Lecture 11- CNS Diseases Flashcards
(16 cards)
The nervous system
2 main parts;
*CNS= includes the brain, spinal cord which process information from PNS
*PNS= includes nerves that branch off the spinal cord + extend to all parts of the body; collecting info and sending it to the CNS
Microbial entry into the CNS;
Skull/backbone fractures
Medical procedures
Along peripheral nerves
Blood/lymph
Brain= protected against microbial invasion by cellular barriers; blood-brain barrier + blood-cerebrospinal fluid barrier
-cells within the CNS= produce an immune response against invading pathogens
Microbial diseases of the nervous system
-microbes= grow in the cerebrospinal fluid in the subarachnoid space of the CNS
-blood brain barrier prevents passage of some materials into the CNS
*meningitis= inflammation of meninges (often bacterial)
*encephalitis= inflammation of the brain (viral)
*myelitis= inflammation of the spinal cord
The meninges and cerebrospinal fluid
Meninges;
3 membranous layers that cover + protect the CNS
-deliver blood to CNS tissue via blood vessels
-produces cerebrospinal fluid; clear fluid that fills the cavities of the cerebral ventricles + surrounds the brain and spinal cord
Bacterial meningitis
Symptoms; fever, headache + stiff neck
-followed by nausea + vomiting
-may progress to convulsions + coma
-most dangerous in young children; caused by E.coli
Haemophilus influenzae Meningitis
Occurs mainly in children; 6months - 4 years
Gram - aerobic bacteria
Capsule antigen type B- protects the bacterium from being recognised by the host
- prevented by Hib vaccine
Listeriosis
listeria monocytogenes;
-gram-negative aerobic rod
-usually foodborne= can be transmitted to the fetus
-reproduce in phagocytes
listeria meningitis;
-occurs in babies, elderly (weak immune systems)
-passed to baby during pregnancy/whilst giving birth
Tetanus and Botulism
Tetanus; clostridium tetani
-gram +, endospore-forming, obligate anaerobes
-grows in deep wounds
*tetanospasmin = released from dead cells blocks relaxation pathways in muscles
-prevention by vaccination with tetanus toxoid + booster
Treatment= tetanus immune globulin
Botulism; clostridium botulinum
-gram +, endospore-forming, obligate anaerobe
-intoxication= from ingesting botulinum toxin
Botox= blocks release of neurotransmitter causing flaccid paralysis
Prevention = nitrites prevent endospore germination in sausages
Botulism
Treatment= supportive care + antitoxin
Infant botulism= botulinum growing in intestines
Wound botulism= growth of C.botulinum in wounds
Leprosy
-mycobacterium leprae
-grows n peripheral nerves and skin cells
Transmission requires prolonged contact with an infected person
*tuberculoid form; loss of sensation in skin areas; positive lepromin test
*lepromatous form; disfiguring nodules over body; negative lepromin test
Poliomyelitis
-poliovirus
Transmitted = ingestion
Initial symptoms= sore throat + nausea
Prevention= vaccination
Rabies virus (rhabdovirus)
Transmitted= animal bite
Virus multiplies in skeletal muscles -> brain cells -> causing encephalitis
Initial symptoms; muscle spasms of mouth, pharynx and hydrophobia
Furious rabies= animals are restless then excitable
Paralytic rabies= animals seem unaware of surroundings
Post exposure treatment= vaccine plus immunoglobulin
Cryptococcus Neoformans Meningitis
Amphotericin B
Cryptococcus neoformans meningitis;
Soil fungus associated with pigeon and chicken droppings
Transmitted to the respiratory route; spreads through blood to CNS
Treatment; Amphotericin B and flucytosine
Amphotericin B;
Only used in severe fungal infections
Extracted from streptomyces sp
Binds to erogosterol; causing leakage of monovalent ions; side effects in treatment
Nisseria meningitis - meningococcal
Gram negative aerobic cocci, capsule
10% of people are healthy nasopharyngeal carriers
Some individuals carry the bacteria without harm/ others develop meningococcal disease
Symptoms; vomiting, malaise + lethargy
Begins as throat infection, rash- not easily spread
Transmitted from person-person by inhaling respiratory secretions/ direct contact
MenB= responsible for 90% of infections; vaccine for babies
Streptococcus pneumoniae meningitis, pneumococcal
Gram + diplococci
70% of people are healthy nasopharyngeal carriers
Common in children
Prevented by vaccine = vaccinate under 2 years old
- protects against pneumonia
African trypanosomiasis
African trypanosmiasis;
Trypanasoma brucie gambiense= chronic infection 2-4y
T.b.rhodesiense = more acute; few months
Prevention= elimination of the vector
Treatment; eflornithine= blocks an enzyme necessary for the parasite
Parasite evades the antibodies through antigenic variaton
Infection occurs in 3 stages
Followed by a haemolymphatic stage; fever, swollen lymph nodes + itching
Meningoencephalitic stage; invasion of CNS; headaches, abnormal behaviour + loss of consciousness
