Esta configuração vhost resolveu meu problema:
<VirtualHost *:80>
ServerName example.com
ServerAlias *.example.com
DocumentRoot /home/someuser/www/example.com/public_html/public
<Directory /home/someuser/www/example.com/public_html/public>
Options FollowSymLinks
AllowOverride none
Order allow,deny
Allow from all
</Directory>
ErrorLog /home/someuser/www/example.com/logs/error.log
CustomLog /home/someuser/www/example.com/logs/access.log combined
RewriteEngine On
RewriteCond %{HTTP_HOST} !^example\.com$ [NC]
RewriteRule ^(.*)$ http://example.com$1 [R=301,L]
</VirtualHost>