Yes. In order to ensure your own wellbeing and comfort as well as the health of others, please inform customs as well as your attending staff (e.g. flight attendants or cruise personnel) of your illness on your return journey home. By informing customs that you have become sick while away or that your symptoms of an existing condition have worsened while travelling, further medical help and assistance will be made available to you if needed. In addition to providing customs with important health data, informing officials of your illness can also help trained officials to stop the spread of illness especially in busy terminals like airports and other borders. For more information on this and other issues such as sicknesses that arises after the return home please visit http://travel.gc.ca/returning/sick