Read the documentation:
"The include() statement includes and evaluates the specified file."
In order for a Perl script to generate output, it must be executed. You're not going to be able to do what you what using the include() statement.
If the Perl script is CGI, then you will need a web server that will execute a Perl interpreter. A web server does so by handling HTTP requests for URLs to the Perl script. Thus you will need an HTTP client library that will submit a request to a web server. And that is where CURL comes in.
Perl / MySQL / HTML+CSS