A measles outbreak in an underimmunized Amish community in Ohio

Measles is a highly contagious, albeit vaccine-preventable, disease that can lead to serious complications. Although endemic transmission of measles in the United States was declared to be eliminated in 2000, importations from countries in which measles is still endemic continue to occur. Despite repeated challenges from measles introductions, most importations of measles do not lead to further spread, and outbreaks are generally small and short-lived. The success of the measles-control program in the United States is the result of a high rate of coverage with a safe and efficacious vaccine (the measles–mumps–rubella [MMR] vaccine), combined with the aggressive implementation of control measures once cases are detected. When measles outbreaks occur in a region in which measles has been eliminated, they occur in clusters of unvaccinated persons,6 including those in religious communities. The Amish, a Christian sect descended from the Swiss Anabaptists, practice group solidarity and rejection of modern conveniences. Although the Amish Church does not specifically prohibit vaccination, the personal and cultural beliefs of the Amish limit participation in preventive health care, which results in low immunization rates and an increased risk of vaccine-preventable diseases. During measles outbreaks, the infection can spread unchecked among community members,11-13,20 which subsequently places susceptible persons in the general population at risk. Such outbreaks afford a unique opportunity to measure the ways in which high baseline immunity in a population and targeted public health responses contribute to the prevention of measles epidemics. During 2014, the World Health Organization reported that there were 21,403 confirmed cases of measles and 110 measles-associated deaths in the Philippines.26 In March 2014, a measles outbreak was reported in the United States after two unvaccinated Amish men had returned to their U.S. communities from the Philippines, where they had been unknowingly infected with measles while performing typhoon relief work. In this article, we describe the epidemiology of the outbreak in this distinctive unvaccinated population and detail the containment efforts instituted by local health departments to limit the spread of the disease.