In developing countries, the donor is sometimes specifically recruited by or for the recipient, typically a family member, and the donation occurs immediately before the transfusion. It is unclear whether applying alcohol swab alone or alcohol swab followed by antiseptic is able to reduce contamination of donors blood. Processing and testing
Donated blood is usually subjected to processing after it is collected, to make it suitable for use in specific patient populations. Collected blood is then separated into blood components by centrifugation: red blood cells, plasma, platelets, albumin protein, clotting factor concentrates, cryoprecipitate, fibrinogen concentrate, and immunoglobulins (antibodies). Red cells, plasma and platelets can also be donated individually via a more complex process called apheresis. The World Health Organization (WHO) recommends that all donated blood be tested for transfusion-transmissible infections. These include HIV, hepatitis B, hepatitis C, Treponema pallidum (syphilis) and, where relevant, other infections that pose a risk to the safety of the blood supply, such as Trypanosoma cruzi (Chagas disease) and Plasmodium species (malaria). According to the WHO, 25 countries are not able to screen all donated blood for one or more of: HIV, hepatitis B, hepatitis C, or syphilis. One of the main reasons for this is because testing kits are not always available. However the prevalence of transfusion-transmitted infections is much higher in low income countries compared to middle and high income countries. All donated blood should also be tested for the ABO blood group system and Rh blood group system to ensure that the patient is receiving compatible blood.
However, in many species (especially horses and dogs), cross matching is not required before the first transfusion, as antibodies against non-self cell surface antigens are not expressed constitutively – i.e. the animal has to be sensitized before it will mount an immune response against the transfused blood. The rare and experimental practice of inter-species blood transfusions is a form of xenograft. See also
Anemia
Arnault Tzanck
Blood transfusion in Sri Lanka
Blood type (non-human)
Xenotransfusion
Young blood transfusion, a pseudoscientific practice involving the transfusion of blood taken from young donors to older recipients that is claimed to have health benefits
AIDS

References
Further reading
Tucker, Holly (2012). Blood Work: A Tale of Medicine and Murder in the Scientific Revolution. W. W. Norton & Company. ISBN 978-0393342239. "Milk as a Substitute for Blood Transfusion", historical account, Scientific American, 13 July 1878, p. 19

External links
Transfusion Evidence Library searchable source of evidence for transfusion medicine. Blood transfusion societies
American Association of Blood Banks (AABB)
British Blood Transfusion Society (BBTS)
International Society of Blood Transfusion (ISBT)

Books
Blood Groups and Red Cell Antigens Free online book at NCBI Bookshelf ID: NBK2261
Handbook of Transfusion Medicine Free book published in the UK 5th edition

Guidelines
American Association of Blood Banks Clinical Practice Guidelines
Australian National Blood Authority Patient Blood Management Guidelines
British Committee for Standards in Haematology
National Institute for Health and Care Excellence Blood Transfusion Guidance UK Guidance for transfusion. Canadian Blood Transfusion Guidelines
German Medical Association Guidelines (English), published 2014. Patient information
Blood Transfusion Leaflets (NHS Blood and Transplant)
Blood Transfusion Leaflets (Welsh Blood Service)
Blood Transfusion Information (Scotland)
Blood Transfusion Information (Australia)
Blood Transfusion Information (American Cancer Society)