In the US, aphids are blamed for the bulk of the disease spread, but as Bill
T. said, any flying creature can and does spread the disease.

If fire blight is new to your area, meaning that growers have not planted
resistant varieties, fire blight will be an enormous problem.  Bees do
spread it, but aphids spread it more because they visit the trees for
several months while bees only visit for a couple of weeks.

Destruction of infected branches and limbs will help slow the spread, but if
saws are not disinfected after every cut, the saws will also spread the
disease!

Best of luck,
Lloyd