Epidemiology of bacterial and parasitic infections of the central nervous system

This chapter looks at the epidemiology of bacterial and parasitic infections of the central nervous system (CNS). Bacteria and parasites are important infections of the CNS, but the epidemiology has changed significantly over the last few decades with the introduction of vaccines; appearance of organisms resistant to antimicrobial and anti-parasitic drugs; increase in number of immunocompromised people from human immunodeficiency virus (HIV) and oncological conditions; and increased movement of people throughout the world. The CNS infections present with a multitude of symptoms and signs, which often overlap, making case definitions for epidemiological studies difficult. The main syndromes of CNS infections are meningitis, encephalitis, epilepsy, and paralysis. Most bacteria gain access to the CNS via blood, although scalp, ear, and oropharyngeal infections are possible routes of infection. The chapter then discusses acute bacterial meningitis, brain abscesses, ventriculitis, tuberculosis meningitis, malaria, cysticercosis, onchocerciasis, sparganosis, and paragonimiasis.