There are several categories of immunocompromised patients. Different viruses cause different clinical symptoms in these patients as shown below. HIV positive/AIDS patients often have different symptoms from transplant recipients and need different treatment and prophylactic strategies.

Organ transplant recipients

See Table 43.1.

Cytomegalovirus (CMV)

Cytomegalovirus is the most important virus infection in transplant recipients. Infection acquired from the donor organ is usually most severe and can be fatal. Eighty per cent of CMV antibody negative patients who receive an organ from a CMV antibody positive donor will acquire primary CMV infection. The severity of their symptoms will depend on the amount and type of immunosuppressive treatment they are receiving. Lung and bowel transplants usually have more severe CMV disease than heart, liver or kidney recipients. Between 30% and 60% of CMV antibody positive organ recipients will experience CMV reactivation from one to three months after transplantation. Antiviral treatment for severe CMV disease is intravenous ganciclovir (or foscarnet or cidofivir if ganciclovir is contraindicated).

Herpes simplex virus (HSV)

Herpes simplex virus infection in transplant recipients is almost always a reactivation of latent infection, which occurs from a few weeks to a few months after transplantation. Symptoms can vary from a small cold sore, genital or skin lesion to extensive skin eruptions and, rarely, encephalitis. It can be treated with oral or intravenous aciclovir (depending on the severity of the symptoms).