00:00 / 00:00
Viral structure and functions
Hepatitis B and Hepatitis D virus
Epstein-Barr virus (Infectious mononucleosis)
Herpes simplex virus
Human herpesvirus 6 (Roseola)
Human herpesvirus 8 (Kaposi sarcoma)
Varicella zoster virus
BK virus (Hemorrhagic cystitis)
JC virus (Progressive multifocal leukoencephalopathy)
Poxvirus (Smallpox and Molluscum contagiosum)
Lymphocytic choriomeningitis virus
Hepatitis C virus
West Nile virus
Yellow fever virus
Human parainfluenza viruses
Respiratory syncytial virus
Hepatitis A and Hepatitis E virus
Human T-lymphotropic virus
Eastern and Western equine encephalitis virus
Prions (Spongiform encephalopathy)
0 / 18 complete
0 / 3 complete
(Pico) Polio Virus
immunodeficient patients p. 116
medical importance p. 164
picornavirus p. 165
unvaccinated children p. 183
poliovirus p. 183
Poliovirus p. 164
restrictive lung disease p. 696
poliomyelitis p. 547
polio presentation p. 547
In poliomyelitis, also called polio, “polio” refers to the poliovirus, which is an enterovirus that invades the intestines, “myel” refers to the spinal cord which is affected in the disease, and -itis refers to inflammation.
So poliomyelitis is an enteroviral disease first enters the body through the intestines, but then spreads and causes nerve injury in the spinal cord.
Former US president Franklin D. Roosevelt contracted polio when he was a baby, and it left him wheelchair-bound.
Broadly speaking, the nervous system consists of two parts.
The central nervous system consists of the brain and the spinal cord.
So the peripheral nervous system includes the nerves that fan out from the central nervous system to reach the skin, muscles, and organs.
Now looking at the cross-section of the brain, there’s gray matter at the periphery of the brain. This is called the cerebral cortex and it consists of nerve cell bodies.
Just inside the gray matter of the brain, is the white matter, and it consists of nerve axons.
In contrast, if you look at the cross-section of the spinal cord, the white matter is on the outside and the gray matter is on the inside, and overall it kinda looks like a butterfly.
If we draw a horizontal line through the spinal cord, the front half is the anterior or ventral half, and the back half is the posterior or dorsal half.
And the butterfly wings are sometimes referred to as horns; so we have two dorsal horns that contain cell bodies for sensory neurons and two ventral horns that contain cell bodies for motor neurons.
Poliovirus is a single-stranded RNA virus, known to cause poliomyelitis. It is transmitted through fecal-oral transmission or by aerosol droplets, and then replicates in the small intestine and oropharynx before it spreads to the central nervous system and causes nerve injury. Symptoms include high fevers, intense muscle pain from spasms and weakness, loss of muscle reflexes, and eventually paralysis. Diagnosis is done by the detection of the poliovirus from a stool or throat, or by analysis of the cerebrospinal fluid. There is no cure for polio, but it can be prevented by polio vaccines.
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