Nervous System Central nervous system – brain and spinal cord Peripheral nervous system
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
Bacterial Diseases of the Nervous System Meningitis Listeriosis Tetanus Botulism Leprosy
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
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
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
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
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
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
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!
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
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
Infant Botulism “ Floppy “ baby syndrome Under 1 year of age 80-100 cases per year in the US 5% cases from honey spores 95% unknown cause
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.
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
Viral Diseases of the Nervous System Polio Rabies
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
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
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
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
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