Diseases of the Nervous System

1. Diseases of the Nervous System

2. Nervous System • Central nervous system – brain and spinal cord • Peripheral nervous system

3. Meninges • Covering of the brain and spinal cord • Three layers • Dura • Arachnoid • Pia • Infection of the fluid around the brain and spinal cord is meningitis • Infection of the brain is encephalitis

4. Bacterial Diseases of the Nervous System • Meningitis • Listeriosis • Tetanus • Botulism • Leprosy

5. Meningitis • Three species of bacteria cause 70% of the cases of meningitis • Haemophilus influenzae • Streptococcus pneumoniae • Neisseria meningitidis • Symptoms generally include fever, headache, stiff neck, nausea, vomiting, convulsions, coma • Antibiotic treatment • High mortality without treatment

6. Haemophilus influenzae • Most common in children under 5, especially at 6 months • The use of the Hib vaccine has reduced the incidence of this type of meningitis • Haemophilus influenzae is now not a leading cause of the disease as it once was

7. Neisseria meningitis • Causes disease in children under 2 years of age • 10% of the population are carriers and reservoir for the disease • Generally begins as throat infection that leads to meningitis • Vaccine is available but not widely used

8. Streptococcus pneumoniae • Leading cause of bacterial meningitis • Common in children, with high mortality rate • Bacteria is carried in the general population is the nasopharynx • Vaccine is available • Increased antibiotic resistance

9. Viral Meningitis(aseptic meningitis) • Most common from of meningitis • 25,000-50,000 hospitalization per year • Cause - many different viruses involved, Enteroviruses most common • Symptoms - fever, severe headache, stiff neck, sensitivity to bright lights, nausea, vomiting • Serious but rarely fatal. Disease course is usually 7-10 days, full recovery typical • Spread generally through direct contact with respiratory droplets • No specific treatment

10. Listeriosis • Listeria monocytogenes • G+ coccobacillus • Commonly found in soil, water, vegetation, and GI tract of animals • Generally mild infection that can lead to meningitis • 2500 cases in US per year • 500 deaths • Dangerous to pregnant woman due to potential fetal damage or death • Food and vegetable sources of the bacteria, cook food well! • Bacteria can grow at cold temperatures and increase in number even in the refrigerator

11. Listeria infection continued • Symptoms - fever, muscle aches, GI symptoms. Nervous system - headache, stiff neck, confusion, convulsions • Pregnant women - 20 times more likely to get listeriosis!

12. Tetanus(Lockjaw) • Causative agent is G+ anaerobic spore former - Clostridium tetani • Symptoms of the disease are the result of a powerful neurotoxin that is released when the organism multiplies • Toxin blocks relaxation of muscles causing a rigid paralysis • Deep puncture wound – “rusty nail” • Rarely seen today because of the DPT vaccine • Vaccine in a TOXOID, made from inactivated toxin

13. Prevalence of Tetanus

14. Botulism • Form of food poisoning caused by the G+ anaerobic spore former - Clostridium botulinum • Bacteria produces a powerful neurotoxin that blocks muscle contraction leading to a flaccid paralysis • Spore contamination of canned food • Food eaten uncooked as in a salad cause the toxic poisoning • Cooking will inactivate the toxin

15. “Floppy “ baby syndrome Under 1 year of age 80-100 cases per year in the US 5% cases from honey spores 95% unknown cause Infant Botulism

16. Botox (poison those wrinkles)

17. Other medical uses of BOTOX • Cervical dystonia • Involuntary contraction of neck muscles • Strabismus • Cross-eyed • Blepharospasm • Uncontrolled muscles contraction of eyelids • Severe axillary hyperhidrosis • Excessive “arm-pit” sweating. Also the hands and feet.

18. Hansen’s Disease(Leprosy) • Caused by the acid-fast bacteria Mycobacterium leprae • Slow growing bacteria that affects the PNS and tissues of the body periphery, fingers, nose, ears, feet • Two forms of the disease • Tuberculoid – mild form of the disease • Lepromatous – more serious form that can lead to loss of body tissue • Leprosy is treated with antibiotics and is not highly contagious

19. Leprosy

20. Incidence of Leprosy

21. Viral Diseases of the Nervous System • Polio • Rabies

22. Polio • Best known cause of paralysis • Only 1% of cases of polio resulted in paralysis • Primary mode of transmission is fecal-oral • “Flu-like” symptoms and immune system may stop the disease at this point • Virus can infect motor neurons and cause paralysis

23. Polio vaccines • Humans are the only reservoirs of the disease so it can be eradicated by vaccination • 1954 Salk IPV vaccine introduced. Made from inactivated virus, given by injection • 1963 Sabin OPV introduced. Made from live, weaken virus, given orally • Few cases of polio from the OPV vaccine. No longer recommended by the CDC • Polio has largely been eliminated from developed areas of the globe

24. Global Polio Incidence

26. Dr. Jonas Salk(1914-1995)

27. Dr. Albert Sabin(1906-1963)

28. The “King” and Polio

29. Rabies • Fatal encephalitis caused by the bite of infected animal • Slow growing virus, long incubation period • Virus spreads from the bite to the CNS • Once the symptoms appear the disease is always fatal • Rabies is carried in the wild mainly by raccoons, skunks, and bats

30. Rabies virus

31. How rabies spreads

32. Distribution of Reservoirs for Rabies

33. Rabies Treatment • If bitten by an animal: • 1. If the animal can be located have it tested for rabies • 2. If the animal cannot be found then • 3. Wash the wound with soap and water • 4. Begin the vaccination series to prevent the disease • REMEMBER: the disease is ALWAYS fatal once the symptoms appear

34. Negri bodies

35. Prion Diseases • Infectious protein • Progressive fatal encephalitis • Examples of prion diseases • Scrapie • Mad cow disease • Kuru • Variant CJD (Creutzfeldt-Jacob disease)