Human viruses in water

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Viruses are a major cause of human waterborne and water-related diseases. Waterborne diseases are caused by water that is contaminated by human and animal urine and feces that contain pathogenic microorganisms. A subject can get infected through contact with or consumption of the contaminated water. Viruses affect all living organisms from single cellular plants, bacteria and animal to the highest forms of plants and animals including human beings. Within a specific kingdom ( Plantae, Animalia, Fungi etc) the localization of viruses colonizing the host can vary: Some human viruses, for example, HIV, colonizes only the immune system, while influenza viruses on the other hand can colonize either the upper respiratory tract or the lower respiratory tract depending on the type (human Influenza virus or avian influenza viruses respectively). [1] Different viruses can have different routes of transmission; for example, HIV is directly transferred by contaminated body fluids from an infected host into the tissue or bloodstream of a new host while influenza is airborne and transmitted through inhalation of contaminated air containing viral particles by a new host. Research has also suggested that solid surface plays a role in the transmission of water viruses. In a experiments that used E.coli phages, Qβ, fr, T4, and MS2 confirmed that viruses survive on a solid surface longer compared to when they are in water. Because of this adaptation to survive longer on solid surfaces, viruses now have a prolonged opportunities to infect humans. [2] Enteric viruses primarily infect the intestinal tract through ingestion of food and water contaminated with viruses of fecal origin. Some viruses can be transmitted through all three routes of transmission.

Contents

Water virology started about half a century ago when scientists attempted to detect the polio virus in water samples. [3] Since then, other pathogenic viruses that are responsible for gastroenteritis, hepatitis, and many other virus strains have replaced enteroviruses as the main aim for detection in the water environment. [3]

History

Major outbreaks

Water virology was born after a large hepatitis outbreak transmitted through water was confirmed in New Delhi between December 1955 and January 1956. [4]

Viruses can cause massive human mortality. The smallpox virus killed an estimated 10 to 15 million people per year until 1967. [3] Smallpox was finally eliminated in 1977 by extinction of the virus through vaccination, and the impact of viruses such as influenza, poliomyelitis and measles are mainly controlled by vaccination. [4]

Despite advances in vaccination and prevention of viral diseases, it is estimated that in the 1980s a child died approximately every six seconds from diarrhea confirmed by WHO.[ citation needed ] Many cases of hepatitis A and/or E, both of which are enteric viruses, are typically transmitted by food and water. Extreme examples include the outbreak of 300,000 cases of hepatitis A and 25,000 cases of gastroenteritis in 1988 in Shanghai caused by shellfish harvested from a sewage polluted estuary. [5] In 1991, an outbreak of 79,000 cases of hepatitis E in Kanpur was ascribed to drinking polluted water. [3]

A more recent outbreak of Hepatitis E in South Sudan killed 88 people. Medecins Sans Frontieres (MSF) said it had treated almost 4,000 patients since the outbreak was identified in South Sudan in July 2012. In this outbreak, Hepatitis E, which causes liver infections, and was thought to be spread by drinking water contaminated with feces. [6] Even more recently In 2014, another Hepatitis E outbreak occurred in south Sudan refugee camp situated in Ethiopia. The outbreak, which began in April of 2014 and ended in January of 2015, claimed a total of twenty-one lives. [7]

Sewage contaminated water contains many viruses, over one hundred species are reported and can lead to diseases that affect human beings. For example, hepatitis, gastroenteritis, meningitis, fever, rash, and conjunctivitis can all be spread through contaminated water. More viruses are being discovered in water because of new detection and characterization methods, although only some of these viruses are human pathogens. [4]

Rotavirus, an example of human water viruses Multiple rotavirus particles.jpg
Rotavirus, an example of human water viruses
FamilyGenusSpeciesCommon NameDisease Caused
Adenovirus Mastadenovirus Human mastadenovirus A through Gadenovirus Adenovirus infection, pharyngitis, conjunctivitis, fever
Astrovirus Mamastrovirus Human astrovirus astrovirusGastroenteritis, diarrhea
Calicivirus Norovirus Norwalk virus norovirus, winter vomiting bugGastroenteritis, fever
Coronaviridae Coronavirinae SARS coronavirus SARS-CoV[ citation needed ] SARS, gastroenteritis, respiratory disease
Coronaviridae Torovirus Human torovirus torovirusGastroenteritis
Hepeviridae Orthohepevirus Orthohepevirus A Hepatitis E virus, HEV Hepatitis E
Picornavirus Enterovirus Enterovirus A Coxsackie A virus Hand, foot, and mouth disease, paralysis, meningitis, fever, respiratory disease, myocarditis, heart anomalies
Picornavirus Enterovirus Enterovirus B echovirus Meningitis, fever, respiratory disease, rush, gastroenteritis
Picornavirus Enterovirus Enterovirus C poliovirus Polio
Picornavirus Hepatovirus Hepatovirus A hepatitis A virus, HAV Hepatitis A
Polyomaviridae Polyomavirus JC virus JC virus Progressive multifocal leukoencephalopathy
Reovirus Rotavirus Rotavirus A, B, & CrotavirusGastroenteritis

Virus survival in water

Viruses need a suitable environment to survive in. There are many characteristics that control the survival of viruses in water such as temperature, light, pH, salinity, organic matter, suspended solids or sediments, and air–water interfaces.

Temperature

Temperature has the highest effect on virus's survival in water since lower temperatures are the key to longer virus survival. For instance, an article published in 2018 noted that it takes one year for certain viruses including poliovirus and echovirus to decrease by a 5log unit at a temperature of 4°C, while it takes only a week to obtain same result at a temperature of 37°C (human body temperature). The rate of protein, nucleic acid denaturation and chemical reactions that destroy the viral capsid are increased at higher temperatures, thus viruses will survive best at low temperatures. Hepatitis A, adenoviruses and parvoviruses have the highest survival rate in low temperatures amongst enteric viruses. [3] [8]

Light

Ultraviolet light (UV) is the light in sunlight and can inactivate viruses by causing cross-linking of the nucleotides in the viral genome. Many viruses in water are exterminated in the presence of sunlight. The combination of higher temperatures and more UV in the summer time corresponds to shorter viral survival in summer compared to winter. Double stranded DNA viruses like adenoviruses are more resistant to UV light inactivation than enteroviruses because they can use their host cell to repair the damage caused by the UV light. [3]

Visible light can also affect virus survival by a process called photodynamic inactivation but the length and intensity of the light exposure can change the inactivation rate. [3]

pH

The pH of most natural water is between 5–9. Enteric viruses are stable in these conditions. On the other hand, many enteric viruses are more stable at pH 3-5 than at pH 9 and 12. Enteroviruses can survive at pH 11–11.5 and 1–2, but for only short periods. Adenoviruses and rotaviruses are delicate to a pH of 10 or greater and leads to inactivation. [3]

Salts and metals

In a general perspective, viruses don't survive in areas with high concentration of salt. Thus, viruses can live longer in a freshwater habitat than water bodies with high salt concentration. It is also known that certain heavy metals are toxic to viruses. [9]

Interface

Some types of coliphages (a type of bacteriophage) are inactive in an of air-water-solid interface. This is due to the unfolding of the viruses' protein capsid (which is a crucial component for infecting the host). Aggravation of this effect is seen when the ionic strength of the solution increases [4]

Aggregation

Aggregation is one of the most known methods for the survival of viruses. In a liquid environment, viruses tend to form a clump (aggregation). This aggregation result in a reduced rate of virus inactivation promptly showing that viral particles that do not aggregate are more easily destroyed. It has also been proven that aggregation may form spontaneously or may result by nucleation on particles of water. [8]

Virus removal from water

Water that is intended for drinking should go through some treatment to reduce pathogenic viral and bacterial concentrations. As the density of the human population has increased the incidence of sewage contamination of water has increased as well, thus the risk to humans from pathogenic viruses will increase if precautions are not taken. [3]

Scientific studies suggest that the most common viruses found are caliciviruses, astroviruses and enteric viruses. Laboratories are still looking for improved methods to detect these pathogenic viruses. Reducing the amount of viruses in drinking water is accomplished by various treatments that are typically part of drinking water treatment systems in developed countries. [3] [10]

Water purification of surface water (water from lakes, rivers, or reservoirs) typically utilizes four treatment stages: coagulation and flocculation, sedimentation, filtration, and disinfection. The first three stages remove mainly dirt and larger particles, although filtration does reduce the number of viruses and bacteria in the water the number of pathogens present after filtration is still considered too high for drinking water. Purification of water from underground aquifers, called ground water, may skip some of these steps as ground water tends to have fewer contaminants than surface water. The last step, disinfection, is primarily responsible for the reduction of pathogenic viruses to safe levels in all drinking water sources. The most common disinfectants used are chlorine and chloramine. Ozone and UV light can also be used to treat large volumes of water to remove pathogens. [11] [10]

In an article published in 2010, it was determined that nanoparticles of silver could significantly inactivate the activity of some water viruses. When 5.4 ml of the nanoparticles of silver was added to a water virus, its activity decreased by 4log. [12]

Prevention of water viruses

The quality of drinking water is ensured through a framework of water safety plans that ensures the safe disposal of human waste so that drinking water supplies are not contaminated. Improving the water supply, sanitation, hygiene and management of our water resources could prevent ten percent of total global disease. [13]

Half of the hospital beds occupied in the world are related to the lack of safe drinking water. Unsafe water leads to the 88% of the global cases of diarrhea and 90% of the deaths of diarreaheal diseases in children under five years old. Most of these deaths occur in developing countries due to poverty and the high cost of safe water. [13] An article published in 2003 by CDC concluded that the death of children (less than five years of age) caused by rotavirus on a global scale ranges between 352,000 to 592,000. [14]

Approximately 1.1 billion people do not have access to improved water and 2.4 billion people do not have access to sanitation facilities. This situation leads to 2 million preventable deaths each year. [15]

See also

Related Research Articles

<span class="mw-page-title-main">Norovirus</span> Type of viruses that cause gastroenteritis

Norovirus, sometimes referred to as the winter vomiting disease, is the most common cause of gastroenteritis. Infection is characterized by non-bloody diarrhea, vomiting, and stomach pain. Fever or headaches may also occur. Symptoms usually develop 12 to 48 hours after being exposed, and recovery typically occurs within one to three days. Complications are uncommon, but may include dehydration, especially in the young, the old, and those with other health problems.

<span class="mw-page-title-main">Hepatitis A</span> Acute infectious disease of the liver

Hepatitis A is an infectious disease of the liver caused by Hepatovirus A (HAV); it is a type of viral hepatitis. Many cases have few or no symptoms, especially in the young. The time between infection and symptoms, in those who develop them, is 2–6 weeks. When symptoms occur, they typically last 8 weeks and may include nausea, vomiting, diarrhea, jaundice, fever, and abdominal pain. Around 10–15% of people experience a recurrence of symptoms during the 6 months after the initial infection. Acute liver failure may rarely occur, with this being more common in the elderly.

<span class="mw-page-title-main">Fecal–oral route</span> Disease transmission via pathogens from fecal particles

The fecal–oral route describes a particular route of transmission of a disease wherein pathogens in fecal particles pass from one person to the mouth of another person. Main causes of fecal–oral disease transmission include lack of adequate sanitation, and poor hygiene practices. If soil or water bodies are polluted with fecal material, humans can be infected with waterborne diseases or soil-transmitted diseases. Fecal contamination of food is another form of fecal-oral transmission. Washing hands properly after changing a baby's diaper or after performing anal hygiene can prevent foodborne illness from spreading.

<i>Influenza A virus</i> Species of virus

Influenza A virus (IAV) is a pathogen that causes the flu in birds and some mammals, including humans. It is an RNA virus whose subtypes have been isolated from wild birds. Occasionally, it is transmitted from wild to domestic birds, and this may cause severe disease, outbreaks, or human influenza pandemics.

<span class="mw-page-title-main">Avian influenza</span> Influenza caused by viruses adapted to birds

Avian influenza, also known as avian flu, is a bird flu caused by the influenza A virus, which can infect people. It is similar to other types of animal flu in that it is caused by a virus strain that has adapted to a specific host. The type with the greatest risk is highly pathogenic avian influenza (HPAI).

<i>Adenoviridae</i> Family of viruses

Adenoviruses are medium-sized, nonenveloped viruses with an icosahedral nucleocapsid containing a double-stranded DNA genome. Their name derives from their initial isolation from human adenoids in 1953.

<span class="mw-page-title-main">Viral hepatitis</span> Liver inflammation from a viral infection

Viral hepatitis is liver inflammation due to a viral infection. It may present in acute form as a recent infection with relatively rapid onset, or in chronic form, typically progressing from a long-lasting asymptomatic condition up to a decompensated hepatic disease and hepatocellular carcinoma (HCC).

In medicine, public health, and biology, transmission is the passing of a pathogen causing communicable disease from an infected host individual or group to a particular individual or group, regardless of whether the other individual was previously infected. The term strictly refers to the transmission of microorganisms directly from one individual to another by one or more of the following means:

A fecal coliform is a facultatively anaerobic, rod-shaped, gram-negative, non-sporulating bacterium. Coliform bacteria generally originate in the intestines of warm-blooded animals. Fecal coliforms are capable of growth in the presence of bile salts or similar surface agents, are oxidase negative, and produce acid and gas from lactose within 48 hours at 44 ± 0.5°C. The term "thermotolerant coliform" is more correct and is gaining acceptance over "fecal coliform".

Wilderness-acquired diarrhea is a variety of traveler's diarrhea in which backpackers and other outdoor enthusiasts are affected. Potential sources are contaminated food or water, or "hand-to-mouth", directly from another person who is infected. Cases generally resolve spontaneously, with or without treatment, and the cause is typically unknown. The National Outdoor Leadership School has recorded about one incident per 5,000 person-field days by following strict protocols on hygiene and water treatment. More limited, separate studies have presented highly varied estimated rates of affliction that range from 3 percent to 74 percent of wilderness visitors. One survey found that long-distance Appalachian Trail hikers reported diarrhea as their most common illness. Based on reviews of epidemiologic data and literature, some researchers believe that the risks have been over-stated and are poorly understood by the public.

<span class="mw-page-title-main">Adenovirus infection</span> Medical condition

Adenovirus infection is a contagious viral disease, caused by adenoviruses, commonly resulting in a respiratory tract infection. Typical symptoms range from those of a common cold, such as nasal congestion, coryza and cough, to difficulty breathing as in pneumonia. Other general symptoms include fever, fatigue, muscle aches, headache, abdominal pain and swollen neck glands. Onset is usually two to fourteen days after exposure to the virus. A mild eye infection may occur on its own, combined with a sore throat and fever, or as a more severe adenoviral keratoconjunctivitis with a painful red eye, intolerance to light and discharge. Very young children may just have an earache. Adenovirus infection can present as a gastroenteritis with vomiting, diarrhoea and abdominal pain, with or without respiratory symptoms. However, some people have no symptoms.

<span class="mw-page-title-main">Transmission and infection of H5N1</span> Spread of an influenza virus

Transmission and infection of H5N1 from infected avian sources to humans has been a concern since the first documented case of human infection in 1997, due to the global spread of H5N1 that constitutes a pandemic threat.

<span class="mw-page-title-main">Astrovirus</span> Family of viruses

Astroviruses (Astroviridae) are a type of virus that was first discovered in 1975 using electron microscopes following an outbreak of diarrhea in humans. In addition to humans, astroviruses have now been isolated from numerous mammalian animal species and from avian species such as ducks, chickens, and turkey poults. Astroviruses are 28–35 nm diameter, icosahedral viruses that have a characteristic five- or six-pointed star-like surface structure when viewed by electron microscopy. Along with the Picornaviridae and the Caliciviridae, the Astroviridae comprise a third family of nonenveloped viruses whose genome is composed of plus-sense, single-stranded RNA. Astrovirus has a non-segmented, single stranded, positive sense RNA genome within a non-enveloped icosahedral capsid. Human astroviruses have been shown in numerous studies to be an important cause of gastroenteritis in young children worldwide. In animals, Astroviruses also cause infection of the gastrointestinal tract but may also result in encephalitis, hepatitis (avian) and nephritis (avian).

<span class="mw-page-title-main">Waterborne diseases</span> Diseases caused by pathogenic microorganisms transmitted by waters

Waterborne diseases are conditions caused by pathogenic micro-organisms that are transmitted by water. These diseases can be spread while bathing, washing, drinking water, or by eating food exposed to contaminated water. They are a pressing issue in rural areas amongst developing countries all over the world. While diarrhea and vomiting are the most commonly reported symptoms of waterborne illness, other symptoms can include skin, ear, respiratory, or eye problems. Lack of clean water supply, sanitation and hygiene (WASH) are major causes for the spread of waterborne diseases in a community. Therefore, reliable access to clean drinking water and sanitation is the main method to prevent waterborne diseases.

<span class="mw-page-title-main">Portable water purification</span> Self-contained, easily transported units used to purify water from untreated sources

Portable water purification devices are self-contained, easily transported units used to purify water from untreated sources for drinking purposes. Their main function is to eliminate pathogens, and often also of suspended solids and some unpalatable or toxic compounds.

<span class="mw-page-title-main">Nitazoxanide</span> Broad-spectrum antiparasitic and antiviral medication

Nitazoxanide, sold under the brand name Alinia among others, is a broad-spectrum antiparasitic and broad-spectrum antiviral medication that is used in medicine for the treatment of various helminthic, protozoal, and viral infections. It is indicated for the treatment of infection by Cryptosporidium parvum and Giardia lamblia in immunocompetent individuals and has been repurposed for the treatment of influenza. Nitazoxanide has also been shown to have in vitro antiparasitic activity and clinical treatment efficacy for infections caused by other protozoa and helminths; evidence as of 2014 suggested that it possesses efficacy in treating a number of viral infections as well.

<span class="mw-page-title-main">Introduction to viruses</span> Non-technical introduction to viruses

A virus is a tiny infectious agent that reproduces inside the cells of living hosts. When infected, the host cell is forced to rapidly produce thousands of identical copies of the original virus. Unlike most living things, viruses do not have cells that divide; new viruses assemble in the infected host cell. But unlike simpler infectious agents like prions, they contain genes, which allow them to mutate and evolve. Over 4,800 species of viruses have been described in detail out of the millions in the environment. Their origin is unclear: some may have evolved from plasmids—pieces of DNA that can move between cells—while others may have evolved from bacteria.

<span class="mw-page-title-main">Influenza</span> Infectious disease, often just "the flu"

Influenza, commonly known as "the flu", is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptoms begin from one to four days after exposure to the virus and last for about 2–8 days. Diarrhea and vomiting can occur, particularly in children. Influenza may progress to pneumonia, which can be caused by the virus or by a subsequent bacterial infection. Other complications of infection include acute respiratory distress syndrome, meningitis, encephalitis, and worsening of pre-existing health problems such as asthma and cardiovascular disease.

<span class="mw-page-title-main">Rotaviral gastroenteritis</span> Medical condition

Rotavirus gastroenteritis is a major cause of severe diarrhoea among infants and young children globally. It is caused by rotavirus, a genus of double-stranded RNA virus in the family Reoviridae. The diarrhea tends to be watery and is frequently accompanied by fever, vomiting and abdominal pain. By the age of five, nearly every child in the world has been infected with rotavirus at least once. However, with each infection, immunity develops, and subsequent infections are less severe; adults are rarely affected. There are five species of this virus, referred to as A, B, C, D, and E. Rotavirus A, the most common, causes more than 90% of infections in humans.

Human adenovirus 41(HAdV-F41), is an enteric Adenovirus, a nonenveloped virus with an icosahedral nucleocapsid containing a double-stranded DNA genome.

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