The transmission is fecal-oral. This means it is transmitted via contaminated water and food, as well as through person to person contact (seen in an outbreak of gastroenteritis in California). Illnesses in adults can also happen as a result of a large exposure to astrovirus or through fomites.
It is partially resistant to chlorination, which is widely used for wastewater treatment in many countries.
“Human Astroviruses.” National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 19 Mar. 2015.
Knipe, David M., and Bernard N. Fields. “Chapter 21: Astroviridae.” Fields’ Virology. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2013. 609-28. Print.
“ViralZone: Astroviridae.” ViralZone: Astroviridae. ExPASy, n.d. Web. 19 Mar. 2015.