You can find here What Infections can be Transmitted by Blood Transfusion?

Several adverse reactions to blood transfusion can occur despite checking, inspecting and testing at several levels. Fortunately, the common adverse reactions to blood transfusion are minor and serious reactions occur very rarely if ever. If any adverse reaction is suspected, the blood transfusion should be stopped immediately and reported to blood bank for investigation.

Commonly two types of adverse reactions to blood transfusion are seen, (1) immune mediated adverse reactions and (2) non immunologic adverse reactions. Complications due to infectious organisms may also occur in blood transfusion.

What are the immune mediated adverse reactions to blood transfusion?

The immune mediated adverse reactions to blood transfusion are FNHTR or febrile non hemolytic transfusion reaction (occurs 1-4 out of 100 units of blood transfusions or 1-4:100),

During the time of evolution of humans, the food supply was intermittent and for survival there was need to store energy in excess of what is required for immediate use. Fat cells did the job of storing energy, which are widely distributed in adipose tissues. The fat cells can store excess energy efficiently as triglyceride and, when needed, release stored energy as free fatty acids for use at other sites. This physiologic system developed during the time of evolution acts through endocrine and neural pathways and even can permit humans to survive starvation for as long as several months. But at present era of nutritional abundance, sedentary lifestyle, and influenced importantly by genetic endowment, this physiologic system of storing energy in adipose tissues can produce obesity and adverse health consequences due to obesity.