Being HIV positive or having AIDS can affect your ability to travel and, if you are not a Canadian citizen, potentially your ability to stay in Canada long-term.
Some countries require you to declare if you are HIV-positive, or to be tested for HIV, before you enter the country. Most countries do not require you to reveal your HIV status or get an HIV test for visits on tourist visas, but some do. Some countries have laws that ban any person with HIV from entering the country, for any purpose or for any length of time, and also allow for a non-resident person with HIV to be deported. You can usually contact the embassy or consulate of the country in question here in Canada, or find information on the website of the country’s government, to find out more.
Canada's immigration law gives officers of Immigration, Refugees And Citizenship Canada the power to refuse entry into Canada to people who, in their opinion, are suffering from a disease likely to endanger public health or safety, or who may pose an “excessive demand” on publicly-funded health or social services during their stay in Canada.
If you want to visit Canada on a short-term basis (i.e., for less than 6 months), you are usually not required to declare your HIV status or have an HIV test when applying for a tourist visa (if you need a visa because of your nationality). Canada does not ban people with HIV from visiting Canada on a short-term basis.
However, if you want to come for a longer period, you likely will have to disclose your HIV status and/or have an HIV test. As mentioned, Canada can refuse newcomers on health-related grounds when their health condition may place an “excessive demand” on the public health care system. However, there are some important exceptions for sponsored family members and for people claiming refugee status.