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Monday, March 6, 2006 - 3:55 PM
26

An Outbreak of Pertussis in an Amish Community— Delaware, 2004-2005

Kathy Kudish1, Amanda Cohn2, Katrina Kretsinger2, Christina Mijalski2, Paula Eggers1, Pam Cassiday3, and Pekka Nuorti2. (1) Delaware Division of Public Health, 417 Federal Street, Dover, DE, USA, (2) National Immunization Program/ESD, Centers for Disease Control and Prevention, Atlanta, GA, USA, (3) Pertussis/Diphtheria Laboratory, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS D-11, Atlanta, GA, USA


Learning Objectives for this Presentation:
By the end of the presentation participants will be able to:
1. Describe the epidemiology of the outbreak
2. Recognize reasons parents declined vaccination


Background:
Despite routine childhood vaccination with diphtheria-tetanus-pertussis (DTP/DTaP), outbreaks of pertussis continue among underimmunized groups and persons whose vaccine-induced immunity has waned. During October 2004–February 2005, a pertussis outbreak occurred in an Amish community in Delaware.

Objectives:
Investigate household transmission patterns and identify barriers to vaccination.

Methods:
We ascertained cases through active surveillance and a self-administered survey. Nasopharyngeal swabs from suspected cases were tested for pertussis by polymerase chain reaction (PCR) at the Delaware Public Health Laboratory. A case was defined as cough illness > 2 weeks in a person living in the Amish community. An adult was interviewed in each household using a standard questionnaire. Cases with cough onset 7-28 days after a primary case in the household were defined as secondary cases. We obtained DTP/DTaP vaccination status from the Delaware Immunization Registry.

Results:
A total of 274 cases occurred in 96 (30%) of 323 Amish households; 12 (4.5%) were aged 0–11 months, 119 (43.5%) 1–5 years, 96 (35%) 6–14 years, and 47 (17%) >15 years. Of nasopharyngeal swabs obtained from 49 persons with cough illness, 30 (61%) tested positive for pertussis by PCR. The secondary attack rate among household contacts was 15% (68/452). Among children aged 6 months–10 years residing in case-households, 34% had >3 doses of DTP/DTaP documented. Among 48 (50%) of 96 households that reported not vaccinating family members, 21 (44%) reported fear of side effects as the reason.

Conclusions:
A large pertussis outbreak occurred in an undervaccinated community. Children aged 1–5 years had the highest attack rate. Culturally appropriate educational messages may improve vaccine coverage and prevent future outbreaks among young children.

See more of Cases of Pertussis: What Counts?
See more of The 40th National Immunization Conference (NIC)