Chapter 22 Microbial diseases of nervous system Flashcards
What are the three layers of the brain membranes?
- Dura mater (outermost)
- Arachnoid matter (middle contains subarachnoid space w/cerebral spinal fluid)
- Pia mater: inner membrane
What are the common routes of CNS invasion of bacteria?
Blood stream and lymphatic vessels
What is meningitis?
Inflammation of the meninges
What is encephalitis?
Inflammation of the brain
What is a major symptom of encephalitis and meningitis? Major difference of symptom?
Similar in both: Headache
Specific to encephalitis: more seizures/ cranial nerve palsies
Specific to meningitis: neck stiffness/ photophobia
What are the four bacteria that commonly cause meningitis?
Streptococcus pneumoniae
Neisseria meningitides
Haemophilus influenza type B (Hib)
Listeria monocytogenes
What are some of the characteristics that the different meningitis pathogens have in common?
most have capsule (protects from phagocytosis) except Listeria monocytogenes
Which type of meningitis is more common in college-aged students?
Neisseria meningitides
Which meningitis bacterial type can be transferred from mother to fetus?
Listeria monocytogenes
What is a critical symptom of meningitis?
inflammation of the meninges (leading to swelling of the brain [encephalitis] which can then lead to death)
How do viral and bacterial meningitis compare?
Viral is more common but more often is mild
Bacterial is more dangerous/deadly
What organism is responsible for botulism?
Clostridium botulinum
Is botulism caused by the organism itself or a released toxin?
Released exotoxin
What type of toxin is botulism caused by? What does this cause?
A type of neurotoxin
Blocks release of acetylcholine
What type of paralysis is caused by botulism?
Flaccid paralysis (muscle weakening)
What is the connection with babies, honey, and botulism?
Bees carry Clostridium botulinum on their bodies, so it is also found in the honey they produce. Babies don’t have a built enough immune system like adults do, so when ingested, the bacteria can take over, produce toxins and cause botulism in babies
what type of organism is associated with leprosy?
Bacteria; Mycobacterium leprae
Know the major misconceptions about leprosy.
Leprosy is thought to be flesh-eating disease; however, it is actually the fact that it really causes loss of feeling in extremities that allows for injuries or secondary infections to occur, leading to need for amputations.
Because of the misguided stigma that leprosy leaves a disfigured appearance, and is super contagious, people with the disease are often ostracized.
It is not deadly; 95% of the population is immune to disease and there are viable treatments
What is the alternate term for leprosy?
Hansen’s disease
Where does leprosy grow in the human body?
Grows in the peripheral nervous system
Why are armadillos associated with leprosy?
Their body temp is optimal for growth of the bacteria, so armadillos are used to help culture the bacteria to study
How do immune responses contribute to the pathogenesis of leprosy?
Because the bacteria grow within the peripheral nervous system, when the body’s adaptive immune system begins to attack, it damages the nerves leading to loss of feeling (numbness)
What type of organism causes tetanus?
Bacteria; Clostridium tetani
Is tetanus caused by the organism itself or a released toxin?
Released toxin
What toxin is released from Clostridium tetani?
Tetanospasmin
How does the tetanospasmin affect a person?
Neurotoxin blocks relaxation pathway in peripheral nerves (causes muscle spasms, lockjaw, opisthotonos)
What type of organism causes polio?
Virus
How is polio commonly transmitted to a new host?
Ingested water contaminated with feces
How do most infections with polio affect the host?
Most asymptomatic or exhibit mild symptoms
What is the chance that infection with poliovirus will result in paralysis?
less than 1%
Which body structure is completely paralyzed by a severe polio infection?
Lungs (not able to breathe)
Why was the first outbreak of polio so significant?
It only affected adolescents and young children because improved sanitization caused there to be a lack of antibody transfer from parent to baby
What is the only disease studied in this chapter that is susceptible to vaccination after the initial exposure?
rabies
Describe hydrophobia.
Sight/thought/exposure to water sets off spasms Due to rabies infection
What type of organism causes rabies?
virus
How is dumb rabies distinct from classical rabies?
Minimal excitability (no foaming of the mouth or biting behavior)
What general type of animal is more likely to show dumb rabies?
cats
What is the vector for arboviral encephalitis?
Mosquitos
How can Zika virus spread person to person?
Sexually
During pregnancy & delivery
Blood transfusions
When is Zika the most severe?
Incidence increase in summer months
What is the etiology of cryptococcosis?
Inhaling contaminated dropping of pigeons
what type of organism can cause meningitis?
bacteria
viruses
fungi
protozoa
what type of organism causes tetanus?
bacteria; Clostridium tetani
what type of organism causes botulism?
bacteria; Clostridium botulinum
what type of organism causes Hansen’s disease?
acid-fast bacteria; Mycobacterium leprae
what type of organism causes zika disease?
virus (ZVD)
what type of organism is Cryptococcus neoformans? where in the body can it effect?
fungus
can effect CNS
how can you tell the difference between encephalitis and meningitis based on symptoms alone?
meningitis = stiff neck
encephalitis = nerve palsies
