KEYWORD1:
Pertussis, vaccine failure, children

BACKGROUND:
This outbreak took place in an isolated rural Pennsylvania community where all children are seen by the same medical group and attend the same associated day care and grade school.

OBJECTIVE:
To learn about the presentation of Pertussis in an immunized cohort.

METHOD:
Epidemiological evaluation of routinely collected pertussis disease reports from a single community.

RESULT:
A total of 10 children met the case definition for pertussis (A cough illness lasting at least 2 weeks with one of the following: paroxysms of coughing, inspiratory "whoop", or post-tussive vomiting, without other apparent cause ). Four of nine children had positive cultures, only one of which was also DFA positive. The index child (who was culture and DFA negative) was a 10 year old. The other children became ill between 9 days and 24 days after the index case and ranged in age from 11 months to 11 years old. All of the children were appropriately vaccinated for age. Two of the children are siblings of the index case. None of the children required hospitalization and all recovered uneventfully. One hundred nineteen family members, class mates and teachers received azithromycin as prophylaxis. No additional cases were reported after administration of the prophylaxis.

CONCLUSION:
Pertussis outbreaks can occur in highly immunized populations. DFA was not an accurate test in this population and culture confirmed only 44% of the cases.

LEARNINGOBJECTIVES:
Pertussis should be considered as a diagnosis in immunized children with paroxysms of coughing, inspiratory “whoop" or post-tussive vomiting.