Malaria RDT Selection: HRP2 vs pLDH for African Procurement Programs

Why HRP2 vs pLDH Selection Matters for African Procurement Programs

The malaria rapid diagnostic test market has matured into two antigen families that procurement teams need to compare head to head before signing a public-sector or donor-funded tender. HRP2-based RDTs detect histidine-rich protein 2, a water-soluble antigen produced during the blood-stage infection by Plasmodium falciparum. pLDH-based RDTs detect plasmodium lactate dehydrogenase, a metabolic enzyme produced by all four human-relevant Plasmodium species. Our buyers see the two antigen families as non-interchangeable: HRP2-only tests catch P. falciparum at very low parasitemia but miss non-falciparum species, while Pan-pLDH tests catch the full species mix but at a higher parasite density threshold.

For African procurement programs, the choice between the two antigen families is no longer a laboratory curiosity. The WHO Global Malaria Programme has spent the last decade recommending HRP2-only tests because P. falciparum is the dominant species on the continent, and HRP2 is the most sensitive antigen at low parasitemia. The emergence of hrp2 and hrp3 gene deletions in circulating P. falciparum strains has changed the math, and procurement specifications written before the deletion data emerged are now being re-tendered. Our reference product in this analysis is the Malaria Ag Pan Test, a chromatographic immunoassay for pLDH detection in whole blood, validated for 4-30 degree Celsius storage and a 24-month shelf life on our manufacturing line.

Our buyers tend to frame the HRP2 vs pLDH choice as a single decision point, but in practice it is a portfolio decision that maps onto country surveillance data, donor compliance frameworks, and field logistics. We walk through the biology first, because the procurement decision only makes sense once antigen behavior is clear, and then turn to specification patterns that work in mixed-endemic African geographies.

Antigen Biology: HRP2 (P. falciparum-specific) vs pLDH (Pan-species)

The HRP2 antigen is produced by P. falciparum trophozoites and gametocytes, accumulates in the parasite and the infected red blood cell, and persists in the bloodstream for up to two weeks after parasite clearance. Persistence is a double-edged sword: a positive HRP2 result can indicate active infection or recent resolved infection, which is why HRP2-based tests are paired with treatment guidelines that account for antigen persistence. Our buyers see the clinical sensitivity advantage as real at low parasite density, and HRP2-only tests typically detect P. falciparum at densities below 200 parasites per microliter, at or below the microscopy threshold for many field labs.

pLDH is a metabolic enzyme produced by all four human-relevant Plasmodium species, and the antigen clears from the bloodstream within hours of parasite clearance. The clinical implication is that a positive pLDH result reliably indicates active infection rather than recent resolved infection, but per-species sensitivity is lower than HRP2 at low parasitemia. Pan-pLDH tests detect P. falciparum, P. vivax, P. malariae, and P. ovale in a single read, and species-specific pLDH tests can differentiate P. falciparum from non-falciparum species on the same strip. CDC’s malaria biology pages walk through the species-specific clinical picture, and our buyers writing a specification should read that material before locking the SKU list.

HRP2/pLDH combo tests combine both antigen families on the same cassette. A combo test typically shows two or three bands: one for HRP2, one for Pan-pLDH, and sometimes a third band for P. vivax-specific pLDH. The combo format gives field workers species-level information that HRP2-only tests cannot provide, while preserving the P. falciparum sensitivity advantage at low parasitemia. The trade-off is unit cost, which is typically higher than either single-antigen format because of the additional antibody pairs on the cassette.

Procurement Decision Tree: When HRP2-only, When Pan-pLDH, When Combo

The choice between the three formats maps onto country surveillance data, donor compliance frameworks, and field logistics. We walk through the decision tree as it actually runs in our procurement conversations, with the operational data that drives each branch.

HRP2-only: when deletion prevalence is low and donor compliance is strict

If the country-level hrp2 deletion prevalence is below 5 percent and the donor funding stream requires WHO-prequalified SKUs, the procurement team can stay on HRP2-only and accept the species coverage trade-off. This is the path that most African national malaria control programs took between 2010 and 2020, and it remains the right path in geographies where the deletion data has been confirmed by WHO-coordinated molecular surveillance. The HRP2-only path has the lowest unit cost and the largest body of field performance data.

Pan-pLDH: when deletion prevalence is high or non-falciparum species are present

If the country-level hrp2 deletion prevalence is above 5 percent, or if the surveillance data shows a meaningful non-falciparum species mix, the procurement team should move to Pan-pLDH or to an HRP2/pLDH combo. The Pan-pLDH path catches the P. falciparum cases that the HRP2-only test would miss because of the deletion, and it also catches the non-falciparum species that HRP2-only tests cannot detect at all. The Pan-pLDH path has a higher unit cost and slightly lower per-species sensitivity at low parasitemia, but the trade-off is the right one when the alternative is a false-negative case management decision. CDC’s diagnostic tools page walks through the same species-coverage trade-off, and our buyers find that the same logic applies to African public-sector case management.

HRP2/pLDH combo: when both deletion coverage and species differentiation are required

If the country-level deletion prevalence is moderate (1-5 percent) and the species mix requires differentiation between P. falciparum and non-falciparum infections, the combo format is the right procurement decision. The combo format gives the field worker both signals on a single cassette, and the unit cost premium over the single-antigen formats is usually recovered through better case management and fewer return visits for re-testing. Combo formats are particularly strong fits for tertiary hospitals, reference laboratories, and surveillance programs that need both signals for epidemiological reporting on our buyer side.

The split-tender pattern

The pattern we see most often in the African procurement data is a split tender, with the HRP2-only or combo SKU as the primary case management test and the Pan-pLDH SKU as the surveillance and re-test SKU. Splitting the volume 60/40 or 70/30 between the two is common, and the actual ratio is driven by the species mix in the country surveillance data. Programs that lock the specification into a single SKU tend to re-tender within 24-36 months when the deletion data shifts, and the cost of the re-tender is usually larger than the unit cost premium of running a dual-SKU specification from day one for our buyers.

The hrp2/3 Gene Deletion Problem: Why Pan-pLDH Coverage Now Matters

The hrp2 gene deletion problem is the single largest driver of the move from HRP2-only to Pan-pLDH or HRP2/pLDH combo tests in our African procurement conversations. When the hrp2 gene is deleted in a circulating P. falciparum strain, the parasite does not produce HRP2 antigen and HRP2-based RDTs return false-negative results even at clinically significant parasite densities. The hrp3 deletion amplifies our problem because the HRP3 protein shares epitopes with HRP2 and can cross-react on HRP2-based tests, so an hrp3 deletion in addition to hrp2 drives the false-negative rate higher.

WHO’s malaria fact sheet and the CDC DPDx malaria pages track documented deletion prevalence by country. The public-domain data shows established deletion transmission in Eritrea, Ethiopia, and Djibouti, with surveillance reports identifying deletion carriers in parts of Sudan, Somalia, and Senegal. Deletion prevalence in the Horn of Africa has crossed the threshold that WHO and the Global Fund use to recommend the move away from HRP2-only at scale, which is why procurement programs serving those geographies now specify Pan-pLDH or combo formats as the primary case management test.

The procurement consequence is that a specification written before 2022 on an HRP2-only basis may now miss a meaningful share of P. falciparum cases in the Horn of Africa, and the case management gap is filled by microscopy reference laboratories or by Pan-pLDH screening followed by HRP2 confirmation. The second pattern, which our buyers prefer, is to specify the HRP2/pLDH combo as the primary case management SKU and the Pan-pLDH as the surveillance and re-test SKU, with the volume ratio set by country surveillance data. This pattern keeps the HRP2 sensitivity advantage at low parasitemia, catches deletion carriers on the pLDH band, and gives our surveillance team a single cassette to read.

WHO Prequalification & Regulatory Pathways for RDT Procurement

Most African public-sector and donor-funded procurements require either WHO prequalification or local National Regulatory Authority (NRA) approval before the SKU can ship, and we recommend buyers check both before tender release. The WHO Prequalification of In Vitro Diagnostics programme maintains a public list of prequalified malaria RDTs, the de facto reference for most donor-funded tenders, updated quarterly. WHO’s malaria health topic page links to the prequalification status of each SKU and to dossier requirements for products not yet prequalified.

For procurements that fall outside the WHO prequalification framework (national tenders, private-sector hospital procurement, veterinary or research settings), the local NRA pathway is the relevant compliance route. The NRA dossier typically includes ISO 13485 certification, performance evaluation reports from reference laboratories, and field performance data from prior shipments in comparable geographies. Our sales team provides the dossier package on request, and we walk procurement teams through the NRA review timeline before the PO is signed.

The compliance picture is layered, and procurement teams that anchor on a single compliance framework often discover the gap when the second funder rejects the SKU. We recommend specifying the compliance envelope by listing the WHO prequalification status and the local NRA approval status for each shipping destination, and by confirming that the SKU carries ISO 13485 and MDSAP certification on our manufacturing side. FDA’s medical devices page is a useful reference for the U.S. side, though most African procurements do not require FDA clearance.

Cold Chain, Stability, and Field Logistics for African Distribution

The field logistics envelope is the second-largest driver of our procurement decision after antigen biology, and our buyers most often discover a gap in this area. Our malaria RDTs are validated for storage between 4 and 30 degrees Celsius, with a 24-month shelf life from manufacture. The 4-30 range eliminates the cold-chain requirement for most African distribution routes and lets our product ride alongside ambient pharmaceutical shipments.

The field stability envelope does not remove the operational discipline that an ambient pharmaceutical chain requires. We coach field workers to keep cassettes out of direct sunlight and out of vehicles above 40 degrees Celsius during transit, and the desiccant in each foil pouch should be checked before the test is run. Our accelerated and real-time stability data sit in our technical file for buyers who need to defend the 4-30 range to a national regulatory authority or donor compliance reviewer, and we walk through the data with our buyers on request.

The format choice is also a logistics decision. Cassette formats ship in 25-test or 40-test pack sizes, and the choice should match facility case volume. A high-volume urban clinic runs through a 40-test pack faster than a 25-test pack, and a low-volume rural facility may take two weeks to use a single 25-test pack. Specifying the format that matches facility case volume reduces open-pack waste and per-test landed cost. Our infectious disease catalog lists format and pack-size options across our malaria RDT portfolio, and our sales team sizes the format to facility case volume on each inquiry. MSF field deployment guidance and FIND procurement frameworks reference the ambient envelope we use for community health worker deployment.

Building a Dual-SKU Procurement Specification for Mixed-Endemic Zones

The procurement specification is the document that ties the biology, the compliance envelope, and the field logistics together, and we find that the specification is the right place to manage the dual-SKU decision. Our buyers tend to write the specification around two SKUs: an HRP2-only or HRP2/pLDH combo SKU for the primary P. falciparum case management decision, and a Pan-pLDH SKU for the non-falciparum screen and deletion-zone re-test. The volume ratio between the two SKUs is driven by country surveillance data, with a 60/40 or 70/30 split toward the primary SKU being common.

The specification should list the SKU by reference to the WHO prequalification status and the local NRA approval status for each shipping destination, and should list the ISO 13485 and MDSAP certification on our manufacturing side. The specification should also call out the storage temperature envelope (4-30 degrees Celsius), the shelf life (24 months from manufacture), and the format and pack-size requirements for each shipping destination. The order quantity should be set at our standard MOQ of 5,000 units per SKU for the catalog format, and at our OEM MOQ of 50,000 units for private-label or donor-specific programs.

The biggest specification mistake we see is locking the program into a single SKU and re-tendering when the deletion data shifts. The second-largest mistake is specifying a single compliance framework when multiple funders are involved. Our buyers avoid both mistakes by writing a dual-SKU specification from day one, listing the compliance envelope per shipping destination, and allowing either catalog or OEM SKUs to satisfy volume. The full Testsealabs malaria RDT portfolio is listed in our infectious disease catalog, and our sales team responds to RFQs through the contact page with a quote and dossier package within two business days.