Blood transfusion is necessary to treat low hematocrit from anemia or blood loss; however, it can transmit infections if the blood is not screened to prevent them. Transfusion transmitted infections (TTI) are a concern, especially in regions where specific viruses, bacteria, and/or parasites may be prevalent. As much as 10% of African HIV transmission may be attributable to blood transfusion. Blood can also cause an immune response and must be typed to avoid it.
Mechanism of Action
Blood safety screening prevents the transmission of infectious agents from donor’s blood to those who need it. The first step in reducing infection is a volunteer based blood donor system and associated risk questionnaire. Reducing incentive to donate potentially contaminated blood has reduced the blood screen-out rate in the United States to approximately 1%. Once the blood has been donated, it is screened for infectious agents.
Depending on resources available, individual samples may be screened for multiple TTIs simultaneously or sequentially. Sequential screening takes time, but may save resources by running the least expensive screens first, throwing out reactive samples, and thereby reducing the number of more expensive tests performed.
Current use in High-resource settings
High-resource settings have systems for blood donation and large batch processing. The FDA requires screening for HepB, HepC, HIV, HTLV, Trypanosoma cruzi, West Nile Virus, and syphilis in addition to non-infectious agents. In general, packed red blood cells are preferred over whole blood, as they are associated with decreased patient risk. In addition to testing, the blood is usually processed into components which a particular patient may need more such as packed red blood cells, platelets, or plasma.
Application to Low-resource settings
Low-resource settings tend to have less systematized blood donation services. 80% of transfusion services in tropical Africa are hospital-based and rely on donors recruited from the patient’s family. When family members are not available, commercial (paid) donors are sometimes used, despite higher risk of TTI. Screening is a major problem, and some estimate that 5-10% of African HIV transmission is through transfusions. Given the personal donation tendency in low-resource settings as well as supply chain and cold chain issues associated with centralized blood banking, point of care diagnostics can be helpful screening tools when blood must be screened in emergency or low-resource situations. Finally, many facilities nearest to births do not have blood transfusion capabilities.
Related Technologies in Development
Dipstick Blood Test