Rapid Diagnostic Tests Compared for Benign Tertian Malaria

The standard method for malaria diagnosis is by the routine microscopic examination of Giemsa-stained blood smears and rapid diagnostic tests (RDTs) that detect malaria parasite proteins by immunochromatography which have been used as complementary detection method for malaria diagnosis.

Recent advances in the development of species-specific RDTs, such as the Plasmodium vivax aldolase-specific test, will greatly enhance the quality of testing and reduce over-administration of anti-malarial drugs in endemic areas to a more species-specific approach to the treatment of malaria.

Scientists at the South China University of Technology (Guangzhou, China) examined slides from 77 P. vivax-positive blood samples and 33 non-P. vivax samples were collected from patients in the Yunnan province of China. Non-P. vivax samples included 31 P. falciparum and 2 P. malariae samples. Healthy blood samples were randomly collected from 423 volunteers in Guangzhou.

Three commercially available Plasmodium lactate dehydrogenase (LDH) or aldolase antigen detection kits were evaluated with P. vivax positive as well as non-P. vivax samples and healthy samples using blood smear examination as standard. The RDTs tested were the One Step Malaria P.f/P.v (Guangzhou Wondfo Biotech; China), the ParaHit Total (Span Diagnostics Ltd.; Surat, India), the SD Bioline Malaria (Standard Diagnostics; Yongin, South Korea), and an in-house anti-P. vivax aldolase-specific monoclonal antibody (mAb) pair 1C3-12 F10.


The mAb 1C3-12 F10 pair targeting P. vivax-specific aldolase exhibited very good specificity and sensitivity of 100% and 97.4%, respectively. The anti-P. vivax LDH in the One-Step Malaria P.f/P.v test showed sensitivity of 93.5%, and a specificity of 98.0%. The ParaHit Total targeting the pan-aldolase antigen showed a sensitivity of 97.4%, and a specificity of 99.6%. The SD Bioline had sensitivity of 93.5%, and a specificity of 100%. The overall sensitivity and specificity of all four RDTs were acceptable, especially for the aldolase detection tests. Five of the P. vivax-positive samples that were confirmed by microscopic examination as well as the two aldolase detection RDTs were undetected by the two LDH detection RDTs. Two positive samples that were positively confirmed by the LDH detection RDTs were also undetected by the aldolase detection test kits.

The authors concluded that aldolase and LDH antigens perform differently in different P. vivax samples and therefore there is a high risk of misdiagnosis when monoclonal antibodies are used against only one particular antigen in the test. A combination of both aldolase and LDH in RDTs for the rapid diagnosis of P. vivax will enhance the sensitivity of the assay and reduce misdiagnosis. The estimated global burden of malaria due to P. vivax is approximately 70 to 80 million cases annually. The study was published on July 11, 2014, in the Malaria Journal.

Related Links:
South China University of Technology
Guangzhou Wondfo Biotech
Span Diagnostics Ltd.