Transcript Chapter 27 Nervous System Infections

Chapter 27
Nervous System Infections
Medgar Evers College
Microbiology
Prof. Santos
Anatomy and Physiology
• The brain and spinal cord make up the central
nervous system.
• The network of nerves throughout the body is
called the peripheral nervous system.
• The PNS is connected to the CNS by bundles of
nerve fibers that penetrate the vertebral body.
• The PNS is made up of Motor Nerves and
Sensory Nerves.
Bacterial Nervous System Infections
• Bacteria can infect the brain and spinal cord,
causing abscesses.
• In Hansen’s disease, they can infect the
peripheral nerves.
• More commonly, bacteria infect the meninges
and cerebrospinal fluid, causing meningitis.
Meningitis
• Meningitis is an intense inflammatory
response.
• White blood cells accumulate in the
cerebrospinal fluid which causes the brain to
swell.
• The three important causes of bacterial
meningitis are Haemophilus influenzae,
Neisseria meningitidis, and Streptococcus
pneumoniae.
Meningitis
• Streptococcus pneumoniae is the leading
cause of meningitis in adults. The organism is
prominent cause of otitis media, sinusitis, and
pneumonia, condition that often proceed
pneumococcal meningitis.
• Neisseria meningitidis differs from the other
causes in that it is often responsible for
epidemics of meningitis.
Bacterial Disease of the Nervous
System
Disease
Cause
Symptoms
Pathogenesis
Treatment
Meningococcal
Meningitis
Neisseria
meningitidis.
The
meningococcus
. A gramnegative
diplococcus.
There are 13
antigenic
groups of
N.meningitidis.
Most serious
infections are
due to A,B,C,Y,
and W135.
incubation
period: 1 to 7
days
Mild cold, severe
throbbing
headache, fever,
pain, stiffness of
the neck and
back, nausea, and
vomiting.
Deafness and
alterations in
consciousness,
progressing to
coma. Purplish
spots called
petechiae may
develop. The
infected person
may develop
shock and die
within 24 hours.
Infection is
acquired by
inhaling airborne
droplets from the
respiratory tract of
another person.
The meningococci
attach to the
mucous
membrane and
multiply. They are
then taken in by
the respiratory
tract epithelial
cells, pass through
them, and invade
the bloodstream.
The blood carries
the organisms to
the meninges and
cerebral spinal
fluid.
A vaccine
composed of
purified A, C, Y,
and W135.
Mass
prophylaxis
treatment with
an appropiate
antibacterial
medications ,
such as
Rifampin, can
help in
controlling
epidemics.
Bacterial Disease of the Nervous
System
Disease
Cause
Symptoms
Pathogenesis
Treatment
Listeriosis ( a
food borne
disease).
Listeria
Monocytogenes
Fever, muscle
aches, and
sometimes
nausea or
diarrhea.
The mode of
entry in
isolated cases
is usually
obscure but it
is generally via
the
gastrointestinal
tract. The
bacteria
penetrate the
intestinal
mucosa and
enter the
bloodstream.
Thoroughly
cook meats
and avoid
contaminated
countertops,
wash all
vegetables, and
pregnant
women should
avoid soft
cheeses. L.
monocytogene
s have
remained
susceptible to
Penicillin.
is a motile ,
non-sporeforming ,
facultatively
anaerobic,
gram positive
rod that can
grow at 4
degrees
Celsius.
Incubation
Period: a few
days to 2-3
months.
Bacterial Disease of the Nervous
System
Disease
Cause
Symptoms
Pathogenesis
Treatment
Hansen’s Disease
(Leprosy)
Mycobacterium
leprae. It is
aerobic, acid-fast,
rod-shaped, and
typically stains in
a beaded
manner.
Incubation
period: 3 months
to 20 years.
Anaesthetic
skin lesions,
deformed face,
loss of fingers
or toes.
Invasion of
small nerves of
skin;
multiplication
in
macrophages;
attack of
immune cells
against
infected nerve
cells causes
deformity.
No vaccine.
Treatment
includes
dapsone plus
rifampin for
months or
years;
clofazimine
added for
lepromatous
disease.
Bacterial Disease of the Nervous
System
Disease
Cause
Symptoms
Pathogenesis
Treatment
Botulism
Clostrium
botulinum. An
anaerobic,
gram-positive,
spore-forming,
rod- shaped
bacterium.
Incubation
period: 12 to
36 hours.
Blurred or
double vision,
weakness,
nausea,
vomiting,
diarrhea;
generalized
paralysis and
respiratory
insufficiency.
C. botulinum
endospores
germinate in
food and release
neurotoxin. Toxin
is ingested, is
absorbed in the
small intestine
and enters the
bloodstream.
Toxin acts by
blocking the
transmission of
nerve signals to
the muscles
producing
paralysis.
Enemas and
stomach
washing to
remove toxin,
cleaning
infected
wounds of dirt
and dead
tissue,
intravenous
administration
of antitoxin
and artificial
respiration.
Viral Disease of the Nervous System
Disease
Cause
Symptoms
Viral Meningitis Most cases: small Abrupt onset,
non-enveloped
fever, severe
RNA
headache, stiff
enteroviruses of
neck, often
the picornavirus
vomiting,
family, usually
sometimes
coxsackie or
sore throat,
echoviruses.
large parotid
Mumps virus
common in
glands, rash, or
unimmunized
chest pain.
populations.
Incubation
Period: 1 to 2
weeks for
enteroviruses. 2
to 4 weeks for
mumps.
Pathogenesis
Treatment
Viremia from
primary
infection seeds
the meninges.
Fewer
leukocytes
enter
cerebrospinal
fluid than with
bacterial
infections, and
many are
mononuclear,
usually no
decrease in CSF
Glucose.
No specific
treatment.
Prevention:
handwashing,
avoiding
crowded
swimming
pools during
enterovirus
epidemics;
mumps
vaccine.
Viral Disease of the Nervous System
Disease
Cause
Symptoms
Pathogenesis
Treatment
Viral
Encephalitis
Usually caused
by one of four
arboviruses,
LaCrosse, St.
Louis, western
equine, or
eastern equine.
Incubation
Period: First
systems within
a few days;
encephalitis
symptoms
often within
the first week.
Abrupt onset,
fever,
headache,
vomiting,
disorientation,
paralysis,
seizures,
deafness,
coma.
Infected
mosquito
introduces virus.
Replication of
virus at the site
of the mosquito
bite, further
replication in
lymph nodes,
them viremia
that seeds brain
tissue. Nerve
cells in the brain
invaded and
destroyed,
causing death, or
permanent
disabilities.
No accepted
treatment for
arboviral
encephalitis.
Prevention:
Chicken
sentinels to
warn of
arbovirus
epidemics.
Insecticides
and other antimosquito
preventative
measures.
Viral Disease of the Nervous System
Disease
Cause
Symptoms
Pathogenesis
Treatment
Infantile
Paralysis, Polio
(Poliomyelitis)
Polioviruses 1,
2, and 3;
members of
the
picornavirus
family.
Incubation
Period: 7 to 14
days.
Headache,
fever, stiff neck,
nausea, pain,
muscle spasm,
followed by
paralysis.
Poliovirus
enters the
body orally;
infect the
throat and
intestinal tract
and then
invade the
bloodstream. It
enters the
nervous system
and attack the
motor nerves
causing
paralysis.
Artificial
ventilation for
respiratory
paralysis;
physical
therapy and
rehabilitation.
Prevented by
injecting Salk’s
inactivated
vaccine or
Sabin’s orally
administered
attenuated
vaccine.
Viral Disease of the Nervous System
Disease
Cause
Symptoms
Pathogenesis
Treatment
Rabies
Rabies virus,
single-stranded
RNA,
rhabdovirus
family; has an
unusual bullet
shape.
Incubation
Period: Usually
30 to 60 days.
Fever,
headache,
nausea,
vomiting, sore
throat, cough
at onset; later,
spasms of the
muscles of
mouth and
throat, coma,
and death.
Bite of rabid
animal. Virus
multiples at
site of bite,
then travels via
nerves to CNS
where it
spreads
outward to
infect heart
and other
organs.
Immediately
wash wound
and apply
antiseptic;
inject rabies
vaccine and
human rabies
antiserum as
soon as
possible. No
effective
treatment once
symptoms
begin.
Fungal Disease of the Nervous System
Disease
Cause
Symptoms
Pathogenesis
Treatment
Cryptococcal
Meningoence
phalitis.
Filobasidiella
(Cryptococcus)
neoformans,
an
encapsulated
yeast.
Incubation
period:
variable.
Headache,
vomiting,
confusion, and
weight loss;
slight or no
fever;
symptoms
may progress
to seizures,
paralysis,
coma and
death.
C.Neoformans
fungus
becomes
airborne with
dust, enters
the body
through
inhalation and
infects the
lung. The
organism
multiples and
enters the
bloodstream
infecting the
meninges and
amphotericin
B with
flucytosine or
itraconazole.
No
preventative
measures
Protozoan Disease of the Nervous
System
Disease
Cause
Symptoms
Pathogenesis
Treatment
African
Sleeping
Sickness
Trypanosoma
brucei, a
flagellated
protozoan.
Incubation
period: weeks
to several
years.
Tender nodule
at site of
tsetse fly bite;
fever,
enlargement
of lymph
nodes; later,
involvement
of the CNS,
uncontrollable
sleepiness,
headache,
poor
concentration,
unsteadiness,
coma, and
During the bite
of an infected
tsetse fly, the
protozoan
enters the
wound in the
fly’s saliva,
multiplies, then
enters the
bloodstream
and lymphatic
system. As new
cycles of
parasites are
released, their
surface protein
changes and the
body is required
Suramin;
when CNS is
involved,
melarsoprol or
eflornithine.
Prevention:
protective
clothing,
insecticides,
clearing of
brush where
flies breed,
pentamidine.
Prion Disease of the Nervous System
Disease
Cause
Symptoms
Pathogenesis
Treatment
Transmissible
Spongiform
Encephalopathy
Proteinaceous
infectious
particles
known as
prions; lack
nucleic acids;
amino acid
sequence to a
normal protein,
but folded
differently, and
relatively
resistant to
proteases,
heat, radiation,
and
disinfectants.
Behavioral
changes,
anxiety,
insomnia,
fatigue,
progressing
over weeks or
months to
muscle jerks,
lack of
coordination
and dementia.
Replication first
occurs in the
spleen and other
lymphoid tissues.
Prions replicate
in dendritic cells
by converting
normal proteins
to more prions;
transmission to
the brain;
aggregation into
masses outside
the nerve cells;
cell malfunction
and death.
There is no
treatment.
invariably