Encephalitis
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- What is the definition of ENCEPHALITIS?
- Encephalitis is an infection of the parenchyma
- What are athe 2 main types of encephalitis?
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1. Acute encephalitis- a direct viral attack on the brain
2. Post infectious encephalitis - an autoimmune system attack in the brain following a viral infection elsewhere in the body. This is the MORE COMMON type of encephalitis. NOTE: some encephalitis can come from bacterial infection, eg Lyme Disease - What is the most common infection to lead to encephalitis in the US?
- Herpes Simplex Virus
- What age groups and geographic areas are most affected by Herpes Simplex Viral Encephalitis?
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ALL age groups
ALL geographic areas
ALL races
ALL seasons of the year - Are the childhood and adult versions of Herpes Simplex Viral Encephalitis usually caused by the same strain of Herpes?
- No. Neonates usually Herpes II (genital). Children usually Herpes 5 and 6. Adults usually Herpes I (the kind that causes cold sores)
- Can measles, cchicken pox, or mumpts cause encephalitis?
- Yes, most infections could cause encephalitis
- What brain areas are preferentially affected by Herpes Simplex Viral Encephalitis?
- Herpes Simplex Virus preferentially attacks the LIMBIC system first; then nearby FRONTAL and TEMPORAL areas
- What is the infectious process in Herpes Simplex Viral Encephalitis?
- With Herpres Simplex I, many people are affected through a throat infection that moves to the trgeminal ganglia and lies dormant for years. The mechanism for translation to encephalitis is unknown
- What are the neurological symptoms of Herpes Simplex Viral Encephalitis?
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1. Cognitive=PROMINENT memory problems, concentration, planning and organization. Child may have difficulty learning to read and do mathematics
2. Emotional- Mood swings, increased aggression, increased temper
3. Motor- tremors, paresis, poor balance and coordination
4. Epilepsy can occur
M - Describe 5 mechanisms for neural tissue damage in viral infections
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1. The virus can enter the nerve cell and hijack the components to replicate itself, thus killing the cell
2. The cell membrane can be altered so that it disturbs the electrical properties of the neuron
3. Infected neurons may be killed by the immune system to limit viral infection
4. The products of the body's defense against infection (WBCs, contents of dead nerve cells, disabled viruses)can alter the extracellular fluid and disrupt transmission
5. Swelling can compress and harm neurons - What is an ARBOVIRUS?
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ARBO=Arthropod-Borne
It is a virus carried by an insect; these are most common May-September - What species carry arboviruses to humans?
- Mostly mosquitoes, sometimes tics. Both species prefer non-human species that are important to their life cycle (like birds, rodents, deer) but they will infect humans as a secondary target
- Are arboviruses common?
- No they are RARE, but theya re the most common cause of epidemic encephalitis
- Name 3 arboviruses
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Here's some choices:
Eastern Equine Encephalitis - often fatal
Western Equine Encechalitis -can kill the elderly
California Encephalitis/LaCrosse Encephalitis- usually hits children and causes seizures
Japanese Encephalitis - from Rice paddy mosquito-common in Asia
Dengue - common in Africa and tropical countries
West Nile Virus - new in US; severe in elderly
St. Louis Encephalitis -severe in the elderly. - ENCEPHALITIS TRIVIA: What is Encephalitis Lethargica?
- THis is the encephalitis that hit the US after the 1917-1919 Spanish Flu epidemic. Cases were recorded between 1918-1929 and it was a "sleeping sickness" treated with L-dopa in the movie Awakenings.