The immune response to infectious diseases of the central nervous system: a tenuous balance.

The outcome of CNS infection is dependent on both the organism and host. Acute infections are usually cleared with minimal residua. However, chronic infections of the CNS, such as HIV, PML, HSV, polio, Lyme neuroborreliosis, and neurosyphilis, are becoming increasingly recognized as a cause of severe neurological morbidity, and are poorly understood. We will need to learn more about the CNS as an immune compartment to increase our knowledge of these infections.