Blood Transfer Devices Assessed for Malaria Test

A comparison has been made of different devices for transferring blood to the rapid diagnostic test (RDT) for malaria in three developing countries.

The five blood transfer devices evaluated were the loop and inverted cup, made of hard plastic; a straw-pipette and calibrated pipette, made of soft plastic, and a glass capillary tube.

A study was conducted between August and November 2009 among 227 health workers in Nigeria, the Philippines, and Uganda, under the auspices of the Foundation for Innovative New Diagnostics, (FIND; Geneva, Switzerland). The participants were recruited from the staff of frontline health centers and community-based malaria programs. The devices were evaluated for accuracy, safety, and ease of use. The participating health workers used each device to transfer blood from a simulated finger prick site to filter paper. Blood volume transferred was calculated from the area of blood spots deposited on filter paper.

The overall mean volumes transferred by devices differed significantly from the target volume of 5 μL which is the minimum amount recommended for the most RDTs. The new inverted cup device transferred a mean of 4.6 μL, which most closely approximated the target volume. The glass capillary was excluded from volume analysis, as the estimation method used is not compatible with this device. The calibrated pipette accounted for the largest proportion of blood exposures to 10% of the health worker. Blood exposures for the other four devices ranged from 2% to 6%. According to 91% of the health workers, the inverted cup was considered easiest to use in blood collection, while the straw-pipette and calibrated pipette were rated the most difficult to use.

Rapid diagnostic tests are becoming the standard method of detection of malaria in poor resource settings. The blood transfer device is an essential part of the kit because the sensitivity of the tests is compromised when an inadequate volume is transferred to the RDT cassette, especially when parasite density falls below 200 parasite/μL. The findings of this study have relevance for any point-of-care diagnostics that require blood sampling. The variability in device performance demonstrated the need to devote attention to this issue when implementing RDT-based diagnostic programs. The study was published online on February 8, 2011, in the Malaria Journal.

Related Links:
Foundation for Innovative New Diagnostics