Plasmodium falciparum malaria is widespread in the tropical and
subtropical regions of the world. There is ongoing effort to eliminate
malaria from endemic regions, and sensitive point-of-care (POC)
diagnostic tests are required to support this effort. However, current
POC tests are not sufficiently sensitive to detect P. falciparum
in asymptomatic individuals. After extensive optimization, we have
developed a highly sensitive and robust POC test for the detection of P. falciparum
infection. The test is based on upconverting nanophosphor-based lateral
flow (UCNP-LF) immunoassay. The developed UCNP-LF test was validated
using whole blood reference panels containing samples at different
parasite densities covering eight strains of P. falciparum from
different geographical areas. The limit of detection was compared to a
WHO-prequalified rapid diagnostic test (RDT). The UCNP-LF achieved a
detection limit of 0.2-2 parasites/μL, depending on the strain, which is
50- to 250-fold improvement in analytical sensitivity over the
conventional RDTs. The developed UCNP-LF is highly stable even at 40 °C
for at least 5 months. The extensively optimized UCNP-LF assay is as
simple as the conventional malaria RDTs and requires 5 μL of whole blood
as sample. Results can be read after 20 min from sample addition, with a
simple photoluminescence reader. In the absence of a reader device at
the testing site, the strips after running the test can be transported
and read at a central location with access to a reader. We have found
that the test and control line signals are stable for at least 10 months
after running the test. The UCNP-LF has potential for diagnostic
testing of both symptomatic and asymptomatic individuals.