inflammation of the meninges (membranes covering the central nervous system) and choroid plexus (an area of the brain that regulates the pressure of cerebrospinal fluid), characterized by marked infiltration of lymphocytes (lymphocyte) into the cerebrospinal fluid. It is a viral infection endemic in lower animals, especially mice (mouse), and is contracted by humans through inhalation of contaminated dust, the bite of an infected animal, or contact with contaminated rodent urine, feces, or nest materials. The disease may be asymptomatic, or it may resemble influenza or develop into a definite meningitis, usually with complete recovery in two to three weeks.