Depends on the organisms and the donor.
Getting blood, either as transfusion or recreational (i.e. IVDA).
Transfusions are immunosuppressive, the more liberal the transfusion, the more hospital acquired infections (PubMed).
Babesiosis, Bacillus spp., Brucella spp., Coagulase-negative Staphylococcus, Cytomegalovirus, E. coli, Ehrlichia, Hepatitis A, Hepatitis B, Hepatitis C, Hepatitis D, HIV, Human T-cell lymphotropic virus, Malaria, any gram-negative rod, Parvovirus B19, Q fever, Relapsing fever, Rocky Mountain spotted fever, Serratia spp, Syphilis, Trypanosoma cruzii, West Nile, Yersinia enterocolitica.
See the specific organism.
Risk from a unit of blood (PubMed):
HIV: 1 in 493,000.
HTLV: 1 in 641,000.
HCV: 1 in 103,000.
HBV: 1 in 63,000.