Transfusion-induced Plasmodium falciparum malaria in a beta thalassaemia patient during the prevention of re-establishment phase in Sri Lanka

Background Malaria was eliminated from Sri Lanka in 2012, and since then 50-60 imported malaria cases have been reported yearly. The country has remained malaria-free since, except for a single case of indigenous malaria in 2018. Blood donors are routinely screened for malaria, and transfusion malaria has not been reported in the country since 1966. Case presentation A 17-year-old splenectomized beta thalassaemia patient developed a transfusion-induced Plasmodium falciparum malaria infection following a blood transfusion 18 days earlier. The blood donor was an armed forces personnel who returned from South Sudan following a United Nations peace-keeping mission. The blood recipient's malaria infection took a complicated clinical course with elevated liver enzymes, lowered blood pressure and a prolonged parasite clearance time of 7 days but he recovered fully after two courses of artemether-lumefantrine interrupted by a course of intravenous artesunate. The prolonged parasite clearance is likely due to lack of splenic clearance of dead or damaged intra-erythrocytic parasites (due to a splenectomy) rather than to the parasite strain being resistant to artemisinin or the partner drug. This is corroborated by the fact that the blood donor's infection responded to artemether-lumefantrine with parasites being cleared on day 3. The blood donor who had not displayed signs or symptoms of malaria, had been screened for malaria on arrival in Sri Lanka and was negative on both microscopy and RDT. At the point of blood donation a blood smear examined microscopically was also reported negative for malaria, but retrospectively, the preserved smear of the donor's blood was found to contain P. falciparum parasites at a very low density. The donor when tested after the transfusion-induced case was diagnosed, also tested positive for malaria and was treated. Conclusions After malaria elimination, transfusion-induced malaria from blood donors returning from malaria endemic countries poses a threat to preventing the re-establishment of the disease. Improved surveillance of arrivals in Sri Lanka from malaria endemic countries using more sensitive methods for screening than microscopy may be required to reduce this risk. More stringent criteria for selecting blood donors, and more effective methods of screening donors for malaria than microscopy may also be necessary.