1. Infectious Diseases of the Nervous System

2. Nervous System CNS: brain and spinal cord PNS: peripheral nerves Cells are called neurons No normal flora

3. Natural Defenses of the Nervous System Skull and vertebrae Microglial cells and macrophages Restricted entry into brain (blood-brain barrier) for: – microorganisms – medications, including antibiotics – immune system

4. Nervous System Diseases Meningitis: inflammation of the meninges = membranes surrounding the brain and spinal cord Encephalitis: inflammation of the brain

5. BACTERIAL INFECTION

6. Meningitis Haemophilus influenzae type b –Infants, newborn –(also, E. coli, Streptococcus agalactiae) Streptococcus pneumoniae –Children 1 month - 4 years –Elderly Neisseria meningitidis –College students Listeria monocytogenes

7. Streptococcal Meningitis Streptococcus pneumoniae Gram + diplococci Virulent strains are encapsulated Children age 1 month – 4 years Elderly Subunit vaccine: induces opsonizing antibody to capsule

8. Meningococcal Meningitis in College Students Neisseria meningitidis Enters through nasal cavity (droplets) Incidence = 2,500 Americans/year –10-15% die, up to 20% long-term disabilities Subunit vaccine: induces opsonizing antibody to capsule

9. Neisseria meningitidis

10. Naegleria Meningoencephalitis A rare infection Naegleria fowleri Small free-living amoebas Found in soil, fresh water, and sewage Can be normal flora Protozoan feeds on bacteria but if introduced into the CNS can feed on human tissue

11. Naegleria meningoencephalitis Acquired from hot tubs, warm ponds and ground water at high temperature Children and young adults Initially infects the nasal mucosa Abrupt onset of symptoms 3 to 10 days after exposure to water Severe headache, fever, stiff neck and coma

12. Naegleria meningoencephalitis Destroys brain and spinal tissue Death occurs within 10 days of the onset of clinical signs No treatment Chlorine kills the organism in spas and pools

13. PROTOZOANS INFECTION

14. Toxoplasmosis Toxoplasma gondii Flagellated protozoan parasite Infects over 200 species of birds and animals Primary reservoir is cats Infection usually handled by immune system

15. Toxoplasmosis Acquired from contaminated meat or ingestion of oocysts in cat feces

16. Toxoplasmosis Causes serious disease in developing fetus –Liver damage –Brain abnormalities –Blindness Serious disease in people with AIDS Prevention: no raw meat, no contact with cat litter box

17. VIRAL INFECTION

18. Viral Infections of the CNS Acute Viral Encephalitis ArbovirusesWest Nile Virus Encephalitis Western or Eastern Equine Encephalitis California Encephalitis La Crosse Encephalitis Herpes simplex 1 or 2 Rabies

19. Arboviral encephalitis is prevalent worldwide

20. Brain encephalitis

21. Arboviral encephalitis…. … Results after the bite of a blood sucking insect, commonly mosquitoes The virus is inoculated directly into the blood stream and grows in monocytes and/or lymphocytes Virus is released into the blood and can enter the brain ….. infecting neurons.

22. Arboviral encephalitis is prevalent worldwide … But each virus has its own locality, due to its host insect vector species (e.g. Culex species, WNV) … Most disease in the USA is mild with symptoms of fever and malaise, and only occasionally leads to infection of the brain … Most disease localities are known and controlled by via virus monitoring, disease monitoring and mosquito control

23. Rabies Viral infection from bite of a “furious” rabid animal: Animal rabies: Wandering, aggression, biting, salivating Virus travels from the bite to the brain, via nerves Thus, variable latent period A fatal zoonotic disease Human “dumb” rabies: fever, confusion, anxiety, encephalitis, death

24. Rabies Bite  Virus grows in muscle  Virus enters sensory nerve ending  Virus travels to cord, brain  Virus grows in brain, changes behavior  Virus travels to salivary gland and is secreted

25. Where is Rabies?

26. Animal Reservoirs of Rabies

27. Negri Bodies Diagnosis of Rabies: Performed via a Post-mortem autopsy on animals Observing neuronal brain cells with intracytoplasmic inclusions (Negri bodies) Identification of Rabies Strain (Bat, Skunk, etc….) Rabid brain stained with Fluorescent anti-rabies antibody Rabid brain stained with Hematoxylin and eosin

28. Prevention of Rabies Pet Animal vaccines Wildlife edible bait vaccines Euthanize (kill) all rabid animals Quarantine biting, aggressive unvaccinated pets or pet animals bitten by wildlife

29. WEST NILE FEVER

30. Caused by arbovirus In the blood of imported birds Main vector are about 46 types of mosquitoes Starts from fever to neuroinvasive disease

31. OTHER BACTERIAL NERVE DISEASE

32. Hansen’s disease Also known as leprosy Might also happen in skin and other area To test, using the lepromin skin test which was similar to tubeculin test Infecting immigrants

33. Causes and symptoms Cause by Mycobacterium leprae Diagnosis similar to M. tuberculosis Can also be identified using PCR and skin test Progression from tuberculoid – lepromatous - lepromas

34. Progression of leprosy TuberculoidLepromas

35. Gram stain

36. Treatment Antibiotic such as rifampin, clofazimine and dapsone Can reduce the nodules of lepromatous but not the lost tissue Vaccine are NOT available, the discovery might take years to succeed

37. TETANUS

38. Causes Tetanus is often associated with rust, especially rusty nails, The rough surface of rusty metal merely provides a prime habitat for a C. tetani endospore to reside, An endospore is a non-metabolizing survival structure that begins to metabolize and cause infection once in an adequate environment. Because C. tetani is an anaerobic bacterium, it and its endospores survive well in an environment that lacks oxygen.

39. Symptoms 4 – 10days incubation Muscle spasm Lockjaw Respiratory muscle paralyzed Heart function disturb

40. Clostridium tetani Producing endospores during lack of oxigen

41. Types of tetanus Neonatal tetanus Local tetanus Cephalic tetanus Generalized tetanus

42. Treatment and prevention Tetanus toxoid vaccine Antibiotic for injured pt Antitoxin to reduce toxin inactivation Tetanus neonatorum (from contaminated knife)

43. BOTULISM

44. Clostridium botulinum

45. Botulism

48. Paralytic Poliomyelitis Neurotropic viral infection acquired by ingestion Paralytic spinal cord infection Effective vaccine (PV-1,2,3) Unvaccinated children are at risk in parts of the world like India, Africa

49. The unique stages of infection and pathogenesis of poliomyelitis. Poliovirus, an “Enterovirus” has an icosahedral capsid shell that protects it from digestion. GI Tract  Blood  Cord  CNS Paralysis of motor neurons

50. Virus travels through blood and the nerves … And each place in the cord that nerve cells are destroyed causes paralysis of that part of the body controlled by those motor neurons.

51. Polio in the USA in spurred the first human vaccines: - Salk Killed Vaccine - Sabin Modified Live Vaccine Summer epidemics in the early 1900s in the USA caused panic

52. Poliomyelitis – World Wide