| Use of PfLDH 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. There are also species specific features.
This means that there are three forms of test antigen:
- PpanLDH - this potentially detects all forms of malaria although sensitivity varies between species
- 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
Characteristics of HRP2 to be aware of
1. P.falciparum-specific forms (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 lower than HRP2 (around 45%). Two advantages over HRP2 sould be considered. First, 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. Second, the antgen is realtively rapidly cleared from the blood, so PfLDH has value in testing rsponse to treatment or for malaria testing in recently infected patients.
P.vivax-specific forms (PvLDH):
"Pan-malaria" forms (PpanLDH):
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