Haemophilus influenzae type b disease among Amish children in Pennsylvania: Reasons for persistent disease

Objective. To identify reservoirs of Haemophilus influenzae type b (Hib) ph aryngeal carriage and assess barriers to vaccination among 2 Amish communit ies in Pennsylvania. Methods. We investigated recent cases, performed community surveys for Hib vaccination coverage and pharyngeal carriage, and administered a questionna ire assessing vaccination knowledge and attitudes to 298 members of 2 Amish communities (A and B) in Pennsylvania and, as a comparison group, 136 non- Amish family members who participated in state immunization clinics. From D ecember 1999 to February 2000, 8 cases of invasive Hib disease occurred amo ng children who were 5 years of age or younger in Pennsylvania. Six of the case-patients were from Amish communities. None of the children had been va ccinated. Results. Among children who were 5 years of age or younger, Hib vaccine cov erage was low in the 2 Amish communities: A (9 [28%] of 32) and B (3 [7%] o f 41) compared with the non-Amish group (19 [95%] of 20). Hib carriage prev alence was higher in both Amish communities than in the non-Amish group (A: 3%; B: 8%; non-Amish: 0%). More households in community B had 1 or more Hi b carriers than in community A (8 [28%] of 29 vs 3 [9%] of 32). Among Amish parents who did not vaccinate their children, only 25% (13 of 51) identifi ed either religious or philosophical objections as a factor; 51% (26 of 51) reported that vaccinating was not a priority compared with other activitie s of daily life. Seventy-three percent (36 of 49) would vaccinate their chi ldren if vaccination were offered locally. Conclusions. Undervaccinated communities in the United States still exist a nd allow circulation of Hib strains, resulting in disease among susceptible children. Identification of undervaccinated populations, such as the Amish , and targeted education and vaccination campaigns are essential to achievi ng elimination of Hib disease.