A suspected transfusion transmitted malaria case.

Sir,

Malarial parasite (MP) detection in donated blood by conventional peripheral blood smear examination (PBS) is quite labor intensive and requires technical skill with big scope for subjectivity. Output in terms of positive yield is also very low in healthy blood donor population.[1] Rapid detection tests (RDT) score over microscopy in terms of sensitivity,[2] objectivity, and less stringent requirement for training. RDT although seem expensive per test vis-à-vis PBS, they do save cost in terms of man-hours per test and almost no requirement for repeat testing. We hereby present a case which highlights the utility of MP test using RDT in blood centers as well as for patients.

A 5-year-old female child presented to emergency with high-grade fever and shock with altered sensorium in the form of drowsiness since morning. There was a history of moderate grade fever for last 7 days relieving temporarily by medications. Past history was not significant.

Child was investigated on the lines of malaria (PBS), hepatitis, enteric fever (Widal), and dengue and was found to be negative for these. Child was managed with I.V. fluids and paracetamol along with other supportive treatment. Child responded and became afebrile after initiation of treatment.

In view of anemia (hemoglobin – 6.9 g/dl) on day 2 of admission, 1 unit of packed red cells was ordered from blood bank. A leukodepleted and compatible unit was transfused uneventfully within 3.5 hours. Patient developed fever which spiked at 103.8°F nearly 7 hours post-transfusion. Fever responded to the treatment and patient became afebrile at 11 am next day as shown in Figure 1.

Figure 1

Temperature charting before and after red cell transfusion

Gradual peaking of fever with absence of other signs and symptoms practically ruled out febrile non-hemolytic transfusion reaction (leukodepleted RBC), sepsis, transfusion related acute lung injury, hemolytic reaction, and other causes of post-transfusion fever. A possibility of blood transfusion acquired malaria was kept and patient was re-tested for malaria. She tested positive for malaria antigen by RDT. Blood bank received a call to investigate the case of post-transfusion malaria.

Routine post-transfusion reaction investigation was inconclusive. TTI record for implicated unit was checked and was found to be correct. Our blood center tests all donated units for MP using RDT (SD Bioline Malaria Ag Pf/Pan [Bio Standard Diagnostics Pvt. Ltd., Gurgaon, India]) and implicated blood unit tested negative initially. It was re-tested for malaria antigen by RDT, thick and thin PBS and was found negative for MP. Patient's pre-transfusion EDTA sample was also tested for malaria antigen in blood bank by RDT, which tested positive for p-lactate dehydrogenase and negative for HRP-II specific for P. falciparum [Figure 2]. The same was confirmed by diagnostic laboratory finding on patient's post-transfusion sample.

Figure 2

Malaria antigen detection in pre-transfusion sample of the patient

Chloroquine phosphate was initiated in appropriate dose and child responded to treatment. Her hemoglobin also improved (11.4 g/dl) and was discharged on day 4.

In a malaria endemic country like India, malaria must always be considered in any patient developing febrile illness post-blood transfusion. This becomes even more important at centers which use leukodepleted blood components, known to decrease incidence of febrile transfusion reactions.[3] Transfusion transmitted malaria (TTM) assumes significance due to high morbidity and mortality associated with it. There is hardly any systematic study on TTM and a study in beta-thallasemia estimates its incidence to be as high as 6.4%.[4]

In our case, it was patient's pre-transfusion sample which helped in clinching the cause of post-transfusion febrile illness and also absolved incriminated blood unit. Pre-transfusion thick and thin PBS of patient did not detect MP. Study by Stauffer et al.[5] clearly showed superiority of RDTs over PBS in terms of higher sensitivity and negative predictive value (NPV) for malaria (sensitivity-97% vs. 85% and NPV-99.6% vs. 98.2% respectively; P = 0.001). In addition, testing by RDT is more objective and reproducible.

All donated blood units, thus need to be screened for MP, preferably by RDTs, to prevent and defend all suspected TTM.