Waterborne Viruses: A Barrier to Safe Drinking Water

What is the Global Status of Access to Safe, Pathogen-Free Drinking Water?Nearly 25% of the global population (1.8 billion people in 2012) is consuming fecallycontaminated water [1].This water can contain bacteria, protozoa, and viruses that can cause a variety of diseases in humans, most notably gastroenteritis.The impact on public health is staggering.Unsafe water, inadequate sanitation, and poor hygiene are responsible for about 90% of diarrheal deaths worldwide [2].Not surprisingly, diarrhea is the second leading cause of death for children under the age of five globally (1.2 million deaths in 2012) [2].In addition to the human cost, the World Bank estimates that lack of access to safe water and sanitation results in a global economic loss of US$260 billion annually [3].The lack of access to improved water disproportionally affects those living in poverty in rural, developing regions; however, even populations living in countries with state-of-the-art water and waste treatment facilities are prone to waterborne disease outbreaks.For example, there were at least 33 outbreaks associated with drinking water reported in the United States of America during 2009-2010 [4].Regardless of the socioeconomic status of a country, illnesses due to contaminated drinking water are considered significantly underreported because people do not seek medical attention for self-limiting infections and because of the current limitations on clinical detection of virus infections [4]. Are Waterborne Viruses a Particular Concern?It is well known that bacteria are major causes of diarrhea transmitted through unsafe drinking water.What is less appreciated are viruses in these same drinking water sources and their impact on human health.Water-transmitted viral pathogens that are classified as having a moderate to high health significance by the World Health Organization (WHO) include adenovirus, astrovirus, hepatitis A and E viruses, rotavirus, norovirus and other caliciviruses, and enteroviruses, including coxsackieviruses and polioviruses [5].Also, viruses that are excreted through urine like polyomaviruses [5] and cytomegalovirus [6] can potentially be spread through water.Other viruses, such as influenza and coronaviruses, have been suggested as organisms that can be transmitted through drinking water, but evidence is inconclusive [5].Most of the above viruses are most commonly associated with gastroenteritis, which can cause diarrhea as well as other symptoms including abdominal cramping, vomiting, and fever.It should be noted that some of these same viruses could also cause more severe illnesses