Polio Research Paper

Microbe Report: Polio

Stephanie May

Microbiology

Poliomyelitis is a life-changing, sometimes deadly disease caused by the poliovirus. This virus, spread through human feces, once paralyzed many, including US President Franklin Delano Roosevelt, leaving some of its victims trapped in an iron lung for the rest of their lives, and even killing many. A vaccine against this virus was developed by Jonas Salk in the 1950s, and polio infections have dropped tremendously, with the Americas being declared polio-free in 1994 by the World Health Organization1. Efforts are underway to eradicate this deadly disease by the year 2018. Poliovirus is an enterovirus, which is a genus of positive-sense single-stranded RNA viruses. Positive-sense single-stranded

Spinal polio, which accounts for about 79% of all cases, is the most common form of paralytic poliomyelitis. In spinal polio, the virus invades the motor neurons of the grey matter of the spinal column. The grey matter is responsible for movement of trunk, limb, and intercostal muscles. As the virus destroys the spinal neurons, the patient loses control of the affected muscles, resulting in paralysis. Usually, paralysis is limited to one side, but sometimes, the patient will experience paralysis on both sides of his or her body. Bulbar polio, which makes up about 2% of the cases of paralytic polio, destroys the neurons in the bulbar region of the brain. This hinders the activity of cranial nerves V (Trigeminal), VII (Facial), IX (Glossopharyngeal), X (Vagal), and XI (Accessory). This causes the patient to experience difficulty breathing, speaking, swallowing, chewing, and the patient may have an abnormal respiratory rate and heart rhythm. Complications of bulbar polio include pulmonary edema and shock. Bulbospinal polio accounts for about 19% of all paralytic poliomyelitis cases. In bulbospinal polio, the virus affects both the bulbar region of the brain and the grey matter of the spinal column. In this subtype of paralytic poliomyelitis, the nerves of cervical vertebrae C3-C5 are affected. The phrenic nerve is part of this plexus, and since this innervates

The polio vaccine has helped lower polio rates tremendously since the 1980s. In 1988, there were about 350,000 cases of polio. This number decreased 99% to 416 cases of polio in 2013. The last case of naturally occurring polio in the US occurred in 1979, but polio is still endemic, or commonly found, in Afghanistan, Pakistan, and Nigeria1. The figure below from the United States Center for Disease Control shows the profound impact that the polio vaccine has had on polio rates. As is snown, when the inactivated vaccine was approved in 1955, poliomyelitis rates