An Outbreak of Pertussis-Like Syndrome in Boulder County, Colorado

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An Outbreak of Pertussis-like Syndrome in Boulder County, Colorado

The yearly incidence of pertussis in the U.S. declined dramatically with the introduction of pertussis vaccine.[1] Unfortunately, sporadic cases and occasional outbreaks still occur,[2-5] and cases reported to the Centers for Disease Control increased from 1982-1986 with only 1987 showing a decrease in reports.[6] Efforts to maintain high immunization rates among preschool and school-age children have been hampered by unfavorable publicity surrounding pertussis vaccine.[7] Health care providers, in particular school nurses, should anticipate additional cases and outbreaks if the current trend continues.


The Boulder County (Colo.) Health Department investigated an outbreak of pertussis-like syndrome that occurred from July through December 1988. The outbreak centered at a private elementary school (enrollment 185) with some spread to a public elementary school (enrollment 425). Both schools are experiential-based learning centers with diverse student populations, where a significant proportion of parents choose alternative approaches to health care for themselves and their children.

The public school district contracts with the county health department for school health services. School nurses hired under this contract work exclusively in the public schools, whereas most school nurses in Colorado are not associated with a health department. Historically, school nurses have provided measures to control the spread of communicable diseases among school-age children.[8] The private school involved in the outbreak does not maintain a school nurse of other health care service.

A case of pertussis was defined as an illness that was either: a) confirmed by positive culture and/or direct fluorescent antibody testing (FA) for Bordetella pertussis, b) diagnosed as pertussis by a physician, or c) characterized by a cough lasting 14 consecutive days or more that had either inspiratory whoop, post-tussive vomiting, or a household member with laboratory confirmed or clinically diagnosed pertussis.

Initial cases were detected through direct physician reports to the local health department. Active surveillance for additional cases included weekly telephone contact with area physicians and school-based surveillance at the two schools for any recent coughing illnesses. The school nurse performed case finding at the public school. The private school relied on teachers to survey students for suspect illnesses. All reported cases were subsequently investigated by the health department and all relevant demographic, clinical, epidemiologic, laboratory, and immunization information was obtained.

A DTP immunization audit was conducted at the private school by the Colorado Department of Health immunization program and at the public school by the assigned school nurse. Children were considered appropriately immunized if their records indicated a minimum of four doses of DTP by age five. Though five doses of DTP vaccine are recommended by the US Public Health Service Immunization Practices Advisory Committee[8] and the American Academy of Pediatrics,[9] four doses meets the minimum state requirement set by the Colorado Department of Health for school-age children.[10]

Both schools used the same approach to control transmission of pertussis. Control efforts consisted of sending a letter home informing parents of the outbreak and the signs and symptoms of pertussis. The letter recommended that contacts be treated with antibiotics for 14 days, and required children suspected of having pertussis be kept home from school or out of day care for five days after beginning antibiotic therapy, or for 21 days after onset of symptoms if no antibiotic was taken. In addition, the county health department encouraged parents to consider the DTP vaccine for all children under age seven who were not age-appropriately immunized. …