© 2004 Wadsworth – Thomson Learning Chapter 25 Infections of the Nervous System

© 2004 Wadsworth – Thomson Learning The Nervous System Figure 25.1

© 2004 Wadsworth – Thomson Learning Meningitis Organisms –Neisseria meningitidis meningococcal –Haemophilus influenzae –Streptococcus pneumoniae pneumococcal –E. coli Pathogenesis –inflammation of the meninges membrane brain and spinal cord –sudden fever, severe headache, neck rigidity –treatment--immediate antibiotics

© 2004 Wadsworth – Thomson Learning Meningitis Aseptic meningitis –viral origin Cryptococcal meningitis –Cryptococcus neoformans

© 2004 Wadsworth – Thomson Learning Tetanus Organism –Clostridium tetani –Spore former –Anaerobic growth deep wounds decaying tissue Pathogenesis –tetanospasmin neurotoxin ink dot enough for 30 deaths –contraction of muscles spastic paralysis lockjaw respiratory distress

© 2004 Wadsworth – Thomson Learning Tetanus Treatment –before clinical symptoms antitoxin blocks toxin –after clinical symptoms no treatment Prevention: –vaccine every 5-10 years –toxoid develop antibodies against toxin, not organism

© 2004 Wadsworth – Thomson Learning Botulism Organism –Clostridium botulinum spores many places growth inhibited by low pH Pathogenesis –blocks release of acetylcholine –interferes with nerve impulse –paralysis of respiratory muscles –mortality 35%

© 2004 Wadsworth – Thomson Learning Botulism Different types of toxin –produced by different strains of C. botulinum –Type A most potent west of Mississippi River Age associated –infant botulism differences in normal biota –adult botulism food poisoning heat-labile toxin

© 2004 Wadsworth – Thomson Learning Rabies bullet-shaped morphology epidemiology –reservoir: all mammals –humans: end of infectious cycle control –reduce exposure of virus in animals wild mammals--uncontrollable reservoir bats--dormant for long periods domestic--vaccine diagnosis : serology/brain tissue (negri body ) treatment: vaccine and immune globulin (RIG)

© 2004 Wadsworth – Thomson Learning Poliomyelitis Pathogenesis –alimentary phase--primary multiplication –lymphatic phase--tonsils, lymph nodes –viremic phase--spread in blood –neurological phase--CNS, extraneural tissue requires persistent viremia low levels of antibodies prevent spread >l% of infections lead to severe paralytic infection –two vaccines oral (OPV)--attenuated--Sabin injected (IPV)--inactivated--Salk –eradication schedule--2000

© 2004 Wadsworth – Thomson Learning Encephalitis Arboviruses Eastern Equine Encephalitis (EEE) –severe Western Equine Encephalitis (WEE) California Encephalitis (CE) St. Louis Encephalitis (SLE) Japanese B encephalitis –endemic areas of Asia mosquito borne Other viruses West Nile Virus

© 2004 Wadsworth – Thomson Learning Spongiform encephalopathy Prions –infectious proteins –Diseases: Creutzfeldt-Jakob disease (CJD) Kuru Scrapie (sheep) Bovine spongiform encephalitis (mad cow)

© 2004 Wadsworth – Thomson Learning African Trypanosomiasis Sleeping Sickness –Trypanosoma brucei gamiense –Trypanosoma brucei rhodesiense –Protozoa –Transmitted by tsetse fly multiply in fly tyrpanosome enters blood spread to spleen, lymph nodes, liver invade CNS coma and death