Increasing urbanization may be a driving factor behind the spread of infectious diseases across the world. A major review led by an interdisciplinary team of researchers from the UK and Canada found that extended urban expansion may have resulted in increasing vulnerability towards the spread of infectious diseases. Published in the journal Urban Studies, the article focused on extended urbanization, particularly the socio-ecological relationships and disruptions that has led to an increasing occurrence of infectious disease in peri-urban and suburban areas. 
Extended urbanization includes suburbanization, post-suburbanization, and peri-urbanization. It occurs at the periphery of cities as they expand. This extension, particularly in developing nations of Asia and Africa, is also changing the way people live and interact with each other. The result is a fluid interaction between urban and rural environments which has created ‘new ecological niches’ that are conducive to the spread of infectious diseases.
The study found that these areas were more likely to be the centre for new as well as re-emerging infectious diseases. The increasing interaction between humans, livestock and displaced wildlife puts these areas at a particular risk for zoonosis, or infectious diseases that jump from animals to humans. The article pinpoints three key factors that have led to the spread of infectious diseases, demographic change, infrastructure, and governance. The study concluded by calling further research in this area to manage possible outbreaks and minimize risks.