Parasite clearance rate - the rate at which malaria parasite levels decline in a patient’s blood after treatment - can be used to assess the body’s response to treatment with artemisinin derivatives, evaluate new antimalarial drugs and assess therapeutic response to severe malaria in patients. WWARN’s Parasite Clearance Estimator (PCE) is a uniform method to describe the parasite clearance rate. It is an important research tool when assessing antimalarial drug efficacy data for signs of change, an early indicator of antimalarial drug resistance.

 Compares the estimated density function of slope half-lives (t½) between populations at different locations.How does PCE work?
  • Provides a consistent, reliable and accurate method to estimate malaria parasite clearance based on the linear portion of the slope of the log-parasitaemia versus time relationship.
  • Uses a standardised approach to facilitate routine monitoring of ACT efficacy and allow comparisons over time and space.
  • Provides information that enables the detection of early changes in Plasmodium falciparum sensitivity to artemisinins and support timely responses in treatment guidelines when needed.

We recommend that assessments using the PCE tool should also be incorporated into routine microscopy quality assurance or quality control protocols to verify that the results obtained are reliable.

Measuring parasitaemia for PCE

The minimum requirements for sampling times for counting parasitaemia are: 0 (0-2), 6 (4-8), 12 (10-14), 24 (22-26), 36 (34-36) and 48 (46-50) hour, and then parasitaemia should be measured at least every 24 hours until clearance. Data should be provided in csv file format; open PCE to download a sample file.

Technical issues

If you need any help using PCE or have any technical issues, please email info [at] wwarn [dot] org. Please include a screenshot of the issue and your user name. 

The benefits of sharing PCE data

95% of datasets analysed with PCE have been shared with WWARN – why not share your data?

Sharing data with WWARN allows better assessment of your data in comparison to all submitted data. You can contribute data to the WWARN project using the same username and password. If you would like to compare your data to existing validated profiles, please email pce [at] wwarn [dot] org.

Acknowledgements

WWARN gratefully acknowledges the use of data from Prakaykaew Charunwatthana, Nick Day, Arjen Dondorp, Francois Nosten, Rick M. Fairhurst, Mahamadou Diakite, Tatiana Lopera, Duong Socheat, Chanaki Amaratunga, Tran Tinh Hien, Mayfong Mayxay, Paul Newton, Harald Noedl and Nguyen Hoan Phu in developing the PCE methodology.

See References for PCE online and Figure 1.