An outbreak of an illness occurs when there is an increase in
the number of people who live in the same area and are infected around the same
time by an organism such as a virus or bacteria. A community may have an
outbreak of the flu or measles as that specific organism spreads through the
water or food in that area.
Organisms passed to people from
insects or rodents can cause outbreaks too. These outbreaks usually do not
spread much beyond the region where the rodents or insects live.