From an article in the Jan 2007 Hospitalist:

"Rickets

The incidence of rickets is increasing, especially in black and Hispanic children and particularly in the north.11,12 Epidemiologists trace the rise to an increase in breast-feeding (good for immunity, but breast milk lacks substantial vitamin D), overuse of sunscreen or lack of exposure to sunlight, and changes in physician recommendations for vitamin supplementation. The effects of rickets alone can be profound, but other long-term consequences of vitamin D deficiency may include type I diabetes, cancer (especially of the prostate), and osteoporosis.12

In the past few decades, physicians have been less likely to recommend vitamin D supplementation for babies, and an interesting study by Davenport and colleagues correlates the year of medical school completion to that decline as well as substantial variability as to the age at which supplement use is begun.12 (See Figures 4a and 4b, left.)

"Most of the cases I have run into have been in [recent] African immigrants, where the mothers stay covered and they are vitamin D deficient," says Dr. Holmes. "It's wonderful that they culturally breast-feed, but they come to the U.S., and they're pretty afraid to go outside in a new society."

Sounds to me like some of our new immigrants need some better education on health needs in a cold and cloudy climate.