Multiplex-RT-PCR-ELISA panel for detecting mosquito-borne pathogens: Plasmodium sp. preserved and eluted from dried blood spots on sample cards

Strategies for Increasing the Throughput of Genetic Screening: Lessons Learned from the COVID-19 Pandemic within a University Community

Amidst the COVID-19 pandemic, the Polytechnic University of Setúbal (IPS) used its expertise in molecular genetics to establish a COVID-19 laboratory, addressing the demand for community-wide testing. Following standard protocols, the IPS COVID Lab received national accreditation in October 2020 and was registered in February 2021. With the emergence of new SARS-CoV-2 variants and safety concerns for students and staff, the lab was further challenged to develop rapid and sensitive diagnostic technologies. Methodologies such as sample-pooling extraction and multiplex protocols were developed to enhance testing efficiency without compromising accuracy. Through Real-Time Reverse Transcription Polymerase Chain Reaction (RT-qPCR) analysis, the effectiveness of sample pooling was validated, proving to be a clear success in COVID-19 screening. Regarding multiplex analysis, the IPS COVID Lab developed an in-house protocol, achieving a sensitivity comparable to that of standard methods while reducing operational time and reagent consumption. This approach, requiring only two wells of a PCR plate (instead of three for samples), presents a more efficient alternative for future testing scenarios, increasing its throughput and testing capacity while upholding accuracy standards. The lessons learned during the SARS-CoV-2 pandemic provide added value for future pandemic situations.

Challenges in Diagnosing and Treating Acutely Febrile Children with Suspected Malaria at Health Care Facilities in the Lake Mwanza Region of Tanzania

Acute febrile diseases transmitted by mosquitos are a diagnostic challenge for pediatricians working in sub-Saharan Africa. Misclassification due to the lack of rapid, reliable diagnostic tests leads to the overuse of antibiotics and antimalarials. Children presenting with acute fever and suspected of having malaria were examined at health care facilities in the Mwanza Region of Tanzania. The sensitivity and specificity of blood smear microscopy and malaria rapid diagnostic tests that targeted histidine-rich protein 2 and Plasmodium lactate dehydrogenase were compared with a multiplex reverse transcriptase-polymerase chain reaction (PCR)-ELISA. Six hundred ninety-eight children presented with acute fever and met the criteria for inclusion; 23% received antibiotics and 23% received antimalarials prior to admission. Subsequently, 20% were confirmed by PCR to have Plasmodium falciparum infection. Blood smear microscopy exhibited 33% sensitivity and 93% specificity. The malaria rapid test provided 87% sensitivity and 98% specificity in detecting acute malaria infections. Only 7% of malaria-negative children received antimalarials at Sengerema Designated District Hospital when treatment was guided by the results of rapid testing. In contrast, 75% of malaria-negative patients were treated with antimalarial drugs at health facilities that used blood smears as the standard diagnostic test. Misclassification and premedication of nonmalarial, febrile illnesses contribute to the emergence of antimalarial and antimicrobial resistance. The incorporation of malaria rapid diagnostic tests into the clinical routine translated into improved treatment and a significant reduction in antimalarial drug prescriptions.

Multiplex Reverse Transcription Polymerase Chain Reaction Combined with a Microwell Hybridization Assay Screening for Arbovirus and Parasitic Infections in Febrile Patients Living in Endemic Regions of Colombia

Acute febrile syndrome is a frequent reason for medical consultations in tropical and subtropical countries where the cause could have an infectious origin. Malaria and dengue are the primary etiologies in Colombia. As such, constant epidemiological surveillance and new diagnostic tools are required to identify the causative agents. A descriptive cross-sectional study was conducted to evaluate the circulation and differential diagnosis of six pathogens in two regions of Colombia. The results obtained via multiplex reverse transcription polymerase chain reaction combined with a microwell hybridization assay (m-RT-PCR-ELISA) were comparable to those obtained using rapid tests conducted at the time of patient enrollment. Of 155 patients evaluated, 25 (16.1%) and 16 (10.3%) were positive for malaria and dengue, respectively; no samples were positive for any of the other infectious agents tested. In most cases, m-RT-PCR-ELISA confirmed the results previously obtained through rapid testing.

Sensitive and Stable Molecular Detection of Dengue, Chikungunya, and Zika Viruses from Dried Blood Spots

Standard molecular detection of many pathogens, in particular RNA viruses, requires appropriate handling in the field for preserving the quality of the sample until processing. This could be challenging in remote tropical areas. Dengue virus (DENV), chikungunya virus (CHIKV), and Zika virus (ZIKV) are RNA viruses, prominent among the causes of fever in the tropics. We aimed to test the stability of arboviral RNA in contrived dried blood spots prepared on Whatman 903 Protein saver cards as a means of sample collection and storage. We were able to detect DENV, CHIKV, and ZIKV by real-time RT-PCR up to 180 days after card inoculation with stable Ct values across the study period. Our study supports dried blood spots (DBS) on protein saver cards as a platform for stable detection of arboviral RNA of sufficient quality to be used in diagnostic RT-PCR assays and next generation sequencing.

Malaria Rapid Diagnostic Tests: Literary Review and Recommendation for a Quality Assurance, Quality Control Algorithm

Malaria rapid diagnostic tests (RDTs) have had an enormous global impact which contributed to the World Health Organization paradigm shift from empiric treatment to obtaining a parasitological diagnosis prior to treatment. Microscopy, the classic standard, requires significant expertise, equipment, electricity, and reagents. Alternatively, RDT’s lower complexity allows utilization in austere environments while achieving similar sensitivities and specificities. Worldwide, there are over 200 different RDT brands that utilize three antigens: Plasmodium histidine-rich protein 2 (PfHRP-2), Plasmodium lactate dehydrogenase (pLDH), and Plasmodium aldolase (pALDO). pfHRP-2 is produced exclusively by Plasmodium falciparum and is very Pf sensitive, but an alternative antigen or antigen combination is required for regions like Asia with significant Plasmodium vivax prevalence. RDT sensitivity also decreases with low parasitemia (<100 parasites/uL), genetic variability, and prozone effect. Thus, proper RDT selection and understanding of test limitations are essential. The Center for Disease Control recommends confirming RDT results by microscopy, but this is challenging, due to the utilization of clinical laboratory standards, like the College of American Pathologists (CAP) and the Clinical Lab Improvement Act (CLIA), and limited recourses. Our focus is to provide quality assurance and quality control strategies for resource-constrained environments and provide education on RDT limitations.