RESUMEN
The Guiana Shield, a small region of South America, is currently one of the main hotspots of malaria transmission on the continent. This Amazonian area is characterised by remarkable socioeconomic, cultural, health, and political heterogeneity and a high degree of regional and cross-border population mobility, which has contributed to the increase of malaria in the region in the past few years. In this context, regional cooperation to control malaria represents both a challenge and an indispensable initiative. This Viewpoint advocates for the creation of a regional cooperative mechanism for the elimination of malaria in the Guiana Shield. This strategy would help address operational and political obstacles to successful technical cooperation in the region and could contribute to reversing the regional upsurge in malaria incidence through creating a functional international control and elimination partnership.
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Malaria , Humanos , Malaria/epidemiología , Malaria/prevención & control , Equipos de SeguridadRESUMEN
In 2020, 77% of malaria cases in the Americas were concentrated in Venezuela, Brazil, and Colombia. These countries are characterized by a heterogeneous malaria landscape and malaria hotspots. Furthermore, the political unrest in Venezuela has led to significant cross-border population movement. Hence, the aim of this study was to describe spatial patterns and identify significant climatic drivers of malaria transmission along the Venezuela-Brazil-Guyana border, focusing on Bolivar state, Venezuela and Roraima state, Brazil. Malaria case data, stratified by species from 2016 to 2018, were obtained from the Brazilian Malaria Epidemiology Surveillance Information System, the Guyana Vector Borne Diseases Program, the Venezuelan Ministry of Health, and civil society organizations. Spatial autocorrelation in malaria incidence was explored using Getis-Ord (Gi*) statistics. A Poisson regression model was developed with a conditional autoregressive prior structure and posterior parameters were estimated using the Bayesian Markov chain Monte Carlo simulation with Gibbs sampling. There were 685,498 malaria cases during the study period. Plasmodium vivax was the predominant species (71.7%, 490,861). Malaria hotspots were located in eight municipalities along the Venezuela and Guyana international borders with Brazil. Plasmodium falciparum increased by 2.6% (95% credible interval [CrI] 2.1%, 2.8%) for one meter increase in altitude, decreased by 1.6% (95% CrI 1.5%, 2.3%) and 0.9% (95% CrI 0.7%, 2.4%) per 1 cm increase in 6-month lagged precipitation and each 1 °C increase of minimum temperature without lag. Each 1 °C increase of 1-month lagged maximum temperature increased P. falciparum by 0.6% (95% CrI 0.4%, 1.9%). P. vivax cases increased by 1.5% (95% CrI 1.3%, 1.6%) for one meter increase in altitude and decreased by 1.1% (95% CrI 1.0%, 1.2%) and 7.3% (95% CrI 6.7%, 9.7%) for each 1 cm increase of precipitation lagged at 6-months and 1 °C increase in minimum temperature lagged at 6-months. Each 1°C increase of two-month lagged maximum temperature increased P. vivax by 1.5% (95% CrI 0.6%, 7.1%). There was no significant residual spatial clustering after accounting for climatic covariates. Malaria hotspots were located along the Venezuela and Guyana international border with Roraima state, Brazil. In addition to population movement, climatic variables were important drivers of malaria transmission in these areas.
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Malaria Falciparum , Malaria Vivax , Malaria , Teorema de Bayes , Brasil/epidemiología , Guyana/epidemiología , Humanos , Incidencia , Malaria/epidemiología , Malaria Falciparum/epidemiología , Malaria Vivax/epidemiología , Venezuela/epidemiologíaRESUMEN
BACKGROUND: Roraima state is the northernmost state in Brazil and the primary border-crossing point between Brazil and Venezuela. The uncontrolled surge of malaria in Venezuela, coupled with mass migration of Venezuelans to neighbouring countries and the upward trend in informal mining in the state, pose a serious threat to the broader region, especially to migrant, indigenous and mining populations, jeopardizing malaria elimination efforts. This study describes changes in the epidemiological profile of malaria in Roraima state related to time, place and populations at risk from 2016 to 2020. METHODS: De-identified malaria surveillance data were obtained from the Malaria Epidemiological Surveillance System from 2016 to 2020. Pearson's chi-square tested differences between imported and autochthonous cases. Multivariable logistic regression was used to identify risk factors for imported versus autochthonous cases by demographic characteristics. RESULTS: Odds of being an imported case were higher for Plasmodium falciparum cases (AOR = 2.08). However, as the number of cases from Venezuela decreased in 2020 following closure of the border, the proportion of P. falciparum cases increased markedly, from 6.24% in 2019 to 18.50% in 2020. Over the 5-year period, the odds of being an imported case among miners were about nine times higher than the general population (AOR = 8.99). The proportion of total malaria cases that were among indigenous people increased from 33.09% in 2016 to 54.83% in 2020. Indigenous children had a higher burden of malaria with over 40% of cases in children 0 to 9 years old, compared to 8% in non-indigenous children 0 to 9 years old. In some municipalities, place of infection differed from place of notification, with a large proportion of cases in these municipalities reporting in Boa Vista. CONCLUSIONS: Malaria remains a serious threat in Roraima state, especially among high-risk populations, such as miners, migrants, and indigenous people. As malaria cases have increased among indigenous people and miners, and the proportion of P. falciparum cases has increased, elimination efforts require understanding of these risk factors to tailor interventions appropriately. Furthermore, cross-border surveillance systems need to be urgently strengthened at formal and unofficial border points, especially since the border with Venezuela reopened in July 2021.
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Malaria Falciparum , Malaria , Migrantes , Brasil/epidemiología , Niño , Preescolar , Emigración e Inmigración , Humanos , Lactante , Recién Nacido , Malaria/epidemiología , Malaria Falciparum/epidemiologíaRESUMEN
Globally, cross-border importation of malaria has become a challenge to malaria elimination. The border areas between Brazil and Venezuela have experienced high numbers of imported cases due to increased population movement and migration out of Venezuela. This study aimed to identify risk factors for imported malaria and delineate imported malaria hotspots in Roraima, Brazil and Bolivar, Venezuela between 2016 and 2018. Data on malaria surveillance cases from Roraima, Brazil and Bolivar, Venezuela from 2016 to 2018 were obtained from national surveillance systems: the Brazilian Malaria Epidemiology Surveillance Information System (SIVEP-Malaria), the Venezuelan Ministry of Health and other non-government organizations. A multivariable logistic regression model was used to identify the risk factors for imported malaria. Spatial autocorrelation in malaria incidence was explored using Getis-Ord (Gi*) statistics. During the study period, there were 11,270 (24.3%) and 4072 (0.7%) imported malaria cases in Roraima, Brazil and Bolivar, Venezuela, respectively. In the multivariable logistic regression for Roraima, men were 28% less likely to be an imported case compared to women (Adjusted Odds Ratio [AOR] = 0.72; 95% confidence interval [CI] 0.665, 0.781). Ages 20-29 and 30-39 were 90% (AOR = 1.90; 95% CI 1.649, 2.181) and 54% (AOR = 1.54; 95% CI 1.331, 1.782) more likely to be an imported case compared to the 0-9 year age group, respectively. Imported cases were 197 times (AOR = 197.03; 95% CI 175.094, 221.712) more likely to occur in miners than those working in agriculture and domestic work. In Bolivar, cases aged 10-19 (AOR = 1.75; 95% CI 1.389, 2.192), 20-29 (AOR = 2.48; 95% CI 1.957, 3.144), and 30-39 (AOR = 2.29; 95% CI 1.803, 2.913) were at higher risk of being an imported case than those in the 0-9 year old group, with older age groups having a slightly higher risk compared to Roraima. Compared to agriculture and domestic workers, tourism, timber and fishing workers (AOR = 6.38; 95% CI 4.393, 9.254) and miners (AOR = 7.03; 95% CI 4.903, 10.092) were between six and seven times more likely to be an imported case. Spatial analysis showed the risk was higher along the international border in the municipalities of Roraima, Brazil. To achieve malaria elimination, cross-border populations in the hotspot municipalities will need targeted intervention strategies tailored to occupation, age and mobility status. Furthermore, all stakeholders, including implementers, policymakers, and donors, should support and explore the introduction of novel approaches to address these hard-to-reach populations with the most cost-effective interventions.
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Malaria , Anciano , Brasil/epidemiología , Niño , Preescolar , Femenino , Humanos , Incidencia , Lactante , Recién Nacido , Malaria/epidemiología , Masculino , Factores de Riesgo , Venezuela/epidemiologíaRESUMEN
BACKGROUND: Venezuela accounted for 55% of the cases and 73% of the malaria deaths in the Americas in 2019. Bolivar state, in the southeast, contributes > 60% of the country's Plasmodium vivax and Plasmodium falciparum cases every year. This study describes the clinical-epidemiological characteristics of clinical malaria patients in this high-transmission area. METHODS: A prospective study was conducted on patients seeking medical attention in three medical centres in the state capital, Ciudad Bolivar, between June and October 2018. Malaria diagnosis was carried out using microscopy following national standards. Malaria-positive patients were examined for clinical symptoms, and haematological tests were performed at the time of diagnosis. Patients were followed up by telephone to evaluate malaria recurrences. RESULTS: Out of 287 patients, 200 (69.7%) were positive for P. vivax, 69 (24%) for P. falciparum, and 18 (6.3%) had mixed (P. vivax/P. falciparum) infections. Patients' median age was 33 years (IQR 20), 168 (69%) were men, and 40% practiced gold mining as the main occupation. Fever (96.5%), chills (91.3%), and headaches (90.6%) were the most frequent symptoms. At least one symptom associated with severe malaria was observed in 69 out of 161 patients with complete clinical evaluation (42.9%). Plasmodium vivax infections were found in 42 out of 69 (60.9%) severe cases; by contrast, P. falciparum and mixed malaria caused 34.8% (24/69) and 4.4% (3/69) of infections, respectively. Two patients died of cerebral malaria. Mean hemoglobin was lower in the patients infected with P. falciparum than those infected with P. vivax. Regardless of the parasite causing the infection, patients presented high levels of total bilirubin, aminotransferases (AST, ALT), and lactate dehydrogenase (LDH). Out of the 142 patients followed up by phone for three months (49.5% of the 287 patients), 35 (24.7%) reported recurrences. CONCLUSIONS: The high malaria prevalence among young male adults practicing gold mining suggests that this occupation is a significant risk factor. The unexpected high prevalence of P. vivax patients with at least one criteria of severe clinical disease is a matter of concern. Whether it is the result of a lack of timely diagnosis and effective treatment should be explored.
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Malaria Falciparum/epidemiología , Malaria Vivax/epidemiología , Enfermedades Profesionales/epidemiología , Plasmodium falciparum/fisiología , Plasmodium vivax/fisiología , Adolescente , Adulto , Anciano , Femenino , Humanos , Malaria Falciparum/parasitología , Malaria Vivax/parasitología , Masculino , Persona de Mediana Edad , Minería , Enfermedades Profesionales/parasitología , Prevalencia , Factores de Riesgo , Venezuela/epidemiología , Adulto JovenRESUMEN
BACKGROUND: Fifty-three percent of all cases of malaria in the Americas in 2019 came from Venezuela, where the epidemic is heavily focused south of the Orinoco river, and where most of the country's Amerindian groups live. Although the disease is known to represent a significant public health problem among these populations, little epidemiological data exists on the subject. This study aims to provide information on malaria incidence, geospatial clustering, and risk factors associated to Plasmodium falciparum infection among these groups. METHODS: This is a descriptive study based on the analysis of published and unpublished programmatic data collected by Venezuelan health authorities and non-government organizations between 2014 and 2018. The Annual Parasite Index among indigenous groups (API-i) in municipalities of three states (Amazonas, Bolivar, and Sucre) were calculated and compared using the Kruskal Wallis test, risk factors for Plasmodium falciparum infection were identified via binomial logistic regression and maps were constructed to identify clusters of malaria cases among indigenous patients via Moran's I and Getis-Ord's hot spot analysis. RESULTS: 116,097 cases of malaria in Amerindian groups were registered during the study period. An increasing trend was observed between 2014 and 2016 but reverted in 2018. Malaria incidence remains higher than in 2014 and hot spots were identified in the three states, although more importantly in the south of Bolivar. Most cases (73.3%) were caused by Plasmodium vivax, but the Hoti, Yanomami, and Eñepa indigenous groups presented higher odds for infection with Plasmodium falciparum. CONCLUSION: Malaria cases among Amerindian populations increased between 2014 and 2018 and seem to have a different geographic distribution than those among the general population. These findings suggest that tailored interventions will be necessary to curb the impact of malaria transmission in these groups.
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Malaria Falciparum/epidemiología , Plasmodium falciparum/aislamiento & purificación , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Análisis por Conglomerados , Femenino , Humanos , Incidencia , Indígenas Sudamericanos , Lactante , Recién Nacido , Malaria Falciparum/parasitología , Masculino , Persona de Mediana Edad , Factores de Riesgo , Análisis Espacial , Venezuela/epidemiología , Adulto JovenRESUMEN
INTRODUCTION: Malaria case management is a pivotal intervention in malaria elimination. However, many remote areas in Brazil still lack access to basic health services. This study describes a community-based approach (CBA) for malaria case management in the large remote area of the Jaú National Park (JNP), Amazonas, Brazil. METHODS: In 2001, a general health CBA was initiated with a motor group (MG); a participative community health diagnosis (PCHD) was subsequently implemented between 2001 and 2005. In 2006, a CBA for malaria case management started with an expanded MG including all sectors with a stake in malaria control, from the local residents to the federal government. In 2008, community microscopists were selected and trained to diagnose hemoparasites. A full malaria strategy was implemented in 2009 with subsequent quality control follow-up. RESULTS: Two educational materials were co-created with local communities. The MG identified malaria as a major health problem and the malaria MG planned the control activities. Ten communities selected a resident to become malaria microscopists, and ten solar-operated health centers were built. The number of slide readings increased from 923 in 2006 to 1,900 in 2009, while malaria infections decreased from 354 cases in 2005 to 20 cases in 2015. The excess time (≥ 48 hours) between first symptoms and diagnosis/treatment decreased from 68.9% of cases in 2005 to 14.3% in 2010. CONCLUSIONS: While many factors were likely involved in the reduction of malaria transmission in the JNP, the CBA played an important role in the sustained success of the initiative.
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Manejo de Caso , Servicios de Salud Comunitaria/organización & administración , Malaria , Población Rural , Brasil , Investigación Participativa Basada en la Comunidad , Humanos , Malaria/diagnóstico , Malaria/tratamiento farmacológico , Salud PúblicaRESUMEN
Abstract INTRODUCTION Malaria case management is a pivotal intervention in malaria elimination. However, many remote areas in Brazil still lack access to basic health services. This study describes a community-based approach (CBA) for malaria case management in the large remote area of the Jaú National Park (JNP), Amazonas, Brazil. METHODS In 2001, a general health CBA was initiated with a motor group (MG); a participative community health diagnosis (PCHD) was subsequently implemented between 2001 and 2005. In 2006, a CBA for malaria case management started with an expanded MG including all sectors with a stake in malaria control, from the local residents to the federal government. In 2008, community microscopists were selected and trained to diagnose hemoparasites. A full malaria strategy was implemented in 2009 with subsequent quality control follow-up. RESULTS Two educational materials were co-created with local communities. The MG identified malaria as a major health problem and the malaria MG planned the control activities. Ten communities selected a resident to become malaria microscopists, and ten solar-operated health centers were built. The number of slide readings increased from 923 in 2006 to 1,900 in 2009, while malaria infections decreased from 354 cases in 2005 to 20 cases in 2015. The excess time (≥ 48 hours) between first symptoms and diagnosis/treatment decreased from 68.9% of cases in 2005 to 14.3% in 2010. CONCLUSIONS While many factors were likely involved in the reduction of malaria transmission in the JNP, the CBA played an important role in the sustained success of the initiative.
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Humanos , Población Rural , Servicios de Salud Comunitaria/organización & administración , Manejo de Caso , Malaria/diagnóstico , Malaria/tratamiento farmacológico , Brasil , Salud Pública , Investigación Participativa Basada en la ComunidadRESUMEN
In the past 5-10 years, Venezuela has faced a severe economic crisis, precipitated by political instability and declining oil revenue. Public health provision has been affected particularly. In this Review, we assess the impact of Venezuela's health-care crisis on vector-borne diseases, and the spillover into neighbouring countries. Between 2000 and 2015, Venezuela witnessed a 359% increase in malaria cases, followed by a 71% increase in 2017 (411â586 cases) compared with 2016 (240â613). Neighbouring countries, such as Brazil, have reported an escalating trend of imported malaria cases from Venezuela, from 1538 in 2014 to 3129 in 2017. In Venezuela, active Chagas disease transmission has been reported, with seroprevalence in children (<10 years), estimated to be as high as 12·5% in one community tested (n=64). Dengue incidence increased by more than four times between 1990 and 2016. The estimated incidence of chikungunya during its epidemic peak is 6975 cases per 100â000 people and that of Zika virus is 2057 cases per 100â000 people. The re-emergence of many vector-borne diseases represents a public health crisis in Venezuela and has the possibility of severely undermining regional disease elimination efforts. National, regional, and global authorities must take action to address these worsening epidemics and prevent their expansion beyond Venezuelan borders.
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Enfermedades Transmisibles Emergentes/epidemiología , Enfermedades Transmisibles Emergentes/transmisión , Epidemias , Enfermedades Transmitidas por Vectores/epidemiología , Enfermedades Transmitidas por Vectores/transmisión , Animales , Control de Enfermedades Transmisibles , Enfermedades Transmisibles Emergentes/prevención & control , Epidemias/prevención & control , Epidemias/estadística & datos numéricos , Geografía Médica , Humanos , Incidencia , Enfermedades Transmitidas por Vectores/prevención & control , Venezuela/epidemiologíaRESUMEN
Hispaniola is the only Caribbean island to which Plasmodium falciparum malaria remains endemic. Resistance to the antimalarial drug chloroquine has rarely been reported in Haiti, which is located on Hispaniola, but the K76T pfcrt (P. falciparum chloroquine resistance transporter) gene mutation that confers chloroquine resistance has been detected intermittently. We analyzed 901 patient samples collected during 2006-2009 and found 2 samples showed possible mixed parasite infections of genetically chloroquine-resistant and -sensitive parasites. Direct sequencing of the pfcrt resistance locus and single-nucleotide polymorphism barcoding did not definitively identify a resistant population, suggesting that sustained propagation of chloroquine-resistant parasites was not occurring in Haiti during the study period. Comparison of parasites from Haiti with those from Colombia, Panama, and Venezuela reveals a geographically distinct population with highly related parasites. Our findings indicate low genetic diversity in the parasite population and low levels of chloroquine resistance in Haiti, raising the possibility that reported cases may be of exogenous origin.
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Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Proteínas de Transporte de Membrana/genética , Mutación , Plasmodium falciparum/genética , Proteínas Protozoarias/genética , Código de Barras del ADN Taxonómico , Geografía , Haití/epidemiología , Historia del Siglo XXI , Humanos , Malaria Falciparum/historia , Filogeografía , Plasmodium falciparum/clasificación , Análisis de Secuencia de ADNRESUMEN
Venezuela had the highest number of human malaria cases in Latin American before 1936. During 18911920,malaria was endemic to >600,000 km2 of this country; malaria death rates led to major population decreases during 18911920. No pathogen, including the influenza virus that caused the 1918 pandemic, caused more deaths than malaria during 19051945. Early reports of malaria eradication in Venezuela helped spark the world's interest in global eradication. We describe early approaches to malaria epidemiology in Venezuela and how this country developed an efficient control program and an approach to eradication.Arnoldo Gabaldón was a key policy maker during this development process. He directed malaria control in Venezuela from the late 1930s to the end of the 1970s and contributed to malaria program planning of the World Health Organization.We discuss how his efforts helped reduce the incidence of malaria in Venezuela and how his approach diverged from World Health Organization guidelines.
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Malaria/historia , Malaria/prevención & control , Política de Salud/historia , Historia del Siglo XIX , Historia del Siglo XX , Humanos , Insecticidas , Control de Mosquitos/métodos , Venezuela/epidemiologíaRESUMEN
Plasmodium vivax is the most prevalent human malaria parasite in the Americas. Previous studies have contrasted the genetic diversity of parasite populations in the Americas with those in Asia and Oceania, concluding that New World populations exhibit low genetic diversity consistent with a recent introduction. Here we used an expanded sample of complete mitochondrial genome sequences to investigate the diversity of P. vivax in the Americas as well as in other continental populations. We show that the diversity of P. vivax in the Americas is comparable to that in Asia and Oceania, and we identify several divergent clades circulating in South America that may have resulted from independent introductions. In particular, we show that several haplotypes sampled in Venezuela and northeastern Brazil belong to a clade that diverged from the other P. vivax lineages at least 30,000 years ago, albeit not necessarily in the Americas. We propose that, unlike in Asia where human migration increases local genetic diversity, the combined effects of the geographical structure and the low incidence of vivax malaria in the Americas has resulted in patterns of low local but high regional genetic diversity. This could explain previous views that P. vivax in the Americas has low genetic diversity because these were based on studies carried out in limited areas. Further elucidation of the complex geographical pattern of P. vivax variation will be important both for diversity assessments of genes encoding candidate vaccine antigens and in the formulation of control and surveillance measures aimed at malaria elimination.
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Evolución Biológica , Variación Genética , Genoma Mitocondrial , Filogenia , Plasmodium vivax/clasificación , Américas , Animales , Asia , Secuencia de Bases , Teorema de Bayes , Haplotipos , Humanos , Malaria Vivax/parasitología , Malaria Vivax/transmisión , Oceanía , Filogeografía , Plasmodium vivax/genéticaRESUMEN
Plasmodium vivax infections remain a major source of malaria-related morbidity and mortality. Early and accurate diagnosis is an integral component of effective malaria control programs. Conventional molecular diagnostic methods provide accurate results but are often resource-intensive, expensive, have a long turnaround time and are beyond the capacity of most malaria-endemic countries. Our laboratory has recently developed a new platform called RealAmp, which combines loop-mediated isothermal amplification (LAMP) with a portable tube scanner real-time isothermal instrument for the rapid detection of malaria parasites. Here we describe new primers for the detection of P. vivax using the RealAmp method. Three pairs of amplification primers required for this method were derived from a conserved DNA sequence unique to the P. vivax genome. The amplification was carried out at 64°C using SYBR Green or SYTO-9 intercalating dyes for 90 minutes with the tube scanner set to collect fluorescence signals at 1-minute intervals. Clinical samples of P. vivax and other human-infecting malaria parasite species were used to determine the sensitivity and specificity of the primers by comparing with an 18S ribosomal RNA-based nested PCR as the gold standard. The new set of primers consistently detected laboratory-maintained isolates of P. vivax from different parts of the world. The primers detected P. vivax in the clinical samples with 94.59% sensitivity (95% CI: 87.48-98.26%) and 100% specificity (95% CI: 90.40-100%) compared to the gold standard nested-PCR method. The new primers also proved to be more sensitive than the published species-specific primers specifically developed for the LAMP method in detecting P. vivax.
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Malaria Vivax/diagnóstico , Técnicas de Amplificación de Ácido Nucleico/métodos , Plasmodium vivax/genética , Plasmodium vivax/aislamiento & purificación , Humanos , Técnicas de Amplificación de Ácido Nucleico/instrumentación , Plasmodium vivax/patogenicidad , ARN Ribosómico 18S/genética , Sensibilidad y Especificidad , Especificidad de la EspecieRESUMEN
BACKGROUND: Regardless of the growing interest in detecting population structures in malarial parasites, there have been limited discussions on how to use this concept in control programmes. In such context, the effects of the parasite population structures will depend on interventions' spatial or temporal scales. This investigation explores the problem of identifying genetic markers, in this case microsatellites, to unveil Plasmodium genetic structures that could affect decisions in the context of elimination. The study was performed in a low-transmission area, which offers a good proxy to better understand problems associated with surveillance at the final stages of malaria elimination. METHODS: Plasmodium vivax samples collected in Tumeremo, Venezuela, between March 2003 and November 2004 were analysed. Since Plasmodium falciparum also circulates in many low endemic areas, P. falciparum samples from the same locality and time period were included for comparison. Plasmodium vivax samples were assayed for an original set of 25 microsatellites and P. falciparum samples were assayed for 12 microsatellites. RESULTS: Not all microsatellite loci assayed offered reliable local data. A complex temporal-cluster dynamics is found in both P. vivax and P. falciparum. Such dynamics affect the numbers and the type of microsatellites required for identifying individual parasites or parasite clusters when performing cross-sectional studies. The minimum number of microsatellites required to differentiate circulating P. vivax clusters differs from the minimum number of hyper-variable microsatellites required to distinguish individuals within these clusters. Regardless the extended number of microsatellites used in P. vivax, it was not possible to separate all individual infections. CONCLUSIONS: Molecular surveillance has great potential; however, it requires preliminary local studies in order to properly interpret the emerging patterns in the context of elimination. Clonal expansions and clusters turnovers need to be taken into account when using molecular markers. Those affect the number and type of microsatellite markers, as well as, the expected genetic patterns in the context of operational investigations. By considering the local dynamics, elimination programmes could cost-effectively use molecular markers. However, population level studies need to consider the local limitations of a given set of loci in terms of providing epidemiologically relevant information.
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Malaria Falciparum/parasitología , Malaria Vivax/parasitología , Plasmodium falciparum/aislamiento & purificación , Plasmodium vivax/aislamiento & purificación , Estudios Transversales , ADN Protozoario/genética , Enfermedades Endémicas/prevención & control , Variación Genética , Humanos , Desequilibrio de Ligamiento , Malaria Falciparum/epidemiología , Malaria Falciparum/prevención & control , Malaria Vivax/epidemiología , Malaria Vivax/prevención & control , Repeticiones de Microsatélite , Epidemiología Molecular , Plasmodium falciparum/genética , Plasmodium vivax/genética , Venezuela/epidemiologíaRESUMEN
BACKGROUND: Suriname was a high malaria risk country before the introduction of a new five-year malaria control program in 2005, the Medical Mission Malaria Programme (MM-MP). Malaria was endemic in the forested interior, where especially the stabile village communities were affected. CASE DESCRIPTION: The interventions of the MM-MP included new strategies for prevention, vector control, case management, behavioral change communication (BCC)/information, education and communication (IEC), and strengthening of the health system (surveillance, monitoring and evaluation and epidemic detection system). After a slow first year with non-satisfying scores for the performance indicators, the MM-MP truly engaged in its intervention activities in 2006 and kept its performance up until the end of 2009. A total of 69,994 long-lasting insecticide-treated nets were distributed and more than 15,000 nets re-impregnated. In high-risk areas, this was complemented with residual spraying of insecticides. Over 10,000 people were screened with active case detection in outbreak and high-risk areas. Additional notification points were established and the national health system was strengthened. DISCUSSION AND EVALUATION: In the current paper, the MM-MP is evaluated both on account of the targets established within the programme and on account of its impact on the malaria situation in Suriname. Malaria vector populations, monitored in sentinel sites, collapsed after 2006 and concurrently the number of national malaria cases decreased from 8,618 in 2005 to 1,509 in 2009. Malaria transmission risk shifted from the stabile village communities to the mobile gold mining communities, especially those along the French Guiana border. CONCLUSIONS: The novel strategies for malaria control introduced in Suriname within the MM-MP have led to a significant decrease in the national malaria burden. The challenge is to further reduce malaria using the available strategies as appropriate in the affected areas and populations. Elimination of malaria in the country will require a thorough understanding of transmission dynamics and a dedicated investment in key effective interventions.
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Control de Enfermedades Transmisibles/métodos , Erradicación de la Enfermedad/métodos , Malaria/epidemiología , Malaria/prevención & control , Animales , Humanos , Suriname/epidemiologíaRESUMEN
Accurate and rapid diagnosis of malaria infections is crucial for implementing species-appropriate treatment and saving lives. Molecular diagnostic tools are the most accurate and sensitive method of detecting Plasmodium, differentiating between Plasmodium species, and detecting subclinical infections. Despite available whole-genome sequence data for Plasmodium falciparum and P. vivax, the majority of PCR-based methods still rely on the 18S rRNA gene targets. Historically, this gene has served as the best target for diagnostic assays. However, it is limited in its ability to detect mixed infections in multiplex assay platforms without the use of nested PCR. New diagnostic targets are needed. Ideal targets will be species specific, highly sensitive, and amenable to both single-step and multiplex PCRs. We have mined the genomes of P. falciparum and P. vivax to identify species-specific, repetitive sequences that serve as new PCR targets for the detection of malaria. We show that these targets (Pvr47 and Pfr364) exist in 14 to 41 copies and are more sensitive than 18S rRNA when utilized in a single-step PCR. Parasites are routinely detected at levels of 1 to 10 parasites/µl. The reaction can be multiplexed to detect both species in a single reaction. We have examined 7 P. falciparum strains and 91 P. falciparum clinical isolates from Tanzania and 10 P. vivax strains and 96 P. vivax clinical isolates from Venezuela, and we have verified a sensitivity and specificity of â¼100% for both targets compared with a nested 18S rRNA approach. We show that bioinformatics approaches can be successfully applied to identify novel diagnostic targets and improve molecular methods for pathogen detection. These novel targets provide a powerful alternative molecular diagnostic method for the detection of P. falciparum and P. vivax in conventional or multiplex PCR platforms.