While reports of infections after tissue transplantation are rare, the true rate of transmission is unknown, although it is estimated in <1 % of solid organ recipients. The risk of infectious transmission has been correlated to microbiological screening, which can vary with national and regional regulations and with the availability and performance of microbiological assays used for potential donors.

Viral, bacterial, parasitic, prion and fungal infections can be transmitted by organs, tissues and cells. Infectious transmissions have often been recognised as clusters of infections among recipients of organs from a common donor. These include Mycobacterium tuberculosis, Candida and Aspergillus species, herpes simplex virus and human herpesvirus 8, lymphocytic choriomeningitis virus, rabies virus, HIV and HCV.

Each infectious disease identified in a donor must be treated before organ recruitment: common infections cured before organ donation do not preclude organ transplant. The use of organs from donors with active or suspected infection reflects the urgency of transplantation, the availability of other organs and the recipient’s informed consent.

General exclusion criteria are rabies, active tuberculosis, HIV or HTLV infection, West Nile virus infection and uncontrolled sepsis. Increased-risk donors include all individuals with uncontrolled sexual behaviour, drug abusers, donors previously treated with human-derived clotting factor concentrates and the prison population. These donors can be considered in a “window period” with very low antibody titres and have to be tested by highly sensitive and specific microbiological assays, such as viral nucleic acid tests [2–5].

The transmission of malignancies is a well-recognised complication of transplantation from donors with and without a history of cancer. The employment of older donors has increased the risk of inadvertent cancer transmission. Donor-transmitted tumours are those that existed in the donor at the time of transplantation. Donor-derived tumours are de novo tumours that develop in transplanted donor cells. Donor-transmitted tumours could be prevented by meticulous donor evaluation.

During the last 10 years, there has been a progressive decrease in the transmission of malignancies, due to the stringent application of guidelines during organ procurement and removal. In 2002 the OPTN/UNOS estimated the risk of cancer transmission to be 0.01 % [6]. In the UK, among 39,765 graft recipients, Desai et al. [7] reported a donor-transmitted cancer in 15 patients (0.05 %) from 13 donors. In no case was cancer detected at the time of transplantation.

Each donor should be investigated for smoking or other cancer related risk factors. If a history of cancer is reported, it is necessary to know the histological diagnosis and the type of tumour, its grading and staging, and the donor’s treatment and follow-up. If the donor is a childbearing woman who died from intracranial haemorrhage or had a history of uterine bleeding, all tests to exclude choriocarcinoma must be performed. All donors with intracranial haemorrhage without evidence of arterial hypertension or aneurysms must be evaluated for possible brain metastasis; in some cases, an intraoperative brain biopsy may be required. A meticulous check of the donor’s skin can reveal scars or skin lesions suspect for melanoma or a previous melanoma.

Italian guidelines (www.​trapianti.​salute.​gov.​it), the Council of Europe [5], Nalesnik et al. [8], and the UK Advisory Committee on the Safety of Blood, Tissues and Organs have defined risk categories for donor tumour transmission. A suggested approach to donor utilisation has been given for each category, recognising the emergent circumstances and clinical urgency. A careful evaluation of the donor before and during organ recruitment is always recommended: [5] palpation of the abdominal organs and lungs, immediate frozen sections of any suspected lesions and preoperative echography of the liver and the kidneys must be performed [9].

The risk profile in the different experiences can be summarised as no significant risk (standard risk), minimal risk, low to intermediate risk, high risk and unacceptable risk. Definition of a risk profile in neoplastic donors is the basis of a careful screening system designed to minimise or remove the risk of cancer transmission from the transplantation process.