How long do rapid diagnostic tests remain positive after anti-malarial treatment?

Area of Science:

• Malariology
• Infectious Disease Diagnostics
• Public Health Surveillance

Background:

• Rapid diagnostic tests (RDTs) are crucial for malaria diagnosis and prevalence surveys in endemic regions.
• Antigen persistence after anti-malarial treatment can lead to variable RDT positivity.
• Existing data on RDT antigen persistence duration post-treatment is inconsistent.

Purpose of the Study:

• To review and analyze published data on RDT positivity duration after malaria treatment.
• To estimate the persistence of RDT positivity using a Bayesian survival model.
• To identify factors influencing RDT positivity duration post-treatment.

Main Methods:

• Systematic review of published studies on RDT positivity post-treatment.
• Application of a bespoke Bayesian survival model to estimate persistence duration.
• Analysis of factors including RDT antigen type, patient age, and treatment regimen.

Main Results:

• Half of histidine-rich protein II (HRP2) RDTs remain positive for 15 days post-treatment, significantly longer than Plasmodium lactate dehydrogenase (pLDH) RDTs.
• Five percent of HRP2 RDTs are still positive up to 36 days post-treatment.
• Children and individuals treated with artemisinin combination therapy exhibit longer RDT positivity persistence.

Conclusions:

• RDT positivity duration post-anti-malarial treatment is highly variable and depends on RDT type, patient age, and treatment regimen.
• The persistence of RDT positivity can significantly affect the interpretation of cross-sectional malaria prevalence data.
• Caution is advised when interpreting RDT results from individuals with recent anti-malarial treatment history.