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.

Bibliometric analysis of researches on the Plasmodium falciparum repetitive interspersed families of polypeptides protein from 1993 to 2022 / 中国血吸虫病防治杂志

Objective To perform a bibliometric analysis of researches on the Plasmodium falciparum repetitive interspersed families of polypeptides (RIFIN) protein from 1993 to 2022 and identify the hot topics in the RIFIN protein research, so as to provide insights into future researches on RIFIN protein. Methods RIFIN protein-associated publications were retrieved in the Web of Science Core Collection from 1993 to 2022 and all bibliometric analyses were performed using the software CiteSpace 6.2.4.0. The annual number of RIFIN protein-associated publications was analyzed from 1993 to 2022, and country, author and institution collaboration networks were created. Keywords were extracted from RIFIN protein-associated publications for plotting keyword co-occurrence, clustering, burst and timeline maps to identify the hot topics in the RIFIN protein research. Results A total of 745 English RIFIN protein-associated publications were included in the final bibliometric analysis, and there were 18 to 36 publications each year from 1993 to 2022. The top three countries with the highest activity in the RIFIN protein research included the United States, the United Kingdom and France, universities and research institutes were highly active in the RIFIN protein research; however, no authors were identified with a high activity in the RIFIN protein research. There were three keyword clusters in the RIFIN protein-associated publications, including repetitive DNA sequence, molecular epidemiology and antigenic variation. Keyword co-occurrence, burst and timeline analyses showed that previous RIFIN protein-associated publications mainly focused on gene properties and functions, involving keywords of repetitive DNA sequence and evolution, and recent hot topics for the RIFIN protein research shifted to genetic diversity and immune response, involving keywords of genetic diversity, antigenic variation and binding. Conclusions The annual number of RIFIN protein-associated publications was relatively stable from 1993 to 2022. This bibliometric analysis may provide insights into future researches on the RIFIN protein.

Plasmodium falciparum malaria with acute abdominal pain as the first symptom: a case report / 中国血吸虫病防治杂志

Plasmodium falciparum malaria, caused by Plasmodium falciparum infection, is an Anopheles mosquito-transmitted infectious diseases, which predominantly occurs in tropical areas of Africa. P. falciparum malaria is characterized by complex and atypical clinical manifestations, and high likelihood of misdiagnosis and missing diagnosis, and may be life-threatening if treated untimely. This case report presents the diagnosis and treatment of a P. falciparum malaria case with acute abdominal pain as the first symptom.

While the priest climbs a post, the devil climbs ten: major biological threats from parasite and vector to malaria control and elimination / 中国血吸虫病防治杂志

Malaria is one of the most serious mosquito-borne infectious diseases in the world. The global malaria control progress has stalled in recent years, which is largely due to the biological threats from the malaria pathogen Plasmodium and the vector Anopheles mosquitoes. This article provides an overview of biological threats to global malaria elimination, including antimalarial drug resistance, deletions in the malaria rapid diagnostic test target P. falciparum histidine-rich protein 2/3 (Pfhrp2/3) genes, vector insecticide resistance and emergence of invasive vector species, so as to provide insights into malaria and vector research and the formulation and adjustment of the malaria control and elimination strategy.

Worldwide distribution, symptoms and diagnosis of the coinfections between malaria and arboviral diseases: a systematic review

The coinfection between malaria (ML) and arboviral diseases represents a major global public health problem, particularly in tropical and subtropical countries. Despite its relevance, this topic is still insufficiently discussed in the current literature. Here, we aimed to investigate the worldwide distribution, symptoms, and diagnosis during coinfection between ML and arboviral diseases. We conducted a systematic review following the Preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement and assessed the selection and eligibility criteria, created and diagrammed maps, and analysed major symptoms with 95% confidence intervals (CI) using prevalence ratio and effect size, also performing latent class analysis. A total of 85,485 studies were retrieved, of which 56 were included: 57.14% in Asia, 25% in Africa, 14.30% in South America, and 3.56% in Europe. A total of 746 individuals were reported to be coinfected with Plasmodium and arbovirus. Concurrent ML, Dengue (DEN), Chikungunya (CHIK), and Zika (ZIK) patients are more likely to present headache and skin rash. Regarding diagnosis, 58,253 were made, of which 38,176 were positive (ML and at least one arboviral disease). The magnitude of these pathogens' coexistence points out the pressing need for improvements in public health policies towards diagnosis and prevention of both diseases, especially in endemic areas.

Challenging diagnosis of Plasmodium ovale malaria in a Colombian traveler: the importance of including P. ovale wallikeri in molecular screening

ABSTRACT This study reports a challenging diagnosis of Plasmodium ovale malaria in a Colombian citizen returning from Cameroon. Initial microscopy screenings conducted at two private hospitals yielded conflicting results, with the first showing negative smears and the second diagnosing P. vivax. Subsequent microscopy examinations at two government laboratories identified P. ovale, although the routine species-specific PCR strategy was negative. PCR confirmation was finally obtained when P. ovale wallikeri primers were used. Although P. ovale is not frequently found in Colombia, there is a clear need to include both P. ovale curtisi and P. ovale wallikeri in the molecular diagnostic strategy. Such need stems primarily from their extended latency period, which affects travelers, the increasing number of African migrants, and the importance of accurately mapping the distribution of Plasmodium species in Colombia.

Changes in the endemic-epidemic pattern of malaria in Colombia, 1978-2021

ABSTRACT Background: Malaria is a major global public health issue with varying epidemiologies across countries. In Colombia, it is a priority endemic-epidemic event included in the national public health policy. However, evidence demonstrating nationwide variations in the disease behavior is limited. This study aimed to analyze changes in the levels and distribution of endemic-epidemic malaria transmission in the eco-epidemiological regions of Colombia from 1978 to 1999 and 2000 to 2021. Methods: We conducted a comprehensive time-series study using official secondary data on malaria-associated morbidity and mortality in Colombia from 1978 to 2021. Temporal-spatial and population variables were analyzed, and the absolute and relative frequency measures of general and regional morbidity and mortality were estimated. Results: We observed an 18% reduction in malaria endemic cases between the two study periods. The frequency and severity of the epidemic transmission of malaria varied less and were comparable across both periods. A shift was observed in the frequency of parasitic infections, with a tendency to match and increase infections by Plasmodium falciparum. The risk of malaria transmission varied significantly among the eco-epidemiological regions during both study periods. This study demonstrated a sustained decrease of 78% in malarial mortality. Conclusions: Although the endemic components of malaria decreased slightly between the two study periods, the epidemic pattern persisted. There were significant variations in the risk of transmission across the different eco-epidemiological regions. These findings underscore the importance of targeted public health interventions in reducing malarial morbidity and mortality rates in Colombia.

Characterisation of the merozoite thrombospondin related anonymous protein (MTRAP) of Plasmodium berghei as a transmission-blocking antigen

BACKGROUND Malaria is an infectious disease caused by protozoan parasites belonging to the genus Plasmodium. Human-to-human transmission depends on a mosquito vector; thus, the interruption of parasite transmission from humans to mosquitoes is an important approach in the fight against malaria. The parasite stages infectious to mosquitoes are the gametocytes, sexual stages that are ingested by the vector during a blood meal and transform into male and female gametes in the midgut. Immunity against sexual stage antigens expressed by gametocytes, gametes, and the zygote formed after fertilisation can interrupt the parasite sexual cycle in the mosquito. This transmission blocking immunity is mediated by specific antibodies ingested during the mosquito blood feed, inhibiting the parasite development in the midgut. Merozoite thrombospondin related anonymous protein (MTRAP) is a merozoite and gametocyte surface protein essential for gamete egress from erythrocytes and for parasite transmission to mosquitoes. OBJECTIVES Here, we evaluated the potential of the P. berghei MTRAP to elicit antibodies with the ability to inhibit gamete fertilisation in vitro. METHODS We expressed a soluble recombinant PbMTRAP and used it to immunise BALB/c mice. The transmission blocking activity of the anti-rPbMTRAP antibodies was tested through in vivo challenge experiments followed by in vitro conversion assays. FINDINGS Immunisations with the rPbMTRAP induced a strong antibody response and the antibodies recognised the native protein by Western Blot and IFA. Anti-rPbMTRAP present in the blood stream of immunised mice partially inhibited gamete conversion into ookinetes. CONCLUSION Our results indicate that antibodies to PbMTRAP may reduce but are not sufficient to completely block transmission.

Aspectos clínico-epidemiológicos en pacientes con malaria grave del Hospital Municipal de Cuimba, Angola / Clinical-epidemiological aspects of severe malaria in patients at the Municipal Hospital of Cuimba, Angola / Aspectos clínico-epidemiológicos da malária grave em pacientes do Hospital Municipal do Cuimba, Angola

Introducción: El Plasmodium falciparum es el causante de más del 90 porciento de los casos de malaria en el mundo. Objetivo: Describir aspectos clínico-epidemiológicos de pacientes con malaria grave, atendidos en el Hospital Municipal de Cuimba, provincia de Zaire, República de Angola. Método: Estudio observacional, descriptivo, de corte transversal y retrospectivo, durante el periodo comprendido entre enero-junio de 2023, en pacientes con diagnóstico de malaria grave. El universo fue conformado por 452 pacientes positivos de malaria, la muestra quedó conformada por 97 pacientes que desarrollaron malaria grave. Se estudiaron variables asociadas como: anemia severa, convulsiones, hiperparasitemia, entre otras. Resultados: La media de edad fue de 14,8 años, el 43,3 porciento menor de cinco años, con predominio del sexo masculino (53,9 porciento). El Plasmodium falciparum estuvo presente en 59 casos (60,8 porciento), con elevadas tasas de parasitemia. Las manifestaciones de disfunción cerebral en asociación con la anemia severa resultaron estar en el cuadro clínico del 31 porciento de los pacientes. El 40,2 porciento de los enfermos no presentó complicaciones en su estadía hospitalaria. El síndrome de dificultad respiratoria aguda (18,6 porciento) fue la complicación más frecuente que sobrellevó al fallecimiento del 12,4 porciento de los pacientes. El artesunato fue usado en 77,3 porciento de los pacientes. Conclusiones: El paludismo representa un problema de salud en el Hospital Municipal de Cuimba, con mayor frecuencia en los menores de cinco años. Prevalece la infección por Plasmodium falciparum en pacientes con anemia severa.(AU)

Introduction: Plasmodium falciparum is responsible for more than 90 percent of malaria worldwide. Objective: Characterization of Clinical-epidemiological aspects of severe malaria in patients treated at the Municipal Hospital of Cuimba, Zaire, Angola. Method: An observational, descriptive, cross-sectional and retrospective study was conducted, during the period January - June 2023, in patients reported with severe malaria. The study involved a total of 452 patients with positive malaria but only 97 of them, who presented a complication of severe malaria, were selected as sample. The variables used were as follow: severe anemia, convulsions, hyperparasitemia, among others. Results: Male sex was predominant, with an average age of 14.8 percent and 43.3 percent of patients under five years of age. Plasmodium falciparum was found in 59 patients (60.8 percent) with a high parasitaemia prevalence. Manifestations of cerebral dysfunction in association with severe anemia were found in the clinical picture of 31 percent of patients. The 40.2 percent of patients had no complications in admission period. Acute Respiratory Distress Syndrome was the most frequent complication (18.6 percent), and it was the leading cause of death in 12.4 percent of patients. Artesunate was used in 77.3 percent of patients. Conclusions: Malaria is a health problem in Municipal Hospital of Cuimba, with a higher incidence in children under five years of age; Plasmodium falciparum infection prevailed in patients with severe anemia.(AU)

Introdução: O Plasmodium falciparum é responsável por mais de 90 porcento da malária em todo o mundo. Objetivo: Caracterização dos aspectos clínico-epidemiológicos da malária grave em pacientes atendidos no Hospital Municipal de Cuimba, Zaire, Angola. Método: Foi realizado um estudo observacional, descritivo, transversal e retrospetivo, durante o período de janeiro a junho de 2023, em doentes notificados com malária grave. O estudo envolveu um total de 452 doentes com malária positiva, mas apenas 97 deles, que apresentavam uma complicação de malária grave, foram seleccionados como amostra. As variáveis utilizadas foram as seguintes: anemia grave, convulsões, hiperparasitemia, entre outras. Resultados: O sexo masculino foi predominante, com uma idade média de 14,8 anos e 43,3 porcento dos doentes com menos de cinco anos de idade. O Plasmodium falciparum foi encontrado em 59 doentes (60,8 porcento) com uma elevada prevalência de parasitemia. Manifestações de disfunção cerebral em associação com anemia grave foram encontradas no quadro clínico de 31 porcento dos doentes. Os 40,2 porcento dos doentes não tiveram complicações no período de admissão. A Síndrome de Angústia Respiratória Aguda foi a complicação mais frequente (18,6 porcento) e foi a principal causa de morte em 12,4 porcento dos doentes. O artesunato foi utilizado em 77,3 porcento dos doentes. Conclusões: A malária é um problema de saúde em Hospital Municipal de Cuimba, com uma maior incidência em crianças com menos de cinco anos de idade; a infeção por Plasmodium falciparum prevaleceu em pacientes com anemia grave.(AU)

Caracterización molecular del dominio de la hélice del gen k13 de Plasmodium falciparum en muestras de comunidades nativas de Condorcanqui, Amazonas, Perú / Molecular characterization of the Plasmodium falciparum k13 gene helix domain in samples from native communities of Condorcanqui, Amazonas, Perú

Introducción. La resistencia de Plasmodium falciparum a diferentes fármacos antipalúdicos es un obstáculo para eliminar la enfermedad. El genotipo resistente de P. falciparum a la artemisinina puede evaluarse examinando los polimorfismos en el dominio de la hélice del gen Pfk13. La Organización Mundial de la Salud recomienda utilizar estas mutaciones como marcadores moleculares para detectar la resistencia a la artemisinina en países donde la malaria por P. falciparum es endémica. Objetivo. Identificar mutaciones relacionadas con la resistencia a artemisinina presentes en el dominio de la hélice del gen k13 de P. falciparum. Materiales y métodos. Mediante la detección pasiva de casos, se recolectaron 51 muestras positivas por microscopía para Plasmodium, provenientes de seis comunidades del distrito de Río Santiago en Condorcanqui, Amazonas. Se realizó la confirmación molecular de la especie mediante PCR en tiempo real y el dominio de la hélice del gen Pfk13 se amplificó y secuenció por electroforesis capilar. Las secuencias obtenidas se compararon con la cepa de referencia 3D7 de fenotipo silvestre. Resultados. Se confirmó un total de 51 muestras positivas para P. falciparum, provenientes de las comunidades de Ayambis, Chapiza, Palometa, Muchinguis, Alianza Progreso y Caterpiza. Después del alineamiento de las secuencias de ADN, se determinó que las muestras no presentaron mutaciones asociadas con resistencia en el gen K13. Discusión. Los resultados obtenidos son coherentes con estudios similares realizados en otros países de Sudamérica, incluyendo Perú. Estos datos proporcionan una línea base para la vigilancia molecular de resistencia a artemisinina en la región Amazonas y refuerzan la eficacia de la terapia combinada con artemisinina en esta área.

Introduction. Resistance of Plasmodium falciparum to different antimalarial drugs is an obstacle to disease elimination. The artemisinin-resistant genotype of P. falciparum can be assessed by examining polymorphisms in the helix domain of the Pfk13 gene. The World Health Organization recommends these mutations as molecular markers to detect artemisinin-resistant in countries where P. falciparum malaria is endemic. Objective. To identify artemisinin resistance-related mutations present in the helix domain of the P. falciparum k13 gene. Materials and methods. We collected a total of 51 samples through passive case detection, positive for Plasmodium by microscopy, from six communities in the district of Río Santiago in Condorcanqui, Amazonas. Molecular species confirmation was performed by real-time PCR and Pfk13 helix domain was amplified and sequenced by capillary electrophoresis. The obtained sequences were compared with the wild type 3D7 reference strain. Results. A total of 51 positive samples were confirmed for P. falciparum from the communities of Ayambis, Chapiza, Palometa, Muchinguis, Alianza Progreso and Caterpiza. DNA sequences alignment showed the absence of resistance-associated mutations in the k13 gene of the collected samples. Discussion. The obtained results are consistent with similar studies conducted in other South American countries, including Perú, so these data provide a baseline for artemisinin- resistance molecular surveillance in the Amazon region and reinforce the efficacy of artemisinin-based combination therapy in this area.

Perfil de notificações de malária em gestantes de Oiapoque, Amapá / Profile of malaria reports in pregnant women from Oiapoque, Amapá / Perfil de notificaciones de malaria en gestantes de Oiapoque, Amapá

Objetivo: caracterizar as notificações de malária em gestantes no município de Oiapoque. Método: estudo documental, descritivo, retrospectivo e com abordagem quantitativa, realizado a partir de dados secundários do Sistema de Vigilância Epidemiológica da Malária em Oiapoque-Amapá, Brasil, no período de 2013 a 2017. Abordam-se as seguintes variáveis de casos autóctones de malária em gestantes: ano, mês de ocorrência, idade gestacional, espécie infectante de Plasmodium e unidade de notificação. Os dados foram apresentados e analisados mediante estatística descritiva e formulação de mapas de distribuição espacial, gerados pelo software ArcGIS. Resultados: predominaram notificações em áreas urbanas, especialmente no bairro Paraíso (74%), sendo o Plasmodium vivax o principal agente (88%), e de maior incidência entre outubro a dezembro (33%), no terceiro trimestre gestacional (35%). Conclusão: o perfil de notificações de malária em gestante desse munícipio assemelha-se a estudos anteriores nessa região quanto ao local de concentração e período de maior ocorrência. No entanto, a introdução gradativa do protozoário Plasmodium falciparum traz um alerta para a mobilização de gestores e profissionais.

Objective: to characterize the notifications of malaria in pregnant women in the municipality of Oiapoque. Method: documentary, descriptive, retrospective and quantitative study, conducted from secondary data of the Epidemiological Surveillance System of Malaria in Oiapoque-Amapá, Brazil, from 2013 to 2017. The following variables of autochthonous cases of malaria in pregnant women are addressed: year, month of occurrence, gestational age, Plasmodium infecting species and notification unit. Data were presented and analyzed using descriptive statistics and formulation of spatial distribution maps, generated by ArcGIS software. Results: notifications predominated in urban areas, especially in the Paraíso neighborhood (74%), with Plasmodium Vivax being the main agent (88%), and with a higher incidence between October and December (33%), in the third gestational quarter (35%). Conclusion: the profile of reports of malaria in pregnant women of this municipality resembles previous studies in this region, regarding the place of concentration and period of greater occurrence. However, the gradual introduction of the protozoan Plasmodium falciparum brings an alert to the mobilization of managers and professionals.

Detection and species determination of malaria parasites by microscopy, antigen detection, polymerase chain reaction, and loop-mediated isothermal amplification assay in a tertiary care hospital

Background: Malaria is a major health issue in tropical and subtropical areas. Out of all subtypes, Plasmodium falciparum (Pf) is the most dangerous form accounting for high mortality and morbidity. It is transmitted by infected female anopheles mosquitoes and infected blood transfusions. Aims and Objectives: The aim of the study is to establish correct diagnosis by direct microscopy, Immunochromatographic test (ICT), and molecular studies. Materials and Methods: This prospective study was conducted in the PG Department of Microbiology, SCB Medical College, Cuttack. Thick blood smears were drawn and then stained with Leishman’s stain to visualize falciparum rings. DNA was extracted from infected blood samples by phenol chloroform method with some modification as described by Sambrook and Russel for molecular analysis. Results: In the present study, 150 cases of malaria were analyzed. The male: female ratio was 1.7:1 and age ranged from 0 to 56 years. The Plasmodium vivax positivity was compared with thin smear to 21 (84%) in ICT, 100% both polymerase chain reaction (PCR) and loop mediated isothermal amplification assay (LAMP) assays followed by the Pf positivity as 76 (92.7%) in ICT, 82 (100%) both PCR and LAMP assays, respectively. The results obtained were statistically significant with P < 0.001. The PCR and LAMP showed 100% response to specificity and positive predictive value. Conclusion: The present study established the role of molecular tests such as PCR and LAMP are highly specific for diagnosis of Plasmodium species whereas they are more or less similar in sensitivity as compared to other diagnostic methods such as ICT and microscopy.

Molecular detection of drug-resistant Plasmodium falciparum mutants in Assam

Background & objectives: The spread of drug-resistant Plasmodium falciparum ( Pf) poses a serious threat to the control and elimination of malaria. The objective of this study was to detect the molecular biomarkers of antimalarial drug resistance in Pf in patients visiting a tertiary care hospital in Assam. Methods: Malaria was first detected in fever cases using microscopy and a rapid diagnostic test (RDT), and then confirmed using PCR. Pf chloroquine resistance transporter (Pfcrt), Pf multidrug resistance-1 (Pfmdr-1), and single-nucleotide polymorphisms linked to delayed parasite clearance after treatment with artemisinin MAL 10-688956 and MAL 13-1718319 and Kelch-13 propeller (PfK-13) genes were evaluated by PCR-restriction fragment length polymorphism (RFLP). Results: Sixty nine cases of malaria were found among 300 cases of fever. Of these, 54 were positive for Pf, 47 of which were confirmed by PCR. Pfcrt-K76T mutation was seen in 96.6 per cent and Pfmdr1-N86Y mutation in 84.2 per cent of cases. Mutation was not detected in MAL10 and MAL13 genes. Sequence analysis of Kelch-13 gene showed the presence of a novel mutation at amino acid position 675. Statistically, no significant association was found between the molecular biomarkers and demographic profile, clinical presentation and outcome of the cases. Interpretation & conclusions: Molecular surveillance is essential to assess the therapeutic efficacy of the drugs against circulating Pf isolates in Assam which are found to be highly resistant to CQ. The role of the new mutation found in the Kelch-13 gene in the development of artemisinin resistance in Assam needs to be thoroughly monitored in future research.

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.

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.

Analysis laboratory results of three cases of COVID-19 complicated with falciparum malaria / 中国热带医学

@#Abstract: Objective　To analyze the laboratory indexes of patients infected with malaria patients and COVID-19, so as to provide reliable evidence for the diagnosis of mixed infection of both. Methods　The routine clinical laboratory items such as routine blood, biochemistry and lymphocyte subsets were tested in three cases of COVID-19 complicated with falciparum malaria who admitted to Guangzhou Eighth People's Hospital Affiliated to Guangzhou Medical University from July to December 2020 were tested. Laboratory data were stage-wise analyzed in conjunction with changes in the course of disease. Results　Three patients confirmed COVID-19 infection recruited all had malaria infection history. Fever, headache, and other symptoms emerged on the 4rd to 11th day after admission. Malaria parasite was detected by malaria parasite antigen testing and blood smear testing, and all three patients had re-ignition of malaria after being confirmed COVID-19 infection. In the early stage of malaria relapse, lymphocytes decreased, CRP and SAA increased, and gradually returned to normal level after antimalarial treatment. Interestingly, we only found one patient at the initial stage of malaria detection showed PLT decreased, no other unnormal changes in other routine blood results (WBC, ESO) and liver function results (ALT, AST, GGT, TBIL, DBIL, CG) were found from the beginning to end course of the disease. Conclusion　COVID-19 infection may promote the resurgence of malaria, so the relapse of malaria should be monitored especially for the patient with malaria infection history who begin to develop fever and other symptoms a few days after the diagnosis of COVID-19. The inflammatory indicators would be worth able as an auxiliary judgment basis for the effective treatment of the two combined infection.

Research progress on stable gene transfection methods of Plasmodium falciparum / 中国热带医学

@#Abstract: Transfection of Plasmodium falciparum is helpful to study the function of its genes, such as drug resistance. However, transgenic manipulation has been very challenging, mainly due to the high A/T base sequence structure (A+T content of about 82%) and low transfection efficiency of the Plasmodium genome. Electroporation-based transfection of Plasmodium falciparum has been successfully applied in the study of certain genes, and electroporation by preloading is currently the preferred method for introducing foreign DNA into Plasmodium falciparum. The site-directed editing of Plasmodium genes mostly adopts the method of two-plasmid transfection. It is generally believed that successful transfection of Plasmodium requires a large amount of high-purity plasmid DNA and an accurate transfection system. In addition to the evaluation of the current commonly used electrotransfection methods, this paper also introduces a new transfection method, namely lyse-reseal erythrocytes for transfection (LyRET). This paper also review the role of factors such as plasmid DNA concentration, the use of transfection reagents, the setting of transfection parameters, the addition of fresh red blood cells, and the markers of successful transfection in improving the success rate and efficiency of Plasmodium transfection, in the hope of providing a reference for study in this field.

Investigation of genetic diversity of Plasmodium knowlesi kelch13-propeller region in Sabah, Malaysia

Aims@#The kelch13 gene mutations of Plasmodium falciparum is associated with delayed parasite clearance after artemisinin-based combination therapy (ACT). It is unclear for P. knowlesi that is predominantly reported in Sabah. Therefore, this study aims to analyse the diversity of the P. knowlesi kelch13 gene in five divisions of Sabah. @*Methodology and results: @#Ninety-five blood samples infected with P. knowlesi were obtained. The DNA of P. knowlesi samples was extracted and the kelch13 gene was amplified. The amplicons were cloned and sequenced. The sequencing data were aligned and analysed using MEGA 11 and DnaSP v6 software. A phylogenetic tree was constructed using the Neighbour-joining approach, which showed a diverse clade of P. knowlesi in Sabah, with a nucleotide diversity (π) of 0.451 and a haplotype diversity of 0.947. The deduced amino acid sequences were classified into 14 haplotypes, providing evidence of distinct P. knowlesi lineages in Sabah. When compared to P. falciparum, the kelch13 sequences of P. knowlesi exhibited a higher π of 0.490 and haplotype diversity of 1.000, and similar mutations that conferred drug resistance to ACT in P. falciparum were detected in P. knowlesi in this study. @*Conclusion, significance and impact of study: @#The kelch13 gene of P. knowlesi isolates in Sabah has high nucleotide and haplotype diversities. Additionally, mutations conferring drug resistance to ACT in P. falciparum were identified in P. knowlesi in Sabah. The findings in this study can be used to better understand the emergence of drug resistance of P. knowlesi in Sabah.

Heterologous expression and purification of calmodulin from Plasmodium knowlesi using codon-optimized synthetic gene

Aims@#Calmodulin (CaM) is vital for the survival of Plasmodium knowlesi, a simian malaria parasite that infects both macaques and humans in Southeast Asia. To advance antimalarial drugs development targeting this protein, it is imperative to produce ample quantities of pure CaM for further research. Hence, this study aims to establish a robust strategy for the heterologous expression and purification of CaM from Plasmodium knowlesi (Pk-CaM). @*Methodology and results@#First, we optimised the gene sequence of Pk-CaM for Escherichia coli expression, chemically synthesised it and integrated it into the pET28a plasmid. The optimised gene displayed a 45.15% GC content and a 0.81 codon-adaptation index, making it highly compatible with E. coli. Pk-CaM expression was assessed under various conditions, with the best results achieved at a post-induction temperature of 20 °C for 16 h, yielding a fully soluble protein. Subsequently, we purified the protein using Ni2+-NTA affinity chromatography and size-exclusion chromatography (SEC), obtaining 15 mg from 1 L of culture. The folding properties of purified Pk-CaM were analysed using far-UV circular dichroism (CD) spectroscopy, revealing a predominance of helical structures, both with and without Ca2+ ions. Binding to Ca2+ ions induced structural changes, increasing the helical content compared to when Ca2+ ions were absent. @*Conclusion, significance and impact of study@#The optimal conditions for the recombinant expression and purification of Pk-CaM in a correctly folded and functional form were successfully established in this study. This achievement provides a solid foundation for conducting further comprehensive research in the pursuit of novel antimalarial drugs.

Inhibition properties of collagen hydrolysates against FKBP35 of Plasmodium knowlesi

Aim@#FK506-binding protein 35 from Plasmodium knowlesi (Pk-FKBP35), a member of peptidyl-prolyl cis-trans isomerase (PPIase), is considered a viable target for the development of the novel antimalarial drug targeting zoonotic malaria in Malaysia. While FK506 effectively inhibits this protein, this drug is not applicable due to its immunosuppressive effects. This study aims to assess the inhibitory potential of different collagen hydrolysates (CH) against Pk-FKBP35, as FK506 replacers.@*Methodology and results@#Recombinant full-length Pk-FKBP35 was initially over-expressed using Escherichia coli (BL21) host cells and subsequently purified via affinity chromatography coupled with size-exclusion chromatography. In this study, four distinct CH were employed, originating from bovine, bone broth, fish and swine. The results revealed that all CH inhibited PPIase catalytic activity of Pk-FKBP35 with IC50 values 1.63 mg/mL (bovine CH), 2.97 mg/mL (fish CH), 33.01 mg/mL (swine CH) and 13.91 mg/mL (bone broth CH), which were much higher than that of FK506. Furthermore, these CHs retained the ability of Pk-FKBP35 to inhibit calcineurin phosphatase activity, yet not as extreme as FK506. @*Conclusion, significance and impact of study@#The inhibition is predicted due to the presence of proline-rich peptides in CH, which were able to block the substrate binding cavity of Pk-FKBP35. This study suggested that CH might have no serious immunosuppressant effect and is promising for further harnessing for antimalarial compounds