Prozone in Malaria Rapid Diagnostic Tests: How Many Cases Are Missed?
Author Information
Author(s): Gillet Philippe, Scheirlinck Annelies, Stokx Jocelijn, De Weggheleire Anja, Chaúque Hélder S, Canhanga Oreana DJV, Tadeu Benvindo T, Mosse Carla DD, Tiago Armindo, Mabunda Samuel, Bruggeman Cathrien, Bottieau Emmanuel, Jacobs Jan
Primary Institution: Institute of Tropical Medicine (ITM), Belgium
Hypothesis
What is the frequency of the prozone effect in malaria rapid diagnostic tests in an endemic field setting?
Conclusion
Prozone occurs at different frequencies and intensities in HRP-2 RDTs and may decrease diagnostic accuracy in the most affected RDTs.
Supporting Evidence
- Prozone affected all six HRP-2 RDT brands in proportions ranging from 6.7% to 38.2%.
- None of the two Pf-pLDH RDTs showed prozone.
- Prozone occurred mainly among young children.
- Negative and faint HRP-2 lines accounted for 3.8% and 14.4% of prozone results.
Takeaway
Sometimes, malaria tests can give wrong results when there are too many parasites in the blood, making it look like there are none. This can happen especially in young children.
Methodology
Blood samples from patients with high parasitaemia were tested undiluted and diluted to assess the frequency of prozone in various RDTs.
Potential Biases
Potential bias due to the non-availability of trained staff and the storage conditions of some RDTs.
Limitations
The study was limited by the low malaria prevalence during the wet season and the inability to assess prozone below a certain parasite density threshold.
Participant Demographics
Patients suspected of malaria, including children and adults, with a focus on those with high parasitaemia.
Statistical Information
P-Value
p<0.05
Confidence Interval
CI: 5.34-19.08
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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