Ragweed as an Example of Worldwide Allergen Expansion

Abstract
Multiple factors are contributing to the expansion of ragweed on a worldwide scale. This review seeks to examine factors that may contribute to allergen expansion with reference to ragweed as a well-studied example. It is our hope that increased surveillance for new pollens in areas not previously affected and awareness of the influence the changing environment plays in allergic disease will lead to better outcomes in susceptible patients.