The Canadian Food Inspection Agency says some sheep in Alberta have been infected with scrapie, a fatal disease that affects the animals' nervous system.

The federal agency's website says classic scrapie, which can be transmitted to other sheep and goats, was confirmed last month in two flocks in Central Alberta.

As a result, the agency said in an email that the two herds are under quarantine.

The movements of the diseased animals are also being traced and epidemiological data is being gathered. No sheep have been killed.

Scrapie belongs to the family of diseases that includes mad cow disease in cattle, chronic wasting disease in deer and elk, and Creutzfeldt-Jakob disease in humans.

Health Canada says there is no known link between scrapie and human health.

The CFIA says scrapie can only been seen in adult sheep between two and five years of age and can take years to develop.

Once an animal appears ill it typically dies within a few months.