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The Journal of Infectious Diseases Apr 2024Recent data indicate that non-Plasmodium falciparum species may be more prevalent than thought in sub-Saharan Africa. Although Plasmodium malariae, Plasmodium ovale...
BACKGROUND
Recent data indicate that non-Plasmodium falciparum species may be more prevalent than thought in sub-Saharan Africa. Although Plasmodium malariae, Plasmodium ovale spp., and Plasmodium vivax are less severe than P. falciparum, treatment and control are more challenging, and their geographic distributions are not well characterized.
METHODS
We randomly selected 3284 of 12 845 samples collected from cross-sectional surveys in 100 health facilities across 10 regions of Mainland Tanzania and performed quantitative real-time PCR to determine presence and parasitemia of each malaria species.
RESULTS
P. falciparum was most prevalent, but P. malariae and P. ovale were found in all but 1 region, with high levels (>5%) of P. ovale in 7 regions. The highest P. malariae positivity rate was 4.5% in Mara and 8 regions had positivity rates ≥1%. We only detected 3 P. vivax infections, all in Kilimanjaro. While most nonfalciparum malaria-positive samples were coinfected with P. falciparum, 23.6% (n = 13 of 55) of P. malariae and 14.7% (n = 24 of 163) of P. ovale spp. were monoinfections.
CONCLUSIONS
P. falciparum remains by far the largest threat, but our data indicate that malaria elimination efforts in Tanzania will require increased surveillance and improved understanding of the biology of nonfalciparum species.
Topics: Humans; Tanzania; Cross-Sectional Studies; Malaria; Malaria, Falciparum; Plasmodium malariae
PubMed: 37992117
DOI: 10.1093/infdis/jiad522 -
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 -
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 -
Genome Biology and Evolution Feb 2024Plasmodium species causing malaria in humans are not monophyletic, sharing common ancestors with nonhuman primate parasites. Plasmodium gonderi is one of the few known...
Plasmodium species causing malaria in humans are not monophyletic, sharing common ancestors with nonhuman primate parasites. Plasmodium gonderi is one of the few known Plasmodium species infecting African old-world monkeys that are not found in apes. This study reports a de novo assembled P. gonderi genome with complete chromosomes. The P. gonderi genome shares codon usage, syntenic blocks, and other characteristics with the human parasites Plasmodium ovale s.l. and Plasmodium malariae, also of African origin, and the human parasite Plasmodium vivax and species found in nonhuman primates from Southeast Asia. Using phylogenetically aware methods, newly identified syntenic blocks were found enriched with conserved metabolic genes. Regions outside those blocks harbored genes encoding proteins involved in the vertebrate host-Plasmodium relationship undergoing faster evolution. Such genome architecture may have facilitated colonizing vertebrate hosts. Phylogenomic analyses estimated the common ancestor between P. vivax and an African ape parasite P. vivax-like, within the Asian nonhuman primates parasites clade. Time estimates incorporating P. gonderi placed the P. vivax and P. vivax-like common ancestor in the late Pleistocene, a time of active migration of hominids between Africa and Asia. Thus, phylogenomic and time-tree analyses are consistent with an Asian origin for P. vivax and an introduction of P. vivax-like into Africa. Unlike other studies, time estimates for the clade with Plasmodium falciparum, the most lethal human malaria parasite, coincide with their host species radiation, African hominids. Overall, the newly assembled genome presented here has the quality to support comparative genomic investigations in Plasmodium.
Topics: Animals; Humans; Parasites; Plasmodium; Malaria; Plasmodium vivax; Plasmodium falciparum; Primates; Hominidae
PubMed: 38376987
DOI: 10.1093/gbe/evae027 -
Parasites & Vectors Mar 2024Recent studies point to the need to incorporate the detection of non-falciparum species into malaria surveillance activities in sub-Saharan Africa, where 95% of the...
BACKGROUND
Recent studies point to the need to incorporate the detection of non-falciparum species into malaria surveillance activities in sub-Saharan Africa, where 95% of the world's malaria cases occur. Although malaria caused by infection with Plasmodium falciparum is typically more severe than malaria caused by the non-falciparum Plasmodium species P. malariae, P. ovale spp. and P. vivax, the latter may be more challenging to diagnose, treat, control and ultimately eliminate. The prevalence of non-falciparum species throughout sub-Saharan Africa is poorly defined. Tanzania has geographical heterogeneity in transmission levels but an overall high malaria burden.
METHODS
To estimate the prevalence of malaria species in Mainland Tanzania, we randomly selected 1428 samples from 6005 asymptomatic isolates collected in previous cross-sectional community surveys across four regions and analyzed these by quantitative PCR to detect and identify the Plasmodium species.
RESULTS
Plasmodium falciparum was the most prevalent species in all samples, with P. malariae and P. ovale spp. detected at a lower prevalence (< 5%) in all four regions; P. vivax was not detected in any sample.
CONCLUSIONS
The results of this study indicate that malaria elimination efforts in Tanzania will need to account for and enhance surveillance of these non-falciparum species.
Topics: Humans; Asymptomatic Infections; Cross-Sectional Studies; Malaria; Malaria, Falciparum; Malaria, Vivax; Plasmodium falciparum; Plasmodium malariae; Prevalence; Tanzania
PubMed: 38519992
DOI: 10.1186/s13071-024-06242-4 -
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 -
Trends in Parasitology Mar 2024
Topics: Plasmodium ovale; Phylogeny
PubMed: 38272740
DOI: 10.1016/j.pt.2024.01.004 -
The American Journal of Tropical... Aug 2023Malaria remains a major public health challenge that needs attention, especially when the world is aiming at malaria elimination in the near future. It is crucial to...
Malaria remains a major public health challenge that needs attention, especially when the world is aiming at malaria elimination in the near future. It is crucial to understand the underlying genetic factors and epigenetics involved in malaria susceptibility and the dynamics of host immune responses that affect disease outcomes and relapses in Plasmodium vivax and Plasmodium ovale. Studies in newborn and adult twins can help in understanding the comparative roles of environmental and genetic factors on disease pathogenesis and outcome. These studies can help in providing insights into the factors responsible for malaria susceptibility, clinical presentation, responsiveness toward existing as well as candidate antimalarials, and even identification of novel therapeutic targets. The results and outcomes from twin studies can be further applied to the entire population. In the present manuscript, we analyze the available literature on malaria and human twins and discuss the significance and benefits of twin studies to help in better understanding malaria.
Topics: Adult; Infant, Newborn; Humans; Malaria; Antimalarials; Plasmodium vivax; Plasmodium ovale; Genetic Linkage; Malaria, Vivax
PubMed: 37277110
DOI: 10.4269/ajtmh.23-0028 -
Malaria Journal Mar 2024Adults infected with Plasmodium spp. in endemic areas need to be re-evaluated in light of global malaria elimination goals. They potentially undermine malaria...
BACKGROUND
Adults infected with Plasmodium spp. in endemic areas need to be re-evaluated in light of global malaria elimination goals. They potentially undermine malaria interventions but remain an overlooked aspect of public health strategies.
METHODS
This study aimed to estimate the prevalence of Plasmodium spp. infections, to identify underlying parasite species, and to assess predicting factors among adults residing in an endemic area from the Democratic Republic of Congo (DRC). A community-based cross-sectional survey in subjects aged 18 years and above was therefore carried out. Study participants were interviewed using a standard questionnaire and tested for Plasmodium spp. using a rapid diagnostic test and a nested polymerase chain reaction assay. Logistic regression models were fitted to assess the effect of potential predictive factors for infections with different Plasmodium spp.
RESULTS
Overall, 420 adults with an estimated prevalence of Plasmodium spp. infections of 60.2% [95% CI 55.5; 64.8] were included. Non-falciparum species infected 26.2% [95% CI 22.2; 30.5] of the study population. Among infected participants, three parasite species were identified, including Plasmodium falciparum (88.5%), Plasmodium malariae (39.9%), and Plasmodium ovale (7.5%) but no Plasmodium vivax. Mixed species accounted for 42.3% of infections while single-species infections predominated with P. falciparum (56.5%) among infected participants. All infected participants were asymptomatic at the time of the survey. Adults belonging to the "most economically disadvantaged" households had increased risks of infections with any Plasmodium spp. (adjusted odds ratio, aOR = 2.87 [95% CI 1.66, 20.07]; p < 0.001), compared to those from the "less economically disadvantaged" households. Conversely, each 1 year increase in age reduced the risk of infections with any Plasmodium spp. (aOR = 0.99 [95% CI 0.97, 0.99]; p = 0.048). Specifically for non-falciparum spp., males had increased risks of infection than females (aOR = 1.83 [95% CI 1.13, 2.96]; p = 0.014).
CONCLUSION
Adults infected with malaria constitute a potentially important latent reservoir for the transmission of the disease in the study setting. They should specifically be taken into account in public health measures and translational research.
Topics: Male; Adult; Female; Humans; Democratic Republic of the Congo; Cross-Sectional Studies; Malaria; Malaria, Falciparum; Plasmodium falciparum; Plasmodium malariae; Prevalence
PubMed: 38500094
DOI: 10.1186/s12936-024-04881-7 -
Malaria Journal Jan 2024Malaria remains a major public health problem in sub-Saharan Africa, particularly in Benin. The present study aims to evaluate the different Plasmodium species...
BACKGROUND
Malaria remains a major public health problem in sub-Saharan Africa, particularly in Benin. The present study aims to evaluate the different Plasmodium species transmitted by malaria vectors in the communes of Cove, Zagnanado and Ouinhi, Southern Benin.
METHODS
The study was conducted between December 2021 and October 2022 in 60 villages spread over the three study communes. Adult mosquitoes were collected from four houses in each village using human landing catches (HLCs). After morphological identification, a subsample of Anopheles gambiae, Anopheles funestus and Anopheles nili was analysed by PCR to test for their infection to the different Plasmodium species.
RESULTS
Anopheles gambiae was collected at higher frequency in all the three study communes, representing 93.5% (95% CI 92.9-94) of all collected mosquitoes (n = 10,465). In total, five molecular species were found, An. gambiae sensu stricto (s.s.) and Anopheles coluzzii of the Gambiae complex, An. funestus and Anopheles leesoni of the Funestus group, and An. nili s.s., the sole species of the Nili group. From the five molecular species, four (An. gambiae s.s., An. coluzzii, An. funestus s.s. and An. nili s.s.) were found to be infected. Plasmodium falciparum was the main Plasmodium species in the study area, followed by Plasmodium vivax and Plasmodium ovale. Only An. gambiae s.s. was infected with all three Plasmodium species, while An. coluzzii was infected with two species, P. falciparum and P. vivax.
CONCLUSIONS
Plasmodium falciparum was the only species tested for in malaria vectors in Benin, and remains the only one against which most control tools are directed. It is, therefore, necessary that particular attention be paid to secondary Plasmodium species for an efficient control of the disease. The presence of P. vivax emphasizes the need for an update of case management for malaria.
Topics: Animals; Adult; Humans; Anopheles; Malaria; Benin; Plasmodium vivax; Mosquito Vectors; Africa, Western; Malaria, Falciparum; Plasmodium falciparum; Plasmodium; Malaria, Vivax
PubMed: 38225627
DOI: 10.1186/s12936-023-04834-6