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Plasmodium lactate dehydrogenase (PLDH): Difference between revisions

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The pLDH assays identify enzymes of the malaria glycolytic pathway, the proteins are distinct from human forms of LDH allowing them to be identified by RDT tests. The LDH antgens are relatively rapidly cleared from the blood, so have value in testing response to treatment or for malaria testing in recently infected patients.There are species-specific forms of LDH, these underle the ''P.falciparum'' and ''P.vivax'' forms of LDH.
The pLDH assays identify enzymes of the malaria glycolytic pathway, the proteins are distinct from human forms of LDH allowing them to be identified by RDT tests. The LDH antgens are relatively rapidly cleared from the blood, so have value in testing response to treatment or for malaria testing in recently infected patients.There are species-specific forms of LDH (see separate description).


There are three forms of species-specific LDH antigen:  
'''The non-species-specific form (PpanLDH)''' is most widely used in combination with a species-specific antigen: most often recognising ''P.falciparum'', although in some geographical areas this is a form that recognises ''P.vivax''. Choice depends very much on local prevalance. For example:
*PfLDH - specifically detects a form expressed by ''P.falciparum'' detecting the species with good sensitivity
*PvLDH - detecting the parasite form of LDH that is specific for ''P.vivax''


Note that the '''non-species-specific form (PpanLDH)''' is also widely used (see separate description)
PF dominant but concern of resistance
PF dominant but other species frequently encountered
PV dominant but PF possible


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<span style="color:navy>'''Characteristics of species-specific forms of LDH'''</span>
Not a general malaria test as has poor sensitivity for some species, expect:


 
<span style="color:navy>'''Characteristics of pan-specific forms of LDH'''</span>
1. '''P.falciparum-specific''' (PfLDH): has very good sensitivity at high parasitaemia that may meet or exceed 90%. However, at lower parasite levels (<1000 parasites/ μL) sensitivity of PfLDH may be less than that of HRP2 (around 45%). An additioanl potential advantage over HRP2 sould be considered - this conserved antigen does not have reported gene-delection so may be an effective choice where malaria arises in ares with high rates of HRP2 deletion.</br>
 
2. '''P.vivax-specific''' (PvLDH): has value for the specific diagnosis of ''P.vivax'' in areas where this is a dominant species (e.g. areas of South America). PvLDH RDTs probably have similar sensitivity for P.vivax as the PpanLDH (of around 70-90% at high paraitaemia, declining when parasite levels are low - around 30-60%), however they do not cross-react with ''P.vivax'' giving them value in distinguishing these two species.</br></br>

Latest revision as of 10:30, 6 August 2024

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Use of PpanLDH in diagnosis


The pLDH assays identify enzymes of the malaria glycolytic pathway, the proteins are distinct from human forms of LDH allowing them to be identified by RDT tests. The LDH antgens are relatively rapidly cleared from the blood, so have value in testing response to treatment or for malaria testing in recently infected patients.There are species-specific forms of LDH (see separate description).

The non-species-specific form (PpanLDH) is most widely used in combination with a species-specific antigen: most often recognising P.falciparum, although in some geographical areas this is a form that recognises P.vivax. Choice depends very much on local prevalance. For example:

PF dominant but concern of resistance PF dominant but other species frequently encountered PV dominant but PF possible

Not a general malaria test as has poor sensitivity for some species, expect:

Characteristics of pan-specific forms of LDH

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