Microfilaria can be transmitted by blood transfusion, particularly in developing countries. However, it is not considered a significant threat, especially when compared to other transfusion-transmitted disorders.
Sources of infection:
(1) blood transfusion in a region endemic for filariasis
(2) blood donation by a visitor/tourist to an endemic region
(3) blood donation by an immigrant from an endemic region
Risk factors for transmission:
(1) failure to use a leukocyte filter during transfusion of blood or platelets
(2) pretransfusion history that failed to identify potential risk
(3) failure to screen products in an endemic region
The infection is typically identified:
(1) incidentally during processing of blood product
(2) in transfusion recipient (allergic reaction, eosinophilia, smear review, etc)
(3) in the donor sometime after the donation
Most infections have been asymptomatic or mild, with microfilaria cleared without treatment in a few months or years. It is believed that the presence of an adult worm is necessary for symptoms and eosinophilia, neither of which are seen with microfilaria alone.
