NAMPA, Idaho (AP) - Health officials in Idaho are encouraging residents to get vaccinated against pertussis - also called  whooping cough - as neighboring Washington state struggles with its worst outbreak of the disease in decades. Southwest District Health spokeswoman Laurie Boston told the Idaho Press-Tribune  that the disease doesn't know state boundary lines, and it's extremely important for people to be vaccinated and get booster shots against the disease. Idaho has had 31 cases of whooping cough between January and April of this year, including one infant in eastern Idaho who died of the disease. The state had 32 cases last year during the same time period. In 2010, the state tallied 43 cases between January and April.