[Infections of the central nervous system in the immuno-compromised]

Infections of the central nervous system (CNS) can be caused by a variety of pathogens, depending on whether the number and function of T-cells or monocytes are impaired (as in HIV patients) or whether the number and function of polymorphonuclear granulocytes are reduced or impaired, as typically seen in patients on immunosuppressive therapy, post transplantation, etc.. The first part of the chapter deals with CNS infections associated with reduced or abnormal T-cell (or monocytic) function and number, mainly seen in HIV patients, such as cerebral toxoplasmosis, CNS cryptococcosis, cytomegalovirus encephalitis, and progressive multifocal leukoencephalopathy. The clinical presentation, diagnostic procedures, as well as therapeutic and prophylactic management of these diseases are described in detail. The second part of the chapter deals with diseases usually seen in patients with impaired or reduced number and function of polymorphonuclear granulocytes. Such CNS infections are frequently caused by viral, bacterial, or fungal pathogens and are described in their clinical presentation, their diagnostic procedures and the best possible therapeutic and prophylactic management.