Caso importado de malaria por Plasmodium vivax en El Salvador. Un abordaje epidemiológico / Imported Case of Malaria by Plasmodium vivax in El Salvador. An Epidemiological Approach

Presentación del caso. Paciente masculino de origen guatemalteco con historia de fiebre alta de tipo intermitente, mialgias, artralgias, debilidad generalizada, mareo y vómito de contenido gástrico. Fue tratado inicialmente en un hospital privado con diagnóstico de síndrome febril agudo y referido a un hospital de la red nacional con diagnóstico de dengue con signos de alarma, al tercer día de estancia hospitalaria se diagnostica como un caso de malaria importado por Plasmodium vivax. Intervención terapéutica. Se le dio tratamiento antimalárico con cloroquina y primaquina. Evolución clínica. Presentó mejoría clínica y las pruebas de laboratorio de control reportaron resultados negativos para Plasmodium vivax

Case presentation. Male patient of Guatemalan origin with history of intermittent high fever, myalgia, arthralgia, generalized weakness, dizziness, and vomiting of gastric contents. He was initially treated in a private hospital with a diagnosis of acute febrile illness and referred to a national network hospital with a diagnosis of dengue with warning signs. On the third day of hospital stay a diagnosis of an imported malaria case by Plasmodium vivax was presented. Treatment. The patient was given antimalarial treatment consisting of chloroquine and primaquine. Outcome. The patient presented clinical improvement, and control laboratory tests were negative for Plasmodium vivax.

Quality assurance of malaria rapid diagnostic tests: An aid in malaria elimination

Background & objectives: India targets malaria elimination by 2030 in a phased manner, so malaria’s assured diagnosis is crucial. Introduction of rapid diagnostic kits in India in 2010 has revolutionized malaria surveillance. The storage temperature of rapid diagnostic tests (RDTs), kit components and handling in transportations impact the results of RDTs. Therefore, quality assurance (QA) is required before it reaches end-users. The Indian Council of Medical Research-National Institute of Malaria Research (ICMR-NIMR) has a World Health Organization (WHO) recognized lot-testing laboratory facility to assure the quality of RDTs. Methods: The ICMR-NIMR receives RDTs from different manufacturing companies as well as various agencies such as National and State Programmes and Central Medical Services Society. The WHO standard protocol is followed to conduct all the tests, including long-term and post-dispatch testing. Results: A total of 323 lots tested during January 2014-March 2021 were received from different agencies. Amongst them, 299 lots passed the quality of test and 24 failed. In long-term testing, 179 lots were tested and only nine failed. A total of 7741 RDTs were received from end-users for post-dispatch testing of which 7540 qualified the QA test with a score of 97.4 per cent. Interpretation & conclusions: RDTs received for quality testing showed compliance with QA evaluation of malaria RDTs based on the protocol recommended by the WHO. However, continuous monitoring of the quality of RDTs is required under QA programme. Quality-assured RDTs have a major role, especially in areas where low parasitaemia of parasites persists.

Identificação, caracterização e determinação de padrões da resposta imune de epítopos imunogênicos de Plasmodium vivax / Identification, characterization and determination of immune response patterns of immunogenic epitopes of Plasmodium vivax

O Plasmodium vivax representa um grande desafio no controle da malária devido a sua vasta distribuição ao redor do globo, grande frequência de infecções sub microscópicas e habilidade de induzir recaídas em consequência das formas evolutivas que podem ficar latentes no fígado por longos períodos (hipnozoítos). O recente aumento de cepas de P. vivax resistentes aos fármacos disponíveis, a evolução de formas mais virulentas do parasito e a produção precoce de gametócitos, característica desta espécie, contribuem para classificar a malária vivax como um problema de saúde pública que merece atenção. Ainda que reconhecido por suas características biológicas peculiares e pelo agravamento recente de sua virulência, poucos investimentos têm sido feitos no desenvolvimento de ferramentas de controle para vivax. Portanto, o presente estudo teve como objetivo identificar e caracterizar novos alvos potenciais utilizando amostras de diferentes áreas endêmicas ao redor do mundo (Brasil, Mali, Camboja e Estados Unidos da América). Para tanto, investigamos e caracterizamos uma proteína recém descoberta na urina de pacientes naturalmente infectados (PvVir14); e descrevemos o potencial imunogênico de epítopos de células B de uma das proteínas mais bem caracterizadas de P. vivax, a PvAMA-1. Anti-IgG circulantes contra PvVir14 apareceram em 61% e 34.5% dos indivíduos do Brasil e Camboja, respectivamente, enquanto que indivíduos de Mali (infectados com falciparum e não expostos a vivax), tiveram 0% de reconhecimento. Ainda, os níveis de anti-PvVir14 correlacionaram-se com aqueles contra outros antígenos de vivax já bem caracterizados, como a PvCSP e a PvDBP, que foram reconhecidos por 7.6% e 42% dos indivíduos respectivamente. Com relação ao perfil celular, indivíduos sororreativos para PvVir14 apresentaram níveis significativamente maiores de células B atípicas circulantes (CD 21- CD 27-), sugerindo que tal tipo celular possa estar ligado à resposta anti-PvVir14. Entre as células T, os níveis de CD4+ e CD8+ diferiram entre indivíduos com e sem anticorpos contra PvVir14 (menor e maior expressão, respectivamente), enquanto que os níveis de células NKT foram mais expressivos em indivíduos sem anti-PvVir14. Se tratando da PvAMA-1, a antigenicidade dos peptídeos com epítopos para células B previamente selecionados foi avaliada através de múltiplos ensaios sorológicos utilizando amostras de indivíduos com infecção aguda por P.vivax do norte do Brasil. Os peptídeos sintéticos foram reconhecidos por 45.5%, 48.7% e 31.2% (PI, PII e PII, respectivamente) dos indivíduos selecionados para o estudo. Quando sintetizados em conjunto (tripeptídeo), a reatividade aumentou para 62%, porcentagem comparável àquela obtida pela proteína em sua forma e tamanho originais (57%). Além disso, a reatividade anti-IgG conta o tripeptídeo foi reduzida em 42% pós-depleção, indicando que tais epítopos podem ser responsáveis por parte considerável da imunogenicidade da proteína. Esses resultados representam uma excelente perspectiva na identificação de novos alvos com potencial imunogênico para compor uma vacina, ou auxiliar no desenvolvimento de outras medidas de controle, como testes diagnósticos, já que contemplar diversos alvos do ciclo de vida do parasito parece ser a chave para alcançar a resposta robusta e protetora que uma vacina contra a malária vivax precisa para ter sucesso.

Plasmodium vivax is a major challenge for malaria control due to its wide geographic distribution, high frequency of submicroscopic infections, and ability to induce relapses due to the latent forms present in the liver (hypnozoites). The recent increase in drug-resistant P. vivax strains, the evolution toward more virulent forms and the early production of gametocytes adds up to make P. vivax malaria a public health issue of increasing importance. Besides its tricky biological features and new awareness of its virulence, minimal investments have been made in vaccine discovery for P. vivax. Given that, this study aimed to discover and characterize potential new targets for future vaccine development using samples from different endemic areas around the world (Brazil, Mali, Cambodia and United States of America). For this purpose, we investigated and characterized a novel protein recently discovered in the urine of naturally infected subjects (PvVir14) and described the immunogenic potential of peptides from a well-known vivax protein (PvAMA-1), which has been proved to have important B cell epitopes that can induce specific immune response. Circulating antibodies against PvVir14 appeared in 61% and 34.5% of subjects from Brazil and Cambodia, respectively, versus none (0%) of the P. falciparum-infected subjects from Mali who have no exposure to P. vivax. PvVir14 antibody levels correlated with those against other well-characterized sporozoite/liver (PvCSP) and blood stage (PvDBP-RII) antigens, which were recognized by 7.6% and 42% of Brazilians, respectively. Concerning the cellular immune profiling of Brazilian subjects, PvVir14 seroreactive individuals displayed significantly higher levels of circulating atypical (CD21− CD27−) B cells, raising the possibility that atypical B cells may be contribute to the PvVir14 antibody response. Among T cells, CD4+ and CD8+ levels differed (lower and higher, respectively) between subjects with versus without antibodies to PvVir14, while NKT cell levels were higher in those without antibodies. As for PvAMA-1, the antigenicity of the selected B-cell peptides was assessed by multiple serological assays using sera from acute P.vivax infected subjects. The synthetic peptides were recognized by 45.5%, 48.7% and 32.2% of infected subjects for peptides I, II and III respectively. Moreover, when synthetized together (tripeptide), the reactivity increases up to 62%, which is comparable to the reactivity found against the whole protein PvAMA-1 (57%). Furthermore, IgG reactivity against the tripeptide after depletion was reduced by 42%, indicating that these epitopes may be responsible for a considerable part of the protein immunogenicity. These results represent an excellent perspective on discovering new targets with immunogenic potential to compose a vaccine, or even to assist the development of other control measures, such as diagnostic tools, since contemplating several targets seems to be the key to achieving a robust and protective response that a malaria vaccine needs to be successful.

Polymorphisms of pvcrt-o and pvmdr1 genes of 48 Plasmodium vivax isolates from the China-Myanmar border / 中国热带医学

@#Abstract: Objective To detect the polymorphisms of drug resistance-related genes pvcrt-o and pvmdr1 of Plasmodium vivax in lazan city in the China-Myanmar border, in order to guide the treatment plan of Plasmodium vivax. Methods A total of 48 Plasmodium vivax samples were collected from Lazan in the China-Myanmar border in 2007, and fragments of pvcrt-o and pvmdr1 genes were amplified by PCR and sequenced. The sequences were aligned with the Salvador I (Sal-I) strain reference genome sequences to determine the presence of SNPs. Results The target fragments of pvcrt-o gene were amplified from 39 Plasmodium vivax samples, while pvmdr1 genes were amplified from 40 samples. Amongst them, 25 samples had AAG insertion before the 10th amino acid (K10 insertion) of pvcrt-o gene, accounting for 64.1%. Non-synonymous mutations were detected at three loci of pvmdr1 gene (T958M, Y976F, and F1076L), the mutation rates were 100%, 22.5%, and 55.0%, respectively. There were three haplotypes of pvmdr1 gene, of which the triple mutant 958M/976F/1076L accounted for 22.5% (9/40), the double mutant 958M/Y976/1076L accounted for 32.5% (13/40), and the single mutant 958M/Y976/F1076 accounted for 45.0% (18/40). The proportion of strains with pvcrt-o and pvmdr1 gene mutation is 63.16%, which is significantly different from those only with pvmdr1 mutation. Conclusions The proportion of pvcrt-o and pvmdr1 gene mutation of 48 Plasmodium vivax isolates is high in the China-Myanmar border, and there is a certain degree of correlation between the two gene mutations. To assess changes in Plasmodium vivax drug resistance in this region, it is required to improve the surveillance of these two molecular markers.

Características espacio temporales de la trasmisión de la malaria en la región Loreto entre los años 2000 y 2019

Introducción: La eliminación de la malaria es la solución definitiva para evitar que la creciente resistencia a los medicamentos e insecticidas amenace los avances alcanzados en la lucha contra la malaria desde comienzos del siglo XXI. Objetivo: Analizar las características espacio temporales de la trasmisión de la malaria en Loreto. Método: Se realizó un estudio de tipo series de tiempo y se analizó la incidencia semanal de malaria en Loreto en los últimos 20 años (2000-2019) utilizando los datos del Sistema de Vigilancia Epidemiológica del Ministerio de Salud. Con esta información se modeló la incidencia semanal de malaria reportada por las unidades de vigilancia epidemiológica de Loreto y se determinaron sus características espacio temporales a nivel macro y microregional. Adicionalmente se caracterizaron las zonas "calientes" así como su estabilidad en el tiempo. Resultados: Durante los últimos 20 años observamos que Loreto tuvo un patrón de trasmisión estacional de la malaria, de intensidad moderada y zonas de trasmisión difusa, Adicionalmente, se observó que las tres redes de salud más "calientes" consistentemente fueron Maynas Ciudad, Loreto y Datem del Marañón, y que cada de estas redes exhibieron diferentes zonas calientes micro regionales de alta estabilidad temporal durante los altibajos estacionales de la malaria. Conclusiones: Loreto es una región receptiva para malaria cuya trasmisión se caracteriza por un patrón estacional, de intensidad moderada, con zonas de trasmisión difusa y presencia de focos activos de elevada trasmisión (zonas calientes macro y micro regionales) de alta estabilidad temporal.

Introduction: The elimination of malaria is the definitive solution to prevent the growing resistance to drugs and insecticides from threatening the progress made since the beginning of the 21st century. Objective: To analyze the spatio-temporal characteristics of malaria transmission in the Loreto region. Methods: We carried out a time series study, and the weekly incidence of malaria in Loreto in the last 20 years (2000-2019) was analyzed using data from the Epidemiological Surveillance System of the Ministry of Health. With this information, we modeled the weekly incidence of malaria across the Loreto surveillance reporting units and determine its spatio-temporal characteristics at the macro and micro-regional levels. Additionally, we characterized the "hot zones" and their stability over time. Results: During the last 20 years, we observed that Loreto has a seasonal malaria transmission, of moderate intensity, with different areas of diffuse transmission, Additionally, we observed that the three "hottest" health networks were, consistently, Maynas Ciudad, Loreto, and Datem del Marañón, with each of them also exhibiting different microregional hot zones of high temporal stability during its seasonal ups and downs. Conclusions: Loreto is a receptive region for malaria whose transmission is characterized by a seasonal pattern, of moderate intensity, with areas of diffuse transmission and the presence of active foci of high transmission (macro and micro-regional hot zones) with high temporal stability.

Malaria en la región eco-epidemiológica del Caribe Colombiano, 1960-2019 / Malaria in the eco-epidemiological region of the Colombian Caribbean, 1960-2019

La malaria en Colombia tiene un comportamiento heterogéneo y variable, entre las regiones. Para establecer su comportamiento epidemiológico en la región del Caribe colombiano entre 1960 y 2019 se realizó un estudio observacional, descriptivo y retrospectivo a partir de registros del Ministerio de Salud y otras fuentes secundarias. Se definieron variables epidemiológicas y se elaboraron medidas de frecuencia y tendencia central. Se registraron 155 096 casos. Las décadas con mayor número de casos fueron 1990-1999 (20,5%) y 1980-1989 (18,9%). El promedio de casos por década fue de 25 849,3. Los índices parasitarios más elevados se registraron en 1970 (3,3 por 1000 habitantes) y 1981 (3,9 por 1000 habitantes). La especie Plasmodium vivax fue la más frecuente y la mayoría de la carga por grupos de edad se registró en menores de 29 años, entre 2010-2019. La malaria presentó un patrón endemo-epidémico de baja y muy baja intensidad de transmisión, con una tendencia al descenso.

Malaria has a heterogeneous and variable behavior among Colombian regions. In order to establish its epidemiological behavior in the Colombian Caribbean region between 1960 and 2019, we carried out an observational, descriptive and retrospective study based on records from the Ministry of Health and other secondary sources. We defined epidemiological variables and used measures of frequency and central tendency. A total of 155,096 cases were registered. The decades with the highest number of cases were 1990-1999 (20.5%) and 1980-1989 (18.9%). The average number of cases per decade was 25,849.3. The highest parasite rates were recorded in 1970 (3.3 per 1000 population) and 1981 (3.9 per 1000 population). Plasmodium vivax was the most frequent species and most of the burden by age group was found in people under 29 years of age, between 2010-2019. Malaria showed an endemic-epidemic pattern of low and very low transmission intensity, with a decreasing trend.

Treatment of Chloroquine-Resistant Plasmodium vivax Malaria in India

Background: Treatment failure in P. vivax Malaria is a major dilemma that faces health care workers. True drug resistance is one of the causes after ruling out compliance and drug quality issues. The other two causes are re-infection during the treatment period or the release of hypnozoites from the liver. Objectives: To find out what antimalarials can be prescribed in India for treating Chloroquine-resistant P. vivax Malaria. Methods: By reviewing documents prepared by the National Center for Vector-Borne Diseases Control (NCVBDC) and doing a PUBMED search for articles that deal with Chloroquine-resistant P. vivax Malaria treatment. Results: It was found that a fixed-dose combination of oral Artemether and Lumefantrine can be given for Chloroquine-resistant P. vivax Malaria. Conclusions: There is a lack of awareness among health care providers on how to treat Chloroquine-resistant P. vivax Malaria. This paper addresses this concern.

Salivary AsHPX12 influences pre-blood meal associated behavioral properties in Anopheles stephensi

Background & objectives: A successful blood meal acquisition process by an adult female mosquito is accomplished through salivary glands, which releases a cocktail of proteins to counteract the vertebrate host’s immune homeostasis. Here, we characterize a salivary-specific Heme peroxidase family member HPX12, originally identified from Plasmodium vivax infected salivary RNAseq data of the mosquito Anopheles stephensi. Methods: To demonstrate we utilized a comprehensive in silico and functional genomics approach. Results: Our dsRNA-mediated silencing experiments demonstrate that salivary AsHPX12 may regulate pre-blood meal-associated behavioral properties such as probing time, probing propensity, and host attraction. Altered expression of the salivary secretory and antennal proteins expression may have accounted for salivary homeostasis disruption resulting in the unusual fast release of salivary cocktail proteins and delayed acquisition of blood meal in the AsHPX12 knockdown mosquitoes. We also observed a significant parallel transcriptional modulation in response to blood feeding and P. vivax infection. Interpretation & conclusion: With this work, we establish a possible functional correlation of AsHPX12 role in the maintenance of salivary physiological-homeostasis, and Plasmodium sporozoites survival/ transmission, though the mechanism is yet to unravel.

Changing pattern of severe manifestations of Plasmodium falciparum and Plasmodium vivax malaria: A retrospective study from Bikaner, India

Background & objectives: Previously there were reports from all over India about the changing spectrum of severe manifestations of Plasmodium falciparum malaria. Consequently, the present retrospective study was conducted to compare the severity of malaria caused by P. falciparum and P. vivax during 2007–08 and 2017–18. Methods: The present study was conducted on the patients admitted with severe malaria in a classified malaria ward of a tertiary care hospital in Bikaner, Rajasthan (Northwest India) during 2007–08 and 2017–18. It included adult patients of both sexes belonging to all age groups. The diagnosis was done by peripheral blood film (PBF), rapid diagnostic test (RDT), and validated by polymerase chain reaction (PCR). All patients were treated with intravenous oral quinine. The specific individual malaria complications registered in 2007–08 and 2017–18 were treated by following the standard WHO protocol. Results: In 2007–08, severe manifestations caused by P. falciparum were dominated by thrombocytopenia (25.98%) followed by jaundice (24.39%), multi-organ dysfunction (MODS) (16.66%), severe anemia (16.17%), cerebral malaria (5.39%), bleeding manifestation (3.92%) and shock (0.49%). While in the same year, P. vivax associated clinical spectrum of complications were observed to be dominated by thrombocytopenia (26.47%) followed by jaundice (25.00%), MODS (14.70%), severe anemia (5.88%), cerebral malaria (5.88%), renal failure (4.41%), bleeding manifestation (2.45%), shock (0.98%) and acute respiratory distress syndrome (ARDS) (0.49%). However, in 2017–18, the clinical spectrum of malaria complications caused by both species has changed. Relative to P. falciparum infections, P. vivax individual complications like thrombocytopenia (51.78%) (p<0.001) followed by jaundice (19.13%) (p<0.001) and severe anemia (4.22%) (p<0.05) were found to have increased significantly. Interpretation & conclusion: Over the last decade there is an apparent spatial and temporal shift in the clinical manifestations of severe malaria caused by the both Plasmodium species. As evident from the patient’s data from 2007–08 and 2017–18, the severity is more inclined towards Plasmodium vivax than Plasmodium falciparum malaria. Moreover, individual P. falciparum-associated complications were decreased significantly in the Bikaner region of Rajasthan, India

Manejo clínico-terapéutico de la malaria grave

La malaria representa un grave problema de salud pública en el país, por su morbilidad y mortalidad. Es importante conocer la patogenia y las manifestaciones clínicas de la malaria grave, en especial revisar el ciclo biológico del parásito, ya que la enfermedad comienza con la ruptura del esquizonte maduro, siendo las primeras manifestaciones clínicas: fiebre y anemia. La infección por Plasmodium falciparum es más severa y es mediada por el fenómeno de secuestro en la microvasculatura venosa profunda, mientras que Plasmodium vivax causa una enfermedad debilitante, rara vez mortal, pero en oportunidades se presentan manifestaciones graves que causan la muerte del paciente. Malaria grave se define por la presencia de signos clínicos y de laboratorio de disfunción de órganos vitales como sistema nervioso central, riñón, gastrointestinal, vías respiratorias y alteraciones hemodinámicas; la cual requiere el rápido reconocimiento de la enfermedad y del grado de severidad. Se debe hacer un manejo de índole general y prestar especial atención a la terapia antimalárica oportuna con Artesunato, primera línea en malaria grave, o Arthemeter o Quinina con Clindamicina según los protocolos nacionales e internacionales, para lograr una evolución satisfactoria. En consecuencia, es un reto enfrentar esta entidad y obliga a la constante actualización en las diferentes opciones cónsonas con las diferentes especies de Plasmodium patógeno.

Malaria represents a serious public health problem in the country, due to its morbidity and mortality. It is of most importance to know the pathogenesis and clinical manifestations of severe malaria, particularly to review the biological cycle of the parasite. The disease begins with the rupture of the mature schizont, with the first clinical manifestations being fever and anemia. Plasmodium falciparum infection is more severe and is mediated by the phenomenon of sequestration in the deep venous microvasculature, while Plasmodium vivax causes a debilitating disease, rarely fatal, but sometimes serious manifestations occur that cause the death of the patient. Severe malaria is defined by the presence of clinical and laboratory signs of dysfunction of vital organs such as the central nervous system, kidney, gastrointestinal, respiratory tract, and pathological hemodynamic changes that requires rapid disease recognition and degree of severity. General management and timely antimalarial therapy with Artesunate, first line in severe malaria, or Arthemeter, or Quinine with Clindamycin following national and international protocols, achieve a favorable outcome. Consequently, it is a challenge to face this entity and requires constant updating in the different options consistent with the different species of pathogenic Plasmodium.

Malaria cerebral con pancitopenia por plasmodium vivax en la amazonía peruana: reporte de caso / Plasmodium vivax cerebral malaria with pancytopenia in the peruvian amazon: case report

RESUMEN Plasmodium vivax es la especie más común en la Amazonía peruana y ocasiona el 81% del total de casos de malaria. Presentamos el caso de un paciente adulto varón con malaria cerebral por Plasmodium vivax, que inicia con malestar general y fiebre, luego presenta convulsiones más de dos veces al día con pérdida de consciencia y limitación funcional motora. Se le realiza gota gruesa donde se observa trofozoítos de Plasmodium vivax y depresión de las tres series sanguíneas. Se inicia tratamiento con artesunato y clindamicina por cinco días, se le transfunde un paquete globular, y continua con primaquina por siete días. El paciente muestra mejoría clínica con secuela neurológica en extremidad inferior izquierda.

ABSTRACT Plasmodium vivax causes 81% of all malaria cases and is the most common species in the Peruvian Amazon. We present the case of a male patient with cerebral malaria caused by Plasmodium vivax, who had general malaise and fever, and then presented seizures more than twice a day with loss of consciousness and motor functional limitation. Plasmodium vivax trophozoites were detected by thick blood smear, besides, we also observed low counts of all three blood cell types. Treatment began with artesunate and clindamycin for five days, then one unit of packed red blood cells was transfused; treatment continued with primaquine for seven days. The patient showed clinical improvement with neurological sequelae in one lower limb.

Validación de un puntaje pronóstico para malaria complicada / Validation of a prognostic score for complicated malaria

Introducción: El reconocimiento temprano de los sujetos con malaria que pueden desarrollar complicaciones es fundamental para orientar el tratamiento. Se requiere un instrumento de predicción basado en características clínicas para predecir las complicaciones. Objetivo: Desarrollar y validar una herramienta de predicción clínica y paraclínica para predecir malaria complicada. Métodos: Se reclutaron de manera secuencial sujetos con diagnóstico de malaria complicada según criterios de la Organización Mundial de la Salud. Las características clínicas que se asociaron a malaria complicada fueron identificadas e incorporadas en un modelo de predicción logístico binario en una cohorte inicial de derivación y posteriormente validadas en una cohorte diferente de sujetos con la infección. Resultados: Se analizaron 584 sujetos en la cohorte de derivación y 898 en la cohorte de validación. La incidencia de malaria complicada fue de 21,2 por ciento y 10,9 por ciento, respectivamente. Las variables asociadas con malaria complicada fueron la disnea, fiebre por más de 72 horas, hemoglobina < 13 mg/dL, bilirrubina total > 6 mg/dL, nitrógeno ureico > 20 mg/dL, y Plasmodium vivax. El área bajo la curva de características operativas del receptor para el puntaje construido con estas variables en la cohorte de derivación fue de 0,70 y en la cohorte de validación fue de 0,69. Conclusión: Un puntaje pronóstico en pacientes con malaria que evalúe la presencia de disnea, fiebre persistente, nivel de hemoglobina, bilirrubina total, nitrógeno ureico e infección por P. vivax puede ser útil para clasificar de manera oportuna y objetiva a los sujetos que pueden desarrollar complicaciones(AU)

Introduction: Early identification of subjects with malaria who may develop complications is critical to guide treatment. A predictive tool based on the clinical characteristics of the disease is required to predict complications. Objective: To develop and validate a clinical and paraclinical tool to predict complicated malaria. Methods: Subjects with a diagnosis of complicated malaria according to the World Health Organization criteria were sequentially recruited. Clinical characteristics associated with complicated malaria were identified and incorporated into a binary logistic prediction model in an initial derivation cohort and, subsequently, validated in a different cohort of subjects with the infection. Results: 584 subjects were analyzed in the derivation cohort and 898 in the validation cohort. The incidence of complicated malaria was 21.2 percent and 10.9 percent, respectively. Variables associated with complicated malaria were dyspnea, fever for more than 72 hours, hemoglobin < 13 mg/dL, total bilirubin > 6 mg/dL, urea nitrogen > 20 mg/dL and Plasmodium vivax. The area under the receiver operating characteristics curve for the score constructed with these variables in the derivation cohort was 0.70 and in the validation cohort, it was 0.69. Conclusion: A prognostic score that evaluates the presence of dyspnea, persistent fever, hemoglobin level, total bilirubin, urea nitrogen and P. vivax infection in patients with malaria may be useful to classify in a timely and objective manner subjects who may develop complications(AU)

Prevalencia de malaria gestacional en Ecuador / Prevalence of gestational malaria in Ecuador

Introducción. La malaria gestacional, definida como la presencia de Plasmodium spp. en sangre periférica materna o el hallazgo del parásito en la placenta, es considerada un importante problema de salud pública en las regiones tropicales y subtropicales. Objetivo. Determinar la frecuencia de casos de malaria gestacional diagnosticados en Ecuador entre 2015 y 2018. Materiales y métodos. Se hizo un estudio descriptivo, retrospectivo y transversal. Resultados. Se determinaron 46 casos de malaria gestacional en el período evaluado, 25 por Plasmodium falciparum y 21 por Plasmodium vivax, siendo el 2018 el año con más casos. En cuanto a las variables de edad y trimestre de gestación, prevalecieron en el grupo de 20 a 29 años (46 %) y en el segundo trimestre (37 %). Solo se observó una diferencia significativa entre los casos por año y la especie parasitaria. Conclusión. La malaria gestacional en Ecuador ha aumentado en los últimos cinco años, por lo que es importante informar a las mujeres en estado de gravidez sobre las medidas preventivas para evitar el contagio con el parásito, dadas las graves consecuencias que conlleva para ellas y sus hijos.

Introduction: Gestational malaria, defined as the presence of Plasmodium spp. in maternal peripheral blood or in the placenta, is considered an important public health problem in tropical and subtropical regions. Objective: To determine the frequency of gestational malaria cases diagnosed in Ecuador between 2015 and 2018. Materials and methods: We conducted a descriptive, retrospective, and cross-sectional study. Results: There were 46 cases of gestational malaria between 2015 and 2018: 25 caused by Plasmodium falciparum and 21 by Plasmodium vivax. The year with the most cases in this period was 2018. The age group most affected was 20 to 29 years old with 21 cases (46%). Prevalence was found to be highest in the second trimester of pregnancy with 17 cases (37%). A significant difference was only observed between cases per year and parasitic species. Conclusion: The prevalence of gestational malaria in Ecuador increased in the last five years. Therefore, it is important to inform pregnant women about preventive measures to avoid infection given its serious consequences both for the mother and her unborn child.

Prevalencia de malaria en Aguarico, comunidad de la Amazonía ecuatoriana / Malaria prevalence in Aguarico, a community in the Ecuadorian Amazon

Objetivo. Determinar el estado actual de la prevalencia de Plasmodium en pacientes febriles que acuden al Hospital Básico Franklin Tello Nuevo Rocafuerte, cantón Aguarico, comparando con los datos de otros estudios epidemiológicos de la misma zona y la frontera con el vecino país de Perú. Métodos. Se realizó un estudio observacional descriptivo, retrospectivo de prevalencia. Desde 2011-2015 se recogieron 2.668 muestras de sangre capilar correspondientes al 55,04% de la población total del cantón Aguarico. Se empleó la técnica Gota Gruesa y Frotis coloreados con Giemsa para determinar positividad de Plasmodium. Resultados. El rango de variación de la prevalencia en los pobladores de las comunidades investigadas osciló entre 2,38% y 28,57%, detectándose mayor prevalencia en el sexo masculino (50,56 %). Estos hallazgos son similares a los estudios previos realizados entre 1992-1995, en la misma región del Aguarico. El Riesgo Relativo es (RR) es de 1,36 y el Odds Ratio (OR) fue de 1,71, siendo mayor el riesgo a desarrollar la enfermedad en los positivos. Conclusiones. Los datos de la investigación confirman la presencia de un foco autóctono de malaria producida por Plasmodium vivax en la selva amazónica ecuatoriana, excepto 2 casos de P. falciparum importados de Perú. Los casos diagnosticados clínicamente y mediante la técnica de la Gota Gruesa, fueron tratados con medicación antipalúdica con excelente adherencia al medicamento.

Objective. To determine the status of the prevalence of Plasmodium in febrile patients who attend the Franklin Tello Nuevo Rocafuerte Basic Hospital, Aguarico town, comparing the results obtained with data from other epidemiological studies in the same area, and places near the border with Peru. Methods. A descriptive, retrospective, observational study of prevalence was carried out. From 2011-2015 2,668 capillary blood samples were collected corresponding to 55.04% of the total population of the Aguarico town. The Thick Drop and Giemsa-stained smear technique was used to determine Plasmodium positivity. Results. The range of variation of the prevalence in the inhabitants of the investigated communities ranged between 2.38% and 28.57%, detecting a higher prevalence in males (50.56%). These findings are like previous studies carried out between 1992-1995, in the same Aguarico region. The Relative Risk (RR) is 1.36 and the Odds Ratio (OR) was 1.71, with the risk of developing the disease being greater in the positives. Conclusions. The research data confirm the presence of an autochthonous focus of malaria produced by Plasmodium vivax in the Ecuadorian Amazon rainforest, except for 2 cases of P. falciparum imported from Peru. The cases diagnosed clinically and using the thick gout technique were treated with antimalarial medication with excellent adherence to the medication.

Electrochemical immunosensor for detection of Plasmodium vivax lactate dehydrogenase

BACKGROUND Malaria is a disease that affects many tropical and subtropical countries, including Brazil. The use of tests for malaria detection is one of the fundamental strategies recommended by the World Health Organization for the control and eradication of the disease. The lack of diagnostic tests leads to an increase in transmission and non-reporting cases. OBJECTIVES This work described an electrochemical immunosensor for detecting Plasmodium vivax lactate dehydrogenase antigen (Ag-PvLDH). METHODS The device has developed by immobilising egg yolk IgY antibodies (Ab-PvLDH) on a gold electrode surface using cysteamine as linker. The immunosensor fabrication was followed by differential pulse voltammetry, and contact angle measurements were performed to characterise the modified gold electrode surface. FINDINGS The results for Ag-PvLDH determination exhibit a linear response at 10-50 µg mL-1 concentration range, with a limit of detection of 455 ng mL-1. The excellent selectivity of the device was confirmed. MAIN CONCLUSIONS The developed immunosensor showed a good performance, therefore, it can be considered an alternative test to detect malaria caused by P. vivax.

Prevalence and force of Plasmodium vivax blood-stage infection and associated clinical malaria burden in the Brazilian Amazon

BACKGROUND Understanding the epidemiology of malaria through the molecular force of the blood-stage infection of Plasmodium vivax (molFOB) may provide a detailed assessment of malaria transmission. OBJECTIVES In this study, we investigated risk factors and spatial-temporal patterns of incidence of Plasmodium infection and clinical malaria episodes in three peri-urban communities of Manaus, Western Brazilian Amazon. METHODS Monthly samples were collected in a cohort of 1,274 individuals between April 2013 and March 2014. DNA samples were subject to Plasmodium species. molFOB was calculated by counting the number of genotypes observed on each visit, which had not been present in the preceding two visits and adjusting these counts by the respective times-at-risk. FINDINGS Respectively, 77.8% and 97.2% of the population remained free of P. vivax and P. falciparum infection. Expected heterozygosity for P. vivax was 0.69 for MSP1_F3 and 0.86 for MS2. Multiplicity of infection in P. vivax was close to the value of 1. The season was associated with P. vivax positivity [adjusted hazard ratio (aHR) 2.6 (1.9-5.7)] and clinical disease [aHR 10.6 (2.4-47.2)]. P. falciparum infection was associated with previous malarial episodes [HR 9.7 (4.5-20.9)]. Subjects who reported possession of a bed net [incidence rate ratio (IRR) 1.6 (1.2-2.2)] or previous malaria episodes [IRR 3.0 (2.0-4.5)] were found to have significantly higher P. vivax molFOB. MAIN CONCLUSIONS Overall, P. vivax infection prevailed in the area and infections were mostly observed as monoclonal. Previous malaria episodes were associated with significantly higher P. vivax molFOB.

An algorithm based on molecular protocols to improve the detection of Plasmodium in autochthonous malarial areas in the Atlantic Forest biome

ABSTRACT Malaria is the most important vector-borne disease in the world and a challenge for control programs. In Brazil, 99% of cases occur in the Amazon region. In the extra-Amazonian region, a non-endemic area, epidemiological surveillance focuses on imported malaria and on autochthonous outbreaks, including cases with mild symptoms and low parasitemia acquired in the Atlantic Forest biome. In this scenario, cases are likely to be underreported, since submicroscopic parasitemias are not detected by thick blood smear, considered the reference test. Molecular tests are more sensitive, detecting asymptomatic individuals and mixed infections. The aim of this study was to propose a more efficient alternative to detect asymptomatic individuals living in areas of low malaria endemicity, as they are reservoirs of Plasmodium that maintain transmission locally. In total, 955 blood samples from residents of 16 municipalities with autochthonous malaria outbreaks in the Sao Paulo State were analyzed; 371 samples were collected in EDTA tubes and 584 in filter paper. All samples were initially screened by a genus-specific qPCR targeting ssrRNA genes (limit of detection of 1 parasite/µL). Then, positive samples were subjected to a nested PCR targeting ssrRNA and dihydrofolate reductase-thymidylate synthase genes (limit of detection of 10 parasites/µL) to determine Plasmodium species. The results showed a statistically significant difference (K = 0.049; p < 0.0001) between microscopy positivity (6.9%) and qPCR (22.9%) for EDTA-blood samples. Conversely, for samples collected in filter paper, no statistical difference was observed, with 2.6% positivity by thick blood smear and 3.1% for qPCR (K = 0.036; p = 0.7). Samples positive by qPCR were assayed by a species-specific nested PCR that was in turn positive in 26% of samples (16 P. vivax and 4 P. malariae ). The results showed that molecular protocols applied to blood samples from residents in areas with autochthonous transmission of malaria were useful to detect asymptomatic patients who act as a source of transmission. The results showed that the genus-specific qPCR was useful for screening positives, with the subsequent identification of species by nested PCR. Additional improvements, such as standardization of blood plotting on filter paper and a more sensitive protocol for species determination, are essential. The qPCR-based algorithm for screening positives followed by nested PCR will contribute to more efficient control of malaria transmission, offering faster and more sensitive tools to detect asymptomatic Plasmodium reservoirs.

Clinically silent Plasmodium vivax infections in native Amazonians of northwestern Brazil: acquired immunity or low parasite virulence?

BACKGROUND Malaria remains common among native Amazonians, challenging Brazil′s elimination efforts. OBJECTIVES We examined the epidemiology of malaria in riverine populations of the country′s main hotspot - the upper Juruá Valley in Acre state, close to the Brazil-Peru border, where Plasmodium vivax accounts for > 80% of cases. METHODS Participants (n = 262) from 10 villages along the Azul River were screened for malaria parasites by microscopy and genus-specific, cytochrome b (cytb) gene-based polymerase chain reaction. Positive samples were further tested with quantitative TaqMan assays targeting P. vivax- and P. falciparum-specific cytb domains. We used multiple logistic regression analysis to identify independent correlates of P. vivax infection. FINDINGS Microscopy detected only one P. vivax and two P. falciparum infections. TaqMan assays detected 33 P. vivax infections (prevalence, 11.1%), 78.1% of which asymptomatic, with a median parasitaemia of 34/mL. Increasing age, male sex and use of insecticide-treated bed nets were significant predictors of elevated P. vivax malaria risk. Children and adults were similarly likely to remain asymptomatic once infected. MAIN CONCLUSIONS Our findings are at odds with the hypothesis of age-related clinical immunity in native Amazonians. The low virulence of local parasites is suggested as an alternative explanation for subclinical infections in isolated populations.

Prevalence of antifolate drug resistance markers in Plasmodium vivax in China / 医学前沿

The dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes of Plasmodium vivax, as antifolate resistance-associated genes were used for drug resistance surveillance. A total of 375 P. vivax isolates collected from different geographical locations in China in 2009-2019 were used to sequence Pvdhfr and Pvdhps. The majority of the isolates harbored a mutant type allele for Pvdhfr (94.5%) and Pvdhps (68.2%). The most predominant point mutations were S117T/N (77.7%) in Pvdhfr and A383G (66.8%) in Pvdhps. Amino acid changes were identified at nine residues in Pvdhfr. A quadruple-mutant haplotype at 57, 58, 61, and 117 was the most frequent (57.4%) among 16 distinct Pvdhfr haplotypes. Mutations in Pvdhps were detected at six codons, and the double-mutant A383G/A553G was the most prevalent (39.3%). Pvdhfr exhibited a higher mutation prevalence and greater diversity than Pvdhps in China. Most isolates from Yunnan carried multiple mutant haplotypes, while the majority of samples from temperate regions and Hainan Island harbored the wild type or single mutant type. This study indicated that the antifolate resistance levels of P. vivax parasites were different across China and molecular markers could be used to rapidly monitor drug resistance. Results provided evidence for updating national drug policy and treatment guidelines.

Sistemas de expresión de proteínas recombinantes para el análisis funcional de antígenos de Plasmodium falciparum y Plasmodium vivax: una revisión / Recombinant Protein Expression Systems for Functional Analysis of Plasmodium falciparum and Plasmodium vivax Antigens: A Review / Sistemas de expressão de proteínas recombinantes para o analise funcional de antígenos de Plasmodium falciparum e Plasmodium vivax: uma revisão

Introducción: Para diseñar vacunas es necesario comprender la función de los antígenos de Plasmodium spp. in-volucrados en la invasión a células hospederas. Diferentes investigaciones han generado proteínas recombinantes utilizando sistemas de expresión heterólogos y así han obtenido moléculas semejantes a las nativas. Con estos avances se desarrollan estrategias que bloquean la infección de estos patógenos. Objetivo: Describir las características y los aspectos metodológicos más importantes de los sistemas de expresión de las proteínas recombinantes en estudios funcionales de Plasmodium spp. Metodología: Revisión descriptiva de estudios publicados en Pubmed, Science Direct, Embase y Medline, entre 2010 y 2020, que incluyeran sistemas recombinantes en células de Escherichia coli, de mamífero y sistemas libres de células, para estudios funcionales de antígenos de Plasmodium falciparum y Plasmodium vivax. Se revisaron 70 artículos originales y 58 cumplieron con los criterios establecidos. Resultados: Obtener proteínas recombinantes mediante un sistema procariota, de mayor rendimiento y bajo costo, ha permitido estudiar un número importante de antígenos. Los sistemas con células de mamífero y libres de células, que permiten modificaciones postraduccionales y plegamiento adecuado de moléculas, se usan para producir librerías de antígenos con estructura conformacional similar a la nativa. Conclusión: El estudio de los antígenos de Plasmodium spp. implicados en la infección y desarrollo de células diana requiere una adecuada selección del método de producción recombinante. El refinamiento de procesos de expresión en sistemas procariotas, eucariotas e in vitro, mediante ingeniería genética y cultivo celular, permitirá mejores rendimientos y menor costo.

Introduction: Understanding the function of Plasmodium spp. Antigens involved in invasion of host cells is necessary to design vaccines. Different studies have generated recombinant proteins using heterologous expression systems, obtaining molecules similar to native ones. These advances are es-sential to develop strategies that block the infection of these pathogens. Objective: Describe the most important characteristics and methodological aspects of recombinant protein expression systems in functional studies of Plasmodium spp. Methodology: Descriptive review of studies published in Pubmed, Science Direct, Embase and Medline, between 2010 and 2020, that included recombinant systems in Escherichia coli cells, mam-malian and cell-free, for functional studies of Plasmodium falciparum and Plasmodium vivax antigens. 70 original articles were reviewed, 58 met the established criteria. Results: Obtaining recombinant proteins by means of a prokaryotic system, with higher performance and low cost, has allowed functional studies of a significant number of antigens. Mammalian cell and cell free systems, which allow for post-translational modifications and adequate folding of molecules, are used to produce antigen libraries with native-like conformational structure. Conclusion:Plasmodium spp. antigen study involved in infection and development in target cells, re-quires adequate selection of the recombinant production method. The refinement of expression pro-cesses in prokaryotic, eukaryotic and in vitro systems, through genetic engineering and cell culture, will allow better yields and lower cost

Introdução: Para desenvolver vacinas, é necessário entender a função dos antígenos de Plasmodium spp. envolvidos na invasão das células hospedeiras. As pesquisas têm gerado proteínas recombinan-tes utilizando sistemas de expressão heterólogos para obter moléculas similares às nativas. Com estes avanços, estratégias que bloqueiam a infecção destes patógenos estão sendo desenvolvidas. Objetivo: Descrever as características mais importantes e aspectos metodológicos dos sistemas de expressão de proteínas recombinantes em estudos funcionais de Plasmodium spp. Metodologia: Revisão descritiva dos estudos publicados em Pubmed, Science Direct, Embase e Medline, entre 2010 e 2020, que incluíram sistemas recombinantes em células de Escherichia coli, de mamífero e sistemas livres de células, para estudos funcionais dos antígenos de Plasmodium fal-ciparum e Plasmodium vivax. Setenta artigos originais foram revisados e 58 preenchiam os critérios estabelecidos. Resultado: A obtenção de proteínas recombinantes usando um sistema procariótico, com maior rendimento e baixo custo, permitiu o estudo de um número significativo de antígenos. Sistemas de células mamíferas e sem células, que permitem modificações pós-tradução e dobramento adequado das moléculas, são usados para produzir bibliotecas de antígenos com uma estrutura semelhante à nativa. Conclusão: O estudo dos antígenos Plasmodium spp. envolvidos na infecção e no desenvolvimento das células-alvo requer uma seleção adequada do método de produção recombinante. O refinamento dos processos de expressão em sistemas procarióticos, eucarióticos e in vitro, através da engenharia genética e da cultura celular, permitirá melhores rendimentos e menores custos.