antibodies: Chemicals produced by the immune system in response to a foreign substance, or antigen.

arbovirus: A virus spread by an arthropod, most commonly by bloodsucking insects.

blood-brain barrier: A biological mechanism that prevents most toxins and pathogens from crossing into the brain from the blood.

blood transfusion: A procedure in which a person who needs blood receives blood from a donor.

cerebrospinal fluid: The liquid that surrounds the brain and spinal cord.

encephalitis: Inflammation of the brain.

epidemic: A widespread outbreak of disease.

epidemiologist: Doctor who specializes in tracking down causes and incidence of infectious diseases.

flavivirus: A type of virus that is transmitted by mosquitoes or ticks.

gene: The basic unit of hereditary information in a cell.

host: Animal that carries an infectious disease.

incubation period: The time between infection and evident symptoms.

intravenous: Into a vein.

meningitis: Inflammation of the meninges, the lining of the...