Pathogens of the Human Central Nervous System- the Major Bacterial Pathogens.

Numerous pathogen infections can initiate potentially fatal neurological inflammation, including encephalitis, meningitis, meningoencephalitis, myelitis, and other inflammations affecting the central nervous system. Several bacterial, viral, fungal, and protozoan parasite pathogens can initiate such neurological disorders. The original infections can be transmitted between humans by aerosols, respiratory droplets, ingestion, or physical contact. Some pathogens can also be transmitted from mother to child. Or the infections can be transmitted to humans by non-human vectors, by means of bites from mosquitoes, ticks, flies, or other insects; or by bites, contact, ingestion, or proximity involving various wild or domestic animals. The geographical ranges of some of these pathogen vectors have recently been increasing, and their corresponding outbreaks of diseases are affecting substantially greater populations. Furthermore, several pathogens have evolved capabilities for latency, which enables them to maintain chronic infections for decades, but these latent pathogens can repeatedly reactivate to initiate active infections after various triggers, including aging, medical treatments causing intentional or unintentional immune system suppression, other pathogen infections, malnutrition, stress, or unusual host cell signaling. In summary, several pathogens either in their original active state or during one of their reactivations after latency are capable of initiating severe and/or lethal types of encephalitis, meningitis, meningoencephalitis, or myelitis.