Potential Spread of H5N1 Virus Via Water and Sewage


Scientists have discovered three types of influenza viruses occurring naturally in the environment. These are A, B and C types. The most deadly of these is influenza A, which can infect humans, avian, swine, horses and other animals in the world. However, wild fowl act as the natural carriers for this virus. This type of influenza has the potential to cause pandemics, either in the human race or in animals. Influenza B, on its part, is dominantly found among humans. It is less severe than the aforementioned type A. the third one, C, has the ability to cause mild infections in humans. As such, the last one is not a major concern to the health officials.

H5N1 is a strain of influenza A. it is also referred to as bird flu due to the fact that it is mainly transmitted by birds. It can affect both humans and other animals in the environment. There are many strains of this H5N1 virus. However, the one that is credited with causing h5n1 flu is the HPA1 A(H5N1). This strain is carried exclusively by birds, and that is the reason why the flu that results from it is referred to as avian flu.

There have been concerns on the way that this virus spreads from one bird to the other and from the birds to humans. It is generally agreed that wild birds, the carriers of this virus, rarely fall ill as a result of it. This is despite the fact that they may be excreting large colonies of this virus through their feces or nasal excretions. However, there has been documented cases of this virus been transmitted from the birds to the humans. This occurs when human beings come into contact with the virus from the birds and it gets to their respiratory tract.

This paper is going to examine the likelihood of this virus spreading through the environment via water and sewage. This is when the wild birds excrete this virus into the water bodies or when

Potential Spread of H5N1 Virus Via Water and Sewage

infected human beings excrete it from their gastrointestinal tract and into the sewerage system. Though there have been concerns to this effect, the writer believes that this does not pose a serious potential risk with the virus.

Objectives of this Study

The writer is trying to dissuade the reader on the potential risk of spread of H5N1 virus via water and sewerage channels. To address this effectively, the writer will need to take the reader through some basics about the H5N1 virus and how it spreads through water and sewerage. The following will be addressed in the process:

1. H5N1 virus: Brief Overview

2. Routes of H5N1 virus entry into water

3. Routes of H5N1 virus entry into sewerage system

4. Persistence of the virus in water and sewerage system

5. Potential risk of the phenomenon

6. Mitigating cases of infections through these routes

H5N1 Virus: A Brief Overview

Potential Spread of H5N1 Virus Via Water and Sewage

Influenza A, under which category H5N1 falls, has various subtypes of viruses (Menno: 33). These subtypes are differentiated by two proteins that are their building blocks. These proteins are H, which stands for haemagglutinin and protein N, which is the initial for neuraminidase (Menno: 33). These proteins are embedded on the surface of the virus. The most important of these proteins is the H one. These are the ones that determine the ability of the virus to attach itself to the cell and finally penetrate it. It should be noted that these viruses have to get access to the human cell for them to be able to multiply, otherwise they cannot achieve the same fete outside the cell (Neumann: 18). However, the importance of the N protein cannot be downplayed. They are the proteins that determine the releasing of the replicated viruses from the cell where the replication occurred and into the surrounding environment (Barratt & Boyes: 15).

From the above discourse, it can be gleaned that H5N1 virus is an acronym depicting a virus that has a combination of H protein type 5 and N protein type 1 (Neumann: 18). This virus spreads very fast from one bird to the other. The wild avian species, as earlier indicated, rarely fall sick from the virus. However, when the virus is passed from the wild to the domesticated avian species, it can cause severe illness and even mortality in the latter (Barratt & Boyes: 15). This virus can be transmitted from the birds and into humans. In the latter, it has the potential of causing pneumonia and other complication that lead to organ failure and eventual death if not controlled earlier.

The first documented case of human infection with this virus was in Hong Kong in 1997 (Kerkhove: 5). Eighteen cases were reported which resulted in six mortality cases (Kerkhove:

5). the second case was reported six years later in 2003. This occurred in Hong Kong still. By mid-March 2009, 413 cases had been reported in fifteen countries around the globe (Kerkhove: 4).

Entry of H5N1 into Water

The virus from the infected birds is shed to the environment from the animals’ feces, saliva and

Potential Spread of H5N1 Virus Via Water and Sewage

nasal excretions (Menno: 34). This occurs after an incubation of two weeks. An infected water

fowl has the capacity to shed 1010 EID50 within a period of 24 hours (Gambotto: 1). This is referred to as the “median egg infective dose” (Gambotto: 1). This shedding is through the ducks feces. Given that these birds can excrete an average of eight kilograms of feces per annum, the amount of egg infective dose can go as high as 3x 109 EID50 (Gambotto: 1).

When these birds are living in the water, it means that the virus will be excreted with the feces into the water bodies. This is made worse by the fact that most of these birds are of migratory nature, meaning that they can spread their viruses far and wide (Barratt & Boyes: 15). This has been proved in Canada where the virus has been found in waters drawn from six lakes that are known for their large numbers of fowl concentrations.

Other ways that the infected feces can access the water ways is through runoffs from farms that have been applied with infected fowls’ feces as fertilizers. The virus can also be carried by the wind to the water bodies, or where infected animals have been disposed near water bodies (Neumann: 18).

However, this should not raise concerns for the reader because these studies that have been conducted on water bodies are not conclusive. There is no data that exists to show the exact amount of H5N1 virus that is detectable in the waters drawn from where the fowls congregate. The studies available are the only ones that have been conducted in Canada, which were not conclusive.

Entry of H5N1 into Sewage

There is a likelihood of the virus entering the sewerage system via the human waste, if the human in this case happens to be infected (Gambotto: 1). This was proved by an examination of the feces of a child who was infected by the virus. The virus was detected from the stool of

Potential Spread of H5N1 Virus Via Water and Sewage

the child (Barratt & Boyes: 15). However, the virus was not detected from the urine of the same child, suggesting that the only possible way that this virus can get to the sewerage system is through the feces of the infected person.

Again, this not need worry the reader. Information on this likelihood, just like in the case of the water infections, is very scarce. This been the case, it is not logical to conclude that this is a risk factor for an epidemic (Gambotto: 1).

Persistence of the Virus in Water and Sewerage

It is unlikely that the virus will get into the water or sewerage system and immediately find a host. After been released, it will have to survive in the outside environment before finding a suitable host for further replication.

There is no data to support the supposition that H5N1 will survive in the water or sewerage system long enough to infect humans or other animals. However, there have been studied that have been conducted on H3N6, a subspecies related to H5N1. It was proved that at 4˚C, the virus could survive for 32 days (Gambotto: 1). At 22˚C, it lasted for only four days, meaning that it prefers cold conditions. Other factors that determine rate of survival are salinity and Ph levels of the water.

The same applies in survival chances of the virus in human excreta; there are several factors that influence it. The first is the type of the virus, since not all of them can withstand the same conditions (Menno: 35). The other is the temperature of the surrounding environment, and this has shown that they can survive for long at low temperatures.

Potential Spread of H5N1 Virus Via Water and Sewage

Given that there are no comprehensively studies that have been conducted to prove the persistence of the H5N1 virus in water or sewerage system, it will be very erroneous to assume that these routes pose a big risk factor as far as this virus is concerned. More studies need to be conducted to prove this point beyond doubt.

Potential Risk of Water and Sewerage Transmission of H5N1 Virus

The concern for many people is not about the survival of the virus in water or sewerage system, but rather, it is on the likelihood of the virus from these sources getting into human system. To address this concern, it is important to understand how the virus finds its way into the human body.

Studies have shown that the virus in humans replicates mainly in the respiratory tract (Gambotto: 1). This is unlike in birds where replication has been proved to mainly occur within the gastrointestinal tract. But there are also cases where the virus can replicate in the gastrointestinal system of the infected human. This is proved by the presence of smaller quantities of the virus in the stool and the development of diarrhea (Neumann: 18).

The virus accesses the body of the human through inhalation mainly. This is where the person inhales infected airborne droplets, for example from the birds exhalation. The virus can also be transmitted indirectly into the respiratory tract if the person touches infected surfaces then touches his nose, mouth or conjunctival mucosa (Barratt & Boyes: 15).

This been the case, it is very hard to prove that the human person stands a greater risk of getting the infection from water or sewage. For this to happen, he will first have to touch the water, then ingest it or make it access his respiratory tract. There had been no cases that have

Potential Spread of H5N1 Virus Via Water and Sewage

been documented of infections happening this way. This means that the fears of water and sewerage systems posing a risk to the human being as far as the virus is concerned are unfounded.

Mitigating Infections of the Virus via the Aforementioned Routes

The likelihood of the human person getting infected by this virus via this route is very minimal. However, there are some steps that can be taken to ensure that this case does not change. The first is to ensure that hygiene is maintained as far as domestic and community matters are concerned. Personal hygiene, for example washing of hands after handling suspected birds, should be encouraged. This is before the person touches his eyes or nose with the hands (Menno: 33). The sewage of the community should be treated effectively to ensure that there are no chances of it mixing with water for human consumption.


Cases of human to human infections of H5N1 virus are very rare. The only risk of transmission is from bird to bird and from bird to human. There have been concerns that this infection can occur to the human via water that is infected or via coming into contact with infected sewage. However, there have been very minimal studies that have been conducted to prove this. As such, the supposition is unfounded in research. Furthermore, there are no cases that had been reported as stemming from this mode of infection.


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Potential Spread of H5N1 Virus Via Water and Sewage

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