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1.
PLoS Pathog ; 19(3): e1011230, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36940219

RESUMO

In Brazil, Leishmania braziliensis is the main causative agent of the neglected tropical disease, cutaneous leishmaniasis (CL). CL presents on a spectrum of disease severity with a high rate of treatment failure. Yet the parasite factors that contribute to disease presentation and treatment outcome are not well understood, in part because successfully isolating and culturing parasites from patient lesions remains a major technical challenge. Here we describe the development of selective whole genome amplification (SWGA) for Leishmania and show that this method enables culture-independent analysis of parasite genomes obtained directly from primary patient skin samples, allowing us to circumvent artifacts associated with adaptation to culture. We show that SWGA can be applied to multiple Leishmania species residing in different host species, suggesting that this method is broadly useful in both experimental infection models and clinical studies. SWGA carried out directly on skin biopsies collected from patients in Corte de Pedra, Bahia, Brazil, showed extensive genomic diversity. Finally, as a proof-of-concept, we demonstrated that SWGA data can be integrated with published whole genome data from cultured parasite isolates to identify variants unique to specific geographic regions in Brazil where treatment failure rates are known to be high. SWGA provides a relatively simple method to generate Leishmania genomes directly from patient samples, unlocking the potential to link parasite genetics with host clinical phenotypes.


Assuntos
Genoma de Protozoário , Leishmaniose Cutânea , Parasitologia , Pele , Genoma de Protozoário/genética , Humanos , Genética Populacional , Pele/parasitologia , Brasil , Leishmaniose Cutânea/parasitologia , Parasitologia/métodos , Leishmania braziliensis/genética
2.
Curr Opin Infect Dis ; 37(5): 357-366, 2024 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-39133581

RESUMO

PURPOSE OF REVIEW: Emerging technologies are revolutionizing parasitology diagnostics and challenging traditional methods reliant on microscopic analysis or serological confirmation, which are known for their limitations in sensitivity and specificity. This article sheds light on the transformative potential of artificial intelligence and molecular assays in the field, promising more accurate and efficient detection methods. RECENT FINDINGS: Artificial intelligence has emerged as a promising tool for blood and stool parasite review, when paired with comprehensive databases and expert oversight result in heightened specificity and sensitivity of diagnoses while also increasing efficiency. Significant strides have been made in nucleic acid testing for multiplex panels for enteric pathogen. Both multiplex and single target panels for Plasmodium , Babesia , filaria, and kinetoplastids have been developed and garnered regulatory approval, notably for blood donor screening in the United States. Additional technologies such as MALDI-TOF, metagenomics, flow cytometry, and CRISPR-Cas are under investigation for their diagnostic utility and are currently in the preliminary stages of research and feasibility assessment. SUMMARY: Recent implementation of artificial intelligence and digital microscopy has enabled swift smear screening and diagnosis, although widespread implementation remains limited. Simultaneously, molecular assays - both targeted and multiplex panels are promising and have demonstrated promise in numerous studies with some assays securing regulatory approval recently. Additional technologies are under investigation for their diagnostic utility and are compelling avenues for future proof-of-concept diagnostics.


Assuntos
Inteligência Artificial , Doenças Parasitárias , Humanos , Doenças Parasitárias/diagnóstico , Técnicas de Diagnóstico Molecular/métodos , Parasitologia/métodos , Sensibilidade e Especificidade
3.
Parasitol Res ; 123(7): 260, 2024 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-38958778

RESUMO

Sauroleishmania spp. comprises one of the four Leishmania subgenera, which has been historically considered a non-pathogenic protozoan of reptiles. However, some strains appear to be transiently infective to mammals, and recent findings have detected these parasites in dogs and humans in areas where leishmaniasis is endemic. Herein, the digestion pattern of PCR-RFLP of the 234 bp-hsp70 fragment was evaluated as a simpler and cheaper tool to distinguish the Sauroleishmania species from the other Leishmania subgenera. As a result, the digestion of the 234 bp-hsp70 fragments with HaeIII produced a banding pattern specific to the four Sauroleishmania strains assessed. This technique could contribute to the identification of Leishmania parasites isolated from sandflies, reptiles, or even mammals in fieldworks as an alternative to the use of laborious and expensive methodologies.


Assuntos
Proteínas de Choque Térmico HSP70 , Leishmania , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Animais , Proteínas de Choque Térmico HSP70/genética , Reação em Cadeia da Polimerase/métodos , Leishmania/genética , Leishmania/classificação , Leishmania/isolamento & purificação , Cães , Humanos , DNA de Protozoário/genética , Parasitologia/métodos , Leishmaniose/parasitologia , Leishmaniose/veterinária , Répteis/parasitologia
4.
BMC Med Educ ; 24(1): 1034, 2024 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-39327560

RESUMO

BACKGROUND: Social media in our networks have been exploited as dynamic learning tools and free platforms. AIMS: The main objective of this study is to determine the impact of VARK learning styles (visual (V), aural (A), read/write (R), and kinesthetic (K)) in enhancing parasitological laboratory skills using social media and various learning theories. METHODS: A research sample of 100 chemists working in Mega Alfa labs underwent online learning of laboratory parasitology skills via Facebook posts and WhatsApp dictated messages for an average of 7 weeks. All posts served various VARK learning styles and were designed based on Zeigarnik's effect (conducting information with tactical breaks), memory storage and retrieval strength theories (repetition of information). Trainees were classified according to their VARK learning style preferences and were evaluated through pre/post-tests. Data on VARK learning styles were summarized using frequency (count) and relative frequency (percentage). Data of pre-test and post-test scores were summarized using mean and standard deviation. T-test was used to compare pre-test and post-test scores. The difference between the pre-test results, the post-test results and the preferred learning style was analyzed using ANOVA with Tukey's post-hoc testing. P-values less than 0.05 were considered statistically significant. RESULTS: In a total of 100 trainees, tri-modal and multimodal learning styles were preferred by 40% and 30% of the trainees respectively; on the contrary, the unimodal and bimodal learning styles were the least preferred. In the trimodal and multimodal groups, the post-test results showed significant increase when compared with the pre-test results. Also, using the ANOVA test and a Tukey's post-hoc comparison, the assemblage of multiple learning styles (tri-modal and multimodal) appeared to significantly improve the learning performance in the post-test results when compared with the unimodal and bimodal groups. CONCLUSION: The tri-modal and multimodal learning styles were found to influence the acquirement of the laboratory parasitology skills much better than the unimodal and bimodal learning styles. Kinesthetic learning should have a special emphasis in training.


Assuntos
Aprendizagem , Mídias Sociais , Humanos , Parasitologia/educação , Ensino , Avaliação Educacional , Educação a Distância
5.
J Clin Microbiol ; 61(5): e0028622, 2023 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-36809084

RESUMO

The taxonomy of medically important parasites continues to evolve. This minireview provides an update of additions and updates in the field of human parasitology from June 2020 through June 2022. A list of previously reported nomenclatural changes that have not been broadly adapted by the medical community is also included.


Assuntos
Cryptosporidium , Parasitos , Animais , Humanos , Parasitologia
6.
J Anim Ecol ; 92(2): 250-262, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-35959636

RESUMO

Many disease ecologists and conservation biologists believe that the world is wormier than it used to be-that is, that parasites are increasing in abundance through time. This argument is intuitively appealing. Ecologists typically see parasitic infections, through their association with disease, as a negative endpoint, and are accustomed to attributing negative outcomes to human interference in the environment, so it slots neatly into our worldview that habitat destruction, biodiversity loss and climate change should have the collateral consequence of causing outbreaks of parasites. But surprisingly, the hypothesis that parasites are increasing in abundance through time remains entirely untested for the vast majority of wildlife parasite species. Historical data on parasites are nearly impossible to find, which leaves no baseline against which to compare contemporary parasite burdens. If we want to know whether the world is wormier than it used to be, there is only one major research avenue that will lead to an answer: parasitological examination of specimens preserved in natural history collections. Recent advances demonstrate that, for many specimen types, it is possible to extract reliable data on parasite presence and abundance. There are millions of suitable specimens that exist in collections around the world. When paired with contemporaneous environmental data, these parasitological data could even point to potential drivers of change in parasite abundance, including climate, pollution or host density change. We explain how to use preserved specimens to address pressing questions in parasite ecology, give a few key examples of how collections-based parasite ecology can resolve these questions, identify some pitfalls and workarounds, and suggest promising areas for research. Natural history specimens are 'parasite time capsules' that give ecologists the opportunity to test whether infectious disease is on the rise and to identify what forces might be driving these changes over time. This approach will facilitate major advances in a new sub-discipline: the historical ecology of parasitism.


Assuntos
Helmintos , Animais , Humanos , Ecologia , Ecossistema , Interações Hospedeiro-Parasita , Parasitologia/tendências , Helmintos/classificação , Helmintos/fisiologia , Helmintíase/epidemiologia , Helmintíase/parasitologia
7.
Parasitology ; 150(12): 1077-1081, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37929593

RESUMO

Founded in 1959, the Italian Society of Parasitology (SoIPa) includes nearly 200 researchers and professionals in the fields of medicine, veterinary medicine, biotechnology, epidemiology and environmental sciences. The diversity of its members, in a historical and continuous collaboration with other international scientific societies, embodies a broad and multidisciplinary field such as parasitology. Since 1959, SoIPa has organized a biennial congress, covering all aspects of general parasitology with participants from all over Italy, Europe and beyond, involved in a dynamic and multi-faceted scientific framework of contributions and symposia. The present Special Issue (SI) contains 6 review papers and 1 research article, focussed on emerging topics presented and discussed during some of the symposia organized within the XXXII SoIPa Congress, held in Naples from 27th June to 30th June 2022. These review papers reflect several emerging subjects (i.e. 'Italian network on Neglected Tropical Diseases', 'Wildlife parasites and citizen science', 'Comparing approaches to parasitological issues', 'Unusual perspectives on the role of parasites') with the aim to explore the new role that parasitologists can play in the future society, working together to promote dialogue on science-informed decisions to support the so-called 'twin green and digital transition'.


Assuntos
Parasitos , Animais , Humanos , Animais Selvagens , Europa (Continente) , Itália , Parasitologia
8.
J Helminthol ; 97: e2, 2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36621869

RESUMO

The Journal of Helminthology (JHL) was first published in 1923 and was originally created as a house journal of the London School of Hygiene and Tropical Medicine. The JHL was devised by its first Editor, Robert Leiper, to allow for rapid publication of results from the Department of Helminthology and its offshoot the Institute of Agricultural Parasitology. From this initial narrow focus the JHL has subsequently become not only internationally recognized but also retained its original emphasis on morphological, taxonomic and life cycle studies while embracing the emergence of new fields and technological advancements. The present review covers the historical development of the JHL over the last century from 1923 to 2023.


Assuntos
Parasitologia , Publicações Periódicas como Assunto , Medicina Tropical , Animais , Parasitologia/história , Instituições Acadêmicas , Medicina Tropical/história , Editoração
9.
J Helminthol ; 97: e29, 2023 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-36927601

RESUMO

Next generation sequencing technologies have facilitated a shift from a few targeted loci in population genetic studies to whole genome approaches. Here, we review the types of questions and inferences regarding the population biology and evolution of parasitic helminths being addressed within the field of population genomics. Topics include parabiome, hybridization, population structure, loci under selection and linkage mapping. We highlight various advances, and note the current trends in the field, particularly a focus on human-related parasites despite the inherent biodiversity of helminth species. We conclude by advocating for a broader application of population genomics to reflect the taxonomic and life history breadth displayed by helminth parasites. As such, our basic knowledge about helminth population biology and evolution would be enhanced while the diversity of helminths in itself would facilitate population genomic comparative studies to address broader ecological and evolutionary concepts.


Assuntos
Helmintos , Metagenômica , Interações Hospedeiro-Parasita/fisiologia , Helmintos/classificação , Helmintos/genética , Hibridização Genética/genética , Variação Genética , Mapeamento Cromossômico , Resistência a Medicamentos/genética , Evolução Biológica , Parasitologia/tendências
10.
J Vet Med Educ ; 49(2): 210-222, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33929940

RESUMO

The School of Veterinary Medicine, University College Dublin, Ireland, restructured the teaching of general pathology, parasitology, and microbiology in third year in 2018 as part of the development of an outcome-based curriculum. A new integrated teaching module was created, called Veterinary Pathobiology, which encompassed the three paraclinical subjects, worth 20 ECTS credits. Subject integration was driven and supported by case-based learning (CBL) activities, and practical classes, which were aimed at facilitating the understanding of basic disease processes, infectious agents, and the application of diagnostic tests. The disciplines maintained their identities within lectures which were aligned by content. The restructuring led to a reduction of contact hours by 20% and of assessment time by 40%. The examinations included integrated questions with an emphasis on the material students had covered in their CBL. Despite positive outcomes, which included equivalent examination scores and positive written feedback by students on teaching and learning, understanding, assessment, relevance, CBL, group work, and generic skills, the average scores for overall student satisfaction dropped dramatically in the second academic year of implementation. This followed the introduction of new regulations by the University relating to student progression, which was capped at "carrying" 10 ECTS credits, thus preventing students that failed the new module from progressing. Other criticisms of the new module by students included too little communication on the changes implemented in its first iteration and a workload perceived to be too heavy. Further restructuring is therefore necessary. This study highlights the process/pitfalls of integration/curricular innovation.


Assuntos
Educação em Veterinária , Animais , Comunicação , Currículo , Humanos , Irlanda , Aprendizagem , Parasitologia/educação , Ensino
11.
J Clin Microbiol ; 59(2)2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33028601

RESUMO

The taxonomy of parasites of medical and public health importance is rapidly evolving. This minireview provides an update of taxonomic revisions and additions in the field of medical parasitology from January 2018 to May 2020. Several established human parasites have been reassigned to different genera over the past 2 years, while a number of novel parasites of humans have been identified. A comprehensive summary of these changes is provided here, and Taenia suihominis is proposed as a replacement name for Taenia asiaticus Eom et al., which is a homonym of Taenia asiatica von Linstow.


Assuntos
Parasitos , Taenia , Animais , Humanos , Parasitologia , Taenia/genética
12.
Arch Microbiol ; 203(2): 763-769, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33044624

RESUMO

The present study aimed to use the loop-mediated isothermal amplification (LAMP) technique in comparison with serological tests to determine the rate of T. gondii infection in women suffering from spontaneous abortion (SA). A total of 140 women suffering from their first SA were included in this study. The collected aborted fetal remains and blood samples from each patient were examined in sterilized conditions using the LAMP technique and ELISA. Of the 140 women, 80 (57.1%) tested seropositive for anti-Toxoplasma antibodies by ELISA, 72 (51.4%) women tested seropositive for the IgG antibody, 8 (5.7%) tested seropositive for the IgM antibody. Among the eight women who'd had their first SA who tested seropositive for IgM antibody by ELISA, only five cases (62.5%) reported positively to the LAMP test. The difference in the frequency distribution of the LAMP results for measuring the Toxoplasma infection in pregnant women under study was statistically significant (P < 0.001) from the results of the serological test (ELISA). Although there was a significant difference between age and positivity in the LAMP test (P = 0.017), no significant difference was observed between positivity in the LAMP test and other variables. The findings of the present investigation suggest that LAMP is a preferred method for determining Toxoplasma infection in pregnant women suffering from SA compared with other routine serological tests. Even in a field with limited facilities and equipment, this technique can be effective and efficient in accurately and specifically diagnosing Toxoplasma infections in women at high risk of SA.


Assuntos
Aborto Espontâneo/etiologia , Técnicas de Diagnóstico Molecular , Técnicas de Amplificação de Ácido Nucleico , Parasitologia/métodos , Toxoplasmose/complicações , Toxoplasmose/diagnóstico , Adulto , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Gravidez , Toxoplasma/imunologia
13.
Parasitology ; 148(2): 234-239, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33004092

RESUMO

Serological tests may yield false-negative results for specific antibodies detection before or at the early seroconversion phase. Tests that detect circulating antigens of Angiostrongylus cantonensis would therefore be of value in diagnosis to distinguish current or past infection. Here, a quick, easy to perform, portable and inexpensive diagnostic device for detection of 31-kDa A. cantonensis specific antigens had been developed. This sandwich dot-immunogold filtration assay (AcDIGFAAg), for detecting active angiostrongyliasis was produced using anti-A. cantonensis polyclonal antibody dotted on the nitrocellulose membrane as a capture agent and colloidal gold-labelled anti-31 kDa A. cantonensis antibody as a detection agent. A well-defined pink dot, indicating positivity, was seen readily by naked eye within 10-15 min. The AcDIGFAAg detected A. cantonensis-specific antigens in cerebrospinal fluid samples from 4 out of 10 serologically confirmed angiostrongyliasis cases and 2 out of 5 suspected cases with negative anti-A. cantonensis antibodies. Among the 19 patient sera with A. cantonensis infection, 2 showed positive reaction by AcDIGFAAg. No positive AcDIGFAAg reaction was observed in all the serum samples with other parasitic diseases, and the healthy controls. The present 'AcDIGFAAg' enables rapid qualitative detection of the specific 31-kDa antigens of A. cantonensis in clinical samples with potential for application even under resource-limited settings.


Assuntos
Imuno-Histoquímica/métodos , Infecções por Strongylida/diagnóstico , Angiostrongylus cantonensis/isolamento & purificação , Animais , Humanos , Parasitologia/métodos , Infecções por Strongylida/parasitologia
14.
Exp Parasitol ; 225: 108113, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33992605

RESUMO

Cryptosporidiosis remains the leading protozoan induced cause of diarrhoea-associated mortality worldwide. Cryptosporidium hominis, the anthroponotically transmitted species within the Cryptosporidium genus, contributes significantly to the global burden of infection, accounting for the majority of clinical cases in many countries. This study applied high resolution melting analysis, a post-real-time PCR application, to the differentiation of six globally prevalent C. hominisgp60-subtypes. This novel method targeted three microsatellite, tandem repeat containing genetic markers, gp60, the genetic marker upon which current Cryptosporidium subtype nomenclature is based, MSB, and MSE, by which to differentiate between C. hominis isolates. This multi-locus approach successfully differentiated between all six C. hominisgp60-subtypes studied, some of which, such as IbA10G2, are known to exhibit global ubiquity. Thus, this method has the potential to be universally employed as a sensitive, cost effective and highly reproducible means to rapidly differentiate between C. hominisgp60-subtypes. Such a method would be of particular utility in epidemiological studies and outbreak scenarios, providing cost effective, clinically accessible alternative to DNA sequencing. The success of this preliminary study also supports further analysis of an expanded C. hominisgp60-subtype range and the potential expansion of the multi-locus panel in order to improve the discriminatory power of this approach.


Assuntos
Cryptosporidium/genética , Parasitologia/métodos , Criptosporidiose/parasitologia , Cryptosporidium/classificação , Cryptosporidium/isolamento & purificação , DNA de Protozoário/genética , Fezes/parasitologia , Marcadores Genéticos , Genótipo , Humanos , Tipagem de Sequências Multilocus , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Análise de Sequência de DNA
15.
J Invertebr Pathol ; 182: 107581, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33798556

RESUMO

Entomopathogenic fungi are important agents for mosquito vector control. We report on the utility of a simple method to detect fungi on living larvae of Aedes aegypti that had been exposed to a fungal entomopathogen. Four species of the hypocrealean genera Metarhizium, Beauveria, Tolypocladium and Culicinomyces, known for their larvicidal activity against mosquito species, were tested. Living larvae previously exposed to a suspension of different conidial concentrations were set directly into the surface water film on non-nutritive agar supplemented with chloramphenicol, thiabendazole and crystal violet and then incubated. Except for C. clavisporus ARSEF 964 (which developed and produced conidia mostly inside the cadaver rather than on its surface in the present study), this method favored external fungal development and conidiogenesis on larvae of different instars after death. The dead larva on the water agar represents the unique and specific source of nutrition for the fungus that killed it. The technique facilitates the detection and posterior isolation of entomopathogenic fungi, and offers a compact, convenient, and rapid means to survey larval mosquito populations for fungal pathogens at the field.


Assuntos
Aedes/microbiologia , Entomologia/métodos , Hypocreales/isolamento & purificação , Controle de Mosquitos/métodos , Parasitologia/métodos , Aedes/crescimento & desenvolvimento , Animais , Beauveria/isolamento & purificação , Larva/crescimento & desenvolvimento , Larva/microbiologia , Metarhizium/isolamento & purificação
16.
J Fish Dis ; 44(8): 1147-1153, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33837562

RESUMO

Diagnostic accuracy of pathogen detection depends upon the selection of suitable tests. Problems can arise when the selected diagnostic test gives false-positive or false-negative results, which can affect control measures, with consequences for the population health. The aim of this study was to compare sensitivity of different diagnostic methods IHC, PCR and qPCR detecting Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease in salmonid fish and as a consequence differences in disease prevalence. We analysed tissue from 388 salmonid specimens sampled from a recirculating system and rivers in the Czech Republic. Overall prevalence of T. bryosalmonae was extremely high at 92.0%, based on positive results of at least one of the above-mentioned screening methods. IHC resulted in a much lower detection rate (30.2%) than both PCR methods (qPCR32: 65.4%, PCR: 81.9%). While qPCR32 produced a good match with IHC (60.8%), all other methods differed significantly (p < .001) in the proportion of samples determined positive. Both PCR methods showed similar sensitivity, though specificity (i.e., the proportion of non-diseased fish classified correctly) differed significantly (p < .05). Sample preservation method significantly (p < .05) influenced the results of PCR, with a much lower DNA yield extracted from paraffin-embedded samples. Use of different methods that differ in diagnostic sensitivity and specificity resulted in random and systematic diagnosis errors, illustrating the importance of interpreting the results of each method carefully.


Assuntos
Testes Diagnósticos de Rotina/veterinária , Doenças dos Peixes/diagnóstico , Myxozoa/isolamento & purificação , Oncorhynchus mykiss , Doenças Parasitárias em Animais/diagnóstico , Parasitologia/métodos , Truta , Animais , Aquicultura , República Tcheca/epidemiologia , Testes Diagnósticos de Rotina/métodos , Doenças dos Peixes/epidemiologia , Doenças dos Peixes/parasitologia , Doenças Parasitárias em Animais/epidemiologia , Doenças Parasitárias em Animais/parasitologia , Prevalência , Rios
17.
J Biol Chem ; 294(2): 405-409, 2019 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-30401750

RESUMO

I was recently awarded the Alice and C. C. Wang Award in Molecular Parasitology for my contributions to antimalarial drug development, including laying the groundbreaking work that has led to two new molecular methods for curing malaria. This award means a great deal to me because I have spent much of my scientific career feeling like an imposter-one with the wrong sort of background and poor credentials. I am grateful for the recognition, and I am beginning to recognize that having an atypical background can be an advantage because it gives you a different perspective on a challenge. More generally, diversity in educational and cultural backgrounds is important because it can stimulate new ways of thinking and discovery.


Assuntos
Arte/história , Malária/história , Parasitologia/história , Antimaláricos/uso terapêutico , Criatividade , História do Século XX , História do Século XXI , Humanos , Malária/tratamento farmacológico , Malária/parasitologia , Plasmodium/efeitos dos fármacos , Plasmodium/genética , Plasmodium/crescimento & desenvolvimento , Plasmodium/fisiologia
18.
Arch Microbiol ; 202(7): 1881-1888, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32448961

RESUMO

Due to defects and drawbacks of most conventional diagnostic methods including serology for the diagnosis of toxoplasmosis as a dangerous opportunistic infection in immunocompromised individuals, the accurate, rapid, and sensitive detection of infection in such patients is essential. In this study, the TaqMan probe-based real-time PCR and, a relatively new nucleic acid amplification method, the loop-mediated isothermal amplification (LAMP) technique was compared based on the repetitive elements (RE) sequence to detect Toxoplasma gondii (T. gondii) DNA in blood samples of immunocompromised individuals. During this study, 119 blood samples from immunocompromised cancer patients with renal failure, undergoing dialysis were studied. After DNA extraction from blood samples using the salt extraction method, the molecular techniques of TaqMan probe-based real-time PCR and LAMP were used to investigate the contamination of the samples with T. gondii, based on the 529 bp (RE) sequence of T. gondii. The analytical sensitivity of LAMP and real-time PCR was evaluated by duplicating the five-step serial dilutions of T. gondii tachyzoites from 0.25 to 5×105 spiked tachyzoites per milliliter of the Toxoplasma seronegative blood sample. The extracted DNA from other parasites and human chromosomal DNA were used to determine the specificity of the molecular methods. The obtained results were analyzed using Kappa statistical test and SPSS22 software. Out of 119 studied samples, 7 (5.8%) and 5 (4.2%) samples were positive for Toxoplasma by TaqMan probe-based real-time PCR and LAMP, respectively. The limits of detection of TaqMan probe-based real-time PCR and RE-LAMP in negative serum samples were one and five tachyzoites (CT 38), respectively. Both real-time PCR and LAMP methods were 100% specific for Toxoplasma detection. Positive results were obtained only with T. gondii DNA, while other DNA samples were negative. The TaqMan probe-based real-time PCR based on the RE sequence showed higher sensitivity to T. gondii DNA detection in blood samples of cancer patients and serial dilutions of parasitic tachyzoites. The results show that TaqMan probe-based real-time PRC is a sensitive and specific method for the detection of toxoplasmosis in immunocompromised individuals, as well as the LAMP assay, which can be used as a suitable alternative diagnostic method for the detection of toxoplasmosis in such patients, without need the for any expensive equipment.


Assuntos
DNA de Protozoário/genética , Técnicas de Amplificação de Ácido Nucleico , Infecções Oportunistas/diagnóstico , Parasitologia/métodos , Reação em Cadeia da Polimerase em Tempo Real , Toxoplasmose/diagnóstico , Animais , DNA de Protozoário/sangue , Humanos , Hospedeiro Imunocomprometido , Infecções Oportunistas/parasitologia , Sensibilidade e Especificidade , Toxoplasma/genética , Toxoplasmose/parasitologia
19.
Malar J ; 19(1): 192, 2020 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-32450861

RESUMO

BACKGROUND: Plasmodium falciparum zygotes develop in the mosquito midgut after an infectious blood meal containing mature male and female gametocytes. Studies of mosquito-produced P. falciparum zygotes to elucidate their biology and development have been hampered by high levels of contaminating mosquito proteins and macromolecules present in zygote preparations. Thus, no zygote-specific surface markers have been identified to date. Here, a methodology is developed to obtain large quantities of highly purified zygotes using in vitro culture, including purification methods that include magnetic column cell separation (MACS) followed by Percoll density gradient centrifugation. This straightforward and effective approach provides ample material for studies to enhance understanding of zygote biology and identify novel zygote surface marker candidates that can be tested as transmission blocking vaccine (TBV) candidates. METHODS: Plasmodium falciparum gametocyte cultures were established and maintained from asexual cultures. Gametocytes were matured for 14 days, then transferred into zygote media for 6 h at 27 ± 2 °C to promote gamete formation and fertilization. Zygotes were then purified using a combination of MACS column separation and Percoll density gradient centrifugation. Purity of the zygotes was determined through morphological studies: the parasite body and nuclear diameter were measured, and zygotes were further transformed into ookinetes. Immunofluorescence assays (IFA) were also performed using the ookinete surface marker, Pfs28. RESULTS: After stimulation, the culture consisted of transformed zygotes and a large number of uninfected red blood cells (RBCs), as well as infected RBCs with parasites at earlier developmental stages, including gametes, gametocytes, and asexual stages. The use of two MACS columns removed the vast majority of the RBCs and gametocytes. Subsequent use of two Percoll density gradients enabled isolation of a pure population of zygotes. These zygotes transformed into viable ookinetes that expressed Pfs28. CONCLUSION: The combined approach of using two MACS columns and two Percoll density gradients yielded zygotes with very high purity (45-fold enrichment and a pure population of zygotes [approximately 100%]) that was devoid of contamination by other parasite stages and uninfected RBCs. These enriched zygotes, free from earlier parasites stages and mosquito-derived macromolecules, can be used to further elucidate the biology and developmental processes of Plasmodium.


Assuntos
Fenômenos Magnéticos , Parasitologia/métodos , Plasmodium falciparum/isolamento & purificação , Povidona/química , Dióxido de Silício/química , Parasitologia/instrumentação , Zigoto
20.
Malar J ; 19(1): 451, 2020 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-33287822

RESUMO

BACKGROUND: An ultrasensitive malaria rapid diagnostic test (RDT) was recently developed for the improved detection of low-density Plasmodium falciparum infections. This study aimed to compare the diagnostic performance of the PfHRP2-based Abbott Malaria Ag P. falciparum ultrasensitive RDT (uRDT) to that of the conventional SD-Bioline Malaria Ag P. falciparum RDT (cRDT) when performed under field conditions. METHODS: Finger-prick blood samples were collected from adults and children in two cross-sectional surveys in May of 2017 in southern Mozambique. Using real-time quantitative PCR (RT-qPCR) as the reference method, the age-specific diagnostic performance indicators of the cRDT and uRDT were compared. The presence of histidine-rich protein 2 (HRP2) and Plasmodium lactate dehydrogenase (pLDH) antigens was evaluated in a subset from dried blood spots by a quantitative antigen assay. pfhrp2 and pfhrp3 gene deletions were assessed in samples positive by RT-qPCR and negative by both RDTs. RESULTS: Among the 4,396 participants with complete test results, the sensitivity of uRDTs (68.2; 95% CI 60.8 to 74.9) was marginally better than that of cRDTs (61.5; 95% CI 53.9 to 68.6) (p-value = 0.004), while the specificities were similar (uRDT: 99.0 [95% CI 98.6 to 99.2], cRDT: 99.2 [95% CI 98.9 to 99.4], p-value = 0.02). While the performance of both RDTs was lowest in ≥ 15-year-olds, driven by the higher prevalence of low parasite density infections in this group, the sensitivity of uRDTs was significantly higher in this age group (54.9, 95% CI 40.3 to 68.9) compared to the sensitivity of cRDTs (39.2, 95% CI 25.8 to 53.9) (p-value = 0.008). Both RDTs detected P. falciparum infections at similar geometric mean parasite densities (112.9  parasites/µL for uRDTs and 145.5 parasites/µL for cRDTs). The presence of HRP2 antigen was similar among false positive (FP) samples of both tests (80.5% among uRDT-FPs and 84.4% among cRDT-FPs). Only one false negative sample was detected with a partial pfhrp2 deletion. CONCLUSION: This study showed that the uRDTs developed by Abbott do not substantially outperform SD-Bioline Pf malaria RDTs in the community and are still not comparable to molecular methods to detect P. falciparum infections in this study setting.


Assuntos
Teste em Amostras de Sangue Seco , Malária Falciparum/diagnóstico , Parasitologia , Adolescente , Adulto , Antígenos de Protozoários/sangue , Antígenos de Protozoários/genética , Criança , Pré-Escolar , Estudos Transversais , Teste em Amostras de Sangue Seco/métodos , Teste em Amostras de Sangue Seco/estatística & dados numéricos , Feminino , Humanos , Masculino , Moçambique , Parasitemia/diagnóstico , Parasitologia/métodos , Parasitologia/estatística & dados numéricos , Plasmodium falciparum/genética , Sensibilidade e Especificidade , Adulto Jovem
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