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1.
Infect Dis Poverty ; 9(1): 21, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-32046780

RESUMO

BACKGROUND: Plasmodium falciparum malaria is endemic in the southern sahelian zone of Mauritania where intense internal and trans-border human and livestock movement occurs. The risk of importation and spread of drug-resistant parasites need to be regularly assessed in this region. The objective of the study was to assess the recent malaria situation near the Mauritania-Mali border. METHODS: Between February 2015 and December 2017, patients with fever or history of fever during the previous 48 h, presenting at the health centre of Kobeni city, were screened for malaria using a rapid diagnostic test (RDT) and microscopic examination of blood smears. The diagnosis was later confirmed by PCR. Cohen's kappa statistics was used to estimate the degree of agreement between diagnostic methods. Fisher's exact test was used to compare proportions. The odds ratio was calculated to measure the association between the use of bed nets and malaria infection. RESULTS: A total of 2326 febrile patients (mean age, 20.2 years) were screened for malaria. The presence of malaria parasites was detected by RDT and microscopy in 53.0% and 49.3% of febrile patients, respectively, and was confirmed by PCR in 59.7% (45 missing data). Of 1361 PCR-positive samples, 1205 (88.5%) were P. falciparum, 47 (3.5%) P. vivax, and 99 (7.3%) P. falciparum-P. vivax mixed infection. Malaria transmission occurred mostly during and shortly after the rainy season. The annual rainfall was relatively low in 2016 (267 mm) and 2017 (274 mm), compared to 2015 (448 mm), and coincided with a decline in malaria prevalence in 2016-2017. Although 71.8% of febrile patients reported to possess at least one bed net in the household in our questionnaire, its reported use was not protective against malaria infection (odds ratio: 1.1, 95% CI: 0.91-1.32). CONCLUSIONS: Our study confirmed that P. falciparum is the dominant species in the sahelian zone and that malaria transmission is seasonal and associated with rainfall in this zone. The application of the current national policy based on rapid and reliable malaria diagnosis, case management with artemisinin-based combination therapy, intermittent preventive treatment for pregnant women, distribution and use of long-lasting insecticide impregnated bed nets, and the planned introduction of seasonal malaria chemoprevention for all children under 6 years old is expected to sustainably reduce malaria transmission in this zone.


Assuntos
Antimaláricos/uso terapêutico , Malária Falciparum/epidemiologia , Malária Vivax/epidemiologia , Adolescente , Artemisininas/uso terapêutico , Criança , Pré-Escolar , Coinfecção/diagnóstico , Coinfecção/tratamento farmacológico , Coinfecção/epidemiologia , Testes Diagnósticos de Rotina/métodos , Quimioterapia Combinada , Feminino , Humanos , Malária Falciparum/diagnóstico , Malária Falciparum/tratamento farmacológico , Malária Vivax/diagnóstico , Malária Vivax/tratamento farmacológico , Masculino , Mauritânia/epidemiologia , Plasmodium falciparum/isolamento & purificação , Plasmodium vivax/isolamento & purificação , Estações do Ano
2.
J Ethnopharmacol ; 247: 112270, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31589965

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Primates forage on a variety of plant parts to balance their dietary intake to meet requirements of energy, nutrition and maintenance, however the reason(s) leading them to ingest some plants which have no nutritional value and/or contain bioactive or even toxic secondary metabolites is recently gaining closer attention. The growing literature suggests that primates consume plants for medicinal purposes (self-medication) as well, particularly when infected with parasites and pathogens (bacteria, viruses, microbes). Interestingly, some of the plants they consume are also used by humans for similar purposes or may have potential uses for humans. MATERIALS AND METHODS: As part of a 16-month study of the parasite ecology of a sub-species of Japanese macaques (Macaca fuscata yakui) on the island of Yakushima, we surveyed their feeding habits and collected a subset of plants and plant parts observed being ingested by macaques. The ethnomedicinal value of these plants was surveyed and methanolic extracts of 45 plant parts were tested in vitro against important parasites of humans, including four protozoan parasites Plasmodium falciparum, Trypanosoma brucei rhodesiense, T. cruzi and Leishmania donovani, and the trematode flatworm Schistosoma mansoni. Potential toxicity of the extracts was also assessed on mammalian cells. RESULTS: A wide range of ethnomedicinal uses in Asia for these plants is noted, with 37% associated with the treatment of parasites, pathogens and related symptoms. Additionally, the 45 extracts tested showed broad and significant activity against our test organisms. All extracts were active against T. b. rhodesiense. The majority (over 80%) inhibited the growth of P. falciparum and L. donovani. Half of the extracts also displayed antiprotozoal potential against T. cruzi while only several extracts were active against both larval and adult stages of S. mansoni. Cytotoxicity was generally low, although several extracts lacked specific toxicity to test parasites. CONCLUSIONS: Our results indicated a number of plants and their parts to have antiparasitic activity not previously reported in the ethnopharmacological literature. Enhanced understanding of the primate diets, particularly during periods of intensified parasite infection risk may help to further narrow down plants of interest for lead compound development. The study of animal self-medication is a complementary approach, with precedence, to drug discovery of new lead drug compounds against human parasitic diseases.


Assuntos
Anti-Helmínticos/farmacologia , Antiprotozoários/farmacologia , Extratos Vegetais/farmacologia , Plantas Medicinais/química , Infecções Protozoárias em Animais/tratamento farmacológico , Esquistossomose mansoni/tratamento farmacológico , Animais , Anti-Helmínticos/uso terapêutico , Antiprotozoários/uso terapêutico , Etnofarmacologia , Comportamento Alimentar , Feminino , Ilhas , Japão , Leishmania donovani/efeitos dos fármacos , Leishmania donovani/isolamento & purificação , Masculino , Medicina Tradicional/métodos , Testes de Sensibilidade Parasitária , Extratos Vegetais/uso terapêutico , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/isolamento & purificação , Infecções Protozoárias em Animais/parasitologia , Schistosoma mansoni/isolamento & purificação , Esquistossomose mansoni/parasitologia , Esquistossomose mansoni/veterinária , Automedicação/veterinária , Testes de Toxicidade , Trypanosoma brucei rhodesiense/isolamento & purificação , Trypanosoma cruzi/efeitos dos fármacos , Trypanosoma cruzi/isolamento & purificação
3.
BMC Infect Dis ; 19(1): 1025, 2019 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-31795967

RESUMO

BACKGROUND: Treatment for severe malaria must be prompt with effective parenteral antimalarial drugs for at least 24 h to achieve fast parasite clearance, and when the patient can tolerate oral therapy, treatment should be completed with effective artemisinin based combination therapy (ACT) for complete parasite clearance and to prevent recrudescence. We evaluated piperaquine concentration and malaria treatment outcomes among Ugandan children treated for severe malaria with intravenous artesunate (AS) or quinine (QN) plus dihydroartemisinin-piperaquine (DP), in Tororo District Hospital in Eastern Uganda. METHODS: Capillary blood piperaquine concentration data were obtained from a randomized clinical trial whose objective was to evaluate parasite clearance, 42-day parasitological treatment outcomes and safety, following treatment of severe malaria with intravenous AS or QN, plus artemether-lumefantrine or DP among children in Tororo District Hospital, in Eastern Uganda. RESULTS: Piperaquine concentration data from 150 participants who received DP were analyzed. Participants with unadjusted treatment failure had lower median day 7 capillary piperaquine concentration than those with treatment success (34.7 (IQR) (17.9-49.1) vs 66.7 (IQR) (41.8-81.9), p < 0.001), and lower than the recommended day 7 cut off level of 57 ng/mL. There was no difference in median capillary piperaquine concentrations among participants with re-infection and recrudescence (35.3 (IQR) (17.9-55.2) vs 34.8 (IQR) (18.1-45.1), p = 0.847). The risk of treatment failure was two times higher among children with low (< 57 ng/mL) day 7 capillary piperaquine concentration (relative risk: 2.1 CI 1.4-3.1), p < 0.001) compared to children with high day 7 capillary piperaquine concentrations (> 57 ng/mL). CONCLUSION: Considering the low day 7 concentrations of piperaquine reported in the patients studied here, we suggest to adopt the recently recommended higher dose of DP in young children or a prolonged 5-day dosing in children living in malaria endemic areas who have suffered an initial episode of severe malaria in order to achieve adequate drug exposures for effective post-treatment prophylactic effects. TRIAL REGISTRATION: The study was registered with the Pan African Clinical Trial Registry (PACTR201110000321348). Registered 7th October 2011.


Assuntos
Antimaláricos/uso terapêutico , Artemisininas/uso terapêutico , Artesunato/uso terapêutico , Malária Falciparum/tratamento farmacológico , Quinina/uso terapêutico , Quinolinas/sangue , Quinolinas/uso terapêutico , Administração Intravenosa , Antimaláricos/administração & dosagem , Artemisininas/administração & dosagem , Artesunato/administração & dosagem , Pré-Escolar , Feminino , Seguimentos , Humanos , Lactente , Malária Falciparum/parasitologia , Masculino , Concentração Osmolar , Plasmodium falciparum/isolamento & purificação , Quinina/administração & dosagem , Quinolinas/administração & dosagem , Recidiva , Resultado do Tratamento , Uganda
4.
Malar J ; 18(1): 354, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31690321

RESUMO

BACKGROUND: CareStart™ malaria HRP2/pLDH (Pf/pan) combo test is one of the several rapid diagnostic tests (RDT) approved for diagnosis of malaria at the point of care in Tanzania. However, there are limited studies on the diagnostic performance of RDT after wide scale use in primary health care facilities in Tanzania. Therefore, this study was carried out to determine the diagnostic performance of RDT when compared with blood smear (BS) microscopy as a reference standard. METHODS: A cross-sectional study was conducted between March and August 2019 at Kibiti Health Centre, Pwani region, Tanzania. Blood samples for malaria tests were collected from patients with malaria symptoms. Diagnostic performance parameters of RDT, i.e. sensitivity, specificity, positive and negative likelihood ratios (LR+/-), diagnostic accuracy and predictive values were determined using contingency table. An agreement between RDT and microscopy was statistically determined by Cohen's kappa test. RESULTS: Of 980 patients screened, 567 (57.9%) were found to be malaria positive by RDT, whereas 510 patients (52%) were positive by microscopy. Of the 510 microscopy-positive patients, 487 (95.5%) were infected with Plasmodium falciparum. The geometric mean parasite density was 2921parasites/µl, whereas majority (68.6%) of patients had parasite density greater than 10,000/µl. The sensitivity, specificity, positive and negative predictive values of CareStart™ were 99.8%, 87.6%, 89.8%, and 99.8%, respectively. The LR+ and LR- were 8.0 and 0.002, respectively. The diagnostic accuracy was 0.5. There was a strong agreement between the results obtained using CareStart™ and BS microscopy (kappa = 0.863, P < 0.0001). CONCLUSION: CareStart™ malaria HRP2/pLDH (Pf/pan) had high sensitivity and strong agreement with microscopy results. However, moderate specificity of RDT resulted in a substantial number of patients with false positive malaria test. Wherever available, microscopy should be used to confirm RDT test results.


Assuntos
Testes Diagnósticos de Rotina/métodos , Malária Falciparum/diagnóstico , Microscopia/métodos , Adolescente , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Lactente , Masculino , Plasmodium falciparum/isolamento & purificação , Sistemas Automatizados de Assistência Junto ao Leito , Sensibilidade e Especificidade , Tanzânia , Adulto Jovem
5.
Pan Afr Med J ; 34: 30, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31762898

RESUMO

Introduction: Placental malaria (PM) is an important predictor of infant morbidity and mortality in sub-Saharan Africa. Although placental histology is the gold standard test to diagnose PM, the placenta impression smears remains widely used in epidemiological studies. This study is set to evaluate the performance of placental impression smears to detect PM in pregnant women in southern Benin. Methods: A cross-sectional analysis was performed on data collected in the framework a multicenter randomized clinical trial (Malaria in Pregnancy Preventive and Alternative Drugs). Samples from 491 pregnant women were examined in the district of Allada, Southern Benin. Plasmodium falciparum infections have been assessed in placental blood and placental biopsy. Results: Placental malaria detected by placenta impression smears and histology were prevalent in 11.4% and 10.8%, respectively. Sensitivity and specificity of placental impression smears were 90.6% and 98.4%. Among 55 pregnant women tested positive by placenta impression smears, 48 were positive by the histology, while 7 were negative (positive predictive value: 87.3%). Four hundred and twenty four (424) of the 429 tested negative by the placenta impression smears, were also negative according to histology whereas the rest (5 of 429) of the women were positive (negative predictive value: 98.8%). Conclusion: Placenta impression smear is an accurate and easy method for the diagnosis of placental malaria.


Assuntos
Malária Falciparum/diagnóstico , Doenças Placentárias/diagnóstico , Plasmodium falciparum/isolamento & purificação , Complicações Parasitárias na Gravidez/diagnóstico , Adulto , Benin , Biópsia , Estudos Transversais , Feminino , Humanos , Doenças Placentárias/parasitologia , Valor Preditivo dos Testes , Gravidez , Sensibilidade e Especificidade , Adulto Jovem
6.
Nat Commun ; 10(1): 4512, 2019 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-31586047

RESUMO

Plasmodium species are frequently host-specific, but little is currently known about the molecular factors restricting host switching. This is particularly relevant for P. falciparum, the only known human-infective species of the Laverania sub-genus, all other members of which infect African apes. Here we show that all tested P. falciparum isolates contain an inactivating mutation in an erythrocyte invasion associated gene, PfEBA165, the homologues of which are intact in all ape-infective Laverania species. Recombinant EBA165 proteins only bind ape, not human, erythrocytes, and this specificity is due to differences in erythrocyte surface sialic acids. Correction of PfEBA165 inactivating mutations by genome editing yields viable parasites, but is associated with down regulation of both PfEBA165 and an adjacent invasion ligand, which suggests that PfEBA165 expression is incompatible with parasite growth in human erythrocytes. Pseudogenization of PfEBA165 may represent a key step in the emergence and evolution of P. falciparum.


Assuntos
Eritrócitos/parasitologia , Especificidade de Hospedeiro/genética , Malária Falciparum/parasitologia , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Animais , Sistemas CRISPR-Cas/genética , Engenharia Celular , Eritrócitos/metabolismo , Evolução Molecular , Mutação da Fase de Leitura , Edição de Genes , Células HEK293 , Humanos , Mutação com Perda de Função , Pan troglodytes/parasitologia , Plasmodium falciparum/isolamento & purificação , Plasmodium falciparum/patogenicidade , Ácidos Siálicos/metabolismo
7.
Malar J ; 18(1): 341, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31590669

RESUMO

BACKGROUND: Epidemiological surveys of malaria currently rely on microscopy, polymerase chain reaction assays (PCR) or rapid diagnostic test kits for Plasmodium infections (RDTs). This study investigated whether mid-infrared (MIR) spectroscopy coupled with supervised machine learning could constitute an alternative method for rapid malaria screening, directly from dried human blood spots. METHODS: Filter papers containing dried blood spots (DBS) were obtained from a cross-sectional malaria survey in 12 wards in southeastern Tanzania in 2018/19. The DBS were scanned using attenuated total reflection-Fourier Transform Infrared (ATR-FTIR) spectrometer to obtain high-resolution MIR spectra in the range 4000 cm-1 to 500 cm-1. The spectra were cleaned to compensate for atmospheric water vapour and CO2 interference bands and used to train different classification algorithms to distinguish between malaria-positive and malaria-negative DBS papers based on PCR test results as reference. The analysis considered 296 individuals, including 123 PCR-confirmed malaria positives and 173 negatives. Model training was done using 80% of the dataset, after which the best-fitting model was optimized by bootstrapping of 80/20 train/test-stratified splits. The trained models were evaluated by predicting Plasmodium falciparum positivity in the 20% validation set of DBS. RESULTS: Logistic regression was the best-performing model. Considering PCR as reference, the models attained overall accuracies of 92% for predicting P. falciparum infections (specificity = 91.7%; sensitivity = 92.8%) and 85% for predicting mixed infections of P. falciparum and Plasmodium ovale (specificity = 85%, sensitivity = 85%) in the field-collected specimen. CONCLUSION: These results demonstrate that mid-infrared spectroscopy coupled with supervised machine learning (MIR-ML) could be used to screen for malaria parasites in human DBS. The approach could have potential for rapid and high-throughput screening of Plasmodium in both non-clinical settings (e.g., field surveys) and clinical settings (diagnosis to aid case management). However, before the approach can be used, we need additional field validation in other study sites with different parasite populations, and in-depth evaluation of the biological basis of the MIR signals. Improving the classification algorithms, and model training on larger datasets could also improve specificity and sensitivity. The MIR-ML spectroscopy system is physically robust, low-cost, and requires minimum maintenance.


Assuntos
Teste em Amostras de Sangue Seco/instrumentação , Malária Falciparum/diagnóstico , Plasmodium falciparum/isolamento & purificação , Espectrofotometria Infravermelho/métodos , Aprendizado de Máquina Supervisionado , Humanos , Modelos Logísticos , Malária Falciparum/sangue , Tanzânia
8.
Malar J ; 18(1): 350, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31619258

RESUMO

BACKGROUND: Malaria elimination requires diagnostic methods able to detect parasite levels well below what is currently possible with microscopy and rapid diagnostic tests. This is particularly true in surveillance of malaria at the population level that includes so-called "asymptomatic" individuals. METHODS: The development of the first ultrasensitive loop mediated amplification method capable of detecting malaria from both whole blood and dried blood spots (DBS) is described. The 18S rRNA and corresponding genes that remain stable on DBS for up to 5 months are targeted. RESULTS: In the case of Plasmodium falciparum, lower limits of detection of 25 parasite/mL and 50-100 parasite/mL from whole blood and DBS were obtained, respectively. A sensitivity of 97.0% (95% CI 82.5-99.8) and specificity of 99.1% (95% CI 97.6-99.7) was obtained for the detection of all species in asymptomatic individuals from Africa and Asia (n = 494). CONCLUSION: This tool is ideally suited for low middle-income countries where malaria is endemic and ultrasensitive surveillance of malaria is highly desirable for elimination.


Assuntos
Teste em Amostras de Sangue Seco , Técnicas de Amplificação de Ácido Nucleico/métodos , Plasmodium falciparum/isolamento & purificação , Testes Diagnósticos de Rotina , Malária Falciparum/prevenção & controle , RNA de Protozoário/análise , RNA Ribossômico 18S/análise , Fatores de Tempo
9.
Korean J Parasitol ; 57(4): 369-377, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31533403

RESUMO

Artemisinin-based combination therapy (ACT) resistance is widespread throughout the Greater Mekong Subregion. This raises concern over the antimalarial treatment in Thailand since it shares borders with Cambodia, Laos, and Myanmar where high ACT failure rates were reported. It is crucial to have information about the spread of ACT resistance for efficient planning and treatment. This study was to identify the molecular markers for antimalarial drug resistance: Pfkelch13 and Pfmdr1 mutations from 5 provinces of southern Thailand, from 2012 to 2017, of which 2 provinces on the Thai- Myanmar border (Chumphon and Ranong), one on Thai-Malaysia border (Yala) and 2 from non-border provinces (Phang Nga and Surat Thani). The results showed that C580Y mutation of Pfkelch13 was found mainly in the province on the Thai-Myanmar border. No mutations in the PfKelch13 gene were found in Surat Thani and Yala. The Pfmdr1 gene isolated from the Thai-Malaysia border was a different pattern from those found in other areas (100% N86Y) whereas wild type strain was present in Phang Nga. Our study indicated that the molecular markers of artemisinin resistance were spread in the provinces bordering along the Thai-Myanmar, and the pattern of Pfmdr1 mutations from the areas along the international border of Thailand differed from those of the non-border provinces. The information of the molecular markers from this study highlighted the recent spread of artemisinin resistant parasites from the endemic area, and the data will be useful for optimizing antimalarial treatment based on regional differences.


Assuntos
Antimaláricos/farmacologia , Artemisininas/farmacologia , Marcadores Genéticos , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/genética , Antimaláricos/administração & dosagem , Antimaláricos/uso terapêutico , Artemisininas/administração & dosagem , Artemisininas/uso terapêutico , Sequência de Bases , DNA de Protozoário/química , Combinação de Medicamentos , Resistência a Medicamentos/genética , Genes MDR/genética , Humanos , Repetição Kelch/genética , Malária Falciparum/sangue , Malária Falciparum/parasitologia , Mutação , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/isolamento & purificação , Reação em Cadeia da Polimerase , Tailândia
10.
Parasit Vectors ; 12(1): 454, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31533794

RESUMO

BACKGROUND: Despite great success in significantly reducing the malaria burden in Viet Nam over recent years, the ongoing presence of malaria vectors and Plasmodium infection in remote forest areas and among marginalised groups presents a challenge to reaching elimination and a threat to re-emergence of transmission. Often transmission persists in a population despite high reported coverage of long-lasting insecticidal nets (LLINs), the mainstay control method for malaria. To investigate what factors may contribute to this, a mixed-methods study was conducted in Son Thai commune, a community in south-central Viet Nam that has ongoing malaria cases despite universal LLIN coverage. A cross-sectional behavioural and net-coverage survey was conducted along with observations of net use and entomological collections in the village, farm huts and forest sites used by members of the community. RESULTS: Most community members owned a farm hut plot and 71.9% of adults aged 18+ years sometimes slept overnight in the farm hut, while one-third slept overnight in the forest. Ownership and use of nets in the village households was high but in the farm huts and forest was much lower; only 44.4% reported regularly using a bednet in the farm and 12.1% in the forest. No primary anopheline species were captured in the village, but Anopheles dirus (s.l.) (n = 271) and An. maculatus (s.l.) (n = 14) were captured as far as 4.5 km away in farm huts and forest. A high proportion of biting was conducted in the early evening before people were under nets. Entomological inoculation rates (EIR) of An. dirus (s.l.) were 17.8 and 25.3 infectious bites per person per year in the outdoor farm hut sites and forest, respectively, for Plasmodium falciparum and 25.3 in the forest sites for P. vivax. CONCLUSIONS: Despite high net coverage in the village, gaps in coverage and access appear in the farm huts and forest where risk of anopheline biting and parasite transmission is much greater. Since subsistence farming and forest activities are integral to these communities, new personal protection methods need to be explored for use in these areas that can ideally engage with the community, be durable, portable and require minimal behavioural change.


Assuntos
Anopheles/crescimento & desenvolvimento , Anopheles/parasitologia , Transmissão de Doença Infecciosa , Malária/transmissão , Plasmodium falciparum/isolamento & purificação , Plasmodium vivax/isolamento & purificação , Animais , Estudos Transversais , Utilização de Equipamentos e Suprimentos/estatística & dados numéricos , Florestas , Humanos , Mosquiteiros , Vietnã/epidemiologia
11.
Malar J ; 18(1): 327, 2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-31547821

RESUMO

BACKGROUND: Different antigens are needed to characterize Plasmodium falciparum infection in terms of seroreactivity and targets for invasion inhibition, in order to guide and identify the proper use of such proteins as tools for the development of serological markers and/or as vaccine candidates. METHODS: IgG responses in 84 serum samples from individuals with P. falciparum infection [classified as symptomatic (Sym) or asymptomatic (Asym)], or acute Plasmodium vivax infection, from the Peruvian Amazon region, were evaluated by enzyme-linked immunosorbent assays specific for a baculovirus-produced recombinant protein P. falciparum Merozoite Surface Protein 10 (rMSP10) and for non-EGF region selected peptides of PfMSP10 selected by a bioinformatics tool (PfMSP10-1, PfMSP10-2 and PfMSP10-3). Monoclonal antibodies against the selected peptides were evaluated by western blotting, confocal microscopy and inhibition invasion assays. RESULTS: Seroreactivity analysis of the P. falciparum Sym- and Asym-infected individuals against rMSP10 showed a higher response as compared to the individuals with P. vivax acute infection. IgG responses against peptide PfMSP10-1 were weak. Interestingly high IgG response was found against peptide PfMSP10-2 and the combination of peptides PfMSP10-1 + PfMSP10-2. Monoclonal antibodies were capable of detecting native PfMSP10 on purified schizonts by western blot and confocal microscopy. A low percentage of inhibition of merozoite invasion of erythrocytes in vitro was observed when the monoclonal antibodies were compared with the control antibody against AMA-1 antigen. Further studies are needed to evaluate the role of PfMSP10 in the merozoite invasion. CONCLUSIONS: The rMSP10 and the PfMSP10-2 peptide synthesized for this study may be useful antigens for evaluation of P. falciparum malaria exposure in Sym and Asym individuals from the Peruvian Amazon region. Moreover, these antigens can be used for further investigation of the role of this protein in other malaria-endemic areas.


Assuntos
Antígenos de Protozoários/análise , Malária Falciparum/diagnóstico , Plasmodium falciparum/isolamento & purificação , Vigilância da População/métodos , Proteínas de Protozoários/análise , Humanos , Peru , Estudos Soroepidemiológicos
12.
Parasitol Int ; 73: 101941, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31442664

RESUMO

Polymerase chain reaction (PCR) is an essential diagnostic method for highly sensitive detection of Plasmodium-infected erythrocytes in patients with malaria. This study compared the performance of filter papers used for the preparation of dried blood spots (DBS) in detecting Plasmodium by PCR. Whole blood spiked with P. falciparum-infected erythrocytes to obtain samples with various levels of parasitemia were applied to Whatman 3MM Chr papers, FTA Cards, or FTA Elute Cards to prepare the DBS. DNA was purified from the DBS using a DNA purification kit and used as the template for nested PCR. In probit analysis, the estimated limit of detection (LoD) was 5.5 parasites/µL blood for Whatman 3MM Chr papers and FTA Cards and 1.6 parasites/µL blood for the FTA Elute Card. This result suggested that the DBS prepared on an FTA Elute Card yield the best template DNA for subsequent high-sensitivity PCR-based detection of P. falciparum-infected erythrocytes. This finding can help improve the accuracy of malarial diagnostic tests.


Assuntos
DNA de Protozoário/análise , Teste em Amostras de Sangue Seco/métodos , Malária Falciparum/diagnóstico , Plasmodium falciparum/isolamento & purificação , Reação em Cadeia da Polimerase/métodos , RNA Ribossômico 18S/análise , Testes Diagnósticos de Rotina/instrumentação , Humanos , Limite de Detecção
13.
Malar J ; 18(1): 262, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31366365

RESUMO

BACKGROUND: The Mindray BC-6800 haematology analyzer (BC-6800) provides a dedicated flag 'Infected RBC' (InR) and the number of InR (InR#)/the permillage of InR (InR‰) in routine blood testing as a screening tool for malaria in endemic areas. This study sought to evaluate the effectiveness of the BC-6800 flag parameter for aiding the diagnosis of malaria. METHODS: A total of 181 samples were tested using the Mindray BC-6800 haematology analyzer, including 117 malaria-infected samples collected from Yunnan, China, and 64 samples from healthy controls. Microscopy examination was conducted as reference when stained thick blood film revealed the presence of malaria parasites identified as Plasmodium vivax and Plasmodium falciparum. The receiver operating characteristic (ROC) curve analysis was developed using Analyse-it v4.92.3. The Kappa value was determined to evaluate the agreement between BC-6800 and light microscopy. RESULTS: The sensitivity of InR‰ generated by BC-6800 for P. vivax and P. falciparum was 88.3 and 24.1%, respectively; specificity of InR‰ for malaria parasites was 84.3 and 84.3%, respectively; positive predictive value and negative predictive value was 89.4 and 82.7% for P. vivax, and 52.8 and 60.3% for P. falciparum. There was a strong correlation between ΔWBC and InR‰ (R2 = 0.9731 for P. vivax and R2 = 0.9757 for P. falciparum). There was also a significant correlation between parasitaemia and InR# in P. vivax-infected samples (R2 = 0.734). InR# was evaluated using ROC curve analysis, the area under the ROC curve is 0.95 with a 95% confidence interval of 0.926 to 0.974, and the cut-off value is 0.01 × 109/L for P. vivax. However, the ring stage and the early trophozoite stage of Plasmodium cannot be detected easily on BC-6800, possibly because of the small size and low nucleic acid content of these stages. CONCLUSIONS: The findings suggest that the flag 'InR' and the parameters 'InR#/InR‰' provided by the BC-6800 haematology analyzer could be used to screen for malaria in a clinical setting.


Assuntos
Análise Química do Sangue/métodos , Sangue/parasitologia , Hematologia/métodos , Malária Falciparum/diagnóstico , Malária Vivax/diagnóstico , Plasmodium falciparum/isolamento & purificação , Plasmodium vivax/isolamento & purificação , Adolescente , Adulto , Idoso , Análise Química do Sangue/instrumentação , Criança , Pré-Escolar , China/epidemiologia , Feminino , Hematologia/instrumentação , Humanos , Malária Falciparum/epidemiologia , Malária Falciparum/parasitologia , Malária Vivax/epidemiologia , Malária Vivax/parasitologia , Masculino , Pessoa de Meia-Idade , Parasitemia/diagnóstico , Parasitemia/epidemiologia , Parasitemia/parasitologia , Prevalência , Curva ROC , Sensibilidade e Especificidade
14.
Malar J ; 18(1): 287, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31455343

RESUMO

BACKGROUND: The human infectious reservoir for malaria consists of individuals capable of infecting mosquitoes. Oocyst prevalence and density are typical indicators of human infectivity to mosquitoes. However, identification of oocysts is challenging, particularly in areas of low malaria transmission intensity where few individuals may infect mosquitoes, and infected mosquitoes tend to have few oocysts. Here, features that differentiate oocysts from other oocyst-like in mosquito midguts are explained and illustrated. In addition, the establishment and maintenance of infrastructure to perform malaria transmission experiments is described. This work may support other initiatives to set up membrane feeding infrastructure and guide oocyst detection in low transmission settings. METHODS: In 2014, an insectary was developed and equipped in Tororo district, Uganda. A colony of Anopheles gambiae s.s. mosquitoes (Kisumu strain) was initiated to support infectivity experiments from participants enrolled in a large cohort study. Venous blood drawn from participants who were naturally infected with malaria parasites was used for membrane feeding assays, using 60-80 mosquitoes per experiment. Approximately 9-10 days after feeding, mosquitoes were dissected, and midguts were stained in mercurochrome and examined by light microscopy for Plasmodium falciparum oocysts and similar structures. In supportive experiments, different staining procedures were compared using in vitro cultured parasites. RESULTS: A stable colony of the Kisumu strain of An. gambiae s.s. was achieved, producing 5000-10,000 adult mosquitoes on a weekly basis. Challenges due to temperature fluctuations, mosquito pathogens and pests were successfully overcome. Oocysts were characterized by: presence of malaria pigment, clearly defined edge, round shape within the mosquito midgut or on the peripheral tissue and always attached to the epithelium. The main distinguishing feature between artifacts and mature oocysts was the presence of defined pigment within the oocysts. CONCLUSIONS: Oocysts may be mistaken for other structures in mosquito midguts. Distinguishing real oocysts from oocyst-like structures may be challenging for inexperienced microscopists due to overlapping features. The characteristics and guidelines outlined here support identification of oocysts and reliable detection at low oocyst densities. Practical advice on sustaining a healthy mosquito colony for feeding experiments is provided. Following the reported optimization, the established infrastructure in Tororo allows assessments of infectivity of naturally infected parasite carriers.


Assuntos
Anopheles/parasitologia , Mosquitos Vetores/parasitologia , Oocistos/isolamento & purificação , Plasmodium falciparum/isolamento & purificação , Animais , Feminino , Humanos , Oocistos/citologia , Oocistos/crescimento & desenvolvimento , Plasmodium falciparum/citologia , Plasmodium falciparum/crescimento & desenvolvimento , Uganda
15.
Malar J ; 18(1): 288, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31455349

RESUMO

BACKGROUND: The Gambia has successfully reduced malaria transmission. The human reservoir of infection could further decrease if malaria-infected individuals could be identified by highly sensitive, field-based, diagnostic tools and then treated. METHODS: A cross-sectional survey was done at the peak of the 2017 malaria season in 47 Gambian villages. From each village, 100 residents were randomly selected for finger-prick blood samples to detect Plasmodium falciparum infections using highly sensitive rapid diagnostic tests (HS-RDT) and PCR. The sensitivity and specificity of the HS-RDT were estimated (assuming PCR as the gold standard) across varying transmission intensities and in different age groups. A deterministic, age-structured, dynamic model of malaria transmission was used to estimate the impact of mass testing and treatment (MTAT) with HS-RDT in four different scenarios of malaria prevalence by PCR: 5, 15, 30, and 60%, and with seasonal transmission. The impact was compared both to MTAT with conventional RDT and mass drug administration (MDA). RESULTS: Malaria prevalence by HS-RDT was 15% (570/3798; 95% CI 13.9-16.1). The HS-RDT sensitivity and specificity were 38.4% (191/497, 95% CI 34.2-42.71) and 88.5% (2922/3301; 95% CI 87.4-89.6), respectively. Sensitivity was the highest (50.9%, 95% CI 43.3-58.5%) in high prevalence villages (20-50% by PCR). The model predicted that in very low transmission areas (≤ 5%), three monthly rounds of MTAT with HS-RDT, starting towards the end of the dry season and testing 65 or 85% of the population for 2 consecutive years, would avert 62 or 78% of malaria cases (over 2 years), respectively. The effect of the intervention would be lower in a moderate transmission setting. In all settings, MDA would be superior to MTAT with HS-RDT which would be superior to MTAT with conventional RDT. CONCLUSION: The HS-RDT's field sensitivity was modest and varied by transmission intensity. In low to very low transmission areas, three monthly rounds per year of MTAT with HS-RDT at 85% coverage for 2 consecutive years would reduce malaria prevalence to such low levels that additional strategies may achieve elimination. The model prediction would need to be confirmed by cluster-randomized trials.


Assuntos
Testes Diagnósticos de Rotina/métodos , Malária Falciparum/diagnóstico , Plasmodium falciparum/isolamento & purificação , Reação em Cadeia da Polimerase/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Estudos Transversais , Feminino , Gâmbia/epidemiologia , Humanos , Lactente , Recém-Nascido , Malária Falciparum/epidemiologia , Masculino , Pessoa de Meia-Idade , Prevalência , Sensibilidade e Especificidade , Adulto Jovem
16.
Science ; 365(6455): 813-816, 2019 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-31439796

RESUMO

Understanding genomic variation and population structure of Plasmodium falciparum across Africa is necessary to sustain progress toward malaria elimination. Genome clustering of 2263 P. falciparum isolates from 24 malaria-endemic settings in 15 African countries identified major western, central, and eastern ancestries, plus a highly divergent Ethiopian population. Ancestry aligned to these regional blocs, overlapping with both the parasite's origin and with historical human migration. The parasite populations are interbred and shared genomic haplotypes, especially across drug resistance loci, which showed the strongest recent identity-by-descent between populations. A recent signature of selection on chromosome 12 with candidate resistance loci against artemisinin derivatives was evident in Ghana and Malawi. Such selection and the emerging substructure may affect treatment-based intervention strategies against P. falciparum malaria.


Assuntos
Antimaláricos/farmacologia , Artemisininas/farmacologia , Resistência a Medicamentos/genética , Malária Falciparum/epidemiologia , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/genética , Antimaláricos/uso terapêutico , Artemisininas/uso terapêutico , Etiópia/epidemiologia , Loci Gênicos , Gana/epidemiologia , Haplótipos , Humanos , Malária Falciparum/tratamento farmacológico , Malaui/epidemiologia , Plasmodium falciparum/isolamento & purificação , Polimorfismo de Nucleotídeo Único , Seleção Genética
17.
Elife ; 82019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31298657

RESUMO

Individual malaria infections can carry multiple strains of Plasmodium falciparum with varying levels of relatedness. Yet, how local epidemiology affects the properties of such mixed infections remains unclear. Here, we develop an enhanced method for strain deconvolution from genome sequencing data, which estimates the number of strains, their proportions, identity-by-descent (IBD) profiles and individual haplotypes. Applying it to the Pf3k data set, we find that the rate of mixed infection varies from 29% to 63% across countries and that 51% of mixed infections involve more than two strains. Furthermore, we estimate that 47% of symptomatic dual infections contain sibling strains likely to have been co-transmitted from a single mosquito, and find evidence of mixed infections propagated over successive infection cycles. Finally, leveraging data from the Malaria Atlas Project, we find that prevalence correlates within Africa, but not Asia, with both the rate of mixed infection and the level of IBD.


Assuntos
Coinfecção/epidemiologia , Coinfecção/parasitologia , Genótipo , Malária Falciparum/epidemiologia , Malária Falciparum/parasitologia , Plasmodium falciparum/classificação , Plasmodium falciparum/genética , África/epidemiologia , Ásia/epidemiologia , Humanos , Plasmodium falciparum/isolamento & purificação , Prevalência , Sequenciamento Completo do Genoma
18.
Sensors (Basel) ; 19(14)2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31295927

RESUMO

The accuracy, reliability, speed and cost of the methods used for malaria diagnosis are key to the diseases' treatment and eventual eradication. However, improvement in any one of these requirements can lead to deterioration of the rest due to their interdependence. We propose an optical method that provides fast detection of malaria-infected red blood cells (RBCs) at a lower cost. The method is based on the combination of deconvolution, topography and three-dimensional (3D) refractive index reconstruction of the malaria-infected RBCs by use of the transport of intensity equation. Using our method, healthy RBCs were identified by their biconcave shape, quasi-uniform spatial distribution of their refractive indices and quasi-uniform concentration of hemoglobin. The values of these optical and biochemical parameters were found to be in agreement with the values reported in the literature. Results for the malaria-infected RBCs were significantly different from those of the healthy RBCs. The topography of the cells and their optical and biochemical parameters enabled identification of their stages of infection. This work introduces a significant method of analyzing malaria-infected RBCs at a lower cost and without the use of fluorescent labels for the parasites.


Assuntos
Eritrócitos/parasitologia , Malária Falciparum/sangue , Microscopia/métodos , Plasmodium falciparum/isolamento & purificação , Humanos , Malária Falciparum/parasitologia , Plasmodium falciparum/patogenicidade
19.
Pathog Glob Health ; 113(4): 158-166, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31296112

RESUMO

Malaria remains a significant public health challenge and is of global importance. Imported malaria is a growing problem in non-endemic areas throughout the world and also in Qatar due to a massive influx of migrants from endemic countries. Antimalarial drug resistance is an important deterrent in our fight against malaria today. Molecular markers mirror intrinsic antimalarial drug resistance and their changes precede clinical resistance. Thus, in the present study, molecular markers of sulphadoxine-pyrimethamine (Pfdhfr and Pfdhps) and artemisinin (PfATPase6 and Pfk13) were sequenced to determine the drug resistance genotypes among 118 imported P. falciparum isolates in Qatar, between 2013 and 2016. All the isolates had mutant Pfdhfr alleles, with either double mutant (51I/108N) (59.3%) or triple mutant (51I, 59R and 108N) (30.6%) genotypes. I164L substitution was not found in this study. In case of Pfdhps, majority of the samples were carriers of either single (S436A/ A437G/ K540E) mutant (47.2%) or double (S436A/K540E, A437G/K540E, K540E/A581G) mutant (39.8%). A single novel point mutation (431V) was observed in the samples originated from Nigeria and Ghana. Polymorphisms in PfATPase6 were absent and only one non-synonymous mutation in Pfk13 was found at codon G453A from a sample of Kenyan origin. High levels of sulphadoxine-pyrimethamine resistance in the present study provide potential information about the spread of antimalarial drug resistance and will be beneficial for the treatment of imported malaria cases in Qatar.


Assuntos
Antiprotozoários/farmacologia , Artemisininas/farmacologia , Doenças Transmissíveis Importadas/parasitologia , Resistência a Medicamentos , Lactonas/farmacologia , Malária Falciparum/parasitologia , Plasmodium falciparum/genética , Pirimetamina/farmacologia , Sulfadoxina/farmacologia , Adulto , Doenças Transmissíveis Importadas/epidemiologia , Combinação de Medicamentos , Monitoramento Epidemiológico , Feminino , Genes de Protozoários , Genótipo , Humanos , Malária Falciparum/epidemiologia , Masculino , Epidemiologia Molecular , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/isolamento & purificação , Catar/epidemiologia , Análise de Sequência de DNA
20.
Korean J Parasitol ; 57(3): 233-242, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31284345

RESUMO

Detailed description of malaria in low transmission areas is crucial for elimination. The current study aimed to provide a comprehensive description for malaria transmission in Jazan, a low transmission district, southwestern Saudi Arabia. Patients at a tertiary care hospital were recruited in our study between August 2016 and September 2018. Malaria diagnosis was performed through a species-specific nested polymerase chain reaction (nested PCR), microscopy and Paramax-3TM rapid detection test (RDT). Malaria was detected in 30 patients by the PCR, with point prevalence of 10.9%. Of these malaria infections, 80% was imported, 26.6% was asymptomatic and 23.3% was sub-microscopic. Malaria was reported throughout the year, with February/March and September/October peaks. Infection was significantly more in males than in females (P=0.01). Likewise, infections were detected more in febrile than in non-febrile patients (P=0.01). Adult aged 15-24 years, fever and travel were identified as high-risk factors. Malaria was primarily attributed to Plasmodium falciparum mono-infections, followed by P. vivax mono-infections and lastly to falciparum/vivax mixed infections accounting 76.6%, 16.6%, and 6.6% of PCR-confirmed malaria cases, respectively. The nested PCR was superior to the smear microscopy (sensitivity 76.6%; specificity 100%) and the RDT (sensitivity 83.3%, specificity 94.2%). The overall percent agreement between microscopy and the RDT was 92.7% (kappa=0.63). High proportion of imported malaria including sub-microscopic and sub-patent cases were described. We suggest that incorporation of molecular tool into the conventional malaria diagnosis is beneficial in Jazan district.


Assuntos
Malária/epidemiologia , Malária/transmissão , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Malária/diagnóstico , Malária/parasitologia , Masculino , Pessoa de Meia-Idade , Plasmodium falciparum/genética , Plasmodium falciparum/isolamento & purificação , Plasmodium falciparum/fisiologia , Plasmodium vivax/genética , Plasmodium vivax/isolamento & purificação , Plasmodium vivax/fisiologia , Reação em Cadeia da Polimerase , Prevalência , Arábia Saudita/epidemiologia , Adulto Jovem
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