From the Guidelines
False positive malaria test results are often caused by the presence of rheumatoid factor and anti-nuclear antibodies, persistence of pfhrp2, and other infections.
Causes of False Positive Results
- Presence of rheumatoid factor and anti-nuclear antibodies 1
- Persistence of pfhrp2 1
- Other infections 1
Diagnostic Tests
- Rapid diagnostic tests (RDTs) can produce false positive results due to the presence of antigens even after eradication of intact parasites 1
- RDTs should be confirmed by examination of thick and thin blood films to confirm the species present and calculate the degree of parasitemia 1
- Nucleic acid amplification tests (NAATs) can also be used for diagnosis, but should not be used to monitor response to therapy as residual DNA can be detected days or even weeks after intact parasites have been eradicated 1
Clinical Considerations
- Clinical and epidemiologic information must be considered when interpreting test results 1
- Repeat blood samples may be indicated if the initial film is negative and malaria is strongly suspected 1
From the Research
Causes of False Positive Malaria Test Results
- Non-Plasmodium infectious agents, such as human African trypanosomiasis, can cause false positive results in malaria rapid diagnostic tests (RDTs) 2
- Immunological factors, including rheumatoid factor (RF) and human anti-mouse antibody (HAMA), can also lead to false positive results in malaria RDTs 2, 3
- Certain bacterial infections, such as Salmonella Typhi, can cause false positive malaria RDT results 4
- Viral infections, including cytomegalovirus (CMV), may also lead to false positive results in malaria RDTs 5
- Other febrile illnesses, such as those caused by bacterial or viral infections, can result in false positive malaria RDT results 6
Factors Influencing False Positive Results
- The presence of RF and HAMA can significantly increase the false positive rate of malaria RDTs 2
- High levels of RF are associated with malaria RDT false positivity 3
- The type of RDT used can also influence the false positive rate, with some tests showing higher rates of false positivity than others 2, 6