(HealthDay News) – Pertussis rates may reach record levels this year in the United States, where Washington state is experiencing an ongoing epidemic.

Chas DeBolt, MPH, of the CDC in Atlanta, and colleagues reviewed all pertussis cases reported between Jan 1–June 16 of this year to assess clinical, epidemiologic, and laboratory factors associated with the rise in pertussis cases in the state of Washington. This rise prompted the state’s Secretary of Health to declare an epidemic in April.

The researchers found that 2,520 pertussis cases were reported in the first six months of 2012, a 1,300% increase over the first six months of 2011. Disease rates were high in infants and children <10, but also in 13–14 year old adolescents who had received the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine, which suggests immunity might wane soon after Tdap vaccination.

“The focus of prevention and control efforts is the protection of infants and others at greatest risk for severe disease and improving vaccination coverage in adolescents and adults, especially those who are pregnant,” DeBolt and colleagues conclude. “Pertussis vaccination remains the single most effective strategy for prevention of infection.”

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