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Microbiology Spectrum Jun 2024Malaria infection remains a serious threat to human health worldwide. Rapid and accurate detection technology is crucial for preventing malaria transmission and...
UNLABELLED
Malaria infection remains a serious threat to human health worldwide. Rapid and accurate detection technology is crucial for preventing malaria transmission and minimizing damage. We aimed to establish and validate a new rapid molecular detection method for malaria, called EasyNAT Malaria Assay, targeting , , , and . The analytical performance of EasyNAT Malaria Assay was determined using positive materials. We identified 42 clinical samples as malaria positive and 95 negative samples. Each sample was examined by four methods: light microscopy, rapid diagnostic test, EasyNAT Malaria Assay, and digital PCR. Diagnostic accuracy and clinical performance were evaluated. The limit of detection (LOD) of EasyNAT Malaria was consistently 40 parasites/mL. It specifically amplified and performed with reliable repeatability and reproducibility. In 137 clinical samples, EasyNAT Malaria detected four more positive samples than microscopic examination and two more positive samples than rapid diagnostic test (RDT). One clinical sample was positive only under digital PCR. However, no significant differences statistically in sensitivity or specificity were observed. Compared with microscopy, the total, positive, and negative concordance rates of EasyNAT were 97.08%, 100%, and 95.79%, respectively. Enhanced diagnostic accuracy of EasyNAT Malaria in patients who had taken anti-malarial medication before their clinical appointment was observed. The EasyNAT Malaria Assay has good detection efficiency for clinical samples, presents a promising molecular detection tool in clinical practice, and is particularly suitable for rapid screening of high-risk populations in the emergency room.
IMPORTANCE
This study established and validated EasyNAT Malaria Assay as a promising molecular detection tool for malaria screening of high-risk populations in clinical practice. This novel isothermal amplification method may effectively facilitate the rapid diagnosis of malaria and prevent its transmission.
PubMed: 38869308
DOI: 10.1128/spectrum.00583-24 -
Microorganisms Apr 2024Malaria is one of the most prevalent diseases worldwide with high incidence and mortality. Among the five species that can infect humans, morphologically resembles ,...
Malaria is one of the most prevalent diseases worldwide with high incidence and mortality. Among the five species that can infect humans, morphologically resembles , resulting in misidentification and confusion in diagnosis, and is responsible for malarial disease relapse due to the formation of hypnozoites. receives relatively less attention compared to other major parasites, such as and , primarily due to its lower pathogenicity, mortality rates, and prevalence rates. To efficiently produce lactate dehydrogenase (LDH), a major target for diagnosing malaria, this study used three strains, BL21(DE3), BL21(DE3)pLysS, and Rosetta(DE3), commonly used for recombinant protein production. These strains were characterized to select the optimal strain for LDH (PoLDH) production. Gene cloning for recombinant PoLDH production and transformation of the three strains for protein expression were performed. The optimal PoLDH overexpression and washing buffer conditions in nickel-based affinity chromatography were established to ensure high-purity PoLDH. The yields of PoLDH expressed by the three strains were as follows: BL21(DE3), 7.6 mg/L; BL21(DE3)pLysS, 7.4 mg/L; and Rosetta(DE3), 9.5 mg/L. These findings are expected to be highly useful for PoLDH-specific diagnosis and development of antimalarial therapeutics.
PubMed: 38792706
DOI: 10.3390/microorganisms12050876 -
The Lancet. Microbe May 2024Mutations in the Plasmodium falciparum dhfr gene confer resistance to pyrimethamine, which is widely used for malaria chemoprevention in Africa. We aimed to evaluate the...
Plasmodium ovale spp dhfr mutations associated with reduced susceptibility to pyrimethamine in sub-Saharan Africa: a retrospective genetic epidemiology and functional study.
BACKGROUND
Mutations in the Plasmodium falciparum dhfr gene confer resistance to pyrimethamine, which is widely used for malaria chemoprevention in Africa. We aimed to evaluate the frequency and evolution of dhfr mutations in Plasmodium ovale spp in Africa and their functional consequences, which are incompletely characterised.
METHODS
We analysed dhfr mutations and their frequencies in P ovale spp isolates collected between Feb 1, 2004, and Aug 31, 2023, from the French National Malaria Reference Centre collection and from field studies in Benin, Gabon, and Kenya. Genetic patterns of positive selection were investigated. Full-length recombinant wild-type and mutant DHFR enzymes from both P ovale curtisi and P ovale wallikeri were expressed in bacteria to test whether the most common mutations reduced pyrimethamine susceptibility.
FINDINGS
We included 518 P ovale spp samples (314 P ovale curtisi and 204 P ovale wallikeri). In P ovale curtisi, Ala15Ser-Ser58Arg was the most common dhfr mutation (39%; 124 of 314 samples). In P ovale wallikeri, dhfr mutations were less frequent, with Phe57Leu-Ser58Arg reaching 17% (34 of 204 samples). These two mutants were the most prevalent in central and east Africa and were fixed in Kenyan isolates. We detected six and four other non-synonymous mutations, representing 8% (24 isolates) and 2% (five isolates) of the P ovale curtisi and P ovale wallikeri isolates, respectively. Whole-genome sequencing and microsatellite analyses revealed reduced genetic diversity around the mutant pocdhfr and powdhfr genes. The mutant DHFR proteins showed structural changes at the pyrimethamine binding site in-silico, confirmed by a 4-times increase in pyrimethamine half-maximal inhibitory concentration in an Escherichia coli growth assay for the Phe57Leu-Ser58Arg mutant and 50-times increase for the Ala15Ser-Ser58Arg mutant, compared with the wild-type counterparts.
INTERPRETATION
The widespread use of sulfadoxine-pyrimethamine for malaria chemoprevention might have exerted fortuitous selection pressure for dhfr mutations in P ovale spp. This calls for closer monitoring of dhfr and dhps mutations in P ovale spp.
FUNDING
French Ministry of Health, Agence Nationale de la Recherche, and Global Emerging Infections Surveillance branch of the Armed Forces Health Surveillance Division.
PubMed: 38761813
DOI: 10.1016/S2666-5247(24)00054-5 -
Malaria Journal May 2024Malaria elimination in Senegal requires accurate diagnosis of all Plasmodium species. Plasmodium falciparum is the most prevalent species in Senegal, although Plasmodium...
BACKGROUND
Malaria elimination in Senegal requires accurate diagnosis of all Plasmodium species. Plasmodium falciparum is the most prevalent species in Senegal, although Plasmodium malariae, Plasmodium ovale, and recently Plasmodium vivax have also been reported. Nonetheless, most malaria control tools, such as Histidine Rich Protein 2 rapid diagnosis test (PfHRP2-RDT,) can only diagnose P. falciparum. Thus, PfHRP2-RDT misses non-falciparum species and P. falciparum infections that fall below the limit of detection. These limitations can be addressed using highly sensitive Next Generation Sequencing (NGS). This study assesses the burden of the four different Plasmodium species in western and eastern regions of Senegal using targeted PCR amplicon sequencing.
METHODS
Three thousand samples from symptomatic and asymptomatic individuals in 2021 from three sites in Senegal (Sessene, Diourbel region; Parcelles Assainies, Kaolack region; Gabou, Tambacounda region) were collected. All samples were tested using PfHRP2-RDT and photoinduced electron transfer polymerase chain reaction (PET-PCR), which detects all Plasmodium species. Targeted sequencing of the nuclear 18S rRNA and the mitochondrial cytochrome B genes was performed on PET-PCR positive samples.
RESULTS
Malaria prevalence by PfHRP2-RDT showed 9.4% (94/1000) and 0.2% (2/1000) in Diourbel (DBL) and Kaolack (KL), respectively. In Tambacounda (TAM) patients who had malaria symptoms and had a negative PfHRP2-RDT were enrolled. The PET-PCR had a positivity rate of 23.5% (295/1255) overall. The PET-PCR positivity rate was 37.6%, 12.3%, and 22.8% in Diourbel, Kaolack, and Tambacounda, respectively. Successful sequencing of 121/295 positive samples detected P. falciparum (93%), P. vivax (2.6%), P. malariae (4.4%), and P. ovale wallikeri (0.9%). Plasmodium vivax was co-identified with P. falciparum in thirteen samples. Sequencing also detected two PfHRP2-RDT-negative mono-infections of P. vivax in Tambacounda and Kaolack.
CONCLUSION
The findings demonstrate the circulation of P. vivax in western and eastern Senegal, highlighting the need for improved malaria control strategies and accurate diagnostic tools to better understand the prevalence of non-falciparum species countrywide.
Topics: Senegal; Humans; Adolescent; Adult; Young Adult; Child; Middle Aged; Male; Female; Plasmodium vivax; Child, Preschool; Malaria, Vivax; Prevalence; Aged; Infant; Polymerase Chain Reaction; Plasmodium ovale
PubMed: 38750583
DOI: 10.1186/s12936-024-04932-z -
Revista Do Instituto de Medicina... 2024This study reports a challenging diagnosis of Plasmodium ovale malaria in a Colombian citizen returning from Cameroon. Initial microscopy screenings conducted at two...
This study reports a challenging diagnosis of Plasmodium ovale malaria in a Colombian citizen returning from Cameroon. Initial microscopy screenings conducted at two private hospitals yielded conflicting results, with the first showing negative smears and the second diagnosing P. vivax. Subsequent microscopy examinations at two government laboratories identified P. ovale, although the routine species-specific PCR strategy was negative. PCR confirmation was finally obtained when P. ovale wallikeri primers were used. Although P. ovale is not frequently found in Colombia, there is a clear need to include both P. ovale curtisi and P. ovale wallikeri in the molecular diagnostic strategy. Such need stems primarily from their extended latency period, which affects travelers, the increasing number of African migrants, and the importance of accurately mapping the distribution of Plasmodium species in Colombia.
Topics: Plasmodium ovale; Humans; Malaria; Colombia; Polymerase Chain Reaction; Travel; Male; DNA, Protozoan; Adult; Cameroon
PubMed: 38747850
DOI: 10.1590/S1678-9946202466029 -
China CDC Weekly Apr 2024China's "1-3-7" approach outlines specific targets to guide and monitor the processes of case reporting, investigation, and response. However, few studies have examined...
WHAT IS ALREADY KNOWN ABOUT THIS TOPIC?
China's "1-3-7" approach outlines specific targets to guide and monitor the processes of case reporting, investigation, and response. However, few studies have examined the time intervals preceding the initial step, and the timeline from the arrival of imported malaria cases in China to their diagnosis has been largely overlooked.
WHAT IS ADDED BY THIS REPORT?
The study demonstrated that the median duration from arrival in China to the onset of symptoms for was 78 days, with 71.59% of imported cases manifesting symptoms after more than one month. For , the median interval was 42 days, with 55.91% exceeding one month. Additionally, the median time from symptom onset to malaria treatment in China between 2014 and 2021 was 2 days, with an interquartile range (IQR) of 1-4 days.
WHAT ARE THE IMPLICATIONS FOR PUBLIC HEALTH PRACTICE?
This study represents the initial effort to delineate the chronology of imported malaria cases, from their arrival in China to their subsequent treatment. The results underscore the importance of providing malaria health education to populations arriving from overseas. Furthermore, enhancing physician training is crucial for improving the diagnosis of malaria.
PubMed: 38737821
DOI: 10.46234/ccdcw2024.070 -
Southern African Journal of Infectious... 2024
PubMed: 38628423
DOI: 10.4102/sajid.v39i1.615 -
Hematology, Transfusion and Cell Therapy Apr 2024
PubMed: 38614930
DOI: 10.1016/j.htct.2023.11.017 -
Diagnostics (Basel, Switzerland) Mar 2024The early diagnosis of malaria is crucial to controlling morbidity and mortality. The World Health Organization (WHO) recommends diagnosing malaria either using light...
The early diagnosis of malaria is crucial to controlling morbidity and mortality. The World Health Organization (WHO) recommends diagnosing malaria either using light microscopy or a malaria rapid diagnostic test (RDT). Most RDTs use antibodies to detect two histidine-rich proteins named PfHRP2 and PfHRP3. However, false-negative results are known to occur due to the poor performance of RDTs depending on the species and the deletion of the and genes. This study evaluated new malaria RDTs for the detection of the human species. The Acro Malaria P.f./P.v./Pan Rapid Test Cassette allows the qualitative detection of parasite antigens, such as PfHRP2 specific to , PvLDH specific to , and/or panLDH genus lactate dehydrogenase, in the blood of infected individuals. This RDT was assessed against 229 samples collected from imported malaria cases, mainly from Africa. The samples were previously diagnosed using light microscopy and RDT (SD Malaria Ag P.f./Pan, SD Bioline Alere Abbott), then confirmed using real time PCR. The two RDTs were evaluated using a comparison with real time PCR as the reference method, and their performances were compared with each other. Compared to SD RDT, the Acro RDT showed a better sensitivity to (96.8% vs. 89.8%), (78.6% vs. 64.3%), (73.7% vs. 5.3%), and (20.0% vs. 0%). The respective specificities of the Acro RDT and SD RDT are 90.7% vs. 95.3% to , 100% to , and 100% vs. 100% to genus. Therefore, Acro RDT showed better performance in the identification of and low parasitaemia of . In addition, Acro RDT has the advantage of detecting PvLDH-specific antigens. The Acro Malaria RDT presents the benefits of detecting a antigen (PfHRP2) and a antigen (PvLDH) with high sensitivity (96.8% and 73.7%, respectively) and specificity (90.7% and 100%, respectively). Acro Malaria P.f./P.v./Pan rapid diagnostic tests could be effectively used in endemic areas, especially when microscopic examination cannot be performed.
PubMed: 38611637
DOI: 10.3390/diagnostics14070721 -
Malaria Journal Apr 2024Plasmodium ovale malaria is usually considered a tropical infectious disease associated with low morbidity and mortality. However, severe disease and death have...
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.
Topics: Male; Humans; Antimalarials; Plasmodium ovale; Splenic Infarction; Malaria; Respiratory Distress Syndrome; Italy
PubMed: 38575935
DOI: 10.1186/s12936-024-04911-4