The proponents of such hypotheses often question the adequacy of nutrient tissue levels, especially vitamin C, for those children currently or recently ill, bacterial infections, those with higher individual requirements, those suffering from environmental challenges (e.g. allergies), and perhaps transient vaccination-related stresses. At the time of this writing, infantile scurvy in the United States is practically nonexistent. No cases of scurvy mimicking SBS or sudden infant death syndrome have been reported, and scurvy typically occurs later in infancy, rarely causes death or intracranial bleeding, and is accompanied by other changes of the bones and skin and invariably an unusually deficient dietary history.