Is there really no risk of waterborne viruses in Oz?

[fiftyeight]

I have been researching about water filtration for some time and I am now contemplating whether a filter is enough.

Seemingly, most filters do not filter out viruses as the pore size is too large, there seem to be some filters which will filter out viruses but they are usually quite large.
e.g LIFESAVER bottle or first-need XLE.

Now I am trying to research whether viruses are even a concern in Australia.
A search through the forum lead me to viewtopic.php?f=15&t=8157 where some user argues that there are no waterborne viruses in Australia.
I also think I saw in some other places that waterborne viral diseases do not really happen in Oz.
THis website: http://globalhydration.com/resources/wa ... epatitis_a
talks specifically about hepatitis viruses which are spread exclusively by humans through feces.
But I wasn't able to find reliable sources which will show me clearly what the risks are of viral disease spreading through water sources and whether all viruses which are dangerous spread exclisively through human feces.

I hope someone has some knowledge about this issue, I believe it is quite important that we know what we are dealing with when drinking from water sources, especially since a lot of us I belive use filters whose pore size is insufficient to filter out viruses.

[Gadgetgeek]

Some interesting stuff there. Hep A is nasty since it is very easily spread, however immunization is a simple and highly effective solution for that. Hep E I'm not as sure about.
http://backcountrywater.com/water-contaminants/viruses/viruses/

This has a decent list. The only other one I'm really familiar with is norwalk, that one is really nasty. shouldn't be a problem in the back-country, but hygiene is really important as it is a fecal-oral route virus, and can last on surfaces for quite some time. Of course that means that you have to hope that someone didn't pick it up right before the trip and possibly infect your group, or isn't contaminating the water upstream.

UV is very effective against viruses, so filtering from clear water or filtering and then SODIS might be a good option.

I would think that your greatest risk would be infection from other trekkers, probably during meal preparation, or just contamination of shared surfaces. The worst part is trying to decontaminate everything to kill the virus.

[icefest]

Wow, I've always called it Norovirus, I didn't realise how wrong I was.

In general, a virus filter is not needed in remote Australia (with careful site selection).

If you done some google searches about water-borne virus transmission rates you should find the risks of infection if exposed to a contaminated source.

For me I don't treat at all in mountainous wilderness areas in Australia, and filter 0.1 micron in other hiking areas.

[GPSGuided]

Wow, I've always called it Norovirus, I didn't realise how wrong I was.

You weren't wrong. Guess the name depends on which textbook you read.
http://www.webmd.com/a-to-z-guides/noro ... c-overview

[icefest]

Apparently it's a Norwalk Virus outbreak and not a Norovirus outbreak.


http://talk.ictvonline.org/files/ictv_d ... /4069.aspx via http://en.wikipedia.org/wiki/Norwalk_virus

[deerndingo]

Hi,
In answer to virus protection, in essence, humans are prone to viruses carried by other humans. Humans shed virus in their waste. If there has been human activity upstream to where you are (walkers, hunters, all soughts) there is a risk of contracting their viruses and becoming ill. Its like when a person goes on holiday, makes contact with groups they have not encountered before and the viruses they carry that you have not encountered before and have no developed immunity to.

I filter my water and if there is a potential for humans upstream I boil it before drinking it. Typically I'll drink a fair bit of tea and wet meals to maintain my body hydration. I'd rather do that than stuff a good walk.

FWIW

[Gadgetgeek]

Yeah, noro, norwalk, they get used interchangeably. I have very thankfully missed out on outbreaks, the only summer I took away from children's camping, and noro went around Calgary for about a month and a half, everyone would shut down, clean up, and then one sick kid would spread it again. My concern would be that if you have someone pick it up in a hostel right before the trip, by the time they get sick and are evac-ed, they could really contaminate a campsite. In fact the most likely place to catch anything would be the toilets at the trailhead. Practicing good sanitation and good handwashing are the more important things. It doesn't matter if all your water comes from sealed, sterilized mylar bags if you have poo on your hands, you will get sick. And as much as I don't like the idea of all the anti-microbials around, the best thing is good soap, good scrubbing, and a little alcohol to keep things under control. And you won't know if you are hiking with typhoid mary until its too late.

[icefest]

Good sanitation and water selection is paramount. I don't think there is a much room for antimicrobial soap in the bush though. I'm even hesitant to use biodegradable soap. I really like alcohol hand sanitisers though. One of the best way to use them is to make sure that others who get sick use them before touching anything. (Having someone at camp pour water for handwashing is good too)

Typhoid is a bateria, but I get the point. Thankfully being colonised with a bacteria doesn't always result in sickness. (IIRC, there a 12% chance that I have MRSA on my skin right now)

[Gadgetgeek]

Yep you caught my point, someone could very easily be a carrier. I'm sure hundreds of hapless canadians have been unwittingly spreading giardia around the globe.
proper soap, even stuff like camp-suds is better than a "anti-microbial hand cleanser" which doesn't do much at all for parasites. gotta be alcohol.

[fiftyeight]

I've went through the pages http://backcountrywater.com/water-conta ... s/viruses/ and eas.health.vic.gov.au/bluebook/food-water.asp and I've read about the following viruses:

Hepatitis
Rotavirus
Adenovirus
Enterovirus
Norovirus
Calicivirus

Did some reading about the in Wikipeda.
It seems that they all are transmitted by the fecal-oral route. I am suspecting that all viruses affecting humans are transmitted exclusively between humans and cannot transmit otherwise. So that if we drink from a stream which has not flown through a civilised area (or previusly civilised) we should be safe. Am I correct?

[Gadgetgeek]

Yep, I'd agree with that statement.

[icefest]

I've went through the pages http://backcountrywater.com/water-conta ... s/viruses/ and eas.health.vic.gov.au/bluebook/food-water.asp and I've read about the following viruses:

Hepatitis
Rotavirus
Adenovirus
Enterovirus
Norovirus
Calicivirus

Did some reading about the in Wikipeda.
It seems that they all are transmitted by the fecal-oral route. I am suspecting that all viruses affecting humans are transmitted exclusively between humans and cannot transmit otherwise. So that if we drink from a stream which has not flown through a civilised area (or previously civilised) we should be safe. Am I correct?

I'm unsure if you have a medical/virology background and apologise if this seems patronising - I'm trying to keep it simple at the expense of accuracy.

Firstly I'd like to mention that virology is a relatively new science, roughly 120 years old, and that methods of identification (mainly PCR) are only about 30 years old. This means that there are significant gaps in the literature, and much of what is known might change over the next 50 years.

No all human viruses are transmitted by the fecal-oral route. Respiratory, zoonotic, blood and contact are all other methods of transmission.

Symptoms and virus transmission modes are all part of varying life cycles of viruses.

This means that viruses that cause gastroenteritis (vomiting and diarrhoea) tend to be spread by the aforementioned excreta (likewise viruses that cause a cough tend to be spread by that selfsame cough). An interesting side effect of this is that viruses that don't cause increased viral shedding tend not to spread as easily; compare influenza and HIV.

----
From the above it is reasonable to assume that most waterbourne viruses are spread by the fecal-oral route, but..
There is also the issue of animal reservoirs. That means, animals that can carry a virus and transmit it to humans. The best known examples of these are rabies and swine/bird flu.
Some Caliciviruses that affect humans can infect rabbits and shellfish.
There is research suggesting hepatitis E has an animal reservoir in pigs, rats and deer.
While not all of these were human serotypes, it is not unreasonable to assume that there are still some as yet undiscovered.

This means you can't assume that "all viruses affecting humans are transmitted exclusively between humans and cannot transmit otherwise".
----
Lastly there is also the question of degree of contamination. While a single virion is theoretically enough to cause infection, a larger exposure is more likely to result in a successful infection. Also, the higher the viral load of the water you drink the higher the likelihood of encountering a strain you are more susceptible to.

---

Lastly I'd like to mention that should you "drink from a stream which has not flown through a civilised area" you should be reasonably safe. There will always be a small risk with untreated water (there even is a risk with treated water) but this risk can be managed by site selection and hygiene.

from XKCD.com

TL;DR Your result is close enough, there is lots of complicated stuff happening but it all roughly evens out.

[GPSGuided]

Bottom line, one can't guarantee the risk down to zero and there's no data on your stream and on your particular day or hour. Risk is clearly low in general but a case of YMMV. Now, how hard is it to filter/treat? There are decisions out there that are dependent on one's desired risk profile. Make your own call.

[fiftyeight]

DELETE THIS

Last edited by fiftyeight on Mon 24 Mar, 2014 7:52 pm, edited 1 time in total.

[fiftyeight]

@Icefest, thank you for the excellent answer.
As for the current state of knowledge, would it be reasonable to say that viruses which are known to be trasmitted from animals are not waterborne and/or are not of risk in Oz?
Rabies and swine flu specifically are not waterborne as far as I've read so far.

[icefest]

@Icefest, thank you for the excellent answer.
As for the current state of knowledge, would it be reasonable to say that viruses which are known to be trasmitted from animals are not waterborne and/or are not of risk in Oz?
Rabies and swine flu specifically are not waterborne as far as I've read so far.

I'll agree with that.

I have yet to decide what I'll do in the main range... Too many people around for my liking...

[Gadgetgeek]

Rabies and lyssa are only known to be transmitted by bites (or scratches and slobber) Both can be immunized against after exposure, so if you do contact a bat or other critter, you have a few days to get immunized.
Swine flu is also not known to be waterborne, and is actually kinda hard to transmit.
In general most viruses don't last outside a host more than a very short time. Hep C is nasty as it can remain viable for up to 30 days, but pretty much must be blood to blood for infection. Noro is up to 15 days in the lab, so protected from UV like in a hut or toilet I'd say its a risk for two weeks. But UV quickly kills it, as does 10% bleach or 99% alcohol. Oxygen is pretty toxic to viruses so most can't last on a dry surface for long.
Bacteria and parasites are always a bigger risk with water, and viruses from people. Plan accordingly and all will be well.

[north-north-west]

I have yet to decide what I'll do in the main range... Too many people around for my liking...

There are certain watercourses up there I wouldn't trust. Not so much from the daywalkers but the areas are just too popular as campsites. The creek at the top of Sentinel Spur, for instance, or Wilkinsons.
But I've never had any issues with water in the Snowies.

[McGinnis]

Noro is up to 15 days in the lab, so protected from UV like in a hut or toilet I'd say its a risk for two weeks. But UV quickly kills it, as does 10% bleach or 99% alcohol. Oxygen is pretty toxic to viruses so most can't last on a dry surface for long.
Bacteria and parasites are always a bigger risk with water, and viruses from people. Plan accordingly and all will be well.

I'm no virologist, but I don't think alcohol is particularly effective against Norovirus, due to its lack of a lipid envelope.

On the alcohol thing, it's generally better to use ~70% than higher alcohol concentrations, so as to avoid rapid protein coagulation (which actually protects the target).

[Gadgetgeek]

You could very well be right on that. I just looked at the CDC site and it as pretty vague. also my bad on the 99% most gels are around 60% I think it depends on the mix as to the actual percentages, (ethyl, methyl or isopropyl) Thanks for the correction

[andrewa]

GP response, for what it's worth! ( but Melbourne based, so limited exposure).

I think it would be very hard work to pick up hepatitis A/E in Oz. Common in 3rd world countries. Last hep A outbreak I heard of was related to Sydney oysters years ago. Norwalk agent /rotavirus etc is a common cause of gastro, but requires people as a vector for transmission, so is commoner around school camps/cruise ships etc.

Amoebic gastro is relatively common in Melb....giardia not so much, but we regularly see blastocystis. It seems quite common up around Cairns, but I regularly see patients in Melb with it. It doesnt always cause symptoms, so some people just carry it, but we do treat it if someone has the *&^%$#@!. I did see a whole family who seemed to have acquired giardia down the Mornington Peninsula just before Christmas -not sure how.....but it clearly followed a weekend down there. Giardia is more commonly acquired overseas, or in Oz through childcare places. Giardia is apparently common in backcountry huts in NZ -carried by possums, which *&%$#! on the roof, and it gets into the hut tanks.

Campylobacter is also common in NZ. I occasionally see it in kids in Melb, but it is mostly a self limiting illness. You can get leptospirosis from swimming in, and ingesting water from the Yarra, when in flood, apparently.

In Victoria, I would be pretty happy to drink , and do drink, most water in backcountry areas, and have not yet got sick. I also regularly drink from trout streams, even if they flow through grazing land, but I'm probably pushing it with this. In NZ I don't drink from water supplies in huts, but do drink from streams, albeit mostly backcountry. I'd do similarly in Snowy Mtns and Tassie. I have only ever had gastro twice in 25 yrs from outdoor activities - one in the Snowies in winter, which I probably wrongly attributed to drinking from the Snowy below Charlottes pass, and one from NZ from drinking water from the Mohikinui Hut, which was prob giardia. The only water I wouldn't drink in Victoria is that at Valenjo Gantner Hut on the Howitt Plains, which is apparently infected with something. I have previously had issues with the water at Cleeve Cole Hut on Bogong, which used to have some little crustacean in it, but I never got sick.

Much of it is common sense....if it looks dodgy, boil it for 5 mins.....but, my personal experience wi water around Vic/SE NSW has been good.

Beyond this though, it is important to note that anyone taking medication that suppresses acid production by their stomach is at far greater risk of getting water born illness, so everyone taking such medication needs to much more vigilant.

A

[icefest]

I have previously had issues with the water at Cleeve Cole Hut on Bogong, which used to have some little crustacean in it
A

I've met the little Cleve Cole crustaceans too. They look like a cross between shrimp and plankton.

Glass shrimp? http://www.aquablueseafoods.com.au/othe ... rimp.shtml

[andrewa]

I've never worked out what they were, but is was very disconcerting finding half a dozen in a billy full of water one night! Maybe I should just have looked at them as extra protein! And, even more amazing, is that the water supply for CC comes, I think from a soak uphill, so I'm not sure where the little buggers fit in to the whole environment, other than contamination in tank. My issue was that if you can end up with a small crustacean in your water supply, then a few sneaky viruses/amoebae/bacteria could probably sneak in too!!

A

[icefest]

I haven't had a chance to see cleve cole hut without snow, so I can't say much about the definitive source.

I did have a bit of a poke around when the crustacean was found

• The water comes to the house via a ~1 inch poly pipe that is above ground for at least 1m.
• The water is continuously flowing. Even when the tap is off the sound of rushing water can be heard - explaining why the water never (hardly ever?) freezes.

From this I assume that the soak is either quite substantial (to keep year round water flow), or that there is an inline reservoir that can be bypassed in winter with the overflow being the freeze protection.

[GPSGuided]

Boiling seemed to be the best solution then. No raw crustacean sashimi nor anything else...

[andrewa]

Somewhat of topic....

Yep, I'm normally only up there in winter too, but I haven't stayed in the hut for at least 15 yrs. I'd rather camp, and, in winter, I tend to camp on the Eskdale, so I can ski the gullies, and get off the mountain quickly if the weather turns bad, which it always seemed to do on the Sundays when we used to ski out from CC 15 yrs ago!!

We manage an "out of winter" trip every few years...when the daughters turn 13, we drag them up there for the weekend, walking up at night, to then enjoy the sunrise above the world, and a weekend "above" Victoria . 4th daughter just turned 13, but beloved not feeling "fit enough" to go up there before winter..which is a bit (lot) of a *&%$#!. But I'll be up there in winter. Daughter 4 will have to wait until spring

A

[icefest]

Regarding risk of waterborne pathogens in CC, they're probably there, but as long as it isn't anthrax or any pathogen where a single low exposure can cause infection I'm not really too bothered.

If I were immunocompromised that would be another story entirely, but I personally think we have more to be worried about eating raw egg mayonnaise than drinking water from CC.

[andrewa]

Not a lot of anthrax in Toorak....probs more in the White House....when they open their letters which contain white powder, which is not cocaine......but ciprofloxacin treats it all!

A

[GPSGuided]

Not sure I'd want to wait for the good old cipro to take effect if I can help it.