However, the disease has also spread from one person to another.
At any rate, there is no evidence that the disease has spread into 30 countries.
By 18 November the disease had spread to the local population.
No one is sure how widely the disease will spread.
For example, students might study how a disease spreads through a community.
Even when the disease has spread, more than 60 percent of the patients are alive after 15 years.
How far the disease may have spread in Toronto is not yet known.
Since then, however, the disease has spread through more residential areas.
Now I see the disease spreading to stores in the area.
But Federal health officials have said the disease does not spread through kissing.