(P-BC-63) The Use of Malaria PCR and Antibody Testing in a Non-Endemic Country to Assess the Malaria Risk in Blood Donors

Background/Case Studies: The risk of transfusion-transmitted malaria in non-endemic countries are primarily due to blood donors who are previous residents of a malaria endemic country. Currently, there is no consensus on what the best way is to screen at risk blood donors for malaria in non-endemic countries, some perform malaria testing (e.g. antibody) while others defer donors for a specific period. To prevent transfusion-transmitted malaria, the Health Sciences Authority implemented malaria antibody testing in addition to PCR (in parallel) to detect malaria in at risk donors. Donors are permanently deferred if Plasmodium DNA is detected using real time PCR (qPCR) and or malaria antibody positive in two donations (later changed in 2022 to one antibody positive donation). Since implementation, we have identified two cases of confirmed malaria antibody negative but qPCR positive donations from donors who are previous residents of a malaria-endemic country. Reported here is a case of a donor who tested positive for malaria antibody and negative for qPCR on the 1^st donation, but Plasmodium DNA was detected on subsequent donation.
 

Study

Design/Methods: The donor is a female in her early 30s from Myanmar who made a whole blood donation for the 2^nd time in 2022. She denied any history of malaria and informed the blood bank that she did not travel outside Singapore after her 1st donation in 2019. The last time she visited Myanmar was in 2017. The donor passed the interview and was allowed to donate but because her previous donation in 2019 was malaria antibody positive and qPCR negative, both malaria antibody and qPCR were again performed in her latest donation to assess the malaria risk in the donor.
 

Results/Findings: Real Time PCR (qPCR) was performed on the donor’s donation and Plasmodium DNA was detected. The reported analytical sensitivity of the qPCR kit used is 1.27 IU/μl [95% CI: 0.57 - 5.42 IU/μl) The species was identified to be Plasmodium vivax. Malaria antibody testing again showed a positive result. The donor was permanently deferred and referred to the National Centre for Infectious Diseases for further evaluation and management.
 

Conclusions:

 In the case presented, the donor did not travel outside Singapore from 2019 onwards so it is likely that the donor may have already been infected during the 1^st donation and that the qPCR missed the detection of the malaria parasite possibly due to low parasitemia. Fortunately, her malaria antibody test was positive which resulted in the discard of her donation and prevented transfusion of a potentially infected unit. Since there is no consensus on what the best strategy or test to use in preventing transfusion-transmitted malaria in non-endemic countries, blood collection centers may consider a combination of different approaches to ensure blood safety taking into consideration the cost, sufficiency of supply, donor impact, and possible sources of malaria infection.