding the survey. Malaria endemicity, educational status, wealth status, and knowledge about malaria were associated with LLINs utilization. In addition, reasons for non-use included perceived absence of malaria, side effects of LLIN, conditions of LLINs, inconvenient space and low awareness.

CONCLUSION

Low LLIN coverage and low utilization were noted. A low level of utilization was associated with malaria endemicity, wealth status and level of awareness. Distribution of LLIN and continuous follow-up with community awareness creation activities are vital to improve coverage and utilization of LLINs, and to ensure the country's malaria elimination goal.

Setting up a data system for monitoring malaria vaccine introduction readiness and uptake in 42 health districts in Cameroon

Three months after the first shipment of RTS,S1/AS01 vaccines, Cameroon started, on 22 January 2024, to roll out malaria vaccines in 42 districts among the most at risk for malaria. Cameroon adopted and implemented the World Health Organization (WHO) malaria vaccine readiness assessment tool to monitor the implementation of preintroduction activities at the district and national levels. One week before the start of the vaccine rollout, overall readiness was estimated at 89% at a national level with two out of the five components of readiness assessment surpassing 95% of performance (vaccine, cold chain and logistics and training) and three components between 80% and 95% (planning, monitoring and supervision, and advocacy, social mobilisation and communication). 'Vaccine, cold chain and logistics' was the component with the highest number of districts recording below 80% readiness. The South-West and North-West, two regions with a high level of insecurity, were the regions with the highest number of districts that recorded a readiness performance below 80% in the five components. To monitor progress in vaccine rollout daily, Cameroon piloted a system for capturing immunisation data by vaccination session coupled with an interactive dashboard using the R Shiny platform. In addition to displaying data on vaccine uptake, this dashboard allows the generation of the monthly immunisation report for all antigens, ensuring linkage to the regular immunisation data system based on the end-of-month reporting through District Health Information Software 2. Such a hybrid system complies with the malaria vaccine rollout principle of full integration into routine immunisation coupled with strengthened management of operations.

Effect of the COVID-19 pandemic on HIV, malaria and tuberculosis indicators in Togo: an interrupted time series analysis

BACKGROUND

Limited data are available on the effects of the COVID-19 pandemic on health-related indicators in sub-Saharan Africa. This study aimed to estimate the effect of the COVID-19 pandemic on nine indicators of HIV, malaria and tuberculosis (TB) in Togo.

METHODS

For this interrupted time series analysis, national health information system data from January 2019 to December 2021 and TB programmatic data from the first quarter of 2018 to the fourth quarter of 2022 were analysed. Nine indicators were included. We used Poisson segmented regression to estimate the immediate impact of the pandemic and per-pandemic period trends through incidence rate ratios (IRRs) with 95% CIs.

RESULTS

Overall, there was a decrease in six of the nine indicators, ranging from 19.3% (IRR 0.807, 95% CI 0.682 to 0.955, p=0.024) for the hospitalisation of patients for malaria to 36.9% (IRR 0.631, 95% CI 0.457 to 0.871, p=0.013) for TB diagnosis by Mycobacterium tuberculosis Xpert immediately after the declaration of the COVID-19 pandemic. A comparison of the observed and predicted trends showed that the trend remained constant between the prepandemic and pandemic periods of COVID-19 for all malaria indicators. A significant downward monthly trend was observed in antiretroviral therapy initiation (IRR 0.909, 95% CI 0.892 to 0.926, p<0.001) and positive TB microscopy (IRR 0.919, 95% CI 0.880 to 0.960, p=0.002).

CONCLUSION

HIV, malaria and TB services were generally maintained over time in Togo despite the COVID-19 pandemic. However, given the decline in levels immediately after the onset of the pandemic, there is an urgent need to improve the preparedness of the healthcare system.

Assessing the implementation fidelity, feasibility, and sustainability of community-based house improvement for malaria control in southern Malawi: a mixed-methods study

BACKGROUND

Despite significant success in the fight against malaria over the past two decades, malaria control programmes rely on only two insecticidal methods: indoor residual spraying and insecticidal-treated nets. House improvement (HI) can complement these interventions by reducing human-mosquito contact, thereby reinforcing the gains in disease reduction. This study assessed the implementation fidelity, which is the assessment of how closely an intervention aligns with its intended design, feasibility, and sustainability of community-led HI in southern Malawi.

METHODS

The study, conducted in 22 villages (2730 households), employed a mixed-methods approach. Implementation fidelity was assessed using a modified framework, with longitudinal surveys collecting data on HI coverage indicators. Quantitative analysis, employing descriptive statistics, evaluated the adherence to HI implementation. Qualitative data came from in-depth interviews, key informant interviews, and focus groups involving project beneficiaries and implementers. Qualitative data were analysed using content analysis guided by the implementation fidelity model to explore facilitators, challenges, and factors affecting intervention feasibility.

RESULTS

The results show that HI was implemented as planned. There was good adherence to the intended community-led HI design; however, the adherence could have been higher but gradually declined over time. In terms of intervention implementation, 74% of houses had attempted to have eaves closed in 2016-17 and 2017-18, compared to 70% in 2018-19. In 2016-17, 42% of houses had all four sides of the eaves closed, compared to 33% in 2018-19. Approximately 72% of houses were screened with gauze wire in 2016-17, compared to 57% in 2018-19. High costs, supply shortages, labour demands, volunteers' poor living conditions and adverse weather were reported to hinder the ideal HI implementation. Overall, the community described community-led HI as feasible and could be sustained by addressing these socioeconomic and contextual challenges.

CONCLUSION

Our study found that although HI was initially implemented as planned, its fidelity declined over time. Using trained volunteers facilitated the fidelity and feasibility of implementing the intervention. A combination of rigorous community education, consistent training, information, education and communication, and intervention modifications may be necessary to address the challenges and enhance the intervention's fidelity, feasibility, and sustainability.

Non-clinical toxicity and immunogenicity evaluation of a Plasmodium vivax malaria vaccine using Poly-ICLC (Hiltonol®) as adjuvant

Malaria caused byPlasmodium vivaxis a pressing public health problem in tropical and subtropical areas.However, little progress has been made toward developing a P. vivaxvaccine, with only three candidates being tested in clinical studies. We previously reported that one chimeric recombinant protein (PvCSP-All epitopes) containing the conserved C-terminus of the P. vivax Circumsporozoite Protein (PvCSP), the three variant repeat domains, and aToll-like receptor-3 agonist,Poly(I:C), as an adjuvant (polyinosinic-polycytidylic acid, a dsRNA analog mimicking viral RNA), elicits strong antibody-mediated immune responses in mice to each of the three allelic forms of PvCSP. In the present study, a pre-clinical safety evaluation was performed to identify potential local and systemic toxic effects of the PvCSP-All epitopes combined with the Poly-ICLC (Poly I:C plus poly-L-lysine, Hiltonol®) or Poly-ICLC when subcutaneously injected into C57BL/6 mice and New Zealand White Rabbits followed by a 21-day recovery period. Overall, all observations were considered non-adverse and were consistent with the expected inflammatory response and immune stimulation following vaccine administration. High levels of vaccine-induced specific antibodies were detected both in mice and rabbits. Furthermore, mice that received the vaccine formulation were protected after the challenge with Plasmodium berghei sporozoites expressing CSP repeats from P. vivax sporozoites (Pb/Pv-VK210). In conclusion, in these non-clinical models, repeated dose administrations of the PvCSP-All epitopes vaccine adjuvanted with a Poly-ICLC were immunogenic, safe, and well tolerated.

Sustained clinical benefit of malaria chemoprevention with sulfadoxine-pyrimethamine (SP) in pregnant women in a region with high SP resistance markers

OBJECTIVE

The effectiveness of intermittent preventive treatment of malaria in pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) is threatened by increasing SP-resistance in Africa. We assessed the level of SP-resistance markers, and the clinical and parasitological effectiveness of IPTp-SP in southern Mozambique.

METHODS

P. falciparum infection, antimalarial antibodies and dhfr/dhps SP-resistance mutants were detected by quantitative polymerase chain reaction (qPCR), suspension array technology and targeted deep sequencing, respectively, among 4016 HIV-negative women in Maputo province (2016-2019). Univariate and multivariate regression models were used to assess the association between taking the recommended three or more IPTp-SP doses (IPTp3+) and parasitological and clinical outcomes.

RESULTS

84.3% (3385/4016) women received three or more IPTp-SP doses. The prevalence of quintuple mutants at first antenatal care (ANC) visit was 94.2%. IPTp3+ was associated with a higher clearance rate of qPCR-detected infections from first ANC visit to delivery (adjusted odds ratio [aOR]=5.9, 95% CI: 1.5-33.3; p = 0.012), lower seroprevalence at delivery of antibodies against the pregnancy-specific antigen VAR2CSADBL34 (aOR=0.72, 95% CI: 0.54-0.95; p = 0.022), and lower prevalence of low birth weight deliveries (aOR: 0.61, 95% CI: 0.41-0.90; p = 0.013).

CONCLUSION

A sustained parasitological effect of IPTp-SP contributes to the clinical effectiveness of IPTp3+ in areas with high prevalence of SP-resistance markers.

A replication competent Plasmodium falciparum parasite completely attenuated by dual gene deletion

Vaccination with infectious Plasmodium falciparum (Pf) sporozoites (SPZ) administered with antimalarial drugs (PfSPZ-CVac), confers superior sterilizing protection against infection when compared to vaccination with replication-deficient, radiation-attenuated PfSPZ. However, the requirement for drug administration constitutes a major limitation for PfSPZ-CVac. To obviate this limitation, we generated late liver stage-arresting replication competent (LARC) parasites by deletion of the Mei2 and LINUP genes (mei2-/linup- or LARC2). We show that Plasmodium yoelii (Py) LARC2 sporozoites did not cause breakthrough blood stage infections and engendered durable sterilizing immunity against various infectious sporozoite challenges in diverse strains of mice. We next genetically engineered a PfLARC2 parasite strain that was devoid of extraneous DNA and produced cryopreserved PfSPZ-LARC2. PfSPZ-LARC2 liver stages replicated robustly in liver-humanized mice but displayed severe defects in late liver stage differentiation and did not form liver stage merozoites. This resulted in complete abrogation of parasite transition to viable blood stage infection. Therefore, PfSPZ-LARC2 is the next-generation vaccine strain expected to unite the safety profile of radiation-attenuated PfSPZ with the superior protective efficacy of PfSPZ-CVac.

Challenges of diagnosing severe malaria with complications in adult patients: a case report

BACKGROUND

Malaria is known to be the main cause of death in malaria-endemic areas. The authors report a case of severe malaria in an adult with no history of travel from an endemic area with good outcomes after hospitalization.

CASE PRESENTATION

A 46-year-old man was brought to the Emergency Room (ER) because of fever and chills for 6 days. Complaints were accompanied by nausea and vomiting three times a day. The patient also experienced headaches, weakness, coughing, and a runny nose after two days of admission. The patient had no history of traveling from a malaria-endemic area. The patient was transferred from the Emergency Department (ED) to the High Care Unit (HCU), and during 1 day of intensive care at the HCU, there was a clinical deterioration characterized by dyspnea, icteric sclerae, acral edema, tenderness in both calves, and rash in the abdominal area. Due to worsening respiratory function, the patient was placed on a ventilator. During intensive treatment, the patient continued to show deterioration. The clinical findings suggested a possible feature of Weil's disease or fulminant hepatitis, and although the patient was in intensive care, there was no clinically significant improvement. Furthermore, microscopic blood smear examination and rapid diagnostic tests (RDTs) for malaria were carried out on the 4th day of treatment with negative results. As there was no clinically significant improvement, it was decided to take a blood smear and repeat RDT on the twelfth day, which showed a positive result for falciparum malaria. Subsequently, artesunate was administered intravenously, and the patient's condition began to improve with a negative parasite count the following day. The patient was discharged in good clinical condition on day 25 of treatment.

CONCLUSION

Good quality malaria diagnostic techniques are essential to diagnose malaria. A timely diagnosis of malaria has the potential to save the patient. Because Jakarta is not a malaria endemic area, it was concluded that this case was an introduced malaria case.

Enhanced anti-malarial efficacy of mefloquine delivered via cationic liposome in a murine model of experimental cerebral malaria

Malaria is a longstanding global health challenge that continues to afflict over 90 countries located in tropical and subtropical regions of the globe. The rise of drug-resistant malarial parasites has curtailed the therapeutic efficacy of a number of once-effective anti-malarials, including mefloquine. In the present study, we have taken advantage of drug encapsulation approach to elevate the anti-malarial potential of mefloquine. Encouragingly, our findings unveil that liposomal formulations of mefloquine outperform equivalent doses of free mefloquine, both in laboratory cultures and in a murine model of malaria. Intriguingly, a cationic liposomal mefloquine formulation, administered at four successive doses of 3 mg/kg body weight, achieves complete resolution of cerebral malaria in the murine model while avoiding noticeable toxic repercussions. Altogether, our study furnishes pre-clinical validation for a therapeutic strategy that can remarkably enhance the drug efficacy, offering a revitalizing solution for failing anti-malarials.

Hemophagocytic lymphohistiocytosis-how common and how severe is it as a complication of malaria? Retrospective case series and review of the literature

BACKGROUND

Infection-associated secondary hemophagocytic lymphohistiocytosis (sHLH) is a potentially life-threatening hyperinflammatory condition caused by various infectious diseases. Malaria has rarely been described as trigger. The aim of this study is to collect data on frequency, clinical spectrum, and outcome of sHLH induced by malaria.

METHODS

We collected case numbers on malaria and malaria-associated sHLH from specialized centers in Germany from 2015 to 2022. In addition, we conducted a literature search on published cases of malaria-associated sHLH and systematically analyzed the literature regarding clinical and diagnostic criteria.

RESULTS

We obtained data from 13 centers treating 1461 malaria cases with different Plasmodium species, of which 5 patients (0.34%) also were diagnosed with sHLH. The literature search revealed detailed case reports from further 51 patients and case series comprising the description of further 24 patients with malaria-associated sHLH. Most cases (48/80; 60%) were reported from Asia. The median time interval between onset of malaria symptoms and hospital admission was 7 days. Severe complications of sHLH were documented in 36% (20/56) of patients, including two patients with multiple organ failure in our case series. Only 41% (23/56) of patients received specific treatment for sHLH, nevertheless the mortality rate (CFR) of 5% is lower compared to the CFR reported for sHLH triggered by other infectious diseases (e.g., 25% in sHLH due to EBV infection).

CONCLUSION

Malaria-associated sHLH appears to have a comparatively good prognosis but may still represent an underdiagnosed and potentially fatal complication of malaria, especially in resource-poor settings.

Disease-specific plasma protein profiles in patients with fever after traveling to tropical areas

Fever is common among individuals seeking healthcare after traveling to tropical regions. Despite the association with potentially severe disease, the etiology is often not determined. Plasma protein patterns can be informative to understand the host response to infection and can potentially indicate the pathogen causing the disease. In this study, we measured 49 proteins in the plasma of 124 patients with fever after travel to tropical or subtropical regions. The patients had confirmed diagnoses of either malaria, dengue fever, influenza, bacterial respiratory tract infection, or bacterial gastroenteritis, representing the most common etiologies. We used multivariate and machine learning methods to identify combinations of proteins that contributed to distinguishing infected patients from healthy controls, and each other. Malaria displayed the most unique protein signature, indicating a strong immunoregulatory response with high levels of IL10, sTNFRI and II, and sCD25 but low levels of sCD40L. In contrast, bacterial gastroenteritis had high levels of sCD40L, APRIL, and IFN-γ, while dengue was the only infection with elevated IFN-α2. These results suggest that characterization of the inflammatory profile of individuals with fever can help to identify disease-specific host responses, which in turn can be used to guide future research on diagnostic strategies and therapeutic interventions.

A randomized first-in-human phase I trial of differentially adjuvanted Pfs48/45 malaria vaccines in Burkinabé adults

BACKGROUNDMalaria transmission-blocking vaccines aim to interrupt the transmission of malaria from one person to another.METHODSThe candidates R0.6C and ProC6C share the 6C domain of the Plasmodium falciparum sexual-stage antigen Pfs48/45. R0.6C utilizes the glutamate-rich protein (GLURP) as a carrier, and ProC6C includes a second domain (Pfs230-Pro) and a short 36-amino acid circumsporozoite protein (CSP) sequence. Healthy adults (n = 125) from a malaria-endemic area of Burkina Faso were immunized with 3 intramuscular injections, 4 weeks apart, of 30 μg or 100 μg R0.6C or ProC6C each adsorbed to Alhydrogel (AlOH) adjuvant alone or in combination with Matrix-M (15 μg or 50 μg, respectively). The allocation was random and double-blind for this phase I trial.RESULTSThe vaccines were safe and well tolerated with no vaccine-related serious adverse events. A total of 7 adverse events, mild to moderate in intensity and considered possibly related to the study vaccines, were recorded. Vaccine-specific antibodies were highest in volunteers immunized with 100 μg ProC6C-AlOH with Matrix-M, and 13 of 20 (65%) individuals in the group showed greater than 80% transmission-reducing activity (TRA) when evaluated in the standard membrane feeding assay at 15 mg/mL IgG. In contrast, R0.6C induced sporadic TRA.CONCLUSIONAll formulations were safe and well tolerated in a malaria-endemic area of Africa in healthy adults. The ProC6C-AlOH/Matrix-M vaccine elicited the highest levels of functional antibodies, meriting further investigation.TRIAL REGISTRATIONPan-African Clinical Trials Registry (https://pactr.samrc.ac.za) PACTR202201848463189.FUNDINGThe study was funded by the European and Developing Countries Clinical Trials Partnership (grant RIA2018SV-2311).

falciparum infection against SE36 malaria vaccine candidate antigen and the resulting limited polymorphism

The call for second generation malaria vaccines needs not only the identification of novel candidate antigens or adjuvants but also a better understanding of immune responses and the underlying protective processes. Plasmodium parasites have evolved a range of strategies to manipulate the host immune system to guarantee survival and establish parasitism. These immune evasion strategies hamper efforts to develop effective malaria vaccines. In the case of a malaria vaccine targeting the N-terminal domain of P. falciparum serine repeat antigen 5 (SE36), now in clinical trials, we observed reduced responsiveness (lowered immunogenicity) which may be attributed to immune tolerance/immune suppression. Here, immunogenicity data and insights into the immune responses to SE36 antigen from epidemiological studies and clinical trials are summarized. Documenting these observations is important to help identify gaps for SE36 continued development and engender hope that highly effective blood-stage/multi-stage vaccines can be achieved.

Moleculargenetic and in Addition Partly Discrepant Infection Serological Malaria Testing in Two Blood Donors

Introduction

According to the guidelines (GL) valid in Germany, persons born or raised in a malaria-endemic area or had continuously stayed in a malaria-endemic area for more than 6 months may only be admitted donating blood if, among other things, validated and quality-assured laboratory diagnostics show that there is no evidence of infectivity. In a statement of the Working Group "Blood" of the Federal Ministry of Health (WGB), a reduction of the deferral period from 4 to 3 years and an antibody test after the deferral period are recommended.

Methods

In accordance with the GL, nucleic acid testing (NAT) by means of PCR is carried out at our institution after a retention period of 4 years. In addition to the validated molecular biological testing, an infection serological examination was performed.

Case Presentation

In the present cases, Plasmodia genome was detected in the respective single PCR in two blood donors originating from malaria-endemic areas after the expiry of the deferral period. However, one donor tested negative for antibodies against Plasmodia.

Discussion/Conclusion

This observation is discussed in the context of a recommendation of the WGB. The question is addressed whether PCR testing is dispensable or whether a combination of infection serological testing and NAT should be favored.

Coinfections and antimicrobial treatment in a cohort of falciparum malaria in a non-endemic country: a 10-year experience

INTRODUCTION

Falciparum malaria remains one of the deadliest infectious diseases worldwide. In Germany, it is mainly an imported infection among travellers. Rates of coinfection are often unknown, and a clinical rationale for the beneficial use of calculated antibiotic therapy in patients with malaria and suspected coinfection is lacking.

METHODS

We conducted an analysis of all in-patients treated with falciparum malaria at a German infectious diseases centre in vicinity to one of Europe's major airports for 2010-2019. Logistic regression and time-to-event analysis were used to evaluate predictors for bacterial coinfection, the use of antibacterial substances, as well as their influence on clinical course.

RESULTS

In total, 264 patients were included. Of those, 64% received an additional antibacterial therapy (n = 169). Twenty-nine patients (11.0%) were found to have suffered from a relevant bacterial coinfection, while only a small fraction had relevant bacteremia (n = 3, 1.4%). However, patients with severe malaria did not suffer from coinfections more frequently (p = 0.283). CRP levels were not a reliable predictor for a bacterial coinfection (OR 0.99, 95% CI 0.94-1.06, p = 0.850), while another clinical focus of infection was positively associated (OR 3.86, 95% CI 1.45-11.55, p  = 0.010).

CONCLUSION

Although bacterial coinfections were rare in patients with malaria at our centre, the risk does not seem negligible. These data point rather towards individual risk assessment in respective patients than to general empiric antibiotic use.

Plasmodium falciparum heat shock proteins as antimalarial drug targets: An update

Global efforts to eradicate malaria are threatened by multiple factors, particularly the emergence of antimalarial drug resistant strains of Plasmodium falciparum. Heat shock proteins (HSPs), particularly P. falciparum HSPs (PfHSPs), represent promising drug targets due to their essential roles in parasite survival and virulence across the various life cycle stages. Despite structural similarities between human and malarial HSPs posing challenges, there is substantial evidence for subtle differences that could be exploited for selective drug targeting. This review provides an update on the potential of targeting various PfHSP families (particularly PfHSP40, PfHSP70, and PfHSP90) and their interactions within PfHSP complexes as a strategy to develop new antimalarial drugs. In addition, the need for a deeper understanding of the role of HSP complexes at the host-parasite interface is highlighted, especially heterologous partnerships between human and malarial HSPs, as this opens novel opportunities for targeting protein-protein interactions crucial for malaria parasite survival and pathogenesis.