1. Glimpses from NIRTH Study Site
Performance of a New Portable, Affordable Diagnostic Test to Detect Malaria Parasites in India
Poster # 84
Session name: POS1
December 13th
Bharti PK1, Thota P2, Kumar R1 , Witte T2, Rocheleau A2, Verma AK1, Rajasubramaniam S1, Kumar P3, Das A1
1ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh India; 2Hemex Health, Inc; Portland, USA; 3Hemex Dx, India.
Abstract
Objective
Results & Summary
RDT+
RDT-
LM+ 42
LM- 17
203
Gazelle +
Gazelle -
LM+ 41 1
LM- 7
213
The objective of the study is to compare the performance of GazelleTM to current diagnostic methods in detecting malaria parasites. We evaluated the diagnostic accuracy of a rapid (<1 minute) malaria detection device, GazelleTMusing blood samples (n= 285) from a high transmission setting (Jagdalpur, India). GazelleTM uses the principle of Magneto-Optical Detection to detect hemozoin (a paramagnetic by-product of the malaria parasite). The accuracy of GazelleTM was compared with RDT and microscopy (gold standard). Results demonstrate that GazelleTM has similar sensitivity and a much higher specificity than RDTs and was much faster at one-minute than either microscopy or RDTs.
To test the accuracy and compare the relative performance of GazelleTM vs. RDT using microscopy as the gold-standard
Methods & Mechanism
We evaluated the diagnostic accuracy of the GazelleTM as a point-of-care diagnostic for malaria, using
samples collected from 300 patients who were enrolled in a pilot study in a high transmission setting
(Jagdalpur-NIRTH, India) patients were included in the analysis. 7 patients were excluded due to
contamination and 31 were excluded due to damaged prototype device.
Microscopy was performed as per WHO guidelines.
Table 1: Comparison of methods of detecting malaria parasites (N=262)
RDT-Rapid Diagnostic Test; LM-Light Microscopy
Background
The Magneto-Optical Detector (MOD) detects a byproduct of malaria infection in a drop of blood. When malaria parasites consume red blood cells, they create paramagnetic iron-containing crystals called hemozoin inside red blood cells
Sensitivity
Specificity
Accuracy
Gazelle
97.6
96.8
97.0
RDT
100
92.3
93.5
Malaria is one of the most severe public health problems worldwide and is prevalent in tropical and subtropical regions. The mainstay of malaria diagnosis has been microscopic examination of blood and more recently rapid diagnostic tests (RDTs).
Mechanism of hemozoin detection by MOD
Magnified photos of hemozoin crystals – the biomarker detected by MOD
Table 2: Effectiveness/accuracy of RDT and Gazelle for detecting Malaria parasites compared to Microscopy (Gold Standard).
In the current study Gazelle performed similar to microscopy and has higher specificity than RDTs
Gazelle showed 97.6% sensitivity and 96.8% specificity when compared to Microscopy
On the same samples RDTs showed 100% sensitivity and 92.3% specificity
Labor & time intensive (~30-60min)
Skilled personnel
Requires power
Poor sensitivity and specificity for lower parasitemia
Inter-operator error in creation, staining, and visual analysis
False positives
Variation in sensitivity across malaria species and variants
20 minutes per test and heat-sensitive
Cannot detect P. falciparum with HRP2 deletion
Cannot reliably detect parasitemia lower than parasites/μL
Testing procedure
Conclusions
15 µl of whole blood collected with cartridge
Snap into bottom chamber
Insert cartridge into reader
Results onscreen in under a minute
Upload results to cloud with touch of a button
This study shows promising early results for Gazelle with good sensitivity and specificity.
Gazelle performed similarly to microscopy and has higher specificity than RDTs.
Gazelle may be a potential solution for areas where there is need for speed, accuracy and ease of use (such as where microscopy is not practical and where
RDTs’ poor specificity is an issue).
Feedback from the field was that a one-minute, battery operated test is unique and useful.
Next steps:
Future studies are planned with larger numbers of subjects that compare results to PCR.
Challenge: There is an acute need for improved malaria diagnostics that are not only cost-effective but also rapid, highly accurate and detect species and strains that other diagnostics may miss, such as low-density infection, and P. falciparum with HRP2 deletion.
Glimpses from NIRTH Study Site
Solution
Gazelle: An inexpensive, rugged and rapid (<1 minute) malaria detection device.
Portable
Water and Heat Resistant
Standalone test
Battery powered
Wi-Fi
Bluetooth
GPS
Acknowledgments
MOD technology was licensed from Case Western Reserve University, Cleveland, OH
The Gazelle reader was developed by Hemex Health, USA & India in collaboration with Tata Elxsi, Pune, India
The study was funded by Hemex Health
Please and with any questions or suggestions
For more information please visit and www. nirth.res.in
Note: This is a prototype unit and not approved for sale in India yet. Final device will include the ability to detect Sickle Cell Disease
Most sensitive hemozoin detector available
Studies on P. vivax yielded higher sensitivity and specificity when compared to RDT and microscopy.