What is the purpose of a Plasmodium falciparum (PF)/Plasmodium antigen (PAN) test?

From the Guidelines

The primary purpose of a Plasmodium falciparum (PF)/Plasmodium antigen (PAN) test, also known as a rapid diagnostic test (RDT), is to diagnose malaria by detecting specific antigens in a patient's blood, providing a rapid result within 15 minutes 1.

Key Features of RDTs

• Sensitivity and Specificity: RDTs have a sensitivity ranging from 67.9 to 100% and a specificity between 93.1 and 100% for P. falciparum, and a sensitivity ranging from 66% to 91% and a specificity from 98% to 100% for P. vivax 1.
• Antigens Detected: RDTs detect antigens such as histidine-rich protein 2 (HRP2) for P. falciparum, lactate dehydrogenase for P. falciparum and P. vivax, and pan-lactate dehydrogenase and aldolase common to all human species of Plasmodium 1.
• Limitations: RDTs may be falsely negative in cases with very low rates of parasitemia and non-falciparum infection, and may be falsely positive due to the presence of rheumatoid factor and anti-nuclear antibodies, persistence of pfhrp2, and other infections 1.

Clinical Use of RDTs

• Initial Screening: RDTs are used for initial screening of malaria in non-endemic countries, particularly in settings where reliable blood films are not readily available 1.
• Confirmation: Positive RDT results should be confirmed by examination of thick and thin blood films, ideally within 12-24 hours of patient presentation, to determine the species present and calculate the degree of parasitemia 1.
• Monitoring: RDTs should not be used to monitor response to therapy, as antigens may still be detected after eradication of intact parasites 1.

Comparison with Other Diagnostic Methods

• Microscopy: Microscopic examination of Giemsa-stained thick and thin blood films is the gold standard method for diagnosis of malaria, but requires skilled and experienced technologists 1.
• Nucleic Acid Amplification Tests (NAATs): NAATs are more sensitive than microscopy and RDTs, but are generally restricted to highly specialized laboratories and are not FDA-cleared 1.

From the Research

Purpose of Plasmodium falciparum (PF)/Plasmodium antigen (PAN) test

The purpose of a Plasmodium falciparum (PF)/Plasmodium antigen (PAN) test is to diagnose malaria by detecting specific antigens in the blood of infected individuals. The test is designed to identify the presence of Plasmodium falciparum and other Plasmodium species, such as Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae.

Key Features of PF/PAN tests

• The tests use antibodies to detect specific antigens, such as histidine-rich protein 2 (HRP2) and pan-plasmodium lactate dehydrogenase (pLDH) 2, 3, 4, 5, 6
• The tests are rapid, easy to perform, and provide results in a short amount of time 2, 3, 4, 5, 6
• The tests have varying levels of sensitivity and specificity, depending on the specific test and the Plasmodium species being detected 2, 3, 4, 5, 6

Advantages of PF/PAN tests

• Rapid diagnosis of malaria, allowing for prompt treatment and reducing the risk of complications 2, 3, 4, 5, 6
• Easy to perform, making them suitable for use in resource-limited settings 2, 3, 4, 5, 6
• High sensitivity and specificity for detecting Plasmodium falciparum and other Plasmodium species 2, 3, 4, 5, 6

Limitations of PF/PAN tests

• Variable sensitivity and specificity, depending on the specific test and the Plasmodium species being detected 2, 3, 4, 5, 6
• Potential for false-negative results, particularly at low parasite densities 2, 3, 4, 5, 6
• May not be suitable for detecting all Plasmodium species, such as Plasmodium ovale and Plasmodium malariae 2, 3, 4, 5, 6