Virus - A Closer Look At Waterborne Viruses

Q. What is a virus?

A virus is a microorganism. They are primarily composed of nucleic acid (DNA or RNA) strands and an outside capsid, or coat of protein. They are extremely small (0.004 to 0.1 micron in diameter) - about 100 times smaller than bacteria. Generally considered a parasite, they are incapable of growth except in the presence of living cells hence, are commonly referred to as a “parasitic infectious microbe”.

Q. What are the physical characteristics of a Virus?

Viruses are simple in their structural composition and vary widely in appearance - some with very complex shapes resembling spiked balls or lunar landing spacecrafts. On their outside surface are receptor sites which are highly adept at recognizing specific host cells suitable for supporting the growth of particular viruses. Although there are a few viruses that cross the species barrier (jump from animal to human hosts), these receptors make viruses largely species specific - human viruses infect humans, plant viruses infect plants, and animal viruses infect animals.

Q. How do viruses grow and multiply?

Replication of viruses can only take place in a living host cell. Once inside the human host, viruses adsorb to the host cell and are either wholly engulfed into the host cell or effectively inject their nucleic acid into the cell wall. The virus genetic material takes over the host cell mechanics, forcing it to create more virus parts. Following replication, virus parts are assembled and released from the cell, now able to invade neighboring cells and repeat the process. Because one virus can enter a single cell and thousands may leave that same cell, virus infections can spread very rapidly throughout the body.

Q. Where are viruses found?

Viruses are commonly present in the environment on surfaces, in the air, and on or in the food and the water we ingest. They can also be transmitted via insect vectors (an organism, typically a biting insect or tick that transmits a disease or parasite from one animal or plant to another). Most viruses ‘of concern’ in food and water are known as enteric (relating to, or occurring in the intestines)viruses. These viruses include enteroviruses, adenoviruses, rotavirus, hepatitus A virus and caliciviruses.   They are spread by fecal/oral route, commonly via contaminated food and water.  

Q. Are viruses harmful?

Infection of a cell by a virus is often, but not always, debilitating to the cell's regular functions. Viral infections may be asymptomatic (causing no noticeable symptoms in the host), or may cause acute or chronic illness. An acute illness is an episode directly associated with infection such as the common cold. Among many types of viruses, more notable and potentially deadly viruses (and associated with diseases) include: Norwalk-like viruses (gastroenteritis); hepatitis A and E (hepatitis), poliovirus (paralysis); rotavirus (gastroenteritis); echovirus (meningitis and encephalitis); coxsackie virus A (meningitis, respiratory disease, fever); and coxsackie virus B (myocarditis, congenital heart disease).

Q. How can viruses be eliminated?

There are several proven water treatment methods that can effectively remove a significant level of virus from a water supply. These methods are chlorination, Ultraviolet (UV), ozonation, distillation, iodinated resin and electro adhesion. Reverse osmosis, nano-filtration, and other forms of ultra filtration have also been used to significantly reduce/remove viruses from a contaminated water supply.

A method of safe water production along with supplies for good hygiene, are critical components of emergency plan – both to avoid exposure and to viruses and prevent the spread of virus. Once the virus has infected any species, treatments are limited and typically involve treating the symptoms rather than the infection itself. Antibiotics are generally not effective against viruses. Antiviral agents have been developed to slow the progress of the viruses, but are rarely a fast or complete cure.