Almost one in four blood bank supplies in certain regions of Africa may have malaria parasites in them, a new study suggests. UK scientists reviewed 26 studies that measured levels of Plasmodium parasites — which cause malaria — among blood donors in sub-Saharan Africa between 2000 and 2017 and found that an average of 23.46% tested positive.
Overall, there is a high risk that a potential blood donor or bag will contain parasites, said Dr. Philippe Guerin, director of the Worldwide Antimalarial Resistance Network and professor of medicine at Oxford University’s Centre for Tropical Medicine and Global Health.
“Malaria is one of the primary infections that can be transmitted through a blood transfusion in sub-Saharan Africa,” said Selali Fiamanya, a research fellow at the Worldwide Antimalarial Resistance Network who also worked on the study.
Blood supplies are typically screened for blood-borne diseases before being made available to recipients, but Guerin believes that screening is not always being conducted systematically and that when it is, current lab techniques are not sensitive enough to spot all malaria parasites, particularly latent infections or when parasites are hiding in people who are infected but symptom-free.
Blood donors are usually adults, and in regions with high rates of malaria, adults often develop some immunity against the parasite, meaning they could have the parasites in their blood but not feel sick, Guerin said.
Meanwhile, pregnant women and children receive the majority of transfusions in this region, Fiamanya said. The transmission risk of contracting malaria through blood supplies is unknown but is likely to be high, Guerin said. “If you’ve got parasites circulating, the infection risk is high.”