Assessment of a highly sensitive rapid diagnostic test for reactive case detection of Plasmodium Falciparum
San Kyawt Khine1, Poe Poe Aung2, Nay Yi Yi Linn1
1Department of Public Health, National Malaria Control Programme, Naypyidaw, Myanmar.
Background:
Recent epidemiological data indicate that 30-50% of all malaria infections are asymptomatic, with parasite densities below the limit of detection of standard diagnostic tests. A highly sensitive rapid diagnostic test (hsRDT) was developed to detect these low-density Plasmodium falciparum infections. This study evaluated the diagnostic performance of both hsRDTs and conventional RDTs (cRDT) in reactive case detection (RACD) activities among individuals (contacts) living and/or working in proximity to an "index case" in Ann Township in Rakhine State, Myanmar.
Methods:
This prospective community-based RACD study was conducted in 2017-2018 among residents aged at least five years old in 50 villages of Ann Township. We assessed the sensitivity, specificity, and positive and negative predictive values of both a hsRDT (NxTek™ Eliminate Malaria Ag P.f) and a cRDT (SD Malaria Ag P.f/P.v) using an ultra-sensitive polymerase chain reaction (usPCR) diagnostic assay as the gold standard.
Results:
A total of 1,990 participants, all contacts of 51 index P. falciparum cases, were recruited. Among them, 28 (1.4%) tested positive by cRDT, 78 (3.9%) by hsRDT, and 171 (8.6%) by usPCR for P. falciparum mono-infection. The sensitivity and specificity of the hsRDT were 27.9% (95% CI 18.2-39.6%) and 98.8% (95% CI 98.2-99.4%), respectively, while the sensitivity and specificity of the cRDT were 13.7% (95% CI 7.6-20.7%) and 100% (95% CI 100-100%), respectively. The differences in sensitivity and specificity between hsRDT and cRDT were statistically significant (p < 0.01 for both).
Conclusions:
Although hsRDTs identified more infected contacts than cRDTs during reactive case detection, they have low overall sensitivity compared to usPCR. In resource-limited settings, such as Myanmar, the use of hsRDTs in RACD should be guided by careful consideration of their field feasibility and cost-effectiveness to support malaria elimination efforts. (285 words).
