Transforming gastrointestinal helminth parasite identification in vertebrate hosts with metabarcoding: a systematic review.

BACKGROUND: Gastrointestinal helminths are a very widespread group of intestinal parasites that can cause major health issues in their hosts, including severe illness or death. Traditional methods of helminth parasite identification using microscopy are time-consuming and poor in terms of taxonomic resolution, and require skilled observers. DNA metabarcoding has emerged as a powerful alternative for assessing community composition in a variety of sample types over the last few decades. While metabarcoding approaches have been reviewed for use in other research areas, the use of metabarcoding for parasites has only recently become widespread. As such, there is a need to synthesize parasite metabarcoding methodology and highlight the considerations to be taken into account when developing a protocol. METHODS: We reviewed published literature that utilized DNA metabarcoding to identify gastrointestinal helminth parasites in vertebrate hosts. We extracted information from 62 peer-reviewed papers published between 2014 and 2023 and created a stepwise guide to the metabarcoding process. RESULTS: We found that studies in our review varied in technique and methodology, such as the sample type utilized, genetic marker regions targeted and bioinformatic databases used. The main limitations of metabarcoding are that parasite abundance data may not be reliably attained from sequence read numbers, metabarcoding data may not be representative of the species present in the host and the cost and bioinformatic expertise required to utilize this method may be prohibitive to some groups. CONCLUSIONS: Overall, using metabarcoding to assess gastrointestinal parasite communities is preferable to traditional methods, yielding higher taxonomic resolution, higher throughput and increased versatility due to its utility in any geographical location, with a variety of sample types, and with virtually any vertebrate host species. Additionally, metabarcoding has the potential for exciting new discoveries regarding host and parasite evolution.

Molecular identification of Giardia spp. in Latin America: An updated systematic review on reports from 2017 to 2021.

BACKGROUND: Giardia spp. is the most common protozoan found in coproparasitoscopic tests; it is the cause of gastrointestinal discomfort, with a high prevalence in children and in low-income areas. This systematic review updates available literature on molecular identification of Giardia spp. in Latin America during 2017 to 2021. METHODOLOGY: The guidelines established in Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were used; the study covers the period from January 1, 2017 to October 03, 2021; the search focused on the "molecular identification of Giardia spp. in Latin America" in six different scientific databases. The material found was reviewed to select only those papers that met the inclusion and exclusion criteria. RESULTS: The search yielded 1036 publications, but only 19 investigations in 6 countries (Brazil, Colombia, Cuba, Ecuador, Mexico, and Venezuela) met the selection criteria. Most were cross-sectional studies carried out in school-age children, the dominant assemblages were A and B while the most frequent subassemblages were AII, BIII and BIV, the most used target genes were tpi and gdh, the prevalence by molecular methods was higher regarding microscopy, the countries with the highest prevalence percentages for Giardiosis were Brazil and Cuba. CONCLUSIONS: More Latin America countries need to generate data of prevalence, incidence, and intensity of Giardiosis. Studies are also needed to estimate the costs of Giardiosis on economic productivity and public health. The present systematic review offers evidence based on the current literature available for the molecular identification of Giardia spp. in Latin America during 2017 to 2021.

A spotlight on the diagnostic methods of a fatal disease Visceral Leishmaniasis.

Leishmania donovani (a causative agent of visceral leishmaniasis) poses a serious health threat to the human population which is fatal if left untreated. The life cycle of Leishmania alternates between vertebrate host and Phlebotomine fly as intermediate ones. Due to the difficulties linked to vector (sandfly) control and the lack of an effective vaccine, the control of leishmaniasis relies mostly on chemotherapy. Unfortunately, the prevalence of parasites becoming resistant to the first-line drug pentavalent antimonial (SbV )/sodium antimony gluconate (SAG) and some other anti-leishmanial drug is increasing in several parts of the world. With the alarming rise of drug resistance and other issues related to VL, there is an urgent need to focus on early detection and quick diagnosis of VL case. Therefore, we have reviewed most of the methods used in the diagnostic process of VL. Along with existing diagnostic methods, developing more effective and sensitive diagnostic methods and biomarkers is also vital for enhancing VL identification and control programs. This review gathers the comprehensive information on diagnostics methods of VL under a single umbrella that could be the prominent tools for the development of rapid, accurate and cost-effective diagnostic kits for VL which can be used in field conditions.