Ultra-Sensitive Rapid Test Evaluated for Malaria
By LabMedica International staff writers Posted on 05 Apr 2018 |
Image: The Malaria Ag P.f test is 10 times more sensitive than current malaria rapid diagnostic tests for the detection of Plasmodium falciparum HRP-II antigen (Photo courtesy of Alere).
In low prevalence regions, subpatent Plasmodium falciparum malaria infections have become an issue of increasing concern. As malaria endemic countries shift from control to elimination, the proportion of low-density P. falciparum infections increases.
Current field diagnostic tools, such as microscopy and rapid diagnostic tests (RDT), with detection limits of approximately 100 to 200 parasites/µL (p/µL) and 800 to1000 pg/mL histidine-rich protein 2 (HRP2), respectively, are unable to detect subpatent infections.
Scientists at Diagnostics Program, PATH (Seattle, WA, USA) tested two commercial available RDTs. The two RDTs are immunochromatographic membrane strip tests, but differ in that the ultra-sensitive (uRDT) one uses biotinylated and carboxyl-modified latex fragment antibodies (FAbs) and polystreptavidin bound to the test line to detect P. falciparum-specific HRP2 in whole blood. The uRDT test requires 5 µL of whole blood specimen and the blood is applied to the sample port in the test followed by application of four drops of assay diluent. Twenty minutes after application of the specimen, the result is interpreted from the result window.
The uRDT used was the Alere Malaria Ag P.f RDT and was compared to the BIOLINE Malaria Ag P.f RDT. The team reported that the uRDT detected dilutions of P. falciparum recombinant strains, as well as cultured strains, diluted in whole blood down to 10 to 40 pg/mL HRP2, depending on the protein tested. The uRDT specificity was 100% against 123 archived frozen whole blood samples. The commercial SD-RDT and uRDT detected pfhrp2 positive strains down to 49 and 3.13 p/µL, respectively. The pfhrp2 deletion strains were detected down to 98 p/µL by both tests.
The authors concludes that the performance of the uRDT was variable depending on the protein, but overall showed a greater than 10-fold improvement over the SD-RDT. The uRDT also exhibited excellent specificity and showed the same cross-reactivity with HRP3 as the SD-RDT. Together, the results support the uRDT as a more sensitive HRP2 test that could be a potentially effective tool in elimination campaigns. The study was published on March 17, 2018, in the Malaria Journal.
Related Links:
Diagnostics Program, PATH
Current field diagnostic tools, such as microscopy and rapid diagnostic tests (RDT), with detection limits of approximately 100 to 200 parasites/µL (p/µL) and 800 to1000 pg/mL histidine-rich protein 2 (HRP2), respectively, are unable to detect subpatent infections.
Scientists at Diagnostics Program, PATH (Seattle, WA, USA) tested two commercial available RDTs. The two RDTs are immunochromatographic membrane strip tests, but differ in that the ultra-sensitive (uRDT) one uses biotinylated and carboxyl-modified latex fragment antibodies (FAbs) and polystreptavidin bound to the test line to detect P. falciparum-specific HRP2 in whole blood. The uRDT test requires 5 µL of whole blood specimen and the blood is applied to the sample port in the test followed by application of four drops of assay diluent. Twenty minutes after application of the specimen, the result is interpreted from the result window.
The uRDT used was the Alere Malaria Ag P.f RDT and was compared to the BIOLINE Malaria Ag P.f RDT. The team reported that the uRDT detected dilutions of P. falciparum recombinant strains, as well as cultured strains, diluted in whole blood down to 10 to 40 pg/mL HRP2, depending on the protein tested. The uRDT specificity was 100% against 123 archived frozen whole blood samples. The commercial SD-RDT and uRDT detected pfhrp2 positive strains down to 49 and 3.13 p/µL, respectively. The pfhrp2 deletion strains were detected down to 98 p/µL by both tests.
The authors concludes that the performance of the uRDT was variable depending on the protein, but overall showed a greater than 10-fold improvement over the SD-RDT. The uRDT also exhibited excellent specificity and showed the same cross-reactivity with HRP3 as the SD-RDT. Together, the results support the uRDT as a more sensitive HRP2 test that could be a potentially effective tool in elimination campaigns. The study was published on March 17, 2018, in the Malaria Journal.
Related Links:
Diagnostics Program, PATH
Latest Microbiology News
- Enhanced Rapid Syndromic Molecular Diagnostic Solution Detects Broad Range of Infectious Diseases
- Clinical Decision Support Software a Game-Changer in Antimicrobial Resistance Battle
- New CE-Marked Hepatitis Assays to Help Diagnose Infections Earlier
- 1 Hour, Direct-From-Blood Multiplex PCR Test Identifies 95% of Sepsis-Causing Pathogens
- Mouth Bacteria Test Could Predict Colon Cancer Progression
- Unique Metabolic Signature Could Enable Sepsis Diagnosis within One Hour of Blood Collection
- Groundbreaking Diagnostic Platform Provides AST Results With Unprecedented Speed
- Simple Blood Test Combined With Personalized Risk Model Improves Sepsis Diagnosis
- Blood Analysis Predicts Sepsis and Organ Failure in Children
- TB Blood Test Could Detect Millions of Silent Spreaders
- New Blood Test Cuts Diagnosis Time for Nontuberculous Mycobacteria Infections from Months to Hours
- New Tuberculosis Test to Expand Testing Access in Low- and Middle-Income Countries
- Rapid Test Diagnoses Tropical Disease within Hours for Faster Antibiotics Treatment
- Rapid Molecular Testing Enables Faster, More Targeted Antibiotic Treatment for Pneumonia
- Rapid AST Platform Provides Targeted Therapeutic Results Days Faster Than Current Standard of Care
- New Analysis Method Detects Pathogens in Blood Faster and More Accurately by Melting DNA