Whooping It Up in Harney County, Oregon: A Middle and High School-Associated Pertussis Outbreak, December 2006-February 2007

Background:
The number of reported pertussis cases has been steadily increasing in Oregon, reaching a 45-year high in 2004. The greatest increase in recent years has been in adolescents and Oregon has experienced a number of large and disruptive outbreaks among middle and high school students. The availability of Tdap offers an opportunity to reduce the increasing burden of pertussis in adolescents. From December 2006-February 2007, a pertussis outbreak primarily among adolescents occurred in Harney County, Oregon.

Setting:
Rural community in Harney County (pop. 5,000)

Population:
The target population was students, school administrators, teachers, parents, medical providers and general public.

Project Description:
The control measures implemented in this outbreak included treatment of cases, active case finding, evaluating and treating symptomatic exposed persons, prompt prophylaxis of high-risk contacts (infants and pregnant women in their third trimester) only, education of “low-risk” contacts, updating immunization through school-based Tdap vaccination clinics, and enhanced outreach and education regarding vaccination and disease.

Results/Lessons Learned:
During December 2006-February 2007, a total of 16 cases (incidence rate: 320/ 100,000) were reported. The median age of persons with pertussis was 15 years and 81% of the cases were associated with schools. During the vaccination clinics 817 students and staff were vaccinated. The statewide ALERT Immunization Information System provided quick and accurate forecasts of immunization status of each student, identified at risk students who were not fully immunized and evaluated the impact of the vaccination clinics. This outbreak highlights the importance of rapid recognition of pertussis transmission in school-settings and rapid response from public health professionals in containing the outbreak. Tdap vaccination should be used as an additional tool in halting disease transmission in settings where repeated exposures occur over an extended period.