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PLoS Neglected Tropical Diseases Jan 2015Plasmodium ovale is comprised of two genetically distinct subspecies, P. ovale curtisi and P. ovale wallikeri. Although P. ovale subspecies are similar based on...
BACKGROUND
Plasmodium ovale is comprised of two genetically distinct subspecies, P. ovale curtisi and P. ovale wallikeri. Although P. ovale subspecies are similar based on morphology and geographical distribution, allelic differences indicate that P. ovale curtisi and P. ovale wallikeri are genetically divergent. Additionally, potential clinical and latency duration differences between P. ovale curtisi and P. ovale wallikeri demonstrate the need for investigation into the contribution of this neglected malaria parasite to the global malaria burden.
METHODS
In order to detect all P. ovale subspecies simultaneously, we developed an inclusive P. ovale-specific real-time PCR assay based on conserved regions between P. ovale curtisi and P. ovale wallikeri in the reticulocyte binding protein 2 (rbp2) gene. Additionally, we characterized the P. ovale subspecies prevalence from 22 asymptomatic malaria infections using multilocus genotyping to discriminate P. ovale curtisi and P. ovale wallikeri.
RESULTS
Our P. ovale rbp2 qPCR assay validation experiments demonstrated a linear dynamic range from 6.25 rbp2 plasmid copies/microliter to 100,000 rbp2 plasmid copies/microliter and a limit of detection of 1.5 rbp2 plasmid copies/microliter. Specificity experiments showed the ability of the rbp2 qPCR assay to detect low-levels of P. ovale in the presence of additional malaria parasite species, including P. falciparum, P. vivax, and P. malariae. We identified P. ovale curtisi and P. ovale wallikeri in Western Kenya by DNA sequencing of the tryptophan-rich antigen gene, the small subunit ribosomal RNA gene, and the rbp2 gene.
CONCLUSIONS
Our novel P. ovale rbp2 qPCR assay detects P. ovale curtisi and P. ovale wallikeri simultaneously and can be utilized to characterize the prevalence, distribution, and burden of P. ovale in malaria endemic regions. Using multilocus genotyping, we also provided the first description of the prevalence of P. ovale curtisi and P. ovale wallikeri in Western Kenya, a region holoendemic for malaria transmission.
Topics: Base Sequence; Genotype; Humans; Kenya; Malaria; Microscopy; Plasmodium ovale; Real-Time Polymerase Chain Reaction; Reproducibility of Results; Sequence Analysis, DNA; Species Specificity
PubMed: 25590587
DOI: 10.1371/journal.pntd.0003469 -
MedRxiv : the Preprint Server For... Oct 2023spp. infections are endemic across multiple African countries and are caused by two distinct non-recombining species, () and (). These species are thought to differ...
BACKGROUND
spp. infections are endemic across multiple African countries and are caused by two distinct non-recombining species, () and (). These species are thought to differ in clinical symptomatology and latency, but existing diagnostic assays have limited ability to detect and distinguish them. In this study, we developed a new duplex assay for the detection and differentiation of and that can be used to improve our understanding of these parasites.
METHODS
Repetitive sequence motifs were identified in available and genomes and used for assay development and validation. We evaluated the analytical sensitivity and specificity of the best-performing assay using a panel of samples from Tanzania and the Democratic Republic of the Congo (DRC), then validated its performance using 55 spp. samples and 40 non-ovale samples from the DRC. and prevalence among symptomatic individuals sampled across three provinces of the DRC were estimated.
RESULTS
The best-performing and targets had 9 and 8 copies within the reference genomes, respectively. Our duplex assay had 100% specificity and 95% confidence lower limits of detection of 4.2 and 41.2 parasite genome equivalents/μl for and , respectively. Species was determined in 80% of all spp.-positive field samples and 100% of those with >10 parasites/μl. Most spp. field samples from the DRC were found to be infections.
CONCLUSIONS
We identified promising multi-copy targets for molecular detection and differentiation of and and used them to develop a new duplex real-time PCR assay that performed well when applied to diverse field samples. Though low-density infections are not reliably detected, the assay is highly specific and can be used for high-throughput studies of spp. epidemiology among symptomatic cases in malaria-endemic countries like the DRC.
PubMed: 37961397
DOI: 10.1101/2023.10.31.23297819 -
Mikrobiyoloji Bulteni Jan 2019Malaria caused by Plasmodium species continues to affect the half of the world population. According to the World Health Organization 2017 data, 445.000 cases of malaria...
Malaria caused by Plasmodium species continues to affect the half of the world population. According to the World Health Organization 2017 data, 445.000 cases of malaria and 219 million cases of new clinical malaria cases were reported during the year. African continent is the geographical region where the disease is most frequent. In recent years there has been an increase in the number of imported cases after travels to this continent. In this case report, relaps caused by Plasmodium ovale in a male Republic of Turkey citizen patient who has travelled to Uganda only and no other place a year and half ago was presented. Thin blood smear was prepared from the peripheral blood of the patient who admitted to our hospital with complaints of fever and chills. The smear was stained with Giemsa and examined with a x100 objective microscope and trophozoites belonging to Plasmodium genus were detected. Considering the size and locality of the trophozoites in the erythrocytes, it is thought that the parasite may be Plasmodium vivax. Nested PCR method was used for the species identification. Nested PCR studies were performed using Plasmodium genus and specific primers for P.vivax, Plasmodium falciparum, P.ovale and Plasmodium malariae. Nested PCR products were run on gel and P.ovale was visualized in 787 bp region. P.vivax, P.malariae, P.falciparum, P.ovale and Plasmodium knowlesi species specific primers and probe-based quantitative real-time PCR (qRt-PCR) study revealed that the patient was infected with P.ovale. The patient had no history of chronic illness but had a history of recovered malaria 7-8 years ago. The patient did not have any complaints other than these complaints. CMV IgM and IgG and Brucella aglutinisation tests were negative. It is clear that relapse cases can also be seen when P.ovale species are in hypnozoite stage in the liver. Although there are 18 reported cases of relapse in the last century, these phenomena do not provide sufficient evidence for the theory of relapse. A true relapse is thought to be mild symptoms and even subclinical disease. It is also known that it is difficult to distinguish a true recurrence in cases of relapses that can occur after a long time from primer infection. The best way to overcome this difficulty is to assume being in a malaria endemic area or not between primary infection and recurrence. We think that the applications that are carried out together with the microscope and molecular studies, especially in cases where there is relapses in which low parasitemia or travel story are insufficient, are extremely important both in terms of diagnosis and accurate identification of species and in the selection of treatment.
Topics: Chronic Disease; Humans; Malaria; Male; Plasmodium ovale; Recurrence; Travel-Related Illness; Turkey
PubMed: 30683044
DOI: 10.5578/mb.67713 -
The Korean Journal of Parasitology Aug 2021The COVID-19 pandemic continues to be a major health problem worldwide. Timely diagnosis of co-infections mimicking COVID-19, such as malaria, might be challenging...
The COVID-19 pandemic continues to be a major health problem worldwide. Timely diagnosis of co-infections mimicking COVID-19, such as malaria, might be challenging particularly in non-endemic areas. We report the first case of COVID-19 and Plasmodium ovale malaria co-infection from our region aiming to highligt the importance of travel history and prophylaxis in malaria management in the context of pandemic. The galloping sound can sometimes be a harbinger of zebra besides the horse.
Topics: Adult; COVID-19; Coinfection; Humans; Malaria; Male; Plasmodium ovale; SARS-CoV-2
PubMed: 34470091
DOI: 10.3347/kjp.2021.59.4.399 -
Parasite (Paris, France) 2020Microsatellites can be utilized to explore genotypes, population structure, and other genomic features of eukaryotes. Systematic characterization of microsatellites has...
Microsatellites can be utilized to explore genotypes, population structure, and other genomic features of eukaryotes. Systematic characterization of microsatellites has not been a focus for several species of Plasmodium, including P. malariae and P. ovale, as the majority of malaria elimination programs are focused on P. falciparum and to a lesser extent P. vivax. Here, five human malaria species (P. falciparum, P. vivax, P. malariae, P. ovale curtisi, and P. knowlesi) were investigated with the aim of conducting in-depth categorization of microsatellites for P. malariae and P. ovale curtisi. Investigation of reference genomes for microsatellites with unit motifs of 1-10 base pairs indicates high diversity among the five Plasmodium species. Plasmodium malariae, with the largest genome size, displays the second highest microsatellite density (1421 No./Mbp; 5% coverage) next to P. falciparum (3634 No./Mbp; 12% coverage). The lowest microsatellite density was observed in P. vivax (773 No./Mbp; 2% coverage). A, AT, and AAT are the most commonly repeated motifs in the Plasmodium species. For P. malariae and P. ovale curtisi, microsatellite-related sequences are observed in approximately 18-29% of coding sequences (CDS). Lysine, asparagine, and glutamic acids are most frequently coded by microsatellite-related CDS. The majority of these CDS could be related to the gene ontology terms "cell parts," "binding," "developmental processes," and "metabolic processes." The present study provides a comprehensive overview of microsatellite distribution and can assist in the planning and development of potentially useful genetic tools for further investigation of P. malariae and P. ovale curtisi epidemiology.
Topics: Gene Ontology; Genome, Protozoan; Genotype; Microsatellite Repeats; Plasmodium; Plasmodium malariae; Plasmodium ovale; Tandem Repeat Sequences
PubMed: 32410726
DOI: 10.1051/parasite/2020034 -
Parasites & Vectors May 2021Loop-mediated isothermal amplification (LAMP) has been widely used to diagnose various infectious diseases. Malaria is a globally distributed infectious disease...
Loop-mediated isothermal amplification (LAMP) assays targeting 18S ribosomal RNA genes for identifying P. vivax and P. ovale species and mitochondrial DNA for detecting the genus Plasmodium.
BACKGROUND
Loop-mediated isothermal amplification (LAMP) has been widely used to diagnose various infectious diseases. Malaria is a globally distributed infectious disease attributed to parasites in the genus Plasmodium. It is known that persons infected with Plasmodium vivax and P. ovale are prone to clinical relapse of symptomatic blood-stage infections. LAMP has not previously been specifically evaluated for its diagnostic performance in detecting P. ovale in an epidemiological study, and no commercial LAMP or rapid diagnostic test (RDT) kits are available for specifically diagnosing infections with P. ovale.
METHODS
An assay was designed to target a portion of mitochondrial DNA (mtDNA) among Plasmodium spp., the five human Plasmodium species and two other assays were designed to target the nuclear 18S ribosomal DNA gene (18S rDNA) of either P. vivax or P. ovale for differentiating the two species. The sensitivity of the assays was compared to that of nested PCR using defined concentrations of plasmids containing the target sequences and using limiting dilutions prepared from clinical isolates derived from Chinese workers who had become infected in Africa or near the Chinese border with Myanmar.
RESULTS
The results showed that 10 copies of the mitochondrial target or 10 and 10 copies of 18S rDNA could be detected from Plasmodium spp., P. vivax and P. ovale, respectively. In 279 clinical samples, the malaria Pan mtDNA LAMP test performed well when compared with a nested PCR assay (95% confidence interval [CI] sensitivity 98.48-100%; specificity 90.75-100%). When diagnosing clinical cases of infection with P. vivax, the 18S rDNA assay demonstrated an even great sensitivity (95.85-100%) and specificity (98.1-100%). The same was true for clinical infections with P. ovale (sensitivity 90.76-99.96%; specificity 98.34-100%). Using plasmid-positive controls, the limits of detection of Malaria Pan, 18S rDNA P. vivax and 18S rDNA P. ovale LAMP were 100-, 100- and tenfold lower than those of PCR, respectively.
CONCLUSION
The novel LAMP assays can greatly aid the rapid, reliable and highly sensitive diagnosis of infections of Plasmodium spp. transmitted among people, including P. vivax and P. ovale, cases of which are most prone to clinical relapse.
Topics: DNA, Mitochondrial; DNA, Protozoan; Humans; Limit of Detection; Malaria; Molecular Diagnostic Techniques; Myanmar; Nucleic Acid Amplification Techniques; Plasmodium; Plasmodium ovale; Plasmodium vivax; RNA, Ribosomal, 18S; Sensitivity and Specificity
PubMed: 34030725
DOI: 10.1186/s13071-021-04764-9 -
The Korean Journal of Parasitology Feb 2020Majority of the imported malaria cases in Korea is attributed to Plasmodium falciparum and P. vivax infections, whereas P. malariae and P. ovale infections are very...
Majority of the imported malaria cases in Korea is attributed to Plasmodium falciparum and P. vivax infections, whereas P. malariae and P. ovale infections are very rare. Falciparum and ovale malaria are mostly imported from Africa, while most of the vivax malaria cases are imported from Southeast Asia. Here, we report 6 Korean imported ovale malaria cases (4 males and 2 females) who had visited in Africa during 2013-2016. These subjects were diagnosed with P. ovale based on microscopic findings, Plasmodium species-specific nested-PCR, and phylogenetic clade using 18S rRNA gene sequences. We identified 2 P. ovale subtypes, 1 P. ovale curtisi (classic type) and 5 P. ovale wallikeri (variant type). All patients were treated with chloroquine and primaquine, and no relapse or recrudescence was reported for 1 year after treatment. With increase of travelers to the countries where existing Plasmodium species, the risk of Plasmodium infection is also increasing. Molecular monitoring for imported malaria parasites should be rigorously and continuously performed to enable diagnosis and certification of Plasmodium spp.
Topics: Asian People; Female; Humans; Malaria; Male; Plasmodium ovale; RNA, Ribosomal, 18S; South Africa; Time Factors; Travel
PubMed: 32145729
DOI: 10.3347/kjp.2020.58.1.61 -
Emerging Infectious Diseases Jun 2023Achieving malaria elimination requires considering both Plasmodium falciparum and non-P. falciparum infections. We determined prevalence and geographic distribution of 4...
Achieving malaria elimination requires considering both Plasmodium falciparum and non-P. falciparum infections. We determined prevalence and geographic distribution of 4 Plasmodium spp. by performing PCR on dried blood spots collected within 8 regions of Tanzania during 2017. Among 3,456 schoolchildren, 22% had P. falciparum, 24% had P. ovale spp., 4% had P. malariae, and 0.3% had P. vivax infections. Most (91%) schoolchildren with P. ovale infections had low parasite densities; 64% of P. ovale infections were single-species infections, and 35% of those were detected in low malaria endemic regions. P. malariae infections were predominantly (73%) co-infections with P. falciparum. P. vivax was detected mostly in northern and eastern regions. Co-infections with >1 non-P. falciparum species occurred in 43% of P. falciparum infections. A high prevalence of P. ovale infections exists among schoolchildren in Tanzania, underscoring the need for detection and treatment strategies that target non-P. falciparum species.
Topics: Humans; Child; Plasmodium falciparum; Prevalence; Tanzania; Coinfection; Plasmodium malariae; Malaria; Malaria, Falciparum; Malaria, Vivax
PubMed: 37209670
DOI: 10.3201/eid2906.221016 -
The Journal of Infectious Diseases Jan 2022Plasmodium falciparum malaria dominates throughout sub-Saharan Africa, but the prevalence of Plasmodium malariae, Plasmodium ovale spp., and Plasmodium vivax...
BACKGROUND
Plasmodium falciparum malaria dominates throughout sub-Saharan Africa, but the prevalence of Plasmodium malariae, Plasmodium ovale spp., and Plasmodium vivax increasingly contribute to infection in countries that control malaria using P. falciparum-specific diagnostic and treatment strategies.
METHODS
We performed quantitative polymerase chain reaction (qPCR) on 2987 dried blood spots from the 2015-2016 Malawi Demographic and Health Survey to identify presence and distribution of nonfalciparum infection. Bivariate models were used to determine species-specific associations with demographic and environmental risk factors.
RESULTS
Nonfalciparum infections had broad spatial distributions. Weighted prevalence was 0.025 (SE, 0.004) for P. malariae, 0.097 (SE, 0.008) for P. ovale spp., and 0.001 (SE, 0.0005) for P. vivax. Most infections (85.6%) had low-density parasitemias ≤ 10 parasites/µL, and 66.7% of P. malariae, 34.6% of P. ovale spp., and 40.0% of P. vivax infections were coinfected with P. falciparum. Risk factors for P. malariae were like those known for P. falciparum; however, there were few risk factors recognized for P. ovale spp. and P. vivax, perhaps due to the potential for relapsing episodes.
CONCLUSIONS
The prevalence of any nonfalciparum infection was 11.7%, with infections distributed across Malawi. Continued monitoring of Plasmodium spp. becomes critical as nonfalciparum infections become important sources of ongoing transmission.
Topics: Adolescent; Adult; Female; Humans; Malaria; Malaria, Vivax; Malawi; Male; Plasmodium malariae; Plasmodium ovale; Plasmodium vivax; Real-Time Polymerase Chain Reaction; Young Adult
PubMed: 34244739
DOI: 10.1093/infdis/jiab353 -
Journal of the Formosan Medical... Jan 2022Malaria is an infectious disease caused by Plasmodium parasites that are mainly transmitted through the bites of infected female Anopheles mosquitoes. The average annual...
Malaria is an infectious disease caused by Plasmodium parasites that are mainly transmitted through the bites of infected female Anopheles mosquitoes. The average annual number of malaria cases was less than ten in Taiwan in the last five years. Most of the cases were caused by Plasmodium vivax and Plasmodium falciparum, and were primarily diagnosed in travelers who returned from Southeast Asia and Africa. Here, we report the first case of Plasmodium ovale infection within five years that was confirmed by peripheral blood smear examination and molecular identification in a 25-year-old Asian female patient who returned from Uganda.
Topics: Adult; Africa, Eastern; Female; Humans; Malaria; Plasmodium ovale; Taiwan
PubMed: 33966940
DOI: 10.1016/j.jfma.2021.04.013