Washington state's worst outbreak of whooping cough in decades has prompted health officials to declare an epidemic.
State officials are seeking help from federal disease experts and are urging residents to get vaccinated amid worry that cases of the highly contagious disease are likely to spike much higher.
It's the first state to declare a whooping cough, or pertussis, epidemic since 2010, when California had more than 9,000 cases, including 10 deaths. Washington has had 10 times the cases reported in 2011, and so has Wisconsin with nearly 2,000 cases this year, but that state has not declared an epidemic.
Washington state officials believe the state could see as many as 3,000 cases by year's end.
