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The Journal of Infectious Diseases Oct 2023Like Plasmodium vivax, both Plasmodium ovale curtisi and Plasmodium ovale wallikeri have the ability to cause relapse in humans, defined as recurring asexual parasitemia...
Like Plasmodium vivax, both Plasmodium ovale curtisi and Plasmodium ovale wallikeri have the ability to cause relapse in humans, defined as recurring asexual parasitemia originating from liver-dormant forms subsequent to a primary infection. Here, we investigated relapse patterns in P ovale wallikeri infections from a cohort of travelers who were exposed to the parasite in sub-Saharan Africa and then experienced relapses after their return to France. Using a novel set of 8 highly polymorphic microsatellite markers, we genotyped 15 P ovale wallikeri relapses. For most relapses, the paired primary and relapse infections were highly genetically related (with 12 being homologous), an observation that was confirmed by whole-genome sequencing for the 4 relapses we further studied. This is, to our knowledge, the first genetic evidence of relapses in P ovale spp.
Topics: Humans; Plasmodium ovale; Malaria; Plasmodium vivax; Recurrence; Microsatellite Repeats
PubMed: 37329228
DOI: 10.1093/infdis/jiad216 -
Oral Diseases Mar 2022The project aims were to identify infectious mechanisms responsible for an extreme form of mandibular osteonecrosis and osteomyelitis in West African populations and...
OBJECTIVES
The project aims were to identify infectious mechanisms responsible for an extreme form of mandibular osteonecrosis and osteomyelitis in West African populations and test the hypothesis that Mycobacterium tuberculosis plays a pivotal role.
MATERIALS AND METHODS
DNA was extracted from mandibular fragments of 9 of 19 patients previously included in a prospective study leading to the mycobacterial hypothesis. Amplified DNAs were used for preparing libraries suitable for next-generation sequencing. For comparison of the whole-genome sequencing data of the 9 patients with DNAs of both microbiota and human tissues, DIAMOND v0.9.26 was used to align sequencing reads to NCBI-nr database and MEGAN 6 for taxonomy binning and identification of Mycobacterium tuberculosis strains.
RESULTS
The data show that mandibular bone fragments of all 9 patients not only contain Homo sapiens and Mycobacterium tuberculosis DNAs; they also contain DNAs of Plasmodium ovale wallikeri, Staphylococcus aureus, Staphylococcus hominis, and Prevotella P3-120/intermedia; as well as large numbers of DNAs from other infectious components.
CONCLUSIONS
The data obtained provide direct evidence to support the conclusion that combinations of Mycobacterium tuberculosis, Plasmodium ovale wallikeri, and other oral bacteria are involved in this particular type of mandibular destruction in West African individuals of many ages.
Topics: Humans; Malaria; Plasmodium ovale; Prospective Studies
PubMed: 33325564
DOI: 10.1111/odi.13756 -
Parasites & Vectors Feb 2022Plasmodium ovale is a neglected malarial parasite that can form latent hypnozoites in the human liver. Over the last decade, molecular surveillance studies of...
BACKGROUND
Plasmodium ovale is a neglected malarial parasite that can form latent hypnozoites in the human liver. Over the last decade, molecular surveillance studies of non-falciparum malaria in Africa have highlighted that P. ovale is circulating below the radar, including areas where Plasmodium falciparum is in decline. To eliminate malaria where P. ovale is endemic, a better understanding of its epidemiology, asymptomatic carriage, and transmission biology is needed.
METHODS
We performed a pilot study on P. ovale transmission as part of an ongoing study of human-to-mosquito transmission of P. falciparum from asymptomatic carriers. To characterize the malaria asymptomatic reservoir, cross-sectional qPCR surveys were conducted in Bagamoyo, Tanzania, over three transmission seasons. Positive individuals were enrolled in transmission studies of P. falciparum using direct skin feeding assays (DFAs) with Anopheles gambiae s.s. (IFAKARA strain) mosquitoes. For a subset of participants who screened positive for P. ovale on the day of DFA, we incubated blood-fed mosquitoes for 14 days to assess sporozoite development.
RESULTS
Molecular surveillance of asymptomatic individuals revealed a P. ovale prevalence of 11% (300/2718), compared to 29% (780/2718) for P. falciparum. Prevalence for P. ovale was highest at the beginning of the long rainy season (15.5%, 128/826) in contrast to P. falciparum, which peaked later in both the long and short rainy seasons. Considering that these early-season P. ovale infections were low-density mono-infections (127/128), we speculate many were due to hypnozoite-induced relapse. Six of eight P. ovale-infected asymptomatic individuals who underwent DFAs successfully transmitted P. ovale parasites to A. gambiae.
CONCLUSIONS
Plasmodium ovale is circulating at 4-15% prevalence among asymptomatic individuals in coastal Tanzania, largely invisible to field diagnostics. A different seasonal peak from co-endemic P. falciparum, the capacity to relapse, and efficient transmission to Anopheles vectors likely contribute to its persistence amid control efforts focused on P. falciparum.
Topics: Animals; Anopheles; Cross-Sectional Studies; Humans; Malaria, Falciparum; Mosquito Vectors; Pilot Projects; Plasmodium falciparum; Plasmodium ovale; Prevalence; Tanzania
PubMed: 35164867
DOI: 10.1186/s13071-022-05181-2 -
Trends in Parasitology Apr 2021The phenomenon of relapsing malaria has been recognised for centuries. It is caused in humans by the parasite species Plasmodium vivax and Plasmodium ovale, which can... (Review)
Review
The phenomenon of relapsing malaria has been recognised for centuries. It is caused in humans by the parasite species Plasmodium vivax and Plasmodium ovale, which can arrest growth at an early, asymptomatic stage as hypnozoites inside liver cells. These dormant parasites can remain quiescent for months or years, then reactivate causing symptomatic malaria. The dynamics of hypnozoite dormancy and reactivation are well documented but the molecular basis remains a complete mystery. Here, I observe that the process has striking parallels with plant vernalisation, whereby plants remain dormant through the winter before flowering in spring. Vernalisation is thoroughly studied in several plant species and its mechanisms are known in exquisite detail. Vernalisation may thus provide a useful framework for interrogating hypnozoite biology.
Topics: Animals; Humans; Life Cycle Stages; Malaria; Plant Dormancy; Plasmodium ovale; Plasmodium vivax
PubMed: 33257270
DOI: 10.1016/j.pt.2020.11.001 -
Journal of Tropical Medicine 2021Although China is moving toward the eradication of malaria and no indigenous malaria has been reported in most Chinese provinces for several years, recent evaluations... (Review)
Review
Although China is moving toward the eradication of malaria and no indigenous malaria has been reported in most Chinese provinces for several years, recent evaluations have revealed that imported cases remain a major challenge to eliminating malaria, with the number of transfusion-transmitted malaria (TTM) cases increasing over time. Here, we review several TTM case reports published after the implementation of the National Malaria Elimination Program in 2010. A total of 12 TTM cases were reported in China between 2013 and 2018. All recipients and donors were diagnosed using rapid diagnosis test and peripheral blood smears. species in donors with low-density parasites were identified using PCR. Nine (75.0%) were identified as , two (16.7%) were identified as , and one (8.3%) was identified as . All were imported from malaria-endemic areas. New action plans designed to meet the challenges of TTM are necessary to ensure the elimination of malaria in China. Paying more attention to the frequency of TTM could help to enhance blood safety in China.
PubMed: 34306101
DOI: 10.1155/2021/3970370 -
Acta Medica Indonesiana Jan 2023Plasmodium ovale consists of two subspecies - P. ovale wallikeri and P. ovale curtisi. Increased reports of imported malaria ovale in non-endemic regions and mixed...
Plasmodium ovale consists of two subspecies - P. ovale wallikeri and P. ovale curtisi. Increased reports of imported malaria ovale in non-endemic regions and mixed infection of P. ovale with other Plasmodium species suggest that P. ovale might be under-detected during routine surveillance. Areas endemic with P. ovale have mostly been reported in African and Western Pacific countries. A recent case report in Indonesia indicated that regions with P. ovale endemicity are not only distributed in Lesser Sunda and Papua, but also in North Sumatra.
Topics: Humans; Plasmodium ovale; Indonesia; Malaria; Coinfection
PubMed: 36999258
DOI: No ID Found -
Diagnostics (Basel, Switzerland) Oct 2021Nowadays, is divided into two non-recombinant sympatric species: and . In this mini review, we summarize the available knowledge on the clinical/biological aspects of... (Review)
Review
Nowadays, is divided into two non-recombinant sympatric species: and . In this mini review, we summarize the available knowledge on the clinical/biological aspects of spp. malaria and current techniques for the diagnosis/characterisation of and . infections are characterized by a deeper thrombocytopenia and shorter latency compared to infections, indicating that is more pathogenic than . Rapid diagnosis for effective management is difficult for spp., since specific rapid diagnostic tests are not available and microscopic diagnosis, which is recognized as the gold standard, requires expert microscopists to differentiate spp. from other species. Neglect in addressing these issues in the prevalence of spp. represents the existing gap in the fight against malaria.
PubMed: 34679597
DOI: 10.3390/diagnostics11101900 -
Scientific Reports Mar 2021Malaria caused by Plasmodium ovale species is considered a neglected tropical disease with limited information about its characteristics. It also remains unclear whether... (Comparative Study)
Comparative Study Meta-Analysis
Malaria caused by Plasmodium ovale species is considered a neglected tropical disease with limited information about its characteristics. It also remains unclear whether the two distinct species P. ovale curtisi and P. ovale wallikeri exhibit differences in their prevalence, geographic distribution, clinical characteristics, or laboratory parameters. Therefore, this study was conducted to clarify these differences to support global malaria control and eradication programs. Studies reporting the occurrence of P. ovale curtisi and P. ovale wallikeri were explored in databases. Differences in proportion, clinical data, and laboratory parameters between the two species were estimated using a random-effects model and expressed as pooled odds ratios (ORs), mean difference (MD), or standardized MD depending on the types of extracted data. The difference in geographical distribution was visualized by mapping the origin of the two species. A total of 1453 P. ovale cases extracted from 35 studies were included in the meta-analysis. The p-value in the meta-analyses provided evidence favoring a real difference between P. ovale curtisi malaria cases (809/1453, 55.7%) and P. ovale wallikeri malaria cases (644/1453, 44.3%) (p: 0.01, OR 1.61, 95% CI 0.71-3.63, I: 77%). Subgroup analyses established evidence favoring a real difference between P. ovale curtisi and P. ovale wallikeri malaria cases among the imported cases (p: 0.02, 1135 cases). The p value in the meta-analyses provided evidence favoring a real difference in the mean latency period between P. ovale curtisi (289 cases) and P. ovale wallikeri malaria (266 cases) (p: 0.03, MD: 27.59, 95% CI 1.99-53.2, I: 94%), total leukocyte count (p < 0.0001, MD: 840, 95% CI 610-1070, I: 0%, two studies) and platelet count (p < 0.0001, MD: 44,750, 95% CI 2900-60,500, I: 32%, three studies). Four continents were found to have reports of P. ovale spp., among which Africa had the highest number of reports for both P. ovale spp. in its 37 countries, with a global proportion of 94.46%, and an almost equal distribution of both P. ovale spp., where P. ovale curtisi and P. ovale wallikeri reflected 53.09% and 46.90% of the continent's proportion, respectively. This is the first systematic review and meta-analysis to demonstrate the differences in the characteristics of the two distinct P. ovale species. Malaria caused by P. ovale curtisi was found in higher proportions among imported cases and had longer latency periods, higher platelet counts, and higher total leukocyte counts than malaria caused by P. ovale wallikeri. Further studies with a larger sample size are required to confirm the differences or similarities between these two species to promote malaria control and effective eradication programs.
Topics: Adolescent; Adult; Africa; Asia; Australia; Child; Child, Preschool; Communicable Diseases, Imported; Europe; Female; Genes, Protozoan; Humans; Malaria; Male; Middle Aged; Neglected Diseases; Plasmodium ovale; Polymerase Chain Reaction; Prevalence; RNA, Protozoan; Young Adult
PubMed: 33742015
DOI: 10.1038/s41598-021-85398-w