This study looks at why some children develop very severe anemia that leads to a blood transfusion. It also checks for diseases in the blood they receive. Researchers are using small samples of dried blood (called dried blood spots) from both the children and the donated blood to find out what might be causing the anemia.

This study includes children at Jinja Regional Referral Hospital (Jinja, Uganda) who need a blood transfusion, whether they are in the clinic, emergency room, or children's ward. After doctors finish the usual blood tests, a small sample of leftover blood will be saved on a special card (called a dried blood spot). The same will be done for all blood transfused during the study. These samples will be frozen and later sent to Cincinnati Children's Hospital for testing.

Inclusion Criteria:

• Children receiving a blood transfusion in Eastern Uganda at Jinja Regional Referral Hospital.

Exclusion Criteria:

• If receiving a blood transfusion, refusal or inability to sign an informed consent.

Patients receiving a blood transfusion in Eastern Uganda at Jinja Regional Referral Hospital.

All samples collected will be de-identified and their collection, storage and analysis constitute no more than minimal risk activities.