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Journal of Microbiology, Immunology,... Oct 2017Plasmodium ovale is widely distributed in tropical countries, whereas it has not been reported in the Americas. It is not a problem globally because it is rarely... (Review)
Review
Plasmodium ovale is widely distributed in tropical countries, whereas it has not been reported in the Americas. It is not a problem globally because it is rarely detected by microscopy owing to low parasite density, which is a feature of clinical ovale malaria. P.o. curtisi and P.o. wallikeri are widespread in both Africa and Asia, and were known to be sympatric in many African countries and in southeast Asian countries. Small subunit ribosomal RNA (SSUrRNA) gene, cytochrome b (cytb) gene, and merozoite surface protein-1 (msp-1) gene were initially studied for molecular discrimination of P.o. curtisi and P.o. wallikeri using polymerase chain reaction (PCR) and DNA sequencing. DNA sequences of other genes from P. ovale in Southeast Asia and the southwestern Pacific regions were also targeted to differentiate the two sympatric types. In terms of clinical manifestations, P.o. wallikeri tended to produce higher parasitemia levels and more severe symptoms. To date, there have been a few studies that used the quantitative PCR method for discrimination of the two distinct P. ovale types. Conventional PCR with consequent DNA sequencing is the common method used to differentiate these two types. It is necessary to identify these two types because relapse periodicity, drug susceptibility, and mosquito species preference need to be studied to reduce ovale malaria. In this article, an easier method of molecular-level discrimination of P.o. curtisi and P.o. wallikeri is proposed.
Topics: Animals; Cytochromes b; DNA, Protozoan; Genes, Protozoan; Genes, rRNA; Humans; Malaria; Merozoite Surface Protein 1; Plasmodium ovale; Polymerase Chain Reaction; Protozoan Proteins; Sequence Analysis, DNA
PubMed: 28065415
DOI: 10.1016/j.jmii.2016.08.004 -
Tropical Parasitology 2023Nonhuman primate (NHP) malaria poses a major threat to the malaria control programs. The last two decades have witnessed a paradigm shift in our understanding of the... (Review)
Review
Nonhuman primate (NHP) malaria poses a major threat to the malaria control programs. The last two decades have witnessed a paradigm shift in our understanding of the malaria caused by species other than the traditionally known human species - , , , and . The emergence of the malaria parasite of long-tailed macaque monkeys, , as the fifth malaria species of humans has made the scientific community consider the risk of other zoonotic malaria, such as , , , and others, to humans. The development of knowledge about as a pathogen which was earlier only known to experimentally cause malaria in humans and rarely cause natural infection, toward its acknowledgment as a significant cause of human malaria and a threat of malaria control programs has been made possible by the use of advanced molecular techniques such as polymerase chain reaction and gene sequencing. This review explores the various aspects of NHP malaria, and the association of various factors with their emergence and potential to cause human malaria which are important to understand to be able to control these emerging infections.
PubMed: 37860614
DOI: 10.4103/tp.tp_79_22 -
Clinical Microbiology Reviews Jul 2005Humans are infected by four recognized species of malaria parasites. The last of these to be recognized and described is Plasmodium ovale. Like the other malaria... (Review)
Review
Humans are infected by four recognized species of malaria parasites. The last of these to be recognized and described is Plasmodium ovale. Like the other malaria parasites of primates, this parasite is only transmitted via the bites of infected Anopheles mosquitoes. The prepatent period in the human ranges from 12 to 20 days. Some forms in the liver have delayed development, and relapse may occur after periods of up to 4 years after infection. The developmental cycle in the blood lasts approximately 49 h. An examination of records from induced infections indicated that there were an average of 10.3 fever episodes of > or = 101 degrees F and 4.5 fever episodes of > or = 104 degrees F. Mean maximum parasite levels were 6,944/microl for sporozoite-induced infections and 7,310/microl for trophozoite-induced infections. Exoerythrocytic stages have been demonstrated in the liver of humans, chimpanzees, and Saimiri monkeys following injection of sporozoites. Many different Anopheles species have been shown to be susceptible to infection with P. ovale, including A. gambiae, A. atroparvus, A. dirus, A. freeborni, A. albimanus, A. quadrimaculatus, A. stephensi, A. maculatus, A. subpictus, and A. farauti. An enzyme-linked immunosorbent assay has been developed to detect mosquitoes infected with P. ovale using a monoclonal antibody directed against the circumsporozoite protein. Plasmodium ovale is primarily distributed throughout sub-Saharan Africa. It has also been reported from numerous islands in the western Pacific. In more recent years, there have been reports of its distribution on the Asian mainland. Whether or not it will become a major public health problem there remains to be seen. The diagnosis of P. ovale is based primarily on the characteristics of the blood stages and its differentiation from P. vivax. The sometimes elliptical shape of the infected erythrocyte is often diagnostic when combined with other, subtler differences in morphology. The advent of molecular techniques, primarily PCR, has made diagnostic confirmation possible. The development of techniques for the long-term frozen preservation of malaria parasites has allowed the development diagnostic reference standards for P. ovale. Infections in chimpanzees are used to provide reference and diagnostic material for serologic and molecular studies because this parasite has not been shown to develop in other nonhuman primates, nor has it adapted to in vitro culture. There is no evidence to suggest that P. ovale is closely related phylogenetically to any other of the primate malaria parasites that have been examined.
Topics: Animals; Anopheles; Humans; Insect Vectors; Malaria; Plasmodium ovale
PubMed: 16020691
DOI: 10.1128/CMR.18.3.570-581.2005 -
Frontiers in Microbiology 2022Malaria elimination includes neglected human malaria parasites spp., and . Biological features such as association with low-density infection and the formation of... (Review)
Review
Malaria elimination includes neglected human malaria parasites spp., and . Biological features such as association with low-density infection and the formation of hypnozoites responsible for relapse make their elimination challenging. Studies on these parasites rely primarily on clinical samples due to the lack of long-term culture techniques. With improved methods to enrich parasite DNA from clinical samples, whole-genome sequencing of the neglected malaria parasites has gained increasing popularity. Population genomics of more than 2200 global isolates has improved our knowledge of parasite biology and host-parasite interactions, identified vaccine targets and potential drug resistance markers, and provided a new way to track parasite migration and introduction and monitor the evolutionary response of local populations to elimination efforts. Here, we review advances in population genomics for neglected malaria parasites, discuss how the rich genomic information is being used to understand parasite biology and epidemiology, and explore opportunities for the applications of malaria genomic data in malaria elimination practice.
PubMed: 36160257
DOI: 10.3389/fmicb.2022.984394 -
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 -
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 -
Malaria Journal Nov 2016The Greater Mekong Subregion is aiming to achieve regional malaria elimination by 2030. Though a shift in malaria parasite species predominance by Plasmodium vivax has...
BACKGROUND
The Greater Mekong Subregion is aiming to achieve regional malaria elimination by 2030. Though a shift in malaria parasite species predominance by Plasmodium vivax has been recently documented, the transmission of the two minor Plasmodium species, Plasmodium malariae and Plasmodium ovale spp., is poorly characterized in the region. This study aims to determine the prevalence of these minor species in the China-Myanmar border area and their genetic diversity.
METHODS
Epidemiology study was conducted during passive case detection in hospitals and clinics in Myanmar and four counties in China along the China-Myanmar border. Cross-sectional surveys were conducted in villages and camps for internally displaced persons to determine the prevalence of malaria infections. Malaria infections were diagnosed initially by microscopy and later in the laboratory using nested PCR for the SSU rRNA genes. Plasmodium malariae and P. ovale infections were confirmed by sequencing the PCR products. The P. ovale subtypes were determined by sequencing the Pocytb, Pocox1 and Pog3p genes. Parasite populations were evaluated by PCR amplification and sequencing of the MSP-1 genes. Antifolate sensitivity was assessed by sequencing the dhfr-ts and dhps genes from the P. malariae and P. ovale isolates.
RESULTS
Analysis of 2701 blood samples collected from the China-Myanmar border by nested PCR targeting the parasite SSU rRNA genes identified 561 malaria cases, including 161 Plasmodium falciparum, 327 P. vivax, 66 P. falciparum/P. vivax mixed infections, 4 P. malariae and 3 P. ovale spp. P. vivax and P. falciparum accounted for >60 and ~30% of all malaria cases, respectively. In comparison, the prevalence of P. malariae and P. ovale spp. was very low and only made up ~1% of all PCR-positive cases. Nevertheless, these two species were often misidentified as P. vivax infections or completely missed by microscopy even among symptomatic patients. Phylogenetic analysis of the SSU rRNA, Pocytb, Pocox1 and Pog3p genes confirmed that the three P. ovale spp. isolates belonged to the subtype P. ovale curtisi. Low-level genetic diversity was detected in the MSP-1, dhfr and dhps genes of these minor parasite species, potentially stemming from the low prevalence of these parasites preventing their mixing. Whereas most of the dhfr and dhps positions equivalent to those conferring antifolate resistance in P. falciparum and P. vivax were wild type, a new mutation S113C corresponding to the S108 position in pfdhfr was identified in two P. ovale curtisi isolates.
CONCLUSIONS
The four human malaria parasite species all occurred sympatrically at the China-Myanmar border. While P. vivax has become the predominant species, the two minor parasite species also occurred at very low prevalence but were often misidentified or missed by conventional microscopy. These minor parasite species displayed low levels of polymorphisms in the msp-1, dhfr and dhps genes.
Topics: Adult; Child; China; Cluster Analysis; Cross-Sectional Studies; DNA, Protozoan; DNA, Ribosomal; Drug Resistance; Female; Genetic Variation; Humans; Malaria; Male; Microscopy; Myanmar; Phylogeny; Plasmodium falciparum; Plasmodium malariae; Plasmodium ovale; Plasmodium vivax; Polymerase Chain Reaction; Prevalence; Protozoan Proteins; RNA, Ribosomal, 18S; Sequence Analysis, DNA; Young Adult
PubMed: 27846879
DOI: 10.1186/s12936-016-1605-y -
Clinical Infectious Diseases : An... Apr 2022The effect of primaquine in preventing Plasmodium vivax relapses from dormant stages is well established. For Plasmodium ovale, the relapse characteristics and the use...
BACKGROUND
The effect of primaquine in preventing Plasmodium vivax relapses from dormant stages is well established. For Plasmodium ovale, the relapse characteristics and the use of primaquine is not as well studied. We set to evaluate the relapsing properties of these 2 species, in relation to primaquine use among imported malaria cases in a nonendemic setting.
METHODS
We performed a nationwide retrospective study of malaria diagnosed in Sweden 1995-2019, by reviewing medical records of 3254 cases. All episodes of P. vivax (n = 972) and P. ovale (n = 251) were selected for analysis.
RESULTS
First time relapses were reported in 80/857 (9.3%) P. vivax and 9/220 (4.1%) P. ovale episodes, respectively (P < .01). Without primaquine, the risk for relapse was higher in P. vivax, 20/60 (33.3%), compared to 3/30 (10.0%) in P. ovale (hazard ratio [HR] 3.5, 95% confidence interval [CI] 1.0-12.0). In P. vivax, patients prescribed primaquine had a reduced risk of relapse compared to episodes without relapse preventing treatment, 7.1% vs 33.3% (HR 0.2, 95% CI .1-.3). In P. ovale, the effect of primaquine on the risk of relapse did not reach statistical significance, with relapses seen in 2.8% of the episodes compared to 10.0% in patients not receiving relapse preventing treatment (HR 0.3, 95% CI .1-1.1).
CONCLUSIONS
The risk of relapse was considerably lower in P. ovale than in P. vivax infections indicating different relapsing features between the two species. Primaquine was effective in preventing P. vivax relapse. In P. ovale, relapse episodes were few, and the supportive evidence for primaquine remains limited.
Topics: Antimalarials; Chronic Disease; Humans; Malaria; Malaria, Vivax; Plasmodium ovale; Plasmodium vivax; Primaquine; Recurrence; Retrospective Studies
PubMed: 34216464
DOI: 10.1093/cid/ciab610 -
Trends in Parasitology Jun 2007Although Plasmodium malariae was first described as an infectious disease of humans by Golgi in 1886 and Plasmodium ovale identified by Stevens in 1922, there are still... (Review)
Review
Although Plasmodium malariae was first described as an infectious disease of humans by Golgi in 1886 and Plasmodium ovale identified by Stevens in 1922, there are still large gaps in our knowledge of the importance of these infections as causes of malaria in different parts of the world. They have traditionally been thought of as mild illnesses that are caused by rare and, in case of P. ovale, short-lived parasites. However, recent advances in sensitive PCR diagnosis are causing a re-evaluation of this assumption. Low-level infection seems to be common across malaria-endemic areas, often as complex mixed infections. The potential interactions of P. malariae and P. ovale with Plasmodium falciparum and Plasmodium vivax might explain some basic questions of malaria epidemiology, and understanding these interactions could have an important influence on the deployment of interventions such as malaria vaccines.
Topics: Adolescent; Adult; Animals; Child; Child, Preschool; Humans; Infant; Infant, Newborn; Malaria; Microscopy; Plasmodium malariae; Plasmodium ovale; Polymerase Chain Reaction; Prevalence
PubMed: 17459775
DOI: 10.1016/j.pt.2007.04.009 -
Emerging Infectious Diseases Feb 2021We retrospectively analyzed epidemiologic, clinical, and biologic characteristics of 368 Plasmodium ovale wallikeri and 309 P. ovale curtisi infections treated in France...
We retrospectively analyzed epidemiologic, clinical, and biologic characteristics of 368 Plasmodium ovale wallikeri and 309 P. ovale curtisi infections treated in France during January 2013–December 2018. P. ovale wallikeri infections displayed deeper thrombocytopenia and shorter latency periods. Despite similar clinical manifestations, P. ovale wallikeri–infected patients were more frequently treated with artemisinin-based combination therapy. Although the difference was not statistically significant, P. ovale wallikeri–infected patients were 5 times more frequently hospitalized in intensive care or intermediate care and had a higher proportion of severe thrombocytopenia than P. ovale curtisi–infected patients. Rapid diagnostic tests that detect aldolase were more efficient than those detecting Plasmodium lactate dehydrogenase. Sequence analysis of the potra gene from 90 P. ovale isolates reveals an insufficient polymorphism for relapse typing.
Topics: France; Humans; Malaria; Plasmodium; Plasmodium ovale; Retrospective Studies
PubMed: 33496652
DOI: 10.3201/eid2702.202143