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metha 2010 chp19
Infectious Diseases Affecting the Nervous System
| Question | Answer |
|---|---|
| Central nervous system (CNS) | – the brain + the spinal cord |
| Peripheral nervous system (PNS) | – nerves that branch off the brain/spinal cord |
| Meninges | - 3 continuous membranes -dura mater |
| subarachnoid space | contains circulating cerebrospinal fluid (CSF) - which is susceptible to infection because few circulating antibodies are found here |
| Blood-brain barrier | Drugs cannot cross the blood-brain barrier unless they are lipid-soluble. . Brain inflammations alter the barrier and do allow antibiotics to cross that normally wouldn’t. |
| Invasion by microbes | 1. physical trauma - spinal tap – by the sampling of the CSF - along the peripheral nerves; but especially though the bloodstream and lymphatic system when inflammation alters the blood-brain permeability 2. meningitis – inflammation of the meninges 3. e |
| Meningitis | 1. Symptoms – high fever - headache - and a stiff neck followed by nausea and vomiting - which may lead to convulsions and coma; symptoms are vague in infants; death occurs quickly; survivors often have some neurological damage – learning disability - hea |
| Neisseria meningitides | - most serious form of acute meningitis |
| Neisseria meningitides endotoxins | cause symptoms and serious tissue damage if bacteria enter the bloodstream; rash in only this form of meningitis – faint purple-red blood spots anywhere on the body caused by the toxins which break down the blood vessel walls allowing the blood to leak o |
| Neisseria meningitides leading cause of bacterial meningitis in | young adults; also affects children under two with the greatest incidence at six months |
| Neisseria meningitides vaccine | – used in the military and recommended for college freshmen - especially those living in dorms (increase in outbreaks over the past 10 years); not effective in young children; antibody levels decrease over 2-3 years; re-vaccination is recommended at 3-5 |
| Neisseria meningitides quadravalent | vaccine for serotypes A - C - Y - and W135 |
| Pneumococcal Meningitis caused by | Streptococcus pneumoniae |
| Pneumococcal Meningitis mortality is high; | antibiotic resistance is an increasing threat |
| Pneumococcal Meningitis pneumonia vaccine | is recommended for children under two; some protection afforded for the elderly b/c of the vaccine recommendation at 65 years |
| Haemophilus influenzae meningitis | a. type b Hib b. was the most common; but expected to be eradicated in US by vaccine that starts at 2 months of age |
| Listeriosis – Listeria monocytogenes | Source – Soil - water - sewage - animal secretions – especially milk - domestic animals or human carriers; as a pathogen - usually food-borne; wide-range of foods - dairy products - hot dogs; can grow at refrigerator temperatures |
| Listeriosis – Listeria monocytogenes Readily killed by | antiseptics and pasteurization |
| Listeriosis – Listeria monocytogenes Phagocytized by | monocytes but rather than being destroyed - multiplies and spreads to adjacent cells - and is protected from antibodies |
| Listeriosis – Listeria monocytogenes. Usually a mild disease in | most adults - but in the immunosuppressed - pregnant - or who have cancer - serious - usually meningitis; TORCH – crosses the placenta and infects the fetus spontaneous abortions - stillbirths - septicemia - meningitis |
| Cryptococcus neoformans meningitis | a. Yeast-like fungus which has a very thick capsule b. Spread is by inhalation of fungus in dried infected pigeon droppings c. Highest rates occur among AIDs patients where it is frequently fatal |
| Viral meningitis | a. Generally milder and resolves within 2 weeks b. Diagnosis by absence of bacteria |
| Neonatal Meningitis | Streptococcus agalactiae + Escherichia coli |
| Streptococcus agalactiae Group B Strep | or GBS (Streptococcus agalactiae) - Leading cause of neonatal sepsis and meningitis in the US and Europe; 1-3 cases per 1000 births with a mortality rate of 50%; 30% of those that survive will suffer CNS damage; |
| Streptococcus agalactiae GBS is found in | the lower intestine of 10-35% of all healthy adults - and in vaginal flora of 10-35% healthy women; not sexually transmitted; all women should be tested between 35 to 37 weeks of pregnancy; those that test positive should have IV antibiotics started at t |
| Streptococcus agalactiae Bacterium is transmitted | to the baby during or after birth (Cesarean sections are not likely to prevent GBS disease. |
| Streptococcus agalactiae Symptoms | of fever - respiratory distress - and lethargy appear w/in a few days of birth – early onset; “late onset” cases 3-8 wks after birth frequently present as meningitis; |
| Streptococcus agalactiae Group B Strep should not be confused with | Group A Strep – Strep Throat (Streptococcus pyogenes) |
| Escherichia coli | a. K1 strain – capsular antigen b. if baby is premature prognosis is not good with 20% mortality and brain injury in those that survive |
| Meningoencephalitis Naegleria fowleri | Amoeba that causes infection when forced up the nasal passages of swimmers in warm (above 80 F) - natural bodies of water Result is PAM – primary amoebic meningoencephalitis - a rapid massive destruction of the brain and spinal tissue that causes hemorrh |
| Acute Encephalitis: | Arboviral Encephalitis |
| Arboviral Encephalitis caused by | mosquito-borne viruses caused by arboviruses – arthropod-borne viruses 2. Symptoms begin with chills - headache - fever - and then - confusion and coma; survivors may have permanent neurological problems 3. Zoonotic - Birds and/or horses or small mammals |
| Acute Encephalitis Arboviral Encephalitis Different types | a. Eastern equine encephalitis (EEE) - East Coast b. St. Louis encephalitis (SLE c. West Nile virus d. Japanese encephalitis |
| Eastern equine encephalitis (EEE) | - East Coast - most severe affecting mostly younger children and younger adults; outbreaks usually follow high periods of rainfall; the disease is seen first in horses and caged birds; high fatality |
| St. Louis encephalitis (SLE) | throughout country but mostly urban areas - usually affecting adults over 40 |
| West Nile virus | 1) Symptoms – Fever - headache - weakness - sometimes nausea or rash as it moves to the CNS 2) Spread - vectored by 36 species of mosquitoes; in the US found in 39 states; 4 -156 cases with 284 deaths reported in 2002; animals are affected as well – epizo |
| Japanese encephalitis | – Japan - Korea - China; vaccination recommended for travelers |
| E. Subacute Encephalitis | Toxoplasma gondii (gon-dee-eye. Prions: Proteinacious infectious particles |
| Toxoplasma gondii (gon-dee-eye): | Toxoplasmosis |
| Toxoplasma gondii Obligate protozoan; | up to 40% of the population test (+) with anti-Toxoplasma antibodies; |
| Toxoplasma gondii Asymptomatic | or symptoms are mild |
| Toxoplasma gondii T in TORCH | - 33% chance of transfer of trophozoites across the placenta; if a fetus in the 1st or 2nd trimester contracts it - or an AIDS patient - brain lesions severe brain damage or vision problems; fatal disruptions of the heart and lungs |
| Toxoplasma gondii oocysts survive | in moist soil several months - herbivores/grazing carnivores from eating infected spp.; cooking or freezing meet at <20C kills oocysts; usually acquired via: |
| Toxoplasma gondii oocysts; usually acquired via: | 1) raw or undercooked meat - e.g. ethnic dishes as steak tartare - German hackpeter (raw pork) - kibbe (Middle Eastern dish of raw lamb); |
| Toxoplasma gondii oocysts alternate hosts | - can infect 200 spp of birds and mammals; the primary reservoir and hosts are members of the feline family: handling of cats - contact with the oocysts on the cat or inhaling contaminated air and dust or direct contact with cat feces - e.g. litter box |
| Prions: Proteinacious infectious particles | Sheep scrapie - variant Creutzfeldt-Jakob disease (vCJD) - Bovine spongiform encephalopathy (BSE) - Mad Cow Disease - Kuru; Chronic wasting disease in deer and elk |
| Prions PrP or protease resistant protein is found in | healthy humans and animals |
| Prions An abnormal PrP enters | the cell and converts the normal PrP to abnormal PrP resulting in holes in the brain |
| Prions. Prion variant responsible for | mad cow disease has the ability to bypass the species barrier to transmission |
| Rabies | (Latin for rage) |
| Rabies Source | – zoonosis; parenteral bite from animals in the wild - raccoons in FL - but also fox - skunks - coyotes - bats – bite can go undetected; domestic pets – dogs or cats; No rabies in Australia - Great Britain - New Zealand - HI; Vaccination of animals - eve |
| Rabies Incubation period | usually 30-50 days - but can be shorter if the bite occurs in the hand or face b/c virus will move through the peripheral nerves to the CNS faster; once symptoms of agitation and hydrophobia begin almost always fatal w/in a few days; there is no treatmen |
| Rabies Postexposure prophylaxis | – an inactivated vaccine in a series of 6 injections during a 28-day period with 2 boosters |
| Poliomyelitis a.k.a | . Polio |
| Polio Symptoms | – a few days of headache - sore throat - and fever; more seriously – paralysis when the virus moves to the CNS; more frequent when infection occurs during adolescence or early childhood; maternal antibodies protect infants who if exposed are usually asym |
| Polio Post-polio syndrome | – may occur 25 or more years after the initial attack; fatigue - weakness - pain - loss of muscles mass |
| Polio Transmission is by | a fecal-oral route. Ingestion of water or food contaminated with feces laden with virus. Sanitation in this country led to outbreaks in children and teens. |
| Polio Vaccination program | – 3 different serotypesa) Salk vaccine – 1954; enhanced inactivated polio vaccine (E-IPV) requires a series of 3 injections; b) Sabin vaccine – 1963; live attenuated virus - oral – OPV; higher level of immunity acquired; live virus excreted in feces; dan |
| Tetanus | – Clostridium tetnai |
| Tetanus Onset | is usually 4 to 10 days following puncture wounds/soil. Neurotoxin – contraction of voluntary muscle groups; clenching of the jaw – lockjaw - followed by extreme arching of the back - flexion of the arms - and extension of the legs; paralysis and respir |
| Tetanus The toxin tetanospasmin attaches to the | junctions of the regulatory neurons and block the release of neurotransmitter that cause relaxation impulses so that opposing muscle groups both contract simultaneously - resulting in the characteristic muscle spasms. |
| Antitoxin therapy with human tetanus immune globulin (TIG) | = antibody containing blood serum of immunized people. (passive immunity). Prevention by vaccination with the tetanus toxoid = the denatured inactivated tetanus toxin used to stimulate the production of antibodies that neutralize the toxin. (active immun |
| Botulism | - Clostridium botulinum |
| Botulism Considered to be the most | toxic form of food poisoning in humans; onset is 12 to 72 hours following ingestion of the botulin neurotoxin; relaxation of involuntary muscle groups; neuromuscular symptoms first affect the head and include double vision - difficulty in swallowing - an |
| Botulin neurotoxin is | highly specific for the synaptic end of the nerve cell - where it blocks the release of acetylcholine - a chemical necessary for transmission of nerve impulses across synapses. |
| Botulism Antitoxins to | neutralize A - B and E botulin toxins for adults; as well supportive respiratory care (as nerve endings regenerate) and cardiac support systems. Floppy baby syndrome – honey - corn syrup - dust; supportive care w/o antitoxin therapy for infants. |
| Botox – injections into the face and neck | temporarily minimize wrinkles. |
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