Malaria Rapid Diagnostic Tests
Rapid Diagnostic Test (RDT) for Malaria in Pediatrics
Rapid Malaria Tests (RDTs) are immunochromatographic tests that detect specific antigens produced by malaria parasites present in the patient's blood.
Key Points
- Provides results within 15-20 minutes
- Suitable for resource-limited settings
- Detects Plasmodium falciparum and non-falciparum species
- Sensitivity: 95% for P. falciparum (>100 parasites/µL)
- Requires minimal training and equipment
Test Principles
- Detects specific antigens:
- Histidine-rich protein 2 (HRP-2) - specific to P. falciparum
- Plasmodium lactate dehydrogenase (pLDH) - present in all species
- Aldolase - pan-malarial antigen
Sample Requirements
- Fresh capillary or venous blood
- Sample volume: 5-10 µL
- Anticoagulated blood (if not immediate testing)
Step-by-Step Procedure
Materials Needed
- RDT kit
- Sterile lancet
- Alcohol swab
- Timer
- Disposable gloves
- Sharps container
Procedure Steps
- Pre-test Preparation:
- Check expiration date
- Bring test to room temperature if refrigerated
- Label test with patient information
- Don personal protective equipment
- Blood Collection:
- Clean finger/heel with alcohol swab
- Allow to air dry completely
- Puncture with sterile lancet
- Wipe away first drop of blood
- Collect required volume using provided device
- Test Performance:
- Apply blood to sample well
- Add buffer drops as specified
- Start timer
- Read results at specified time (usually 15-20 minutes)
Result Interpretation
Valid Test
- Control line must appear
- Background must clear
- Read within specified timeframe
Results Interpretation
- Positive P. falciparum:
- Control line + HRP2 line visible
- Indicates presence of P. falciparum
- Positive non-falciparum:
- Control line + pLDH/Aldolase line
- Indicates P. vivax, P. ovale, or P. malariae
- Negative:
- Only control line visible
- No parasites detected
- Invalid:
- No control line visible
- Test must be repeated
Limitations and Considerations
Clinical Limitations
- False Negatives:
- Low parasite density (<100 parasites/µL)
- Early infection stages
- HRP2 gene deletions
- False Positives:
- Persistent HRP2 after treatment (2-6 weeks)
- Rheumatoid factor interference
- Cross-reactivity with non-malarial antigens
Technical Considerations
- Storage conditions critical (temperature, humidity)
- Quality control essential
- Regular staff training needed
- Result documentation important
