Transcript Poliomyelitis

U.S. Centers for Disease Control and Prevention
Poliomyelitis
U.S. Centers for Disease Control and Prevention
Ijeoma Ohadugha
4/1/10
Infectious Diseases
http://www.immune.org.nz/site_resources/Professionals/Diseases/Polio/Polio.jpg
Poliomyelitis is an infection of the
CNS
• poliós -Greek word “grey”, +
myelós “spinal cord’ + suffix –
itis “inflammation =poliomyelitis
• Viral infection of the nerves of
the CNS
Poliomyelitis is caused by an
enteric RNA virus
– Caused by an
Enterovirus
called the
poliovirus
– Enteric, small
RNA virus
F.P. Williams, U.S. EPA
Transmission by fecal-oral route
http://www.co.washington.or.us/HHS/EnvironmentalHealth/PublicPools/
Risk Factors
– Not being vaccinated in areas where polio is
common
– infants, pregnant women,
immunocompromised (eg. HIV)
WHO, 2008.
Three basic patterns
• Subclinical infection(95% of infections),
Three basic patterns
• Subclinical infection(95% of infections),
• Nonparalytic poliomyelitis(1-2%)
Three basic patterns
•
•
•
•
Subclinical infection(95% of infections),
Nonparalytic poliomyelitis(1-2%)
Paralytic poliomyelitis(0.1–0.5%)
-result of accidental transfer of virus from
GI tissue to neural tissue
– Spinal polio - 79% of paralytic cases—
Bulbospinal polio - 19% of paralytic cases—
Bulbar polio - 2% of paralytic cases
Polio afflicted everyone socially as
well as medically
• Franklin Delano
Roosevelt
• “Once you’ve spent
two years trying to
wiggle one toe,
everything is in
proportion.”
—Franklin D.
Roosevelt, 1945
http://americanhistory.si.edu/polio/howpolio/fdr.htm
Heine named polio as a clinical condition;
Lansteiner discovered the virus
Jakob Heine(1840)
Karl Landsteiner (1909)
– poliovirus enters
digestive tract via
mouth
– Primary site of infection
is epithelial and
lymphoid
tissue associated with
the oropharynx and gut
• Virus production at this
site leads to a transient
viremia, following which
the virus may infect the
CNS
http://cmbi.bjmu.edu.cn/www-learn/micro-ac-uk/335/Picornaviruses.html
Dual Tropism Thought to be the Cause
of Poliomyelitis from Poliovirus
• Reflects the distribution of the
poliovirus receptor CD155 on cells
lymphoid cells as well as the epithelial
cells in the gut and on neurons in the
CNS
• Viral Tropism relies on host cell
permissiveness and receptor
susceptibility
Virus Replicates Through Viropexis
– attachment of the virus to specific cellular
receptors of cells with CD155
– penetration and uncoating of the virus is
energy dependent, and occurs by receptormediated endocytosis (viropexis)
Interferons May Prevent Susceptibility of
Most Cells with CD155
– CD155 is present on most human cells, so
does not explain why it infects certain
tissues
– Recent studies-suggest human type I
interferon receptors possibly prevent
– Interferon- protein released by lymphocyte
in response to pathogen to trigger immune
defenses
Only IPV used in US today
– OPV known to in rare cases become virulent
and cause iatrogenic (vaccine-induced) polio
– Both used today in the world
– IN US, only IPV used since 1990s from
policy changes
– Only cases of polio (8-10 per year) were from
people with vaccine-induced polio
Jonas Salk- Injected Poliovirus Vaccine(IPV) Albert Sabin
– oral live attenuated virus (OPV)
1952
1957
SV40 Contamination Concerns
– In 1960, SV40
(Simian Vius40) found in
vaccine from
rhesus monkey
kidney cells
used to prepare
vaccine
Vaccines with SV40 contamination
was accused as cause for HIV
• Accusations in 1990s that vaccines with SV40
caused conditions favorable for SIV jump
from monkey to humans, causing HIV/AIDS
Accusation now debunked, but
stigma lingers for new reasons
– New reasons for vaccination stigma such as
rumors of sterility in some areas
Treatment in the past often ineffective
until Elizabeth Kenny’s procedures
– crutches or wheelchair for motor muscle
degeneration
– “convalescent serum”-1920s
– iron lung for respiratory failure
– early 1940s- Sister Elizabeth Kenny’s procedureshotpacks and heating pads w/massages, still used
today
Present Treatments Offer Relief to
Symptoms
– No current cure
– Respiratory apparatus
– Antibiotics for UTIs, medication for urine
retention
– Heating pads and towels for muscle spasms
& pain
– Physical therapy, braces, or orthopedic
surgery for recovery of muscle
strength/function
What still needs to be done
• Eradication efforts
– Get rid of stigma surrounding vaccine in
Africa and other polio-afflicted places
– Develop new targets for polio cure
References
• http://www.polioeradication.org/
• https://health.google.com/health/ref/Poliomyelitis
• http://www.mayoclinic.com/health/polio/DS00572/D
SECTION=risk-factors
• http://www.cloudnet.com/~edrbsass/poliotimeline.ht
m
• http://www.vaccineinformation.org/polio/qandavax.as