Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

@Joe, sorry, I overlooked you answer. Thanks for the links. Seems I need to do some more reading. As I understand, we then have a dilemma of E.Coli (I guess the same applies to fecal coliforms etc.) not being a good indicator, while measuring a wider range of pathogenic bacteria is prohibitively expensive.
But I still not agree that helminths (e.g. Ascaris) would be a better indicator. At least E.Coli or FC is much more close to the behaviour of bacterial pathogens in the environment than are worm eggs.

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

muench wrote: Note by moderator (EvM) regarding Keith's post above:

In my opinion this post does not fit into this thread, it is off topic. We already had a discussion about ciliate protozoans and wastewater treatment plants here on the forum:

forum.susana.org/forum/categories/39-any...mit=12&start=24#6833

If you want to discuss it further, please do it in that other thread, not here.


I beg to differ, Elisabeth. The question in this thread is "What pathogens should we test?" and protozoans are used as indicator in activated sludge for good reason. It's quite pertinent to this discussion.

Also, continuing to discuss protozoans in a thread about anammox bacteria isn't appropriate, so if you'd prefer, I'd be happy to begin a new thread devoted to the issue of protozoans, especially ciliates, but we can also discuss malaria.

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

In general, I'm not so concinced in the utility or the need for the end user of having some montitoring tools that measure the actual indicator organisms. I think often it is much more practical and useful to use simple and easy to control "indicator actions", behaviours or pracitices that are known to lead to a safe result.

E.g. for handwashing. One could aim at useing some fancy tools to do a bacteria count on washed hands to see if washing was effective, or one could aim at a behaviour known to be suffciently safe (e.g. wash hands before cooking and eating, after toilet use, for 1 min, using soap.).

For helminth removal that would be to rather aim at measuring storagte time, treatment temperature that need to be respected than at measureing the helminths directly.

I totally agree with you that hygiene practice and following well documented guidelines is necessary, but I do not think that they should replace monitoring. Yes, I agree that it may be too much to ask for the end-user to conduct the monitoring himself, but this is where community based organizations might play a role.
I'm here to learn

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

Note by moderator (EvM) regarding Keith's post above:

In my opinion this post does not fit into this thread, it is off topic. We already had a discussion about ciliate protozoans and wastewater treatment plants here on the forum:

forum.susana.org/forum/categories/39-any...mit=12&start=24#6833

If you want to discuss it further, please do it in that other thread, not here.
Dr. Elisabeth von Muench
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My Wikipedia user profile: en.wikipedia.org/wiki/User:EMsmile
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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

I don't have the answers, but just wanted to add that free-swimming ciliate protozoans are used as indicator of "good" quality sludge as they feed on bacteria and clarify effluent. This is quite ironic since they are parasites by definition, yet purposely multiplied in WWTP sludge, then released into the environment unregulated by obsolete law.

What happens when these parasites find their way to the intestines of people? Do they then consume commensal gut flora?

water.me.vccs.edu/courses/ENV295Micro/lesson6_5.htm
www.sciencedirect.com/science/article/pii/S0011916409010923
www.tandfonline.com/doi/abs/10.1080/1125...3373797#.U2ASeOZdV9s

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

OK, well this paper by Sidhu et al is one primer on pathgoens in faeces.

The 'why not' is hard to answer - but basically it doesn't model the breakdown of pathogens very well.

This is another relevant paper from Harwood et al

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

joeturner wrote: I'm not suggesting everyone should do this, because it is very expensive. But there has been a considerable argument about the value of using E.coli as a measure, and I'd say the consensus is that on its own it doesn't really show anything very much.


My "why not?" was an honest question, because I don't know much about this considerable argument you are referring to. So I'd be interested in some info about this, a link would do.
Thanks, Florian

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

Well,

E. coli O157,
Salmonella
Cryptosporidium
Listeria
Campylobacter
and enteroviruses.

I'm not suggesting everyone should do this, because it is very expensive. But there has been a considerable argument about the value of using E.coli as a measure, and I'd say the consensus is that on its own it doesn't really show anything very much.

Even if there are problems with using Helminths as an indicator of the overall presence of pathogens, I'd say there are far fewer problems than using only E.coli.

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

joeturner wrote: I don't agree that it is even a good indicator of other bacteria, never mind pathogenic bacteria.

Why not?

What would be a better indicator for measuring pathogenic bacteria in sanitation systems?

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

You both have good points.

For treatment or disinfection systems it is basically the log-reduction of total plate counts that matter. But E.coli can also be used as a substitute for total plate counts in case of human fecal sludge. However as we are talking about very high bacteria counts the dilution series necessary can be quite extensive and maybe beyond of what a simple field kit can do.

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

E.coli is a poor measure of anything other than presence/absence of faecal contamination. Given that we know that there is faecal contamination (we're talking about testing human faeces), I don't agree that it is even a good indicator of other bacteria, never mind pathogenic bacteria.

It is commonly used because it is an easy measure, but it is not a good measure.

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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way?

joeturner wrote: Helminths yes, E.coli no. Helminths are hard to destroy, so if you had them in the waste and destroyed them in the treatment, you are very likely to have destroyed everything else as well. E.coli are easy to destroy, and are not even all pathogens, so this doesn't really show anything.


Just a short comment on this, because I do not think that the idea of just using helminths as indicator is a good approach.

Using Ascaris and E.coli (or often also fecal coliforms) as indicators is nothing new, and certainly still makes sense.

Ascaris acts as indictor for helminths, e.Coli as indicator for bacteria. Bacteria and helminth eggs have different behavior regarding their persistence in the environment, their behaviour in treatment systems, and also their impact on human health. That is why it is important to consider both indicators.
Just two examples:
- In some wastewater treatment systems, e.g. settling tanks or filtration systems, helminths eggs are quite easily removed, but bacteria not at all. In other systems (e.g. UV-treatment), it's just the other way round.
- Some bacteiral diseases are much more dangerous than helminth infections. Imagine a cholera epidemic: In that case it is extremly crucial that treatment systems remove or contain all bacteria, while letting pass some helminth eggs would consitute are rather minor risk.

Taking helminth eggs alone only makes sense for some situations, but not as a general rule. One could even argue that more indicators should be included, e.g. to appropiately cover viruses or protozoa, which again show different behaviours than helminths or bacteria.

I would like to again stress on the importance of an low-cost and easy-to-use technology as pointed out by both Canaday and Turner. In my opinion, this monitoring should be conducted by the user itself or by local community groups.


In general, I'm not so concinced in the utility or the need for the end user of having some montitoring tools that measure the actual indicator organisms. I think often it is much more practical and useful to use simple and easy to control "indicator actions", behaviours or pracitices that are known to lead to a safe result.

E.g. for handwashing. One could aim at useing some fancy tools to do a bacteria count on washed hands to see if washing was effective, or one could aim at a behaviour known to be suffciently safe (e.g. wash hands before cooking and eating, after toilet use, for 1 min, using soap.).

For helminth removal that would be to rather aim at measuring storagte time, treatment temperature that need to be respected than at measureing the helminths directly.

I am a strong believer that having good measurement and quick monitoring is crucial for innovation and system sustainability.


However definitly agree to this, I agree that for monitoring in reasearch and development, or the operation of larger treatment systems, better (cheaper and more reliable) monitoring tools are needed.

What should be the price point? Right now we are thinking under $1,000


One last remark to the costs. 1000 $ doesn't tell you much if you don't include how many samples you can analyise with that. Typically, test kits are only cheap if the number of samples taken are small. For larger monitoring campains it's offten cheaper to do analyis in a professional lab.






Best, Florian

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