| plasmodium ovale curtisi and plasmodium ovale wallikeri circulate simultaneously in african communities. | it has been proposed that ovale malaria in humans is caused by two closely related but distinct species of malaria parasite, plasmodium ovale curtisi and plasmodium ovale wallikeri. it was recently shown that these two parasite types are sympatric at the country level. however, it remains possible that localised geographic, temporal or ecological barriers exist within endemic countries which prevent recombination between the genomes of the two species. here, using conventional and real-time quan ... | 2011 | 21315074 |
| recent advances in detection of plasmodium ovale: implications of separation into the two species plasmodium ovale wallikeri and plasmodium ovale curtisi. | recent molecular studies indicate that plasmodium ovale malaria is caused by two closely related species of protozoan parasites, thereby imposing new challenges for detection and species differentiation. this minireview explores the potential value of innovative methods for the molecular diagnosis of malaria with a strong emphasis on the discrimination and genotyping of p. ovale wallikeri and p. ovale curtisi as well as tools for the simultaneous detection of p. ovale sp. an update for the widel ... | 2013 | 24478466 |
| persistent detection of plasmodium falciparum, p. malariae, p. ovale curtisi and p. ovale wallikeri after act treatment of asymptomatic ghanaian school-children. | two hundred and seventy four asymptomatic ghanaian school-children aged 5 to 17 years were screened for malaria parasites by examination of blood films. one hundred and fifty five microscopically-positive individuals were treated with dihydroartemisinin-piperaquine and followed for 3 weeks. retrospective species-specific pcr of all 274 screened samples identified an additional 60 children with sub-patent parasitaemia, and a substantial proportion of co-infections with plasmodium malariae, plasmo ... | 2013 | 24533292 |
| real-time pcr assay for discrimination of plasmodium ovale curtisi and plasmodium ovale wallikeri in the ivory coast and in the comoros islands. | plasmodium ovale is one of the five malaria species infecting humans. recent data have shown that the name of this neglected species masks two distinct genotypes also called curtisi and wallikeri. some authors show that these species could be sympatric. these two subspecies are not differentiated by microscopy techniques and malaria rapid diagnostic tests. this diagnostic defect is the result of low parasitaemia, antigenic polymorphism and absence of antibodies performance and requires the use o ... | 2012 | 22947418 |
| diagnosis of an imported plasmodium ovale wallikeri infection in malaysia. | plasmodium ovale is rare and not exactly known to be autochthonous in malaysia. there are two distinct forms of the parasite, namely p. ovale curtisi (classic form) and p. ovale wallikeri (variant form). here, the first sequence confirmed case of an imported p. ovale wallikeri infection in malaysia is presented. microscopy found plasmodium parasites with morphology similar to p. ovale or plasmodium vivax in the blood films. further confirmation using polymerase chain reaction (pcr) targeting the ... | 2016 | 26738724 |
| molecular characterization of misidentified plasmodium ovale imported cases in singapore. | plasmodium ovale, considered the rarest of the malaria parasites of humans, consists of two morphologically identical but genetically distinct sympatric species, plasmodium ovale curtisi and plasmodium ovale wallikeri. these parasites resemble morphologically to plasmodium vivax with which they also share a tertian periodicity and the ability to cause relapses, making them easily misidentified as p. vivax. plasmodium ovale infections are rarely reported, but given the likelihood of misidentifica ... | 2015 | 26577930 |
| the increasing importance of plasmodium ovale and plasmodium malariae in a malaria elimination setting: an observational study of imported cases in jiangsu province, china, 2011-2014. | following initiation of china's national malaria elimination action plan in 2010, indigenous malaria infections in jiangsu province decreased significantly. meanwhile imported plasmodium infections have increased substantially, particularly plasmodium ovale and plasmodium malariae. given the risk for malaria resurgence, there is an urgent need to understand the increase in imported p. ovale and p. malariae infections as china works to achieve national malaria elimination. | 2016 | 27604629 |
| malaria in children of tshimbulu (western kasai, democratic republic of the congo): epidemiological data and accuracy of diagnostic assays applied in a limited resource setting. | the literature data on malaria in western kasai, drc, are limited and inadequate. a recent molecular survey there has detected plasmodium ovale and plasmodium malariae as mixed infections with plasmodium falciparum. in tshimbulu, western kasai, during a humanitarian initiative designed to provide children with free preventive screening and to reduce the local high malaria death rate, accurate species identification was performed, in order to collect unambiguous epidemiological data and to evalua ... | 2016 | 26864461 |
| dengue infection as a potential trigger of an imported plasmodium ovale malaria relapse or a long incubation period in a non-endemic malaria region. | to report that dengue fever (df) could have triggered plasmodium ovale wallikeri malaria. | 2016 | 26809125 |
| evidence of non-plasmodium falciparum malaria infection in kédougou, sénégal. | expanded malaria control efforts in sénégal have resulted in increased use of rapid diagnostic tests (rdt) to identify the primary disease-causing plasmodium species, plasmodium falciparum. however, the type of rdt utilized in sénégal does not detect other malaria-causing species such as plasmodium ovale spp., plasmodium malariae, or plasmodium vivax. consequently, there is a lack of information about the frequency and types of malaria infections occurring in sénégal. this study set out to bette ... | 2017 | 28049489 |
| non-falciparum malaria in dakar: a confirmed case of plasmodium ovale wallikeri infection. | plasmodium ovale is rarely described in senegal. a case of clinical malaria due to p. ovale wallikeri in west central of senegal is reported. | 2016 | 27557982 |
| human malaria diagnosis using a single-step direct-pcr based on the plasmodium cytochrome oxidase iii gene. | nested pcrs based on the plasmodium 18s-rrna gene have been extensively used for human malaria diagnosis. however, they are not practical when large quantities of samples need to be processed, further there have been challenges in the performance and when interpreting results, especially when submicroscopic infections are analysed. here the use of "direct pcr" was investigated with the aim of improving diagnosis in the malaria elimination era. | 2016 | 26928594 |
| plasmodium ovale curtisi and plasmodium ovale wallikeri in north-west ethiopia. | in ethiopia plasmodium falciparum and plasmodium vivax are the dominant species accounting for roughly 60 and 40% of malaria cases, respectively. recently a major shift from p. falciparum to p. vivax has been observed in various parts of the country but the epidemiology of the other human malaria species, plasmodium ovale spp. and plasmodium malariae remains poorly understood. the aim of this study was to assess p. ovale curtisi and wallikeri infection in north-west ethiopia by using microscopy ... | 2013 | 24073668 |
| use of qpcr and genomic sequencing to diagnose plasmodium ovale wallikeri malaria in a returned soldier in the setting of a negative rapid diagnostic assay. | plasmodium ovale is one of several clinically relevant malaria species known to cause disease in humans. however, in contrast to plasmodium falciparum and plasmodium vivax, which are responsible for most cases of human malaria, p. ovale has a wide distribution but low prevalence in tropical regions. here, we report the case of a soldier returning from liberia with p. ovale wallikeri malaria. this case highlights the limitations of both microscopy and the malaria rapid diagnostic test for diagnos ... | 2013 | 23836567 |
| an observational study of malaria in british travellers: plasmodium ovale wallikeri and plasmodium ovale curtisi differ significantly in the duration of latency. | ovale malaria is caused by two closely related species of protozoan parasite: plasmodium ovale curtisi and plasmodium ovale wallikeri although clearly distinct genetically, there have been no studies comparing the morphology, life cycle or epidemiology of these parasites. we tested the hypothesis that the two species differ in the duration of latency prior to presentation with symptoms of blood-stage infection. | 2013 | 23793668 |
| accurate identification of the six human plasmodium spp. causing imported malaria, including plasmodium ovale wallikeri and plasmodium knowlesi. | accurate identification of plasmodium infections in non-endemic countries is of critical importance with regard to the administration of a targeted therapy having a positive impact on patient health and management and allowing the prevention of the risk of re-introduction of endemic malaria in such countries. malaria is no longer endemic in italy where it is the most commonly imported disease, with one of the highest rates of imported malaria among european non-endemic countries including france ... | 2013 | 24034175 |
| persistent parasitism: the adaptive biology of malariae and ovale malaria. | plasmodium malariae causes malaria in humans throughout the tropics and subtropics. plasmodium ovale curtisi and plasmodium ovale wallikeri are sympatric sibling species common in sub-saharan africa and also found in oceania and asia. although rarely identified as the cause of malaria cases in endemic countries, pcr detection has confirmed all three parasite species to be more prevalent, and persistent, than previously thought. chronic, low-density, multispecies asymptomatic infection is a succe ... | 2016 | 27480365 |
| genome-scale comparison of expanded gene families in plasmodium ovale wallikeri and plasmodium ovale curtisi with plasmodium malariae and with other plasmodium species. | malaria in humans is caused by six species of plasmodium parasites, of which the nuclear genome sequences for the two plasmodium ovale spp., p. ovale curtisi and p. ovale wallikeri, and plasmodium malariae have not yet been analyzed. here we present an analysis of the nuclear genome sequences of these three parasites, and describe gene family expansions therein. plasmodium ovale curtisi and p. ovale wallikeri are genetically distinct but morphologically indistinguishable and have sympatric range ... | 2016 | 27392654 |
| two sympatric types of plasmodium ovale and discrimination by molecular methods. | 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 m ... | 2016 | 28065415 |
| parasitological correlates of plasmodium ovale curtisi and plasmodium ovale wallikeri infection. | malaria, due to plasmodium ovale, can be challenging to diagnose due to clinically mild disease and low parasite burden. two genetically distinct sub-species of p. ovale exist: plasmodium ovale curtisi (classic) and plasmodium ovale wallikeri (variant). it is presently unknown if the sub-species causing infection affects performance of malaria diagnostic tests. the aim of this work was to understand how the genetically distinct sub-species, p. o. curtisi and p. o. wallikeri, affect malaria diagn ... | 2016 | 27832785 |
| dimorphism in genes encoding sexual-stage proteins of plasmodium ovale curtisi and plasmodium ovale wallikeri. | plasmodium ovale curtisi and plasmodium ovale wallikeri are distinct species of malaria parasite which are sympatric throughout the tropics, except for the americas. despite this complete overlap in geographic range, these two species do not recombine. although morphologically very similar, the two taxa must possess distinct characters which prevent recombination between them. we hypothesised that proteins required for sexual reproduction have sufficiently diverged between the two species to pre ... | 2015 | 25817462 |
| [iditification of five imported cases of plasmodium ovale wallikeri infection in zhejiang province]. | to identify and analyze plasmodium ovale wallikeri in 5 imported malaria cases, who were detected positive by microscopy and negative by conventional pcr. | 2014 | 25726600 |
| new type of ssurdna sequence was detected from both plasmodium ovale curtisi and plasmodium ovale wallikeri samples. | plasmodium ovale is relatively unfamiliar to chinese staff engaged in malaria diagnosis. in 2013, dried blood spots of four unidentified but suspected ovale malaria samples were sent to the national malaria reference laboratory (nmrl) for reconfirmation. | 2014 | 24893846 |
| [overviews on plasmodium ovale wallikeri and its genetic detection system]. | in recent years, some microscopy-positive but nest-pcr negative (based on small subunit ribosomal rna gene) ovale malaria cases were reported. the detection failure was due to the genetic variations between plasomdoium ovale wallikeri and p. ovale curtisi. this paper reviews the discovery and validation processes of p. ovale wallikeri and the detection systems for identification of p. ovale. | 2014 | 24822370 |
| comparison of imported plasmodium ovale curtisi and p. ovale wallikeri infections among patients in spain, 2005-2011. | sequencing data from plasmodium ovale genotypes co-circulating in multiple countries support the hypothesis that p. ovale curtisi and p. ovale wallikeri are 2 separate species. we conducted a multicenter, retrospective, comparative study in spain of 21 patients who had imported p. ovale curtisi infections and 14 who had imported p. ovale wallikeri infections confirmed by pcr and gene sequencing during june 2005-december 2011. the only significant finding was more severe thrombocytopenia among pa ... | 2014 | 24572501 |
| a case of plasmodium ovale wallikeri infection in a chinese worker returning from west africa. | in contrast to the gradual reduction in the number of locally transmitted malaria cases in china, the number of imported malaria cases has been increasing since 2008. here, we report a case of a 39-year-old chinese man who acquired plasmodium ovale wallikeri infection while staying in ghana, west africa for 6 months in 2012. microscopic examinations of giemsa-stained thin and thick blood smears indicated plasmodium vivax infection. however, the results of rapid diagnostic tests, which were condu ... | 2013 | 24327782 |
| genetic marker suitable for identification and genotyping of plasmodium ovale curtisi and plasmodium ovale wallikeri. | we present a seminested pcr method that specifically discriminates between plasmodium ovale curtisi and p. ovale wallikeri with high sensitivity. the test is based on species-specific amplification of a size-polymorphic fragment of the tryptophan-rich antigen gene, potra, which also permits discrimination of intraspecific sequence variants at this locus. | 2013 | 24068009 |
| a new real-time pcr for the detection of plasmodium ovale wallikeri. | it has been proposed that ovale malaria in humans is caused by two closely related but distinct species of malaria parasites: p. ovale curtisi and p. ovale wallikeri. we have extended and optimized a real-time pcr assay targeting the parasite's small subunit ribosomal rna (ssrrna) gene to detect both these species. when the assay was applied to 31 archival blood samples from patients diagnosed with p. ovale, it was found that the infection in 20 was due to p. ovale curtisi and in the remaining 1 ... | 2012 | 23110165 |
| two techniques for simultaneous identification of plasmodium ovale curtisi and plasmodium ovale wallikeri by use of the small-subunit rrna gene. | the primers traditionally used to detect plasmodium ovale infections are known for not binding all p. ovale parasites within the small-subunit rrna gene when used alone. we describe a simple, cost- and time-efficient multiplex nested pcr and a nested pcr using a novel set of primers for the simultaneous detection of p. ovale curtisi and p. ovale wallikeri. | 2012 | 23015675 |
| plasmodium ovale in bangladesh: genetic diversity and the first known evidence of the sympatric distribution of plasmodium ovale curtisi and plasmodium ovale wallikeri in southern asia. | in spite of the high prevalence of malaria in bangladesh and other southern asian countries, there remains a substantial shortage of knowledge about the less common human malaria parasites. recent studies indicate that plasmodium ovale is made up of two species, namely plasmodium ovale wallikeri and plasmodium ovale curtisi. genus- and species-specific nested pcr analyses of the ssrrna gene was used to detect p. ovale infections among 2,246 diagnostic samples. plasmodium ovale infections were fu ... | 2012 | 22633951 |
| distinction of plasmodium ovale wallikeri and plasmodium ovale curtisi using quantitative polymerase chain reaction with high resolution melting revelation. | plasmodium ovale curtisi (poc) and plasmodium ovale wallikeri (pow) have been described as two distinct species, only distinguishable by molecular methods such as pcr. because of no well-defined endemic area and a variable clinical presentation as higher thrombocytopenia and nausea associated with pow infection and asymptomatic forms of the pathology with poc infection, rapid and specific identification of plasmodium ovale curtisi and plasmodium ovale wallikeri are needed. the aim of the study w ... | 2018 | 29321578 |
| [plasmodium ovale wallikeri and plasmodium ovale curtisi malaria in senegal in 2016]. | recently in senegal, a case of plasmodium ovale malaria had led to a diagnostic difficulty due to the ignorance of this parasite and the neglect of it. the objective of this study was to actively investigate cases of p. ovale malaria that would be misdiagnosed in the health centre structures of senegal. the study was conducted in three areas that reflect different epidemiological strata of malaria. microscopy was performed by microscopy experts on suspected malaria patients. the results were val ... | 2017 | 29127650 |
| species and genotype diversity of plasmodium in malaria patients from gabon analysed by next generation sequencing. | six plasmodium species are known to naturally infect humans. mixed species infections occur regularly but morphological discrimination by microscopy is difficult and multiplicity of infection (moi) can only be evaluated by molecular methods. this study investigated the complexity of plasmodium infections in patients treated for microscopically detected non-falciparum or mixed species malaria in gabon. | 2017 | 28974215 |
| a novel diagnostic method for malaria using loop-mediated isothermal amplification (lamp) and minion™ nanopore sequencer. | a simple and accurate molecular diagnostic method for malaria is urgently needed due to the limitations of conventional microscopic examination. in this study, we demonstrate a new diagnostic procedure for human malaria using loop mediated isothermal amplification (lamp) and the minion™ nanopore sequencer. | 2017 | 28903726 |