Pathogens of the Human Central Nervous System-the Major Protozoan Parasites and Helminths

Numerous pathogen infections can initiate potentially fatal neurological inflammation, including encephalitis, meningitis, meningoencephalitis, and myelitis. Several protozoan parasites and helminths can initiate neurological disorders. Pathogens can achieve this either by their original active infections, or by reactivated infections after a period of latency. The pathogens can be transmitted between humans or to humans by respiratory droplets, ingestion, or physical contact. Or the infections can be transmitted to humans by nonhuman vectors, by means of bites from mosquitoes, ticks, flies, or other insects, or by bites, contact, or ingestion involving various wild or domestic mammals or birds. Some pathogens can also be transmitted from mother-to-child. The most easily transmissible and pervasive pathogens capable of causing neurological inflammation would include some of the endoparasites including protozoan parasite pathogens and helminths. The evolved capabilities of some protozoan parasites for latency enable them to maintain chronic infections for decades, but these latent pathogens can repeatedly reactivate to initiate active infections after various triggers. In summary, several pathogens either in their original infection or during one of their reactivations after latency are capable of initiating severe and dangerous types of neurological inflammation.