Lot testing: pre and post-purchase

Lot testing of malaria RDTs involves testing of samples of RDTs for a manufacturing lot to ensure performance reaches an acceptable standard. This can be done pre-purchase or post-purchase before or after arrival in the country, before or after the distribution to the field.

Why is lot testing needed?

• Allows for performance assessment against highly characterized specimens that may not be available in-country, to control for lot variation, noted in most products.
• Ensures no damage during transport to country.
• Provides information on RDT stability over the shelf life, reflecting how RDTs can be expected to function under similar storage conditions in the field.
• Provides information on anomalies identified during testing that may signal a problem with a lot.
• Gives confidence to clinicians / users / regulatory authorities that the tests they are using have adequate performance for clinical use.

Producing and storing quality control dilutions of parasites obtained from field samples

Testing malaria RDTs in a laboratory setting against stored samples allows greater consistency and control of testing methods, and greater control over the parasite densities used as standards, but has the disadvantage that stored blood and parasites may react differently than fresh parasitized blood on an RDT. To guide this process, a methods manual has been produced and is updated serially.

Lot testing is readily accessible

Lot-testing capacity has been developed through a joint programme of the WHO and the Foundation for Innovative New Diagnostics (FIND). It is currently performed at lot-testing centres in the Western Pacific Region, specifically the Research Institute for Tropical Medicine (RITM, Manila) which can test for programmes globally and at the National Institute of Malaria Research, New Delhi, India and the University of Lagos, Nigeria which can test products entering their respective countries.

Since December 2017, WHO is coordinating the lot testing procedures for malaria RDTs, operated by the Research Institute for Tropical Medicine (RITM, Manila), serving the global community. 

Who can request lot testing?

Any national programme or organization procuring malaria RDTs may request lot testing from this programme. Lot testing is performed free of charge when arranged through the WHO RDT lot-testing programme. The requesting institution must cover transport costs for the RDTs and provide the required number of RDTs.

How to request lot testing?

At least 2 weeks before you are ready to send the RDTs, please contact the lot testing coordinator: malariardt_lt@ritm.gov.ph with copy to malaria_rdt@who.int and attach a completed lot testing request form.

How is lot testing performed?

1. Documentation and shipping

Following receipt of your request, you will be provided with details regarding the volume of RDTs required for lot testing, shipping instructions, etc. These must be followed carefully to ensure that the shipment is not held at customs.

The proper forms must be filled in accurately by the requesting institution. Failure to do so may result in shipment delays. Once the invoice is checked by the lot testing coordinator, and provided everything is in order, the goods can then be dispatched.

2. RDT sampling

It is recommended that all purchased lots be tested. The number of tests required depends on the type of RDT (i.e., a combination or a P. falciparum only test) and the expiry date of the product. Usually, a sample of approximately 100 P. falciparum-only RDTs, or 150 combined P. falciparum and pan-specific (or P. vivax-specific) RDTs is required from each lot.

3. Test evaluation

RDT lots are tested in lot-testing laboratories that have undergone quality assessment and been approved by the WHO RDT Lot Testing Programme.

An initial assessment is performed on a sample of the RDTs using panels of parasite-positive and parasite-negative blood. These panels are prepared according to the same standard operating procedures as the panels for the global malaria specimen bank. The remaining RDTs are then stored in controlled conditions at one of two temperatures (depending on the manufacturer’s recommended maximum storage temperature) and re-tested 6 months prior to expiry.

Any revisions to procedures will posted on this website and will be incorporated into subsequent versions of the Methods manual for laboratory control testing of malaria rapid diagnostic tests.

4. Results

Initial results are usually returned within 7 working days of RDT receipt at the lot-testing laboratory.

A malaria RDT lot testing quality control report form is generated and emailed confidentially to the requesting institution. This is accompanied by a guide for the interpretation of observations noted during lot testing. A report with the results of re-testing during shelf-life is also sent to the requester.

RDTs must detect parasite-positive panels at 200 parasites per microlitre of blood in order to pass the quality control evaluation. False positive results obtained with parasite-negative samples, as well as any unusual observations, such as poor blood clearing or incomplete test lines, are also noted. Illustration of the comments encountered during testing and photos of the testing are provided with the report when the testing workload allows it.

The lot testing reports and photos of the testing results cannot be released to any third party without the agreement of the requesting party. In all cases it is the requesting party that can make the report available, and not the lot testing programme. Summarized product-specific lot testing results are released every 6 months.

The programme is not responsible for final decisions to accept or reject an RDT lot by a procurement agent or malaria programme. This decision is to be taken by the requester of the lot testing. The lot testing programme aims to provide data on which this decision can be based.

Lot-testing results (2007-2022)

Biannually, lot testing results are compiled and reported on a product-specific basis. This includes results of initial and interval testing (following incubation and 6 months prior to expiry). Interval testing results are particularly useful in verifying that product performance is being maintained over the entire product shelf-life. An overview of the results of the FIND-WHO lot testing programme for malaria RDTs is available for the entire period.