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Interpretation guide: MULTI BAND tests: Difference between revisions

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<span style="font-size:90%">[[MalariaETC Index|Main Malaria Index]]''</span></br>
<span style="font-size:90%">[[MalariaETC Index|Main Malaria Index]]''</span></br>
<span style="font-size:90%">>[[Rapid diagnostic tests (RDTs)|RDT main page]]''</span></br>
<span style="font-size:90%">>[[Rapid diagnostic tests (RDTs)|RDT main page]]''</span></br>
<span style="font-size:90%">>>This page: '''Single band RDT tests'''</span>
<span style="font-size:90%">>>This page: '''Multi band RDT tests'''</span>
----
----
<span style="font-size:160%; color:navy">Multi-band RDT tests</br></span>
<span style="font-size:160%; color:navy">Multi-band RDT tests</br></span>
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{| class="wikitable" style="border-style: none; border-width: 2px; border-color: gainsboro; color:black"
{| class="wikitable" style="border-style: none; border-width: 2px; border-color: gainsboro; color:black"
|colspan="1" style = "font-size:100%; color:black; background: gainsboro |'''RESULT PATTERN 1  
|colspan="1" style = "font-size:100%; color:black; background: gainsboro |'''RESULT PATTERN 1'''
 
'''
|}
|}
<span style="font-size:90%; color:red">'''Failed test:''' No band appears in the control area (black arrow)</span>: </br></br>
<span style="font-size:90%; color:maroon">These are '''invalid tests''' No band appears in the control area (black arrow)</span>: </br></br>


<gallery mode="nolines" widths=80px heights=160px>
<gallery mode="nolines" widths=80px heights=160px>
File:RDT_multi_no_band1.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_no_band1.jpg}}
File:RDT_multi_fail1.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_fail1.jpg}}
File:RDT_multi_no_band2.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_no_band2.jpg}}
File:RDT_multi_fail2.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_fail1.jpg}}
File:RDT_multi_no_band3.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_no_band3.jpg}}
File:RDT_multi_fail3.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_fail1.jpg}}
File:RDT_multi_no_band4.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_no_band4.jpg}}
File:RDT_multi_fail4.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_fail1.jpg}}
</gallery>
</gallery>
<span style="font-size:90%">Irrespective of whether any other bands are present, this is always an invalid test: '''do not interpret.''' Report as failed test</br>Action:</span>  
<span style="font-size:90%">Irrespective of whether any other bands are present, this is always an invalid test: '''do not interpret.''' Report as failed test</br>Action:</span>  
*<span style="font-size:90%">Repeat the test</br></span>
*<span style="font-size:90%">Repeat the test</br></span>
*<span style="font-size:90%">Consider the reasons for [ [[Practical reasons for test failure|test failure]] ]</span>
*<span style="font-size:90%">Consider the reasons for [ [[Practical reasons for test failure 1|test failure]] ]</span>
</br>
</br>


{| class="wikitable" style="border-style: none; border-width: 2px; border-color: gainsboro; color:black"
{| class="wikitable" style="border-style: none; border-width: 2px; border-color: gainsboro; color:black"
|colspan="1" style = "font-size:100%; color:black; background: gainsboro |'''RESULT PATTERN 2'''
|colspan="1" style = "font-size:100%; color:black; background: gainsboro |'''RESULT PATTERN 2'''
|}
There has a '''valid control line''' (black arrow) showing a technically successful test, but '''no malaria bands are detected''' either the species specifc or pan malaria areas.
<gallery mode="nolines" widths=80px heights=160px>
File:RDT_multi_neg.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_neg.jpg}}
</gallery>
<span style="font-size:90%">'''Most likely interpretation:''' No malaria parasites are present</br></span>
<span style="font-size:90%">'''Less likely but possible interpretations:'''</span>
*<span style="font-size:90%">Malaria infection is present, but is not detected because it is below the detection limit of the test</span>
*<span style="font-size:90%">Bands are present but may be faint and not seen by the operator</span>
</br>
{| class="wikitable" style="border-style: none; border-width: 2px; border-color: gainsboro; color:black"
|colspan="1" style = "font-size:100%; color:black; background: gainsboro |'''RESULT PATTERN 3'''
|}
<span style="font-size:90%">The test has '''valid control line''' (black arrow) and has bands in the '''pan-specific area''' and the '''species specific area''' (red arrows)</span>
<gallery mode="nolines" widths=80px heights=160px>
File:RDT_multi_posPF1.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_posPF1.jpg}}
</gallery>
<span style="font-size:90%">'''Most likely interpretation:''' The single species detected by the species specific band is present (this same species is also detected the pan-malaria band)
<span style="font-size:90%">'''Less likely but possible interpretations:'''</span>
*<span style="font-size:90%">There are two species present in the sample (likelihood depends on country of origin, but is less likely) [ [[Co-infection with two species2|Co-infection with two species]] ]</span>
*<span style="font-size:90%">There is a false positive result causing both bands (unlikely) [ [[False positive reaction in RDT tests 2|False positive reaction in RDT tests]] ]</span>
{| class="wikitable" style="border-style: none; border-width: 2px; border-color: gainsboro; color:black"
|colspan="1" style = "font-size:100%; color:black; background: gainsboro |'''RESULT PATTERN 4'''
|}
|}


<span style="font-size:90%">The test has '''valid control line''' (black arrow) and a '''band in the species-specific area only''' (red arrow)</span>
<span style="font-size:90%">The test has '''valid control line''' (black arrow) and a '''band in the species-specific area only''' (red arrow)</span>
<gallery mode="nolines" widths=80px heights=160px>
<gallery mode="nolines" widths=80px heights=160px>
File:RDT_multi_pos2.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_pos2.jpg}}
File:RDT_multi_posPF2.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_posPF2.jpg}}
</gallery>
</gallery>


<span style="font-size:90%">'''Most likely interpretation:''' The species detected by the test is present and is the only malaria species infecting the individual</br></span>
<span style="font-size:90%">'''Most likely interpretation:''' The species detected by the test is present and is the only malaria species infecting the individual</br></span>
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*<span style="font-size:90%">The "specific band" is a false positive result (infrequent but observed) [ [[False positive reaction in RDT tests 2|False positive reaction in RDT tests]] ]</span>
*<span style="font-size:90%">The "specific band" is a false positive result (infrequent but observed) [ [[False positive reaction in RDT tests 2|False positive reaction in RDT tests]] ]</span>
</br>
</br>


{| class="wikitable" style="border-style: none; border-width: 2px; border-color: gainsboro; color:black"
{| class="wikitable" style="border-style: none; border-width: 2px; border-color: gainsboro; color:black"
|colspan="1" style = "font-size:100%; color:black; background: gainsboro |'''RESULT PATTERN 3'''
|colspan="1" style = "font-size:100%; color:black; background: gainsboro |'''RESULT PATTERN 5'''
|}
|}


<span style="font-size:90%">The test has '''valid control line''' (black arrow) and a '''band in the pan-specific area only''' (red arrow)</span>
<span style="font-size:90%">The test has '''valid control line''' (black arrow) and a '''band in the pan-specific area only''' (red arrow)</span>
<gallery mode="nolines" widths=80px heights=160px>
<gallery mode="nolines" widths=80px heights=160px>
File:RDT_multi_pos1.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_pos1.jpg}}
File:RDT_multi_pan1.jpg|<span style="font-size:90%"></span>|link={{filepath:RDT_multi_pan1.jpg}}
</gallery>
</gallery>


<span style="font-size:90%">'''Most likely interpretation:''' A malaria infection is detected (pan band), but is not caused by the species detected by the specific antibody (Sp band)</br></span>
<span style="font-size:90%">'''Most likely interpretation:''' A malaria infection is detected (pan band), but is not caused by the species detected by the specific antibody (Sp band)</br></span>


<span style="font-size:90%">'''Less likely but possible interpretations:'''</span>
<span style="font-size:90%">'''Less likely but possible interpretations:'''</span>
*<span style="font-size:90%">The species detected by the specific band is present (as a single infection or dual infection), but has not been detected by the specific band [ [[prozone, mutation]] ]</span>
*<span style="font-size:90%">The species detected by the specific band is present (as a single infection or dual infection), but has not been detected by the specific band [ [[Prozone_effect_alt|Prozone-like effect]] ], [ [[HRP2_gene_deletion_alt|HRP2 gene deletion]] ]</span>
*<span style="font-size:90%">The patient recently received successful treatment, but the antigen has not yet cleared [ [[Clearance of parasite antigens from blood 2|Clearance of parasite antigens from blood]] ]</span>
*<span style="font-size:90%">The "specific band" is a false positive result (infrequent but observed) [ [[False positive reaction in RDT tests 2|False positive reaction in RDT tests]] ]</span>
*<span style="font-size:90%">The "specific band" is a false positive result (infrequent but observed) [ [[False positive reaction in RDT tests 2|False positive reaction in RDT tests]] ]</span>


----
(2) No band present in species-specific area
Most common: the species is not present
Possible alternatives:
A faint band was present but not seen by observer*
The species is present but not detected due to low parasite concentration (link to reasons)
The species is present but not detected for technical reasons
The species is present, but there is gene deletion of the target antigen (HRP2 tests)
The species is present but exceeds test capacity due to very high parasite Pyrome effect (mainly HRP2 tests)
----
(3) A band appears in the pan-malaria area only
The most common cause is infection is present with a malaria species not detected by the specific antibody
Possible alternatives:
The specific band has failed (see causes above) but pan-malaria antigen still detects that species
No malaria is present and the band in the pan-malaria area is a false positive (cross reaction)
----
(4) A band appears in both the species-specific and pan malarial area
A single specific species and is detected by specific and pan-malaria antigens (95%)
There are two species present in the sample (5%)
False positive result in both bands (least common cause)
----
----

Latest revision as of 15:17, 14 April 2025


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Multi-band RDT tests



RESULT PATTERN 1

These are invalid tests No band appears in the control area (black arrow):

Irrespective of whether any other bands are present, this is always an invalid test: do not interpret. Report as failed test
Action:



RESULT PATTERN 2

There has a valid control line (black arrow) showing a technically successful test, but no malaria bands are detected either the species specifc or pan malaria areas.


Most likely interpretation: No malaria parasites are present

Less likely but possible interpretations:

  • Malaria infection is present, but is not detected because it is below the detection limit of the test
  • Bands are present but may be faint and not seen by the operator



RESULT PATTERN 3

The test has valid control line (black arrow) and has bands in the pan-specific area and the species specific area (red arrows)


Most likely interpretation: The single species detected by the species specific band is present (this same species is also detected the pan-malaria band)

Less likely but possible interpretations:


RESULT PATTERN 4

The test has valid control line (black arrow) and a band in the species-specific area only (red arrow)


Most likely interpretation: The species detected by the test is present and is the only malaria species infecting the individual

Less likely but possible interpretations:



RESULT PATTERN 5


The test has valid control line (black arrow) and a band in the pan-specific area only (red arrow)

Most likely interpretation: A malaria infection is detected (pan band), but is not caused by the species detected by the specific antibody (Sp band)

Less likely but possible interpretations: