The 8-month-old Amish girl, whose name has been withheld by health officials, has an immune deficiency that makes her unable to rid her body of the [polio] virus. How she contracted the virus remains a mystery. She may have been infected in a hospital by another immune-deficient patient who nursed it for years. A doctor or nurse may have served as a go-between. Or there may have been a chain of carriers in the Amish community. The virus is spread from stool to mouth, a surprisingly efficient form of transmission.
Regardless, the girl is now a wellspring for polio, a modern-day Typhoid Mary who can pass it along to others. Anyone who has not been vaccinated is vulnerable. And though vaccination rates in the United States are at historic highs, an increasing number of parents are resisting inoculations for their children, fearing that they may cause disorders like autism, a connection scientists have almost universally discounted.
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