Pan-specific Plasmodium lactate dehydrogenase (PpanLDH)

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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 it may be combined with antibodies that sepcifically recognise P.vivax (or even both). The choice depends very much on the species that are likely to be encountered. Most often: Where P.falciparum is dominant, but other species are also frequently encountered, the pan-malria antibody can indicate the presence of a non-falciparum or mixed infection. (or do we tend to use aldolase??) Other uses: Where P.falciparum is dominant the dominant species, but there is concern of HRP2 gene deletion, a pan-malaria antibody may improve sensitivity for deleted cases Where P.vivax is dominant, but other species are also frequently encountered, the pan-malria antibody can indicate the presence of a non-falciparum or mixed infection Characteristics of pan-specific forms of LDH It is important to realise that while PpanLDH can detect all species, it has low sensitivity for some species so should not be considered a general malaria test for malaria infection. Overall, for effective RDTs stored and used correctly, the performance at high parasitaemia is good P.falciparum (sensitivity is x%) and P.vivax (sensitivity is y%), but declines significantly as parasite conectration falls below x (expect...). For P.knowlesi reports suggest performance may also be reasonable at high parasite levels. Sensitivity for P.ovale and P.malariae is poor at all parasite concentrations (expect x-y%).