ATLANTA - The Centers for Disease Control and Prevention (CDC) recently sent epidemiological intelligence service (EIS) officers to Pennsylvania's Amish country to investigate a possible outbreak after five cases of invasive Haemophilus influenzae type b (Hib) disease occurred in late December 1999 in unvaccinated Amish children ranging from 10 days to 3 years.
Two additional cases, one in January and one in February, occurred this year. One of the most recent cases resulted in the death of an 8-month-old.
The number marked a 700% increase in disease incidence from 1998, according to the Pennsylvania Department of Health.
Perrianne Lurie, MD, MPH, public health physician, division of communicable disease epidemiology, Pennsylvania Department of Health, said although the incidences occurred around the same time, she is reluctant to call it an outbreak because they occurred in different counties and no clonal pattern was established.
"Even the word `cluster' is one that has to be used with caution because we only have preliminary data," said Alicia Fry, MD, MPH, EIS officer, CDC. "We don't have enough facts at this point to say that any of the cases are related in any way that would constitute a cluster. Right now it's an increased number of cases among an undervaccinated population."
Hib vaccine is recommended for all children younger than 5 years, according to the routine harmonized schedule. According to Fry, the fact that there are populations of people who are not vaccinated means that they are under served by the current medical care system.
"Those populations need to be identified and educated in a culturally appropriate method - and they need to be vaccinated. That's the bottom line," said Fry.
There are 37 counties in Pennsylvania with Amish populations, and Lancaster County alone has an estimated 20,000 Amish people. The number is estimated because little census data exists on the actual number of Amish in the state. Also, the Amish live in areas called districts, or a group of households that work together and range from 30 to 35 households that meet on a regular basis in the community.
Researchers from the CDC designed an extensive questionnaire to find out why the Amish were not vaccinating their children. Contrary to the obvious, it was not primarily due to religious exemption.
"Over half of the respondents basically said that in daily life it just wasn't a priority," said Alison Mawle, MD, Office of the Director, National Center for Infectious Diseases, CDC. "Getting somewhere to get the vaccine when compared with everything else they had to do just wasn't a priority. The resistance was not so much from the parents in terms of them not wanting the vaccine, it just wasn't easily available to them."
According to Lurie, many Amish children are vaccinated against other diseases - although there have been measles and polio outbreaks in the past - but not Hib. "They see it as more of a day care disease," said Lurie. She added that the Hib vaccine has always been available to the Amish at health department clinics and at various outreach sites.
To confound the problem, midwives deliver many Amish children and parents may not get the same vaccination information they would receive under a physician's care.
The Pennsylvania Department of Health is putting together a multipronged effort to encourage vaccination in this population. They are also working with the CDC to help alert health officials in other states with large Amish populations, such as Ohio, New York, Maryland, and even areas in Canada, since many of the Amish have an extended social network.
You can express your views on this article, or other relevant themes, in the Infectious Diseases in Children Specialty Forums.