RESUMEN
Introduction: Plasmodium malariae is the most common non-falciparum species in sub-Saharan Africa. Despite this, data on its genetic diversity is scarce. Therefore, we aimed to establish a P. malariae genotyping approach based on size polymorphic regions that can be easily applied in molecular epidemiological studies. Methods: Four potential genotyping markers, Pm02, Pm09, P. malariae thrombospondin-related anonymous protein (pmtrap), and P. malariae merozoite surface protein fragment 2 (pmmsp1 F2) were amplified via nested PCR and analysed using automated capillary gel electrophoresis. Results: We observed the highest allelic diversity for pmtrap (MOI = 1.61) and pmmsp1 F2 (He = 0.81). Further applying the two markers pmtrap and pmmsp1 F2 on a different sample set of 21 P. malariae positive individuals followed up over one week, we saw a high consistency in their performance. The results show a large complexity and high dynamics of P. malariae infections in the asymptomatic Gabonese study population. Discussion: We successfully implemented a new genotyping panel for P. malariae consisting of only two markers: pmtrap and pmmsp1 F2. It can be easily applied in other settings to investigate the genotype diversity of P. malariae populations, providing further important data on the molecular epidemiology of this parasite species.
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Variación Genética , Genotipo , Malaria , Epidemiología Molecular , Plasmodium malariae , Proteínas Protozoarias , Plasmodium malariae/genética , Plasmodium malariae/aislamiento & purificación , Humanos , Malaria/epidemiología , Malaria/parasitología , Epidemiología Molecular/métodos , África del Sur del Sahara/epidemiología , Proteínas Protozoarias/genética , Técnicas de Genotipaje/métodos , Reacción en Cadena de la Polimerasa/métodos , ADN Protozoario/genética , Alelos , Gabón/epidemiología , Marcadores GenéticosRESUMEN
INTRODUCTION: According to the World Health Organization, Microscopy is the gold standard for diagnosing malaria. However, the performance of this examination depends on the experience of the microscopist and the level of parasitemia. Thus, molecular biology detection of malaria could be an alternative technique. AIM: evaluate the contribution of molecular biology in detecting imported malaria. METHODS: This was a descriptive, prospective study, including all students, from the Monastir region, and foreigners, from countries endemic to malaria. The study period was from September 2020 to April 2021. Each subject was screened for malaria by three methods: direct microscopic detection of Plasmodium, detection of plasmodial antigens, and detection of plasmodial DNA by nested PCR. RESULTS: Among the 127 subjects screened, only one had a positive microscopic examination for Plasmodium falciparum. Among the 126 subjects with a negative microscopic examination, twelve students had a positive nested PCR result, i.e. 9.5%. Molecular sequencing allowed the identification of ten isolates of Plasmodium falciparum, one Plasmodium malariae and one Plasmodium ovale. Our study showed that the results of nested PCR agreed with those of microscopy in 90.6% of cases. CONCLUSION: Nested PCR seems more sensitive for the detection of low parasitemias. Hence the importance of including molecular biology as a malaria screening tool to ensure better detection of imported cases.
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Malaria , Reacción en Cadena de la Polimerasa , Humanos , Reacción en Cadena de la Polimerasa/métodos , Malaria/diagnóstico , Estudios Prospectivos , Femenino , Masculino , Adulto Joven , Adulto , Tamizaje Masivo/métodos , Tamizaje Masivo/normas , Plasmodium falciparum/aislamiento & purificación , Plasmodium falciparum/genética , Microscopía/métodos , Biología Molecular/métodos , Adolescente , Parasitemia/diagnóstico , Enfermedades Transmisibles Importadas/diagnóstico , Enfermedades Transmisibles Importadas/epidemiología , Enfermedades Transmisibles Importadas/parasitología , Túnez/epidemiología , Sensibilidad y Especificidad , ADN Protozoario/análisis , Plasmodium/aislamiento & purificación , Plasmodium/genética , Plasmodium malariae/aislamiento & purificación , Plasmodium malariae/genéticaRESUMEN
BACKGROUND: Plasmodium falciparum is the dominant malaria species in the sub-Saharan Africa and the main cause of severe disease and death. Notwithstanding, severe malaria and death due to non-falciparum infections have been reported, but at much lower rates than P. falciparum infections. Following increasing use of molecular detection techniques in epidemiological studies, a higher prevalence of non-falciparum species has been reported in the region than previously thought. This article reviews the literature on the prevalence of non-falciparum malaria species in Uganda and the clinical figures of their severe diseases. It aims to elucidate the extent to which mono non-falciparum malaria infections in a highly malaria-endemic country contribute to malaria mortality and outline its policy implications on malaria case management. METHODS: The available English-language published peer-reviewed literature up to March 2024 was sought via PubMed and Google Scholar. The keywords used were severe malaria, AND P. falciparum, P. malariae, P. vivax, P. ovale spp., mixed infections AND Uganda. The review encompassed 53 articles. Articles using molecular diagnosis methods were accounted for analysis. RESULTS: The literature reported a substantial prevalence of non-falciparum infections in Uganda. Plasmodium malariae and Plasmodium ovale spp. were the second and third most prevalent reported malaria species respectively after P. falciparum as dominant species. Non-falciparum malaria infections often occur as mixed infections rather than mono-infections. Besides, molecular diagnostics revealed that 21% of initially reported mono-infections of P. falciparum were, in fact, mixed infections. No article was found on the prevalence of severe malaria or case fatality rate due to mixed or non-falciparum infections. CONCLUSION: A critical knowledge gap exists regarding the impact of mixed and non-falciparum species on severe malaria and death in Uganda. Robust evidence on prevalence, recurrent parasitaemia, and severe clinical manifestations of mixed and non-falciparum malaria infections is crucial for evidence-based and effective policymaking regarding malaria case management.
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Malaria , Uganda/epidemiología , Humanos , Malaria/epidemiología , Malaria/parasitología , Prevalencia , Plasmodium ovale/aislamiento & purificación , Plasmodium malariae/aislamiento & purificaciónRESUMEN
Malaria-causing protozoa of the genus Plasmodium have exerted one of the strongest selective pressures on the human genome, and resistance alleles provide biomolecular footprints that outline the historical reach of these species1. Nevertheless, debate persists over when and how malaria parasites emerged as human pathogens and spread around the globe1,2. To address these questions, we generated high-coverage ancient mitochondrial and nuclear genome-wide data from P. falciparum, P. vivax and P. malariae from 16 countries spanning around 5,500 years of human history. We identified P. vivax and P. falciparum across geographically disparate regions of Eurasia from as early as the fourth and first millennia BCE, respectively; for P. vivax, this evidence pre-dates textual references by several millennia3. Genomic analysis supports distinct disease histories for P. falciparum and P. vivax in the Americas: similarities between now-eliminated European and peri-contact South American strains indicate that European colonizers were the source of American P. vivax, whereas the trans-Atlantic slave trade probably introduced P. falciparum into the Americas. Our data underscore the role of cross-cultural contacts in the dissemination of malaria, laying the biomolecular foundation for future palaeo-epidemiological research into the impact of Plasmodium parasites on human history. Finally, our unexpected discovery of P. falciparum in the high-altitude Himalayas provides a rare case study in which individual mobility can be inferred from infection status, adding to our knowledge of cross-cultural connectivity in the region nearly three millennia ago.
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ADN Antiguo , Genoma Mitocondrial , Genoma de Protozoos , Malaria , Plasmodium , Femenino , Humanos , Masculino , Altitud , Américas/epidemiología , Asia/epidemiología , Evolución Biológica , Resistencia a la Enfermedad/genética , ADN Antiguo/análisis , Europa (Continente)/epidemiología , Genoma Mitocondrial/genética , Genoma de Protozoos/genética , Historia Antigua , Malaria/parasitología , Malaria/historia , Malaria/transmisión , Malaria/epidemiología , Malaria Falciparum/epidemiología , Malaria Falciparum/historia , Malaria Falciparum/parasitología , Malaria Falciparum/transmisión , Malaria Vivax/epidemiología , Malaria Vivax/historia , Malaria Vivax/parasitología , Malaria Vivax/transmisión , Plasmodium/genética , Plasmodium/clasificación , Plasmodium falciparum/genética , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/genética , Plasmodium malariae/aislamiento & purificación , Plasmodium vivax/genética , Plasmodium vivax/aislamiento & purificaciónRESUMEN
BACKGROUND: Surveillance programmes often use malaria rapid diagnostic tests (RDTs) to determine the proportion of the population carrying parasites in their peripheral blood to assess the malaria transmission intensity. Despite an increasing number of reports on false-negative and false-positive RDT results, there is a lack of systematic quality control activities for RDTs deployed in malaria surveillance programmes. METHODS: The diagnostic performance of field-deployed RDTs used for malaria surveys was assessed by retrospective molecular analysis of the blood retained on the tests. RESULTS: Of the 2865 RDTs that were collected in 2018 on Bioko Island and analysed in this study, 4.7% had a false-negative result. These false-negative RDTs were associated with low parasite density infections. In 16.6% of analysed samples, masked pfhrp2 and pfhrp3 gene deletions were identified, in which at least one Plasmodium falciparum strain carried a gene deletion. Among all positive RDTs analysed, 28.4% were tested negative by qPCR and therefore considered to be false-positive. Analysing the questionnaire data collected from the participants, this high proportion of false-positive RDTs could be explained by P. falciparum histidine rich protein 2 (PfHRP2) antigen persistence after recent malaria treatment. CONCLUSION: Malaria surveillance depending solely on RDTs needs well-integrated quality control procedures to assess the extent and impact of reduced sensitivity and specificity of RDTs on malaria control programmes.
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Antígenos de Protozoos/análisis , Coinfección/diagnóstico , Pruebas Diagnósticas de Rutina/estadística & datos numéricos , Malaria/diagnóstico , Vigilancia de la Población , Proteínas Protozoarias/análisis , Coinfección/epidemiología , Guinea Ecuatorial/epidemiología , Reacciones Falso Positivas , Incidencia , Malaria/epidemiología , Malaria Falciparum/diagnóstico , Malaria Falciparum/epidemiología , Ácidos Nucleicos/análisis , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/aislamiento & purificación , Plasmodium ovale/aislamiento & purificación , Estudios RetrospectivosRESUMEN
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 parasitemiasâ ≤â 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.
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Malaria/epidemiología , Plasmodium malariae/aislamiento & purificación , Plasmodium ovale/aislamiento & purificación , Plasmodium vivax/aislamiento & purificación , Adolescente , Adulto , Femenino , Humanos , Malaria/diagnóstico , Malaria Vivax/epidemiología , Malaui/epidemiología , Masculino , Plasmodium malariae/genética , Plasmodium ovale/genética , Plasmodium vivax/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Adulto JovenRESUMEN
BACKGROUND: Information on the foci of Plasmodium species infections is essential for any country heading towards elimination. Odisha, one of the malaria-endemic states of India is targeting elimination of malaria by 2030. To support decision-making regarding targeted intervention, the distribution of Plasmodium species infections was investigated in hard-to-reach areas where a special malaria elimination drive, namely Durgama Anchalare Malaria Nirakaran (DAMaN) began in 2017. METHODS: A cross-sectional survey was conducted in 2228 households during July to November 2019 in six districts, to evaluate the occurrence of Plasmodium species. The species were identified by polymerase chain reaction (PCR) followed by sequencing, in case of Plasmodium ovale. RESULTS: Of the 3557 blood specimens tested, malaria infection was detected in 282 (7.8%) specimens by PCR. Of the total positive samples, 14.1% were P. ovale spp. and 10.3% were Plasmodium malariae infections. The majority of P. ovale spp. (75.8%) infections were mixed with either Plasmodium falciparum and/or Plasmodium vivax and found to be distributed in three geophysical regions (Northern-plateau, Central Tableland and Eastern Ghat) of the State, while P. malariae has been found in Northern-plateau and Eastern Ghat regions. Speciation revealed occurrence of both Plasmodium ovale curtisi (classic type) and Plasmodium ovale wallikeri (variant type). CONCLUSIONS: In the present study a considerable number of P. ovale spp. and P. malariae were detected in a wide geographical areas of Odisha State, which contributes around 40% of the country's total malaria burden. For successful elimination of malaria within the framework of national programme, P. ovale spp. along with P. malariae needs to be incorporated in surveillance system, especially when P. falciparum and P. vivax spp. are in rapid decline.
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Erradicación de la Enfermedad/estadística & datos numéricos , Malaria/epidemiología , Enfermedades Desatendidas/epidemiología , Plasmodium malariae/aislamiento & purificación , Plasmodium ovale/aislamiento & purificación , Humanos , India/epidemiología , Malaria/parasitología , Enfermedades Desatendidas/parasitología , PrevalenciaRESUMEN
Plasmodium malariae infections are often asymptomatic and long-lasting. Mixed infections are often underdetected in areas where P. malariae, P. vivax, and P. falciparum are coendemic. In this study, we described the occurrence of these species circulating as single or mixed infections in Pará state, Brazil, in the Amazon region, with the purpose of clarifying the impact of misidentification of parasite species based only on morphological description using thick blood smear. By using real-time polymerase chain reaction based on the amplification of the mitochondrial DNA, we detected a prevalence of 46% (58/126) mixed infections with 33.3% P. malariae/P. vivax which were read as P. vivax monoinfections by microscopy detection. Our findings confirmed the high circulation of P. malariae in a malaria endemic area in the Brazilian Amazon region.
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Coinfección/diagnóstico , Coinfección/epidemiología , Malaria/diagnóstico , Malaria/epidemiología , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/aislamiento & purificación , Plasmodium vivax/aislamiento & purificación , Brasil/epidemiología , Enfermedades Endémicas , Humanos , PrevalenciaRESUMEN
BACKGROUND: Malaria control and elimination strategies are based on levels of transmission that are usually determined by data collected from health facilities. In endemic areas, asymptomatic Plasmodium infection is thought to represent the majority of infections, though they are not diagnosed nor treated. Therefore, there might be an underestimation of the malaria reservoir, resulting in inadequate control strategies. In addition, these untreated asymptomatic Plasmodium infections maintain transmission, making it difficult or impossible to reach malaria elimination goals. Thus, the aim of this study was to determine the prevalence of asymptomatic Plasmodium infections in southeastern Senegal. METHODS: A cross sectional study was conducted among asymptomatic individuals (N = 122) living in the village of Andiel located in Bandafassi, Kédougou, which consisted of about 200 inhabitants during the malaria transmission season in late October 2019. For each individual without malaria-related symptoms and who consented to participate, a rapid diagnostic test (RDT) was performed in the field. Results were confirmed in the laboratory with photo-induced electron transfer (PET-PCR). RESULTS: Malaria prevalence was 70.3% by PET-PCR and 41.8% by RDT. During the same period, the health post of the area reported 49. 1% test positivity rate by RDT. The majority of the infected study population, 92.9%, was infected with a single species and 7.1% had two or three species of Plasmodium. Plasmodium falciparum was predominant and represented 90.2% of the infections, while 6.5% were due to Plasmodium ovale and 3.3% to Plasmodium malariae. 59.4% of children targeted for SMC (zero to ten years old) were infected. CONCLUSION: In southeastern Senegal, where the transmission is the highest, malaria control strategies should address asymptomatic Plasmodium infections at the community level. The results suggest that this area could be eligible for mass drug administration. Moreover, non-falciparum species could be more common and its prevalence should be determined countrywide.
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Infecciones Asintomáticas/epidemiología , Malaria/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Humanos , Lactante , Malaria/parasitología , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Malaria Vivax/epidemiología , Malaria Vivax/parasitología , Masculino , Persona de Mediana Edad , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/aislamiento & purificación , Plasmodium ovale/aislamiento & purificación , Plasmodium vivax/aislamiento & purificación , Prevalencia , Senegal/epidemiología , Adulto JovenRESUMEN
BACKGROUND: Plasmodium knowlesi is recognized as the fifth Plasmodium species causing malaria in humans. It is morphologically similar to the human malaria parasite Plasmodium malariae, so molecular detection should be used to clearly discriminate between these Plasmodium species. This study aimed to quantify the rate at which P. knowlesi is misidentified as P. malariae by microscopy in endemic and non-endemic areas. METHODS: The protocol of this systematic review was registered in the PROSPERO International Prospective Register of Systematic Reviews (ID = CRD42020204770). Studies reporting the misidentification of P. knowlesi as P. malariae by microscopy and confirmation of this by molecular methods in MEDLINE, Web of Science and Scopus were reviewed. The risk of bias in the included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS). The pooled prevalence and 95% confidence interval (CI) of the misidentification of P. knowlesi as P. malariae by microscopy were estimated using a random effects model. Subgroup analysis of the study sites was performed to demonstrate any differences in the misidentification rates in different areas. Heterogeneity across the included studies was assessed and quantified using Cochran's Q and I2 statistics, respectively. Publication bias in the included studies was assessed using the funnel plot, Egger's test and contour-enhanced funnel plot. RESULTS: Among 375 reviewed studies, 11 studies with a total of 1569 confirmed P. knowlesi cases in humans were included. Overall, the pooled prevalence of the misidentification of P. knowlesi as P. malariae by microscopy was estimated at 57% (95% CI 37-77%, I2: 99.3%). Subgroup analysis demonstrated the highest rate of misidentification in Sawarak, Malaysia (87%, 95% CI 83-90%, I2: 95%), followed by Sabah, Malaysia (85%, 95% CI 79-92%, I2: 85.1%), Indonesia (16%, 95% CI 6-38%), and then Thailand (4%, 95% CI 2-9%, I2: 95%). CONCLUSION: Although the World Health Organization (WHO) recommends that all P. malariae-positive diagnoses made by microscopy in P. knowlesi endemic areas be reported as P. malariae/P. knowlesi malaria, the possibility of microscopists misidentifying P. knowlesi as P. malariae is a diagnostic challenge. The use of molecular techniques in cases with malariae-like Plasmodium with high parasite density as determined by microscopy could help identify human P. knowlesi cases in non-endemic countries.
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Malaria/clasificación , Plasmodium knowlesi/aislamiento & purificación , Plasmodium malariae/aislamiento & purificación , Humanos , Malaria/diagnóstico , Malaria/epidemiología , Microscopía , PrevalenciaRESUMEN
The impact of different types of reactive case detection and/or treatment strategies for malaria elimination depends on high coverage and participants' adherence. However, strategies to optimise adherence are limited, particularly for people with asymptomatic or no infections. As part of a cluster-randomized trial to evaluate the effect of reactive treatment in The Gambia, all residents in the compound of a diagnosed clinical malaria patient received dihydro-artemisinin-piperaquine (DP). Using a mixed method approach, we assessed which factors contribute to adherence among the contacts of malaria cases that showed no symptoms. Adherence was defined as the proportion of compound members that (1) returned all medicine bags empty and (2) self-reported (3-day) treatment completion. Among the 273 individuals from 14 compounds who received DP, 227 (83.1%) were available for and willing to participate in the survey; 85.3% (233/273) returned empty medicine bags and 91.6% (208/227) self-reported treatment completion. Although clinical malaria was not considered a major health problem, reported adherence was high. The drivers of adherence were the strong sense of responsibility towards protecting the individual, compound and the village. Adherence can be optimised through a transdisciplinary implementation research process of engaging communities to bridge the gap between research goals and social realities.
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Artemisininas/uso terapéutico , Infecciones Asintomáticas/terapia , Malaria/tratamiento farmacológico , Cumplimiento de la Medicación/psicología , Quinolinas/uso terapéutico , Adolescente , Adulto , Antimaláricos/uso terapéutico , Infecciones Asintomáticas/epidemiología , Infecciones Asintomáticas/psicología , Niño , Preescolar , Femenino , Gambia/epidemiología , Humanos , Lactante , Recién Nacido , Malaria/diagnóstico , Malaria/epidemiología , Malaria/psicología , Masculino , Cooperación del Paciente/psicología , Plasmodium malariae/aislamiento & purificación , Adulto JovenRESUMEN
Malaria is an infectious vector-borne disease with other important routes of transmission, such as blood transfusion and organ/tissue transplantation, due to asymptomatic reservoirs of Plasmodium presenting with low parasitemia. Reports of transfusion-transmitted malaria have shown that in immunosuppressed recipients, infections can be fatal if they are not diagnosed and timely treated. All Plasmodium species can survive on blood components at temperatures from 2 to 6 °C for some days or even weeks. This report describes two candidates for blood donation harboring Plasmodium, infected in an area considered non-endemic. Blood samples were collected from donors who attended a blood bank in Sao Paulo and tested by microscopy, qPCR for Plasmodium genus-specific amplification, targeting the parasite 18S ribosomal subunit gene and a multiplex qPCR based on mtDNA of the five species. Under microscopy, only structures resembling Plasmodium were observed. The qPCR whose standard curve tested parasites varying from 2 to 0.1 parasites/ µL, showed the presence of Plasmodium DNA in the two blood donors, as did the multiplex qPCR that revealed the presence of P. malariae. The prevalence of positive donors varies according to the level of transmission, ranging from 0.7 to 55% in endemic areas. In non-endemic regions, prevalences are lower, however, transfusion malaria can evolve to severe cases, due to the lack of suspicion of this transmission route. Asymptomatic donors from low transmission regions pose a risk to blood banks, with particular emphasis on those located in areas with malaria elimination goals.
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Anticuerpos Antiprotozoarios/sangre , Malaria/sangre , Plasmodium malariae/aislamiento & purificación , Adulto , Donantes de Sangre , Femenino , Humanos , Malaria/diagnóstico , Malaria/parasitología , Masculino , Reacción en Cadena de la Polimerasa Multiplex , Parasitemia , Plasmodium malariae/genéticaRESUMEN
BACKGROUND: Imported malaria is a major challenge for countries that are in malaria elimination stage such as Zambia. Legitimate cross-border activities add to the risk of transmission, necessitating determination of prevalence, characteristics and risk factors of imported and local malaria. METHODS: This cross-sectional study was conducted in 103 consented child and adult patients with clinical malaria symptoms, from selected health facilities in north-western Zambia. Patient demographic data and blood samples for malaria microscopy and full blood count were obtained. Chi-square and penalized logistic regression were performed to describe the characteristics and assess the risk factors of imported and local malaria in North-Western Province. RESULTS: Overall, malaria prevalence was 78.6% with 93.8% Plasmodium falciparum and 6.2% other species. The local cases were 72 (88.9%) while the imported were 9 (11.1%) out of the 81 positive participants. About 98.6% of the local cases were P. falciparum compared to 55.6% (χ2 = 52.4; p < 0.01) P. falciparum among the imported cases. Among the imported cases, 44% were species other than P. falciparum (χ2 = 48; p < 0.01) while among the local cases only 1.4% were. Gametocytes were present in 44% of the imported malaria cases and only in 2.8% of the local cases (χ2 = 48; p < 0.01). About 48.6% of local participants had severe anaemia compared to 33.3% of participants from the two neighbouring countries who had (χ2 = 4.9; p = 0.03). In the final model, only country of residence related positively to presence of species other than P. falciparum (OR = 39.0, CI [5.9, 445.9]; p < 0.01) and presence of gametocytes (OR = 23.1, CI [4.2, 161.6]; p < 0.01). CONCLUSION: Malaria prevalence in North-Western Province is high, with P. falciparum as the predominant species although importation of Plasmodium ovale and Plasmodium malariae is happening as well. Country of residence of patients is a major risk factor for malaria species and gametocyte presence. The need for enhanced malaria control with specific focus on border controls to detect and treat, for specific diagnosis and treatment according to species obtaining, for further research in the role of species and gametocytaemia in imported malaria, cannot be overemphasized.
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Enfermedades Transmisibles Importadas/epidemiología , Malaria Falciparum/epidemiología , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/aislamiento & purificación , Plasmodium ovale/aislamiento & purificación , Adolescente , Adulto , Anciano , Niño , Preescolar , Estudios Transversales , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Prevalencia , Factores de Riesgo , Adulto Joven , Zambia/epidemiologíaRESUMEN
BACKGROUND: Ghana is among the high-burden countries for malaria infections and recently reported a notable increase in malaria cases. While asymptomatic parasitaemia is increasingly recognized as a hurdle for malaria elimination, studies on asymptomatic malaria are scarce, and usually focus on children and on non-falciparum species. The present study aims to assess the prevalence of asymptomatic Plasmodium falciparum and non-falciparum infections in Ghanaian adults in the Ashanti region during the high transmission season. METHODS: Asymptomatic adult residents from five villages in the Ashanti Region, Ghana, were screened for Plasmodium species by rapid diagnostic test (RDT) and polymerase chain reaction (PCR) during the rainy season. Samples tested positive were subtyped using species-specific real-time PCR. For all Plasmodium ovale infections additional sub-species identification was performed. RESULTS: Molecular prevalence of asymptomatic Plasmodium infection was 284/391 (73%); only 126 (32%) infections were detected by RDT. While 266 (68%) participants were infected with Plasmodium falciparum, 33 (8%) were infected with Plasmodium malariae and 34 (9%) with P. ovale. The sub-species P. ovale curtisi and P. ovale wallikeri were identified to similar proportions. Non-falciparum infections usually presented as mixed infections with P. falciparum. CONCLUSIONS: Most adult residents in the Ghanaian forest zone are asymptomatic Plasmodium carriers. The high Plasmodium prevalence not detected by RDT in adults highlights that malaria eradication efforts must target all members of the population. Beneath Plasmodium falciparum, screening and treatment must also include infections with P. malariae, P. o. curtisi and P. o. wallikeri.
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Malaria/epidemiología , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/aislamiento & purificación , Plasmodium ovale/aislamiento & purificación , Adulto , Infecciones Asintomáticas/epidemiología , Pruebas Diagnósticas de Rutina , Femenino , Ghana/epidemiología , Humanos , Malaria Falciparum/epidemiología , Masculino , Persona de Mediana Edad , Prevalencia , Reacción en Cadena en Tiempo Real de la Polimerasa , Adulto JovenRESUMEN
BACKGROUND: The monkey parasite Plasmodium knowlesi is an emerging public health issue in Southeast Asia. In Sabah, Malaysia, P. knowlesi is now the dominant cause of human malaria. Molecular detection methods for P. knowlesi are essential for accurate diagnosis and in monitoring progress towards malaria elimination of other Plasmodium species. However, recent commercially available PCR malaria kits have unpublished P. knowlesi gene targets or have not been evaluated against clinical samples. METHODS: Two real-time PCR methods currently used in Sabah for confirmatory malaria diagnosis and surveillance reporting were evaluated: the QuantiFast™ Multiplex PCR kit (Qiagen, Germany) targeting the P. knowlesi 18S SSU rRNA; and the abTES™ Malaria 5 qPCR II kit (AITbiotech, Singapore), with an undisclosed P. knowlesi gene target. Diagnostic accuracy was evaluated using 52 P. knowlesi, 25 Plasmodium vivax, 21 Plasmodium falciparum, and 10 Plasmodium malariae clinical isolates, and 26 malaria negative controls, and compared against a validated reference nested PCR assay. The limit of detection (LOD) for each PCR method and Plasmodium species was also evaluated. RESULTS: The sensitivity of the QuantiFast™ and abTES™ assays for detecting P. knowlesi was comparable at 98.1% (95% CI 89.7-100) and 100% (95% CI 93.2-100), respectively. Specificity of the QuantiFast™ and abTES™ for P. knowlesi was high at 98.8% (95% CI 93.4-100) for both assays. The QuantiFast™ assay demonstrated falsely-positive mixed Plasmodium species at low parasitaemias in both the primary and LOD analysis. Diagnostic accuracy of both PCR kits for detecting P. vivax, P. falciparum, and P. malariae was comparable to P. knowlesi. The abTES™ assay demonstrated a lower LOD for P. knowlesi of ≤ 0.125 parasites/µL compared to QuantiFast™ with a LOD of 20 parasites/µL. Hospital microscopy demonstrated a sensitivity of 78.8% (95% CI 65.3-88.9) and specificity of 80.4% (95% CI 67.6-89.8) compared to reference PCR for detecting P. knowlesi. CONCLUSION: The QuantiFast™ and abTES™ commercial PCR kits performed well for the accurate detection of P. knowlesi infections. Although the QuantiFast™ kit is cheaper, the abTES™ kit demonstrated a lower LOD, supporting its use as a second-line referral-laboratory diagnostic tool in Sabah, Malaysia.
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Pruebas Diagnósticas de Rutina/estadística & datos numéricos , Monitoreo Epidemiológico , Plasmodium knowlesi/aislamiento & purificación , Reacción en Cadena en Tiempo Real de la Polimerasa/estadística & datos numéricos , Adolescente , Adulto , Niño , Femenino , Humanos , Malasia/epidemiología , Masculino , Persona de Mediana Edad , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/aislamiento & purificación , Plasmodium vivax/aislamiento & purificación , Adulto JovenRESUMEN
BACKGROUND: There have been an increasing number of imported cases of malaria in Hubei Province in recent years. In particular, the number of cases of Plasmodium ovale spp. and Plasmodium malariae significantly increased, which resulted in increased risks during the malaria elimination phase. The purpose of this study was to acquire a better understanding of the epidemiological characteristics of P. ovale spp. and P. malariae imported to Hubei Province, China, so as to improve case management. METHODS: Data on all malaria cases from January 2014 to December 2018 in Hubei Province were extracted from the China national diseases surveillance information system (CNDSIS). This descriptive study was conducted to analyse the prevalence trends, latency periods, interval from onset of illness to diagnosis, and misdiagnosis of cases of P. ovale spp. and P. malariae malaria. RESULTS: During this period, 634 imported malaria cases were reported, of which 87 P. ovale spp. (61 P. ovale curtisi and 26 P. ovale wallikeri) and 18 P. malariae cases were confirmed. The latency periods of P. ovale spp., P. malariae, Plasmodium vivax, and Plasmodium falciparum differed significantly, whereas those of P. ovale curtisi and P. ovale wallikeri were no significant difference. The proportion of correct diagnosis of P. ovale spp. and P. malariae malaria cases were 48.3% and 44.4%, respectively, in the hospital or lower-level Centers for Disease Control and Prevention (CDC). In the Provincial Reference Laboratory, the sensitivity of microscopy and rapid diagnostic tests was 94.3% and 70.1%, respectively, for detecting P. ovale spp., and 88.9% and 38.9%, respectively, for detecting P. malariae. Overall, 97.7% (85/87) of P. ovale spp. cases and 94.4% (17/18) of P. malariae cases originated from Africa. CONCLUSION: The increase in the number of imported P. ovale spp. and P. malariae cases, long latency periods, and misdiagnosis pose a challenge to this region. Therefore, more attention should be paid to surveillance of imported cases of P. ovale spp. and P. malariae infection to reduce the burden of public health and potential risk of malaria.
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Enfermedades Transmisibles Importadas/epidemiología , Errores Diagnósticos/estadística & datos numéricos , Infección Latente/diagnóstico , Malaria , Plasmodium malariae/aislamiento & purificación , Plasmodium ovale/aislamiento & purificación , China/epidemiología , Infección Latente/epidemiología , Malaria/diagnóstico , Malaria/epidemiología , Malaria/transmisión , PrevalenciaRESUMEN
BACKGROUND: Several refugee settlements in Bangladesh have provided housing and medical care for the forcibly-displaced Myanmar nationals (FDMN, also known as Rohingya) population. The identification of malaria infection status in the refugee settlements is useful in treating infected persons and in developing malaria prevention recommendations. Assays for Plasmodium antigens and human IgG against Plasmodium parasites can be used as indicators to determine malaria infection status and exposure. METHODS: Dried blood spot (DBS) samples (N = 1239) from a household survey performed April-May 2018 in three settlements in Cox's Bazar district, Bangladesh were utilized for a sample population of children from ages 1-14 years of age. The samples were tested using a bead-based multiplex antigen assay for presence of the pan-Plasmodium antigen aldolase as well as Plasmodium falciparum histidine rich protein 2 (HRP2). A bead-based multiplex assay was also used to measure human IgG antibody response to P. falciparum, Plasmodium malariae, and Plasmodium vivax merozoite surface protein 1 antigen (MSP1) isoforms, and P. falciparum antigens LSA1, CSP, and GLURP-R0. RESULTS: There were no detectable Plasmodium antigens in any samples, suggesting no active malaria parasite infections in the tested children. IgG seroprevalence was highest to P. vivax (3.1%), but this was not significantly different from the percentages of children antibody responses to P. falciparum (2.1%) and P. malariae (1.8%). The likelihood of an anti-Plasmodium IgG response increased with age for all three malaria species. Evidence of exposure to any malaria species was highest for children residing 8-10 months in the settlements, and was lower for children arriving before and after this period of time. CONCLUSIONS: Absence of Plasmodium antigen in this population provides evidence that children in these three Bangladeshi refugee settlements did not have malaria at time of sampling. Higher rates of anti-malarial IgG carriage from children who were leaving Myanmar during the malaria high-transmission season indicate these migrant populations were likely at increased risk of malaria exposure during their transit.
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Anticuerpos Antiprotozoarios/aislamiento & purificación , Antígenos de Protozoos/aislamiento & purificación , Fructosa-Bifosfato Aldolasa/aislamiento & purificación , Inmunoglobulina G/aislamiento & purificación , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/aislamiento & purificación , Plasmodium vivax/aislamiento & purificación , Proteínas Protozoarias/aislamiento & purificación , Adolescente , Bangladesh/epidemiología , Niño , Preescolar , Etnicidad/estadística & datos numéricos , Humanos , Lactante , Malaria/epidemiología , Mianmar/etnología , Prevalencia , Refugiados/estadística & datos numéricos , Estudios SeroepidemiológicosRESUMEN
BACKGROUND: Malaria remains a leading transfusion associated infectious risk in endemic areas. However, the prevalence of malaria parasitemia has not been well characterized in blood donor populations. This study sought to determine the prevalence of Plasmodium in red blood cell (RBC) and whole blood (WB) units after the rainy season in Uganda. METHODS AND MATERIALS: Between May and July 2018, blood was collected from the sample diversion pouch of 1000 WB donors in Kampala and Jinja, Uganda. The RBC pellet from ethylenediamine tetraacetic acid (EDTA) anticoagulated blood was stored at -80°C until testing. DNA was extracted and nested PCR was used to screen samples at the genus level for Plasmodium, with positive samples further tested for species identification. RESULTS: Malaria parasitemia among asymptomatic, eligible blood donors in two regions of Uganda was 15.4%; 87.7% (135/154) of infections were with P. falciparum, while P. malariae and P. ovale were also detected. There were 4.3% of blood donors who had mixed infection with multiple species. Older donors (>30 years vs. 17-19 years; aPR = 0.31 [95% CI = 0.17-0.58]), females (aPR = 0.60 [95% CI = 0.42-0.87]), repeat donors (aPR = 0.44 [95% CI = 0.27-0.72]) and those donating near the capital city of Kampala versus rural Jinja region (aPR = 0.49 [95% CI = 0.34-0.69]) had a lower prevalence of malaria parasitemia. CONCLUSIONS: A high proportion of asymptomatic blood donors residing in a malaria endemic region demonstrate evidence of parasitemia at time of donation. Further research is needed to quantify the risk and associated burden of transfusion-transmitted malaria (TTM) in order to inform strategies to prevent TTM.
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Donantes de Sangre/estadística & datos numéricos , Malaria/epidemiología , Parasitemia/epidemiología , Adolescente , Adulto , Infecciones Asintomáticas/epidemiología , Transfusión Sanguínea/estadística & datos numéricos , Estudios Transversales , Femenino , Humanos , Malaria/sangre , Malaria Falciparum/sangre , Malaria Falciparum/epidemiología , Masculino , Persona de Mediana Edad , Parasitemia/sangre , Plasmodium falciparum/crecimiento & desarrollo , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/crecimiento & desarrollo , Plasmodium malariae/aislamiento & purificación , Plasmodium ovale/crecimiento & desarrollo , Plasmodium ovale/aislamiento & purificación , Prevalencia , Uganda/epidemiología , Adulto JovenRESUMEN
BACKGROUND: To date, most of the recent publications on malaria in Malaysia were conducted in Sabah, East Malaysia focusing on the emergence of Plasmodium knowlesi. This analysis aims to describe the incidence, mortality and case fatality rate of malaria caused by all Plasmodium species between Peninsular Malaysia and East Malaysia (Sabah and Sarawak) over a 5-year period (2013-2017). METHODS: This is a secondary data review of all diagnosed and reported malaria confirmed cases notified to the Ministry of Health, Malaysia between January 2013 and December 2017. RESULTS: From 2013 to 2017, a total of 16,500 malaria cases were notified in Malaysia. The cases were mainly contributed from Sabah (7150; 43.3%) and Sarawak (5684; 34.4%). Majority of the patients were male (13,552; 82.1%). The most common age group in Peninsular Malaysia was 20 to 29 years (1286; 35.1%), while Sabah and Sarawak reported highest number of malaria cases in age group of 30 to 39 years (2776; 21.6%). The top two races with malaria in Sabah and Sarawak were Bumiputera Sabah (5613; 43.7%) and Bumiputera Sarawak (4512; 35.1%), whereas other ethnic group (1232; 33.6%) and Malays (1025; 28.0%) were the two most common races in Peninsular Malaysia. Plasmodium knowlesi was the commonest species in Sabah and Sarawak (9902; 77.1%), while there were more Plasmodium vivax cases (1548; 42.2%) in Peninsular Malaysia. The overall average incidence rate, mortality rate and case fatality rates for malaria from 2013 to 2017 in Malaysia were 0.106/1000, 0.030/100,000 and 0.27%, respectively. Sarawak reported the highest average incidence rate of 0.420/1000 population followed by Sabah (0.383/1000). Other states in Peninsular Malaysia reported below the national average incidence rate with less than 0.100/1000. CONCLUSIONS: There were different trends and characteristics of notified malaria cases in Peninsular Malaysia and Sabah and Sarawak. They provide useful information to modify current prevention and control measures so that they are customised to the peculiarities of disease patterns in the two regions in order to successfully achieve the pre-elimination of human-only species in the near future.
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Malaria/epidemiología , Adolescente , Adulto , Distribución por Edad , Niño , Femenino , Humanos , Incidencia , Malaria/etnología , Malaria/mortalidad , Malaria/parasitología , Malasia/epidemiología , Masculino , Persona de Mediana Edad , Plasmodium falciparum/aislamiento & purificación , Plasmodium knowlesi/aislamiento & purificación , Plasmodium malariae/aislamiento & purificación , Plasmodium ovale/aislamiento & purificación , Distribución por Sexo , Adulto JovenRESUMEN
BACKGROUND: Molecular genotyping in Plasmodium serves many aims including providing tools for studying parasite population genetics and distinguishing recrudescence from reinfection. Microsatellite typing, insertion-deletion (INDEL) and single nucleotide polymorphisms is used for genotyping, but only limited information is available for Plasmodium malariae, an important human malaria species. This study aimed to provide a set of genetic markers to facilitate the study of P. malariae population genetics. METHODS: Markers for microsatellite genotyping and pmmsp1 gene polymorphisms were developed and validated in symptomatic P. malariae field isolates from Myanmar (N = 37). Fragment analysis was used to determine allele sizes at each locus to calculate multiplicity of infections (MOI), linkage disequilibrium, heterozygosity and construct dendrograms. Nucleotide diversity (π), number of haplotypes, and genetic diversity (Hd) were assessed and a phylogenetic tree was constructed. Genome-wide microsatellite maps with annotated regions of newly identified markers were constructed. RESULTS: Six microsatellite markers were developed and tested in 37 P. malariae isolates which showed sufficient heterozygosity (0.530-0.922), and absence of linkage disequilibrium (IAS=0.03, p value > 0.05) (N = 37). In addition, a tandem repeat (VNTR)-based pmmsp1 INDEL polymorphisms marker was developed and assessed in 27 P. malariae isolates showing a nucleotide diversity of 0.0976, haplotype gene diversity of 0.698 and identified 14 unique variants. The size of VNTR consensus repeat unit adopted as allele was 27 base pairs. The markers Pm12_426 and pmmsp1 showed greatest diversity with heterozygosity scores of 0.920 and 0.835, respectively. Using six microsatellites markers, the likelihood that any two parasite strains would have the same microsatellite genotypes was 8.46 × 10-4 and was further reduced to 1.66 × 10-4 when pmmsp1 polymorphisms were included. CONCLUSIONS: Six novel microsatellites genotyping markers and a set of pmmsp1 VNTR-based INDEL polymorphisms markers for P. malariae were developed and validated. Each marker could be independently or in combination employed to access genotyping of the parasite. The newly developed markers may serve as a useful tool for investigating parasite diversity, population genetics, molecular epidemiology and for distinguishing recrudescence from reinfection in drug efficacy studies.