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PLoS Neglected Tropical Diseases Dec 2023Plasmodium ovale curtisi (Poc) and Plasmodium ovale wallikeri (Pow) represent distinct non-recombining Plasmodium species that are increasing in prevalence in...
Plasmodium ovale curtisi (Poc) and Plasmodium ovale wallikeri (Pow) represent distinct non-recombining Plasmodium species that are increasing in prevalence in sub-Saharan Africa. Though they circulate sympatrically, co-infection within human and mosquito hosts has rarely been described. Separate 18S rRNA real-time PCR assays that detect Poc and Pow were modified to allow species determination in parallel under identical cycling conditions. The lower limit of detection was 0.6 plasmid copies/μL (95% CI 0.4-1.6) for Poc and 4.5 plasmid copies/μL (95% CI 2.7-18) for Pow, or 0.1 and 0.8 parasites/μL, respectively, assuming 6 copies of 18s rRNA per genome. However, the assays showed cross-reactivity at concentrations greater than 103 plasmid copies/μL (roughly 200 parasites/μL). Mock mixtures were used to establish criteria for classifying mixed Poc/Pow infections that prevented false-positive detection while maintaining sensitive detection of the minority ovale species down to 100 copies/μL (<1 parasite/μL). When the modified real-time PCR assays were applied to field-collected blood samples from Tanzania and Cameroon, species identification by real-time PCR was concordant with nested PCR in 19 samples, but additionally detected two mixed Poc/Pow infections where nested PCR detected a single Po species. When real-time PCR was applied to oocyst-positive Anopheles midguts saved from mosquitoes fed on P. ovale-infected persons, mixed Poc/Pow infections were detected in 11/14 (79%). Based on these results, 8/9 P. ovale carriers transmitted both P. ovale species to mosquitoes, though both Po species could only be detected in the blood of two carriers. The described real-time PCR approach can be used to identify the natural occurrence of mixed Poc/Pow infections in human and mosquito hosts and reveals that such co-infections and co-transmission are likely more common than appreciated.
Topics: Animals; Humans; Real-Time Polymerase Chain Reaction; Plasmodium ovale; RNA, Ribosomal, 18S; Nucleic Acid Amplification Techniques; Anopheles; Malaria
PubMed: 38064489
DOI: 10.1371/journal.pntd.0011274 -
Parasites & Vectors Jun 2021Recent studies indicate that the prevalence of non-falciparum malaria, including Plasmodium malariae and Plasmodium ovale spp., is increasing, with some complications in... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Recent studies indicate that the prevalence of non-falciparum malaria, including Plasmodium malariae and Plasmodium ovale spp., is increasing, with some complications in infected individuals. The aim of this review is to provide a better understanding of the malaria prevalence and disease burden due to P. malariae and P. ovale spp.
METHODS
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and the Joanna Briggs Institute prevalence study assessment tool were used to select and evaluate the studies, respectively. Six databases: PubMed, WHOLIS, Wiley Library, ScienceDirect, Web of Science and Google Scholar were used to screen articles published during the period January 2000-December 2020. The pooled prevalence estimates for P. malariae and P. ovale spp. were analysed using a random-effects model and the possible sources of heterogeneity were evaluated through subgroup analysis and meta-regression.
RESULTS
Out of the 3297 studies screened, only 113 studies were included; among which 51.33% were from the African Region. The P. malariae and P. ovale spp. pooled prevalence were 2.01% (95% CI 1.31-2.85%) and 0.77% (95% CI 0.50-1.10%) respectively, with the highest prevalence in the African Region. P. malariae was equally distributed among adults (2.13%), children (2.90%) and pregnant women (2.77%) (p = 0.862), whereas P. ovale spp. was more prevalent in pregnant women (2.90%) than in children ≤ 15 years (0.97%) and in patients > 15 years old (0.39%) (p = 0.021). In this review, data analysis revealed that P. malariae and P. ovale spp. have decreased in the last 20 years, but not significantly, and these species were more commonly present with other Plasmodium species as co-infections. No difference in prevalence between symptomatic and asymptomatic patients was observed for either P. malariae or P. ovale spp.
CONCLUSION
Our analysis suggests that knowledge of the worldwide burden of P. malariae and P. ovale spp. is very important for malaria elimination programmes and a particular focus towards improved tools for monitoring transmission for these non-falciparum species should be stressed upon to deal with increased infections in the future.
Topics: Coinfection; Global Health; Humans; Malaria; Plasmodium falciparum; Plasmodium malariae; Plasmodium ovale; Prevalence; Time Factors
PubMed: 34082791
DOI: 10.1186/s13071-021-04797-0 -
Parasitology International Oct 2021The recent World Malaria report shows that progress in malaria elimination has stalled. Current data acquisition by NMCPs depend on passive case detection and clinical...
The recent World Malaria report shows that progress in malaria elimination has stalled. Current data acquisition by NMCPs depend on passive case detection and clinical reports focused mainly on Plasmodium falciparum (Pf). In recent times, several countries in sub-Saharan Africa have reported cases of Plasmodium vivax (Pv) with a considerable number being Duffy negative. The burden of Pv and Plasmodium ovale (Po) appear to be more than acknowledged. Similarly, the contribution of asymptomatic malaria in transmission is hardly considered by NMCPs in Africa. Inclusion of these as targets in malaria elimination agenda is necessary to achieve elimination goal, as these harbor hypnozoites. The Pan African Vivax and Ovale Network (PAVON) is a new consortium of African Scientists working in Africa on the transmission profile of Pv and Po. The group collaborates with African NMCPs to train in Plasmodium molecular diagnostics, microscopy, and interpretation of molecular data from active surveys to translate into policy. Details of the mission, rational and modus operandi of the group are outlined.
Topics: Africa; Asymptomatic Infections; Malaria; Malaria, Vivax; Plasmodium ovale; Plasmodium vivax
PubMed: 34216801
DOI: 10.1016/j.parint.2021.102415 -
The American Journal of Tropical... Nov 2021Plasmodium falciparum and Plasmodium vivax are co-endemic in Ethiopia. This study investigated whether mixed infections were missed by microscopy from a 2017 therapeutic...
Plasmodium falciparum and Plasmodium vivax are co-endemic in Ethiopia. This study investigated whether mixed infections were missed by microscopy from a 2017 therapeutic efficacy study at two health facilities in Ethiopia. All patients (N = 304) were initially classified as having single-species P. falciparum (n = 148 samples) or P. vivax infections (n = 156). Dried blood spots were tested for Plasmodium antigens by bead-based multiplex assay for pan-Plasmodium aldolase, pan-Plasmodium lactate dehydrogenase, P. vivax lactate dehydrogenase, and histidine-rich protein 2. Of 304 blood samples, 13 (4.3%) contained both P. falciparum and P. vivax antigens and were analyzed by polymerase chain reaction for species-specific DNA. Of these 13 samples, five were confirmed by polymerase chain reaction for P. falciparum/P. vivax co-infection. One sample, initially classified as P. vivax by microscopy, was found to only have Plasmodium ovale DNA. Plasmodium falciparum/P. vivax mixed infections can be missed by microscopy even in the context of a therapeutic efficacy study with multiple trained readers.
Topics: Adolescent; Child; Child, Preschool; Coinfection; DNA, Protozoan; Disease Eradication; Ethiopia; Female; Humans; Malaria, Falciparum; Malaria, Vivax; Male; Plasmodium falciparum; Plasmodium vivax; Young Adult
PubMed: 34847530
DOI: 10.4269/ajtmh.21-0796 -
Malaria Journal Jul 2016In an effort to improve surveillance for epidemiological and clinical outcomes, rapid diagnostic tests (RDTs) have become increasingly widespread as cost-effective and...
Low prevalence of Plasmodium malariae and Plasmodium ovale mono-infections among children in the Democratic Republic of the Congo: a population-based, cross-sectional study.
BACKGROUND
In an effort to improve surveillance for epidemiological and clinical outcomes, rapid diagnostic tests (RDTs) have become increasingly widespread as cost-effective and field-ready methods of malaria diagnosis. However, there are concerns that using RDTs specific to Plasmodium falciparum may lead to missed detection of other malaria species such as Plasmodium malariae and Plasmodium ovale.
METHODS
Four hundred and sixty six samples were selected from children under 5 years old in the Democratic Republic of the Congo (DRC) who took part in a Demographic and Health Survey (DHS) in 2013-14. These samples were first tested for all Plasmodium species using an 18S ribosomal RNA-targeted real-time PCR; malaria-positive samples were then tested for P. falciparum, P. malariae and P. ovale using a highly sensitive nested PCR.
RESULTS
The prevalence of P. falciparum, P. malariae and P. ovale were 46.6, 12.9 and 8.3 %, respectively. Most P. malariae and P. ovale infections were co-infected with P. falciparum-the prevalence of mono-infections of these species were only 1.0 and 0.6 %, respectively. Six out of these eight mono-infections were negative by RDT. The prevalence of P. falciparum by the more sensitive nested PCR was higher than that found previously by real-time PCR.
CONCLUSIONS
Plasmodium malariae and P. ovale remain endemic at a low rate in the DRC, but the risk of missing malarial infections of these species due to falciparum-specific RDT use is low. The observed prevalence of P. falciparum is higher with a more sensitive PCR method.
Topics: Adult; Child, Preschool; Cross-Sectional Studies; Democratic Republic of the Congo; Female; Humans; Infant; Infant, Newborn; Malaria; Male; Plasmodium malariae; Plasmodium ovale; Polymerase Chain Reaction; Prevalence; RNA, Protozoan; RNA, Ribosomal, 18S; Real-Time Polymerase Chain Reaction
PubMed: 27392905
DOI: 10.1186/s12936-016-1409-0 -
BioRxiv : the Preprint Server For... Mar 2023and represent distinct non-recombining malaria species that are increasing in prevalence in sub-Saharan Africa. Though they circulate sympatrically, co-infection...
and represent distinct non-recombining malaria species that are increasing in prevalence in sub-Saharan Africa. Though they circulate sympatrically, co-infection within human and mosquito hosts has rarely been described. Separate 18S rRNA real-time PCR assays that detect and were modified to allow species determination in parallel under identical cycling conditions. The lower limit of detection was 0.6 plasmid copies/μL (95% CI 0.4-1.6) for and 4.5 plasmid copies/μL (95% CI( 2.7- 18) for , or 0.1 and 0.8 parasites/μL, respectively, assuming 6 copies of 18s rRNA per genome. However, the assays showed cross-reactivity at concentrations greater than 10 plasmid copies/μL (roughly 200 parasites/μL). Mock mixtures were used to establish criteria for classifying mixed infections that prevented false-positive detection while maintaining sensitive detection of the minority ovale species down to 10° copies/μL (<1 parasite/μL). When the modified real-time PCR assays were applied to field-collected blood samples from Tanzania and Cameroon, species identification by real-time PCR was concordant with nested PCR, but additionally detected two mixed infections where nested PCR detected a single species. When real-time PCR was applied to 14 oocyst-positive midguts saved from mosquitoes fed on -infected persons, mixed infections were detected in 11 (79%). Based on these results, 8/9 carriers transmitted both species to mosquitoes, though both species could only be detected in the blood of two carriers. The described real-time PCR approach can be used to identify the natural occurrence of mixed infections in human and mosquito hosts and reveals that such co-infections and co-transmission are likely more common than appreciated.
PubMed: 37034766
DOI: 10.1101/2023.03.31.535020 -
PLoS Neglected Tropical Diseases May 2019A reduction in the global burden of malaria over the past two decades has encouraged efforts for regional malaria elimination. Despite the need to target all Plasmodium...
A reduction in the global burden of malaria over the past two decades has encouraged efforts for regional malaria elimination. Despite the need to target all Plasmodium species, current focus is mainly directed towards Plasmodium falciparum, and to a lesser extent P. vivax. There is a substantial lack of data on both global and local transmission patterns of the neglected malaria parasites P. malariae and P. ovale spp. We used a species-specific real-time PCR assay targeting the Plasmodium 18s rRNA gene to evaluate temporal trends in the prevalence of all human malaria parasites over a 22-year period in a rural village in Tanzania.We tested 2897 blood samples collected in five cross-sectional surveys conducted between 1994 and 2016. Infections with P. falciparum, P. malariae, and P. ovale spp. were detected throughout the study period, while P. vivax was not detected. Between 1994 and 2010, we found a more than 90% reduction in the odds of infection with all detected species. The odds of P. falciparum infection was further reduced in 2016, while the odds of P. malariae and P. ovale spp. infection increased 2- and 6-fold, respectively, compared to 2010. In 2016, non-falciparum species occurred more often as mono-infections. The results demonstrate the persistent transmission of P. ovale spp., and to a lesser extent P. malariae despite a continued decline in P. falciparum transmission. This illustrates that the transmission patterns of the non-falciparum species do not necessarily follow those of P. falciparum, stressing the need for attention towards non-falciparum malaria in Africa. Malaria elimination will require a better understanding of the epidemiology of P. malariae and P. ovale spp. and improved tools for monitoring the transmission of all Plasmodium species, with a particular focus towards identifying asymptomatic carriers of infection and designing appropriate interventions to enhance malaria control.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Child; Child, Preschool; DNA, Protozoan; Female; Humans; Infant; Malaria; Male; Middle Aged; Plasmodium falciparum; Plasmodium malariae; Plasmodium ovale; Prevalence; RNA, Ribosomal, 18S; Real-Time Polymerase Chain Reaction; Tanzania; Young Adult
PubMed: 31136585
DOI: 10.1371/journal.pntd.0007414 -
Malaria Journal Sep 2016Following initiation of China's National Malaria Elimination Action Plan in 2010, indigenous malaria infections in Jiangsu Province decreased significantly. Meanwhile... (Observational Study)
Observational Study
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.
BACKGROUND
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.
METHODS
An observational study of imported malaria cases in Jiangsu Province, China was carried out for the period of 2011-2014.
RESULTS
A total of 1268 malaria cases were reported in Jiangsu Province from 2011 to 2014. Although imported Plasmodium falciparum cases (n = 1058) accounted for 83.4 % of all reported cases in Jiangsu, P. ovale cases (14, 19, 30, and 46) and their proportion (3.7, 9.6, 8.8, and 13.0 %) of all malaria cases increased over the 4 years. Similarly, P. malariae cases (seven, two, nine, and 10) and proportion (1.9, 1.0, 2.6, and 2.8 %) of all malaria cases increased slightly during this time. A total of 98 cases of Plasmodium ovale curtisi (47/98, 48 %) and Plasmodium ovale wallikeri (51/98, 52 %) were identified as well. Latency periods were significant among these Plasmodium infections (p = 0.00). Also, this study found that the latency periods of P. ovale sp., P. malariae and Plasmodium vivax were significantly longer than P. falciparum. However, for both P. ovale curtisi and P. ovale wallikeri infections, the latency period analysis was not significant (p = 0.81). Misdiagnosis of both P. ovale and P. malariae was greater than 71.5 and 71.4 %, respectively. The P. ovale cases were misdiagnosed as P. falciparum (35 cases, 32.1 %), P. vivax (43 cases, 39.4 %) by lower levels of CDCs or hospitals. And, the P. malariae cases were misdiagnosed as P. falciparum (ten cases, 35.7 %), P. vivax (nine cases, 32.1 %) and P. ovale sp. (one case, 3.6 %). Geographic distribution of imported P. ovale sp. and P. malariae cases in Jiangsu Province mainly originated from sub-Saharan Africa such as Equatorial Guinea, Nigeria, and Angola.
CONCLUSIONS
Although the vast majority of imported malaria cases were due to P. falciparum, the increase in other rare Plasmodium species originating from sub-Saharan Africa and Southeast Asia should be closely monitored at all levels of health providers focusing on diagnosis and treatment of malaria. In addition to a receptive vector environment, long latency periods and misdiagnosis of P. malariae and P. ovale sp. increase the risk of re-introduction of malaria in China.
Topics: Adult; China; Disease Eradication; Disease Transmission, Infectious; Female; Humans; Incidence; Malaria; Male; Middle Aged; Plasmodium; Travel; Young Adult
PubMed: 27604629
DOI: 10.1186/s12936-016-1504-2 -
Rhode Island Medical Journal (2013) Aug 2020We report two cases of malaria diagnosed in Rhode Island. First, a 21-year-old female who presented with 5 days of fevers, chills, headache, and myalgias after returning...
We report two cases of malaria diagnosed in Rhode Island. First, a 21-year-old female who presented with 5 days of fevers, chills, headache, and myalgias after returning from a trip to Liberia, found to have uncomplicated malaria due to P. ovale which was treated successfully with atovaquone/proguanil and primaquine. Second, a chronically ill 55-year-old male presented with 3 days of headache followed by altered mental status, fever, and new-onset seizures after a recent visit to Sierra Leone, found to have P. falciparum malaria requiring ICU admission and IV artesunate treatment. The diagnosis and management of malaria in the United States (US), as well as its rare association with subdural hemorrhage are subsequently reviewed.
Topics: Antimalarials; Female; Fever; Humans; Liberia; Malaria, Cerebral; Malaria, Falciparum; Male; Middle Aged; Plasmodium falciparum; Plasmodium ovale; Rhode Island; Sierra Leone; Travel; Young Adult
PubMed: 32752571
DOI: No ID Found -
Journal of Clinical Microbiology Feb 2014Recent molecular studies indicate that Plasmodium ovale malaria is caused by two closely related species of protozoan parasites, thereby imposing new challenges for... (Review)
Review
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 widely used NP-1993 to NP-2005 (SSU rRNA) protocols for all human malaria parasites is discussed.
Topics: Humans; Malaria; Molecular Diagnostic Techniques; Parasitology; Plasmodium ovale
PubMed: 24478466
DOI: 10.1128/JCM.02760-13