- The poliovirus primarily enters the body through the oral route and initially replicates in the mucosal cells of the small intestine.
- This site provides the necessary environment for viral multiplication due to the presence of susceptible epithelial cells in the gut-associated lymphoid tissue.
- Replication here leads to viral shedding and potential spread to the central nervous system.
- Other sites like lymph nodes and respiratory tract are involved later or less prominently.

Reference: Principles of Virology, Volume 1, Chapter 5