Final answer:
Poliovirus infection starts in the pharynx and gastrointestinal tract and can spread to the CNS, leading to paralysis. Transmission occurs via the fecal-oral route and occasionally by aerosols. RT-PCR can detect the virus, and two vaccines, Salk and Sabin, are effective at preventing the disease.
Step-by-step explanation:
The poliovirus begins its infection by entering through the mouth, where it first replicates in the pharynx and gastrointestinal tract.
The presence of poliovirus can be detected in the throat and stool before symptoms appear. Poliovirus then invades local lymphoid tissue, enters the bloodstream, and may proceed to infect cells of the central nervous system (CNS).
Replication in motor neurons, such as those in the anterior horn cells of the spinal cord, brain stem, or motor cortex, results in cell destruction and can lead to flaccid paralysis. Severe cases may involve respiratory failure, necessitating the use of positive-pressure ventilation systems.
Transmission of poliovirus is predominantly through the fecal-oral route, but it can also occur via aerosol or droplets. Most poliovirus infections are asymptomatic, while some cause mild intestinal symptoms. However, a small percentage can lead to serious nervous system impairment.
Direct detection methods like reverse transcriptase PCR (RT-PCR) or genomic sequencing can confirm the infection.
Regarding prevention, two main vaccines have greatly reduced polio incidence worldwide: the Salk vaccine, an inactivated virus given via injection, and the Sabin vaccine, an oral vaccine containing attenuated virus. Both vaccines offer protection against the three serotypes of poliovirus responsible for human disease.