Introduction

Can the Parainfluenza virus survive water? Short answer, yes, it absolutely can. If somebody had a viral infection, be it Parainfluenza or any other virus, using just water to wash your hands will not be sufficient to kill or more accurately inactivate the virus (since they aren’t technically living things). In regular drinking water (potable water) however, the water has been treated to remove any kind of pathogenic microorganisms, so you are highly unlikely to get an infection from drinking tap water. Having said that, in some parts of the world wastewater management may not be as good and drinking this could lead to diseases caused by microorganisms. Even so, since Parainfluenza is a respiratory infection, it is unlikely to be passed on through drinking water, however, if an infected person has not washed their hands properly using soap, they are more likely to pass it on to someone else via direct contact. In this article we will be looking at what Parainfluenza virus is, the significance of water for viruses, and survival and destruction of viruses.

What is Parainfluenza virus?

Structure

Parainfluenza are enveloped viruses that cause respiratory diseases in humans and the genetic material they contain is a single-stranded RNA. They belong to the family of Paramyxoviridae viruses and there are 4 types of them.¹

Clinical manifestations

Human parainfluenza virus (HPIV) causes respiratory diseases in both adults and children. They attach to ciliated epithelial cells in various parts of the respiratory tract and depending on where they bind and replicate, the severity of the infection can vary. Clinical manifestations range from common colds and croup to bronchiolitis and pneumonia. It places a significant burden on the NHS as 40% of children hospitalized for lower respiratory tract infections are caused by HPIVs. Also, 75% of cases of croup are caused by human parainfluenza virus. Immunocompromised adults tend to have the most severe symptoms¹.

Transmission

The virus is transmitted via direct contact with an infected individual or from large droplets (like from coughs of infected individuals). It is common for outbreaks to occur in places like daycares, nursing homes and within households.¹

The importance of water for virus particles

Viruses require a living host (humans, animals or even bacteria) for replication, however, to survive outside the host and prepare itself for invading host cells, research shows that viruses require water or moisture. Water is important for virus self-assembly at various stages as it provides hydrophobic forces that are required for this. Studies found that viruses have higher survival rate in low temperatures and high humidity. When temperature is too high virus particles begin to inactivate, likely due to high temperatures causing important proteins to lose their shape and no longer function, so these cannot infect a host. And high humidity which would mean more moisture for virus assembly.²

Factors for virus survival and virus destruction

The virus requires a host for replication so will not increase in number in water. It will either decrease or stay the same.³

Survival

One mechanism that helps virus particles to resist environmental stresses when in water is the formation of aggregates. What this means is that the viral particles clump together to prevent themselves from getting damaged. Think about how easy it would be to snap one twig in half compared to 50 all at once. The concept of aggregation is similar - there is strength in numbers!³

They would also try to adhere to surfaces of other objects or organic particles.³

Freezing and thawing cycles of water may also protect viruses that have lipid envelopes (like Parainfluenza). The envelope goes from having an oily consistency to a more gel like one as the temperature drops. This would protect the virus from UV radiation as it is more difficult for sunlight to reach them when frozen. Envelopes of viruses derived from mammalian cells better at surviving than, for example, ones from avian cells.³

Destruction

Factors that cause virus inactivation in water include extreme pH, increased oxygen levels, higher concentration of antimicrobials and more sunlight since UV radiation is damaging to nucleic acids.³

Removal of virus particles from wastewater

Wastewater contains many biological samples such as mucus, sputum and of course urine and faeces which contain viral particles. Therefore, virus particles including Parainfluenza virus are detected in wastewater. It is important for wastewater to be managed effectively to prevent transmission of viral infection through drinking water.⁴

Summary

So, Parainfluenza virus CAN survive in water, however, it is mostly transferred from person-to-person contact or from droplets of coughs and sneezes from infected individuals. Still, it is important for wastewater to be managed effectively so that no viral infection is passed through drinking water. In places where drinking water may not be as clean, boiling it and cooling it down before using it may help since high temperatures inactivate viruses. Covering your mouth when coughing and sneezing would help prevent respiratory infections such as those caused by Parainfluenza virus from spreading. And, since viruses can survive in water, it is important to use soap when washing your hands to prevent transmission of infection to other people through you.