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Emerging Infectious Diseases Nov 2019We reviewed Giemsa-stained thick blood smears, obtained through the national malaria surveillance program in the Amazon region of Ecuador, by light microscopy for...
We reviewed Giemsa-stained thick blood smears, obtained through the national malaria surveillance program in the Amazon region of Ecuador, by light microscopy for Mansonella spp. microfilariae. Of 2,756 slides examined, 566 (20.5%) were positive. Nested PCR confirmed that the microfilariae were those of M. ozzardi nematodes, indicating that this parasite is endemic to this region.
Topics: Animals; Ecuador; Female; Geography, Medical; Humans; Male; Mansonella; Mansonelliasis; Polymerase Chain Reaction; Prevalence; Public Health Surveillance
PubMed: 31625843
DOI: 10.3201/eid2511.181964 -
PloS One 2019Vector-borne pathogens are a significant public health concern worldwide. Infections with these pathogens, some of which are emerging, are likely under-recognized due to...
BACKGROUND
Vector-borne pathogens are a significant public health concern worldwide. Infections with these pathogens, some of which are emerging, are likely under-recognized due to the lack of widely-available laboratory tests. There is an urgent need for further advancement in diagnostic modalities to detect new and known vector-borne pathogens. We evaluated the utility of metagenomic shotgun sequencing (MGS) as a pathogen agnostic approach for detecting vector-borne pathogens from human blood samples.
METHODS
Residual whole blood samples from patients with known infection with Babesia microti, Borrelia hermsii, Plasmodium falciparum, Mansonella perstans, Anaplasma phagocytophilum or Ehrlichia chaffeensis were studied. Samples underwent DNA extraction, removal of human DNA, whole genome amplification, and paired-end library preparation, followed by sequencing on Illumina HiSeq 2500. Bioinformatic analysis was performed using the Livermore Metagenomics Analysis Toolkit (LMAT), Metagenomic Phylogenetic Analysis (MetaPhlAn2), Genomic Origin Through Taxonomic CHAllenge (GOTTCHA) and Kraken 2.
RESULTS
Eight samples were included in the study (2 samples each for P. falciparum and A. phagocytophilum). An average of 27.5 million read pairs was generated per sample (range, 18.3-38.8 million) prior to removal of human reads. At least one of the analytic tools was able to detect four of six organisms at the genus level, and the organism present in five of eight specimens at the species level. Mansonella and Ehrlichia species were not detected by any of the tools; however, mitochondrial cytochrome c oxidase subunit I amino acid sequence analysis suggested the presence of M. perstans genetic material.
CONCLUSIONS
MGS is a promising tool with the potential to evolve as a non-hypothesis driven diagnostic test to detect vector-borne pathogens, including protozoa and helminths.
Topics: Animals; Disease Vectors; Genes, Mitochondrial; Humans; Infections; Metagenomics; Phylogeny; Sequence Analysis, DNA; Species Specificity
PubMed: 31577814
DOI: 10.1371/journal.pone.0222915 -
Journal of Clinical Microbiology Oct 2019The morphologic similarities of the microfilariae and their infrequency in clinical specimens in settings of endemicity present challenges to clinical laboratories in... (Review)
Review
The morphologic similarities of the microfilariae and their infrequency in clinical specimens in settings of endemicity present challenges to clinical laboratories in maintaining competence for accurate identification and differentiation. We present here a review of the primary filarial nematodes causing human infection, including an illustrated key, which we hope will improve the diagnostic capabilities of hematologists, microbiologists, medical technologists, and similarly qualified laboratorians.
Topics: Animals; Humans; Immunoassay; Life Cycle Stages; Microfilariae; Microscopy; Molecular Diagnostic Techniques; Nematode Infections; Specimen Handling
PubMed: 31340993
DOI: 10.1128/JCM.00706-19 -
Scientific Reports Jul 2019Mansonelliasis is a widespread yet neglected tropical infection of humans in Africa and South America caused by the filarial nematodes, Mansonella perstans, M. ozzardi,...
Mansonelliasis is a widespread yet neglected tropical infection of humans in Africa and South America caused by the filarial nematodes, Mansonella perstans, M. ozzardi, M. rodhaini and M. streptocerca. Clinical symptoms are non-distinct and diagnosis mainly relies on the detection of microfilariae in skin or blood. Species-specific DNA repeat sequences have been used as highly sensitive biomarkers for filarial nematodes. We have developed a bioinformatic pipeline to mine Illumina reads obtained from sequencing M. perstans and M. ozzardi genomic DNA for new repeat biomarker candidates which were used to develop loop-mediated isothermal amplification (LAMP) diagnostic tests. The M. perstans assay based on the Mp419 repeat has a limit of detection of 0.1 pg, equivalent of 1/1000 of a microfilaria, while the M. ozzardi assay based on the Mo2 repeat can detect as little as 0.01 pg. Both LAMP tests possess remarkable species-specificity as they did not amplify non-target DNAs from closely related filarial species, human or vectors. We show that both assays perform successfully on infected human samples. Additionally, we demonstrate the suitability of Mp419 to detect M. perstans infection in Culicoides midges. These new tools are field deployable and suitable for the surveillance of these understudied filarial infections.
Topics: Africa; Animals; Computer Simulation; DNA, Protozoan; Diagnostic Tests, Routine; Female; Genetic Markers; High-Throughput Nucleotide Sequencing; Humans; Male; Mansonella; Mansonelliasis; Molecular Diagnostic Techniques; Neglected Diseases; Nucleic Acid Amplification Techniques; Repetitive Sequences, Nucleic Acid; Sensitivity and Specificity; Sequence Analysis, DNA; South America
PubMed: 31311985
DOI: 10.1038/s41598-019-46550-9