Ch. 16 - Viral Infections Of The Nervous System Flashcards
Rabies
Bullet shaped morphology
Most deadly virus –> once symptoms arise, almost always fatal
Enter through skin wound with contaminated bodily fluid of infected animal ( warm-blooded animal, saliva)
Incubation period: 6 days - 1 year
-depending on the location of entry and amount of virus entering the body –> the closer the bite is to a nerve/spinal cord, the shorter the incubation period
Symptoms: fever, headache, increased muscle tension
Become alert, aggressive, followed by paralysis and brain degeneration = Encephalitis
Hydrophobia - brain inflammation and inability to swallow - violent reaction to water
Death from respiratory paralysis
Post exposure immunization of rabies IgG
Polio (poliomyelitis)
Infect grey matter of the spinal cord and brain (nervous tissue)
Enter through contaminated food or water
Replicate in gut, tonsils, lymph nodes
Pass blood-brain barrier to meninges –>paralysis of limbs and trunk
(Paralytic poliomyelitis)
Postpolio syndrome - individuals who have had the disease before; reactivated virus or autoimmune reaction (attack motor neurons as if foreign objects); muscle weakness, atrophy
Vaccine:
1. Salk - dead, inactivated virus; injection; 4 doses; only pieces of virus (cannot replicate)
- Savin - live, attenuated virus; oral; not given in US; live virus (can replicate)
Not fully eradicated - new vaccine-derived virus –> emergence of new strains; by 2000 99% fewer cases
Viral Hemorrhagic Fever (VHF) Viruses
Ex: Yellow Fever, Dengue Fever, Lassa, Ebola, Marbug
RNA viruses
Animal insect/host = natural reservoir
Eg (Ebola reservoir = fruit bats)
Damage endothelial cells –> massive internal bleeding and hemorrhaging
Humans infected when come into contact with infected host; can infect one another when in contact with blood or bodily secretions (or contaminated objects)
No cure or drug treatments (exception - Lassa Fever: Ribavirin)
Mortality rate: 50-90%
Chikungunya
Viral Hemorrhagic Fever (2006)
= to walk bent over (reference to sever joint pain)
Symptoms: fever, headache, vomiting, severe long lasting joint pain
Vector: mosquito –> transmit to other humans
Jet travel: endemic to areas around Indian Ocean -and- Southern Europe
Spread through blood to liver, muscle, brain, lymphatic tissue, and joints
No specific antiviral treatment –> all cases resolved
MERS = Middle Eastern Respiratory Syndrome
Emerging infection (Saudi Arabia 2012)
Viral respiratory illness - transmitted via respiratory droplets
Animal source - camels?
West Nile
Primary transmission: crows –> mosquito
Incidental Transmission: mosquito –> horse, human (dead end host)
Most: asymptomatic - fever, aches, fatigue
Few: develop encephalitis, meningitis –> permanent neurological damage or death (elderly, immunocompromised)
No vaccine or treatment
