Infections transfusion-related

Iatrogenic CJD is the second most common acquired human prion disease and these cases are the result of accidental infection due to contact with prion contaminated tissues or instruments during medical procedures (Table 29.1). The mode of prion infection include surgical equipment (e.g., surgical insd uments, depth electrodes), transplantation of human tissues (comeal, dura mater), intramuscular injections with growth hormone or gonadotrophin extracted from human pituitary tissues, or blood transfusion (reviewed by Will, 2003). The most likely source of infection is from donors with subclinical sCJD, except for the tw o transfusion-related cases that have been linked to blood donors who developed vCJD several years later (reviewed by Ironside, 2006). The incubation period in these transfusion related cases was 5 to 6 years, v hich is shorter than primary vCJD infection in humans. 

Bacterial infections transmitted by contaminated erythrocyte concentrates have been caused mainly by Yersinia enterocolitica. This enteric organism is capable of efficient proliferation and even selective growth at refrigeration temperatures. Of the 182 reports of transfusion-related fatalities which the US FDA received between 1986 and 1991, 29 (16%) were due to bacterial contamination, and 8 of these were caused by contamination with Yersinia enterocolitica (142). 

Two major classes of complications in the use of these proteins have emerged (1). First, transfusion-related infections with various blood-borne viruses, such as hepatitis B and C and human immunodeficiency virus (HIV). Secondly, alloimmune antibodies (inhibitors) against the deficient coagulation factors. 

The implementation of screening for HBV in blood banks since 1970s has greatly reduced the transfusion related infection. Screening of plasma, organ, tissue, and semen donors, virus inactivation of plasma-derived products and maintenance of strict control by the authorities over the precautions that need to be followed in healthcare, dental and cosmetic application centres are mandatory as shown by Schmunis et al. (2001). 

The risk of contamination of blood products with human immunodeficiency virus (HIV) and hepatitis B/C has been reduced to around 1 in 750000. However, bacterial contamination occurs more often /i97-Improvements in production processes and the introduction of safety interventions for infectious organisms have led to a dramatic reduction in transfusion-related infections [9, 29 ]. 

Bacteria The annual report of the UK Hemovigilance Office mentions one fatal transfusion-related infection (0.08% of all reports) associated with bacterial contamination of erythrocytes [7 ]. In the USA two fatal cases comprised 5% of all transfusion-related fatalities reported [8 ]. Of Dutch reports of post-transfusion bacteremia, one was assessed as having plausibly resulted from a bacterially contaminated blood component [6 ]. 

The risk of ABO-incompatible blood transfusion, although completely preventable, is 1000 to 10 000 times higher than the risk of viral infection from blood. However, geographical location is important in evaluation of the risk of transfusion-related infections [3 ]. 

Bacteria Transfusion-related infections are mainly caused by contamination with skin-commensal bacteria [3 ]. One in every 3000 donated blood units is contaminated with bacteria. The estimated prevalence of... 

Virases The risk of transfusion-related viral infection is significantly lower than the risk of bacterial infections [3 ]. Of all human herpesviruses, cytomegalovirus (CMV) is the most significant cause of transfusion-related morbidity and mortality. Because CMV may be associated with leukocytes in blood products, the incidence of transfusion-related CMV infection is significantly reduced after the use of leukocyte reduction techniques. The residual risks of transfusion-related infection with hepatitis B virus, hepatitis C virus, and HIV are respectively... 

Protozoa In Western countries transfusion-related malaria is rare. However, on a global scale malaria remains one of the most common transfusion-related infections [3 ]. 

Adverse events related to transfusion of blood components have been reported, including febrile non-hemolytic transfusion reactions, mild febrile reactions, acute and delayed hemolytic transfusion reactions, transfusion-related acute lung injury (TRALl), anaphylactic and other allergic reactions, graft-versus-host disease (GvHD), transfusion-associated circulatory overload (TACO), viral infections, post-transfusion bacteremia, transfusion-associated sepsis (TAS), hemosiderosis, post-transfusion purpura, and new allo-antibody formation [18 , 19 ]. Whole blood, erythrocytes, leukocytes, platelets, and plasma for transfusion (fresh frozen plasma, FFP) are involved. Quite a number of these adverse effects, such as TRALl, TACO, TAS, and allergic/anaphylactic reactions can be difficult to evaluate. 

Leukocyte contamination has been associated with increased transfusion associated mortality as a result of transfusion-related immune modulation, with cancer growth and impaired immunity against infections as suspected consequences. However, in two randomized studies, cancer growth was not found to be influenced by transfusion of leukodepleted and non-depleted erythrocytes [25 ]. The association with postoperative infections and leukocyte-containing transfusions could not be confirmed in a meta-analysis [26 ]. 

Buddeberg F, Schimmer BB, Spahn DR. Transfusion-transmissible infections and transfusion-related immunomodulation. 

Severe, and in particular chronic, infection can also sometimes induce anaemia, which is often made worse by drugs used to combat the infection. For example, anaemia is evident in 8 per cent of patients with asymptomatic HIV infection. This incidence increases to 20 per cent for those with AIDS-related complex, and is greater than 60 per cent for patients who have developed Kaposi s sarcoma. Up to a third of AIDS patients treated with zidovudine also develop anaemia. Again, several trials have confirmed that EPO treatment of AIDS sufferers (be they receiving zidovudine or not) can increase haematocrit values and decrease transfusion requirements. 

Treatment of anemia related to zidovudine therapy in HIV-infected patients To elevate or maintain the red blood cell level (as manifested by the hematocrit or hemoglobin determinations) and to decrease the need for transfusions in these patients when the endogenous erythropoietin level is less than or equal to 500 milliunits/mL and the dose of zidovudine is less than or equal to 4200 mg/week. Treatment of anemia in cancer patients on chemotherapy Jreatment of anemia in patients with nonmyeloid malignancies where anemia is due to the effect of concomitantly administered chemotherapy. It is intended to decrease the need for transfusions in patients who will be receiving chemotherapy for a minimum of 2 months. 

Several other viruses have been proposed as causes of liver injury these include hepatitis G yirus (discussed below), transfusion-transmitted virus (TTV), and the closely related SEN-V virus. Although all three are blood borne chronic viral infections and, in the case of TTV and SEN-V, have been known to replicate in the liver, none of these viruses appear to cause acute or chronic liver injuryd " The various hepatitis viruses are outlined in Table 47-2. 

Other pharmacoeconomic factors to consider include morbidity and mortality of transfusion reactions, related infections, potential for medical errors, and availability of RBCs as a resource. Length of ICU and total hospital stay and length of time on mechanical ventilation are also key factors. 

In A Others v. National Blood Authority Others the claimants had been infected with hepatitis C in blood given to them in transfusions in the period from 1 March 1988 when the Consumer Protection Act came into force. They claimed that the blood was defective within the meaning of the Act and that the defendants were liable even though the virus had not been identified until May 1988 and a screening test not introduced until 1989. The court ruled that the Act related to the safety of the blood and not to whether tests were available or had been carried out. 

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