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

Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 09 Apr 2014 10:36 #8161

  • AFoote
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Dear SuSanA community,

For awhile now I've been a bit frustrated by how difficult it is to understand if treatment solutions are being effective. As far as I know, there is no real quick test on how to tell if something is working or if it's quick it is very expensive. I am a strong believer that having good measurement and quick monitoring is crucial for innovation and system sustainability. Is anyone already using a system or know of one out there?

I think as a SunSanA community we can come up with a better way to test pathogens reduction. I'd love to see us develop something like the Del Agua but for sanitation systems (
)

I've put together and update on how Sanivation is starting to address this issue and I'd love your input! See: http://sanivation.com/our-projects/mobile-pathogen-kit/

Some of the initial questions we are debating are:

  • What pathogens should we test? Right now we are planning on a kit for helminth and E.coli
  • What should be the price point? Right now we are thinking under $1,000
  • What is the right mix of precision and labor required? Right now we are wanting to be able to do log reductions


What do you think? Please reply to this topic as a way to share ideas and to collaborate on designing a kit that meets all of our needs.

Very excited about this project!
Andrew
Andrew Foote
Co-founder
www.sanivation.com
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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 09 Apr 2014 11:11 #8162

  • joeturner
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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.

log reductions are not the way to you as what you really want to know is whether the remaining levels of pathogens are safe, not how many you've managed to destroy.

In my view, the only way to do the above is with a Quantitative Microbiological Risk Assessment (QMRA) using a Monte Carlo simulation - we have discussed this before on this forum.

Once the above analysis has been done and a baseline 'safe' exposure has been calculated, I think what is then needed is a rapid system to analyse whether the treatment has met the standard or not.

Personally I think the price-point is another critical factor. All systems need to be tested regularly, preferably on a batch-testing regime. So I think $1000 is far too high.

In an ideal world, $1000 would be the cost to establish safe dose levels from reference pathogens of particular sanitation technologies in particular places, then the actual testing of samples would be as near to $0 as possible. I would see this as a validation mechanism using known microbiological techniques followed by some kind of instantaneous scanning electrical device to establish the presence/absence of the model pathogen, most likely ascaris helminths. I read once that there was work on building low cost hand-held Raman Spectroscopy unitss - which is currently under investigation by microbiologists as a way to identify microbes - which sounds to me like it would tick all the boxes.

I am not offering to do any of this, sadly I am not an engineer or a microbiologist. But that's the direction I would be looking in.
I don't work for anyone, I am a philosopher interested to think about how we think about WASH and sanitation. All thoughts are mine alone, I am responsible for any errors.

Previously trained and worked as a Soil Scientist and worked on projects composting sewage sludge.
Last Edit: 09 Apr 2014 11:15 by joeturner. Reason: typo
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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 10 Apr 2014 11:12 #8176

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Hi Andrew and Joe,

Very important topic that needs to be fine-tuned.

Joe, I had a look at the article on Raman Spectroscopy in Wikipedia and I did not see how this could search for an Ascaris egg in a pile of dirt. Please enlighten us on this.
en.wikipedia.org/wiki/Raman_spectroscopy

I agree that Ascaris is the organism to look for, since there seems to be a good consensus this is the most resistant of all fecal pathogens AND we can actually see it and identify it with a microscope. (Andrew, I understand why you had to use the canine helminth Toxocara in your study in Chile, as almost no one had Ascaris, but it is better to work on the actual human parasite (Ascaris).)

I suggest we work out a protocol that does not require anything specialized or expensive beyond a microscope (which is extremely hard to do without). This may involve washing a large sample of treated feces (say a kilogram) with something like a saturated salt solution, straining it through a mesh into a 3-liter Coke bottle, and allowing the Ascaris eggs to float to the top overnight and stick to the microscope slide placed on the mouth of the bottle. A quick examination of the slide under the microscope the next day should give a fairly definitive answer to the question of whether or not there are Ascaris eggs in the sample. This is based on a WHO document cited in the following post, only taken to a bigger scale to have a more definitive answer with less microscopy:
forum.susana.org/forum/categories/34-uri...lum-sanitation#2495.

I also suggest that small envelopes of plastic mesh containing feces known to have Ascaris could be dropped periodically into UDDTs, for analysis at the end of the process. This would reduce or eliminate the need to concentrate the Ascaris eggs.

Anyone looking for a thesis?

Best wishes,
Chris Canaday
Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 10 Apr 2014 15:12 #8188

  • joeturner
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canaday wrote:
Hi Andrew and Joe,

Very important topic that needs to be fine-tuned.

Joe, I had a look at the article on Raman Spectroscopy in Wikipedia and I did not see how this could search for an Ascaris egg in a pile of dirt. Please enlighten us on this.
en.wikipedia.org/wiki/Raman_spectroscopy


Hi Chris - I was offering this as a possible 'ideal' solution rather than anything which could be implimented soon.

The public laboratory have been working on producing a very low cost desktop spectrometry system, see here: store.publiclab.org/products/desktop-spectrometry-kit

Raman spectrometry is, apparently, possible using low-tech pointers see here optics.org/news/3/10/15

And microbiologists are investigating the use of raman spectrometry in identifying microbes in samples, see for example here www.ncbi.nlm.nih.gov/pubmed/21958140

Of course, you are right that this is all speculation - but if we're talking about what we'd like to see, then being able to use a cup of faeces, shaking it up in water and shining a hand-held and low-cost scientific gadget into it to determine the presence or absence of seems to me to be hard to beat. I repeat that I don't have the skills to put these things together - just remarking that it'd be great if it was possible.

I suggest we work out a protocol that does not require anything specialized or expensive beyond a microscope (which is extremely hard to do without). This may involve washing a large sample of treated feces (say a kilogram) with something like a saturated salt solution, straining it through a mesh into a 3-liter Coke bottle, and allowing the Ascaris eggs to float to the top overnight and stick to the microscope slide placed on the mouth of the bottle. A quick examination of the slide under the microscope the next day should give a fairly definitive answer to the question of whether or not there are Ascaris eggs in the sample. This is based on a WHO document cited in the following post, only taken to a bigger scale to have a more definitive answer with less microscopy:
forum.susana.org/forum/categories/34-uri...lum-sanitation#2495.


I remember when we discussed this before that we were told that the protocol is not as simple as just presence or absence of ascaris, because it can be present but not active. Personally I'm not sure that this is the way to go as it seems to require significant input from highly trained microbiologists.

In my view, some kind of mechanised test (perhaps using a simple DNA based dye test or something) is ideally what we want.

I also suggest that small envelopes of plastic mesh containing feces known to have Ascaris could be dropped periodically into UDDTs, for analysis at the end of the process. This would reduce or eliminate the need to concentrate the Ascaris eggs.


I agree, spiking of samples with Ascaris (or other index pathogen) seems like a very good idea. Some samples might have none present at the end of the process simply because there was none there in the first place. Good point Chris, I hadn't thought of that.
I don't work for anyone, I am a philosopher interested to think about how we think about WASH and sanitation. All thoughts are mine alone, I am responsible for any errors.

Previously trained and worked as a Soil Scientist and worked on projects composting sewage sludge.

Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 11 Apr 2014 09:11 #8199

  • ben
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Dear all,

Just to share this apps mWater, which isn't detailed at all on the website ... anyone heard some more about ? play.google.com/store/apps/details?id=co.mwater.clientapp

Article from the last Sandec News (07/2013) :

Android App to Count E. Coli

New enzyme-based tests for indicator bacte- ria are changing the way microbial water quality monitoring can be done. Sandec has partnered with the non- profit tech startup, mWater, to develop an An- droid app with which cellphone cameras can count E. coli and total coliform colonies on one such product, the Nissui Compact Dry EC plates. An automatic counter can reduce user error and simplify sample processing, especially when large numbers of samples must be analyzed. The mWater app already includes a colony counter for a similar testing product (3M Petrifilm), along with Sanitary Inspection forms and GPS functions. It requires a 5 MP autofocus camera for best results and is a free download in the Google Play store at: play.google.com/store/apps/ details?id=co.mwater.clientapp

Wishing you a good day,

Ben

Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 11 Apr 2014 12:02 #8202

  • PatrickBBB
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Hi Ben,

as far as I know this technology is meant to test drinking water sources and not effluent from sanitation systems. Of course it is possible still to use this for sanitation systems, but while E.coli is a good indicator organism (proving fecal contamination) it is a bad way to assess the performance of a sanitation system.

With that said, we should rather look at low cost, easy-to-use approaches like the one mWater is promoting rather than something similar to Del Agua. Providing technology and methodology that is viable for the user himself (or a local community sanitation volunteer) to use is the way for sustainable monitoring.

Attaching a guide made by UN-Habitat for more details on the approach mWater is promoting.

------------------------------------------------------------------------------
Regarding a better way to test pathogen inactivation:

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.

As for a microscope, it might be viable in some situations, where knowledge of how to use it is available, but as I said I would rather see a technology that is cheap and requires little training.

Raman spectroscopy seems quite interesting, but I am a bit skeptical to the scenario that you envision Joe. I would think the environment in which the test is to be conducted has to be quite stable to have a reliable output which can be interpreted. The level of sophistication in this technology is not something that I think can fit into a handheld gadget, at least not for a long time.

It does though remind me of
:pinch: Warning: Spoiler!
it also uses light scattering.
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Last Edit: 11 Apr 2014 12:05 by PatrickBBB.

Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 29 Apr 2014 12:44 #8367

  • JKMakowka
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Something like this should be more than sufficient to replace a microscope for ascari eggs: www.scientificcomputing.com/news/2014/04...esolution-microscope
(or most off the shelf microscopic lens attachments for mobile-phones)

And maybe one could even train a clever image recognition algorithm to pre-highlight potential eggs in the viewing app.

The main issue I see it to come up with a easy and less labor & time consuming procedure to concentrate the eggs.

A system to artificially spike sludge with canine ascari eggs prior to a treatment would probably need to be included too.

I saw on the sanivation site that you have an upcoming trial on this soon? Please keep us informed!
Krischan Makowka
“You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete” - Buckminster Fuller
Last Edit: 29 Apr 2014 12:49 by JKMakowka.

Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 29 Apr 2014 13:55 #8370

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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
Florian Klingel
Water and Sanitation Specialist at Skat Consulting Ltd.
Last Edit: 29 Apr 2014 14:18 by Florian.
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Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 29 Apr 2014 16:06 #8373

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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.
I don't work for anyone, I am a philosopher interested to think about how we think about WASH and sanitation. All thoughts are mine alone, I am responsible for any errors.

Previously trained and worked as a Soil Scientist and worked on projects composting sewage sludge.

Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 29 Apr 2014 16:17 #8374

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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.
Krischan Makowka
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Last Edit: 29 Apr 2014 16:18 by JKMakowka.

Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 29 Apr 2014 16:19 #8376

  • Florian
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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?
Florian Klingel
Water and Sanitation Specialist at Skat Consulting Ltd.

Re: Wanting a better way to test pathogen inactivation? Us too! Can you help me crowdsource a better way? 29 Apr 2014 16:32 #8377

  • joeturner
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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.
I don't work for anyone, I am a philosopher interested to think about how we think about WASH and sanitation. All thoughts are mine alone, I am responsible for any errors.

Previously trained and worked as a Soil Scientist and worked on projects composting sewage sludge.
Last Edit: 29 Apr 2014 16:34 by joeturner.
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