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For the latest from the Lancet go to:
ebola.thelancet.com/

Hi all
I just checked the rather informative Ebola page www.ebola.org.za/ , the EU ECDC site www.ecdc.europa.eu/en/healthtopics/ebola...eak-west-africa.aspx and the CDC site www.cdc.gov/vhf/ebola/ all of which provide up to date info and data.

There are little data on resilience in sewage and low temperatures but the virus can remain virulent outside the body in bodily fluids for 6 days (CDC) and for 5 weeks at 4 degrees C according to these websites. The problem with Ebola is that it is extremely infectious requiring very small inoculum to create an infection.

What concerns me is that this viral disease has been seen primarily as a medical challenge where infected patients are the priority and not much can be done until a vaccine that works (like the one that fruit bats have evolved) is made available. Surely the aspects of prevention and hygiene among communities (the 25 million people in Sierra Leone, Liberia and Guinea) may be even more important if we are to avoid a full blown continental epidemic. And this is where sanitation and hygiene come to the fore. Because sanitation coverage and functionality is poor, most of the necessary protection will need to come from hand washing, treatment of drinking water, cooking of food and similar measures. Sanitation (containment and treatment) in the health care units where infected persons are being taken require secure toilet systems like dry (lime-treated) or incineration. Exactly how excreta is being dealt with is a question for the SuSanA Forum. And I hope we can get input from those that have been working on site.

Best wishes.


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I would like to stress that this is not scientific nor based on any form of data, but in the areas in which we work in Sierra Leone, and where we have put in community UDDTs and safe water facilities, there are no cases of ebola. We do provide hygiene training as part of our sanitation programme so perhaps that has also helped.

However, to put this in perspective, there are few cases in Pujehun (SE Sierra Leone) as a whole. It is an interesting observation though.

I will keep you posted as to developments.

I just asked a virologist about the survival time in faeces and he said that at present there are not good numbers, but that he very much doubts the virus would survive prolonged storage in a latrine.

However he also said that the risks of handling faeces from a ebola patient and using a latrine which had been used by a patient were high.

Dear Niall,

Thank you, the opinion of experts on the ground regarding survival time outside host is very important information. I will reply to your post within 1 day as I need some time to think through your question. It is a matter of strength of evidence base (opinion of field experts and published information & recommendations of national public health agencies) as well as matters to be considered based on information available and not available in three situations: (a) suggestions for emergency response, (b) ensuring continued operations of toilets already built in as much business-as-usual way as possible and (c) notes to be used in assessment of scaling up of technologies.

Warm regards,

Sowmya

Dear Thomas,

Thank you for your interest and query - it is so wonderful to see that Ebola is being taken up for serious discussion by both sanitation and health experts.

As far as Ebola is concerned, I do not think municipal workers would be at significant risk. The reason being:

(1) “Ebola is transmitted through direct contact with virus-infected body fluids such as blood, saliva, vomitus, stools and possibly sweat. ... The Ebola virus is not airborne, but infected droplet spray from a patient may effectively transmit the virus if it comes into contact with mucous membranes.” ( 1997 WHO Guidelines on Ebola management )

(2) Domestic wastewater has been found to contain pathogenic bacteria, virus and worm eggs. Therefore, considering that domestic wastewater is not neutralized for pathogens, it is likely that blood, vomitus, stools and urine containing active Ebola virus could be transferred to municipal wastewater.

(3) Following from point no. 2 above, how long can the Ebola virus remain active in municipal wastewater?

The PHAC FactSheet states the following regarding susceptibility to disinfectants: Ebolavirus is susceptible to 3% acetic acid, 1% glutaraldehyde, alcohol-based products, and dilutions (1:10-1:100 for ≥10 minutes) of 5.25% household bleach (sodium hypochlorite), and calcium hypochlorite (bleach powder). The WHO recommendations for cleaning up spills of blood or body fluids suggest flooding the area with a 1:10 dilutions of 5.25% household bleach for 10 minutes for surfaces that can tolerate stronger bleach solutions (e.g., cement, metal). For surfaces that may corrode or discolour, they recommend careful cleaning to remove visible stains followed by contact with a 1:100 dilution of 5.25% household bleach for more than 10 minutes.

Further, “Infection control protocols included decontamination of floors with 0.5% bleach daily and decontamination of visibly contaminated surfaces with 0.5% bleach as necessary.” ( PHAC FactSheet on Ebola )

(4) As seen from point no. 1 above, Ebola virus is susceptible to a range of chemicals within a short duration. While the above chemicals have been clearly found to deactivate Ebola virus, there are possibly other chemicals as well that can deactivate Ebola.

(5) The sources of municipal wastewater are domestic wastewater, wastewater from institutions, industrial wastewater, infiltration into sewers, stormwater, leachate and septic tank wastewater. Domestic wastewater contains organic materials (detergents, pesticides, solvents, phenol, cyanide, etc.,) as well as inorganic materials (acids, for example, hydrogen sulphide, bases). ( Wastewater Characterization ) Industrial effluents (untreated, partially treated or fully treated) introduced into municipal wastewater systems could also result in a higher proportion of chemicals that inactivate Ebola.

(6) Going by point no. 5 above, the municipal wastewater is likely to contain chemicals that can inactivate Ebola virus. With respect to Ebola risk for municipal workers, the important question is whether the concentration and exposure of the appropriate chemicals would be adequate to inactivate Ebola at any point during transport of wastewater to the treatment plants. This appears likely.

(7) Considering that the chemical composition of wastewater can vary significantly between regions and between various time periods as well, in case the virus does manage to survive by the time it reaches the pumping station / treatment plant, what is the time duration required for Ebola virus to infiltrate the skin? I do not know the exact time requirement (one of the unanswered questions?) but Ebola is considered extremely contagious (bio-safety level 4).

(8 ) While the PHAC FactSheet gives information regarding survival time outside host, it is “based on experimental findings only and not based on observations in nature. This information is intended to be used to support local risk assessments in a laboratory setting.” Therefore, while survival time outside host may be high/low based on experimental findings, we probably do not need to consider this aspect at all (as a risk or risk mitigant) given that it is highly probable that the Ebola virus might be neutralized by the chemicals present in municipal wastewater by the time it reaches the treatment plant / pumping station.

(9) Summarizing the above, while municipal wastewater carry a range of pathogenic micro-organisms, the possibility of Ebola virus to remain active by the time it reaches pumping stations / treatment plants do not appear to be high with the result that (a) survival time outside host probably need not be considered as a risk / risk mitigant as it is highly probable that the Ebola virus might be neutralized by the chemicals in municipal wastewater and (b) while Ebola is considered extremely contagious and the exact time required for the virus to infiltrate skin / mucous membranes is not known, the probability of the virus remaining active by the time it reaches treatment plants / pumping station is not high.

(10) Therefore, municipal workers are most probably not under significant risk of contracting Ebola at treatment plants / pumping stations.

Warm regards,

Sowmya

Dear all,

My name is Niall Boot and I am the Global WASH Advisor for GOAL, an Irish NGO. We have a WASH team responding to the Ebola outbreak in Sierra Leone. From our conversations with specialists on the ground we understand the virus to be very weak and unable to live outside of the human body for long and that conditions presented in pit latrines and dry toilets would kill it quite quickly (24-48 hours has been mentioned). I am wondering if you could verify your sources of survival time information, there is one reference below to 6 months.

Regards,

Niall Boot

If an Ebola patient's fecal matter and urine are flushed into a municipal sewer system, will that have any impact on municipal sanitation workers working at pump stations and at sewage treatment plants?

Thanks

Dear All,

I am so glad that the Ebola risk is being discussed in relation to sanitation.

Recommendation (in brief):

1. For the 30 ecosan toilets that have already been constructed, the sanitation workers could be provided complete training in infection-control guidelines as well as necessary Personal Protective Equipment (PPE) with necessary systems support for the sanitation workers.
2. Since these toilets have double vaults, there is time till the vaults are getting full to provide the necessary training and supply of appropriate PPE.
3. Alternatively, individual households can incinerate the feces and urine and add the ash to the vaults in the toilet when there is Ebola risk.
4. Please note that the same recommendation may not be applicable for assessing scaling up possibilities.
5. Please see notes below regarding Ebola virus survival time outside the host and its possible implications for sanitation technologies.

The optimal solution would be to ensure that (a) the system continues to function effectively, (b) the sanitation workers do not face a higher risk of contracting infection and (c) how to turn the debilitating situation into an empowering situation for the staff, people and the system.

Warm regards,

Sowmya



Notes:

1. Ebola - An Overview: Ebola is a highly virulent zoonotic disease that can spread very easily (from animal-to-human and human-to-human) through a variety of transmission modes (even sweat and urine which is generally held to be pathogen-free can transmit Ebola). There are five known strains of Ebola virus (viz., Zaire, Sudan, Bundibugyo, Tai Forest (formerly known as Côte d’Ivoire), and Reston, each named after the location in which it was first identified). Death rates are high, survival time of infected patient is low and there is no known cure or vaccine. Additionally, Ebola is only one of the virulent Viral Hemorrhagic Fevers (VHF), the others being Lassa, Marburg, etc. Further, several questions remain unanswered about Ebola (for instance, it has not been possible to identify the natural reservoir of this disease; while fruit bats are suspected to be the carriers, Ebola can be transmitted by infected chimpanzees, gorillas, mokeys, forest antelopes and porcupines; it is not known whether infected humans can transmit the disease to wild / stray / domesticated animals). Ebola is labelled bio-safety level 4 which is the highest biohazard level . Therefore, sanitation techniques need to maintain very high levels of infection control to reduce / prevent the spread of Ebola. Please see the other post regarding unanswered questions about Ebola.
2. Personal Protective Equipment (PPE) required for infection control: The WHO FAQ on Ebola strongly recommends the use of PPE (consisting of gloves, impermeable gown, boots/closed shoes with overshoes, masks and eye protection for splashes) for healthcare staff, care givers in the home setting and even visitors. Not all of the PPE is reused after sterlization resulting in higher quantities required. In addition to hygiene practices for the individual, infection control guidelines include safe management of sharp objects, regular and rigorous environmental cleaning, decontamination of surfaces and equipment as well as management of soiled linen and waste. Therefore, sanitation workers who need to handle larger quantities of potentially infected material (Ebola labelled at bio-safety level 4) should also be provided the PPE and necessary training. The PHAC Interim Guidelines for Laboratories regarding handling Ebola "specimens" is an excellent resource to understand the level of precaution required to handle even small quantities of infected material. In resource-scarce settings, even healthcare providers, such as hospitals, find it difficult to maintain an adequate supply of PPE. Therefore, ensuring availability of PPE for sanitation workers (sanitation workers are larger in number compared to health workers while health workers have to treat other diseases also) would probably be more difficult / have lower priority.
3. Risk of transmission while collecting fresh feces: Some articles (see for instance, the Wiki page and UpToDate article ) and the 1997 WHO guidelines ( URL for document on Medbox ) state that Ebola is particularly prone to nosocomial spread (ie., disease spread in a professional healthcare setting which can happen when quarantine facilities are inadequate and / or healthcare staff do not completely follow the necessary procedures). Considering this fact, the risk for sanitation workers is probably equally high or higher (given that they do not have medical / clinical training).
4. Practical challenges in ensuring adherence to infection-control guidelines: Hand hygiene is critical and the WHO FAQ on Ebola urges everyone to note that "neglecting to perform hand hygiene after removing PPE will reduce or negate any benefits of the PPE". Over 1.5 centuries after Dr. Ignaz Semmelweiss discovered (in year 1847) that the simple procedure of handwashing could drastically cut spread of fatal infections among patients, we continue to struggle with making handwashing an ubiquitous practice. Therefore, while adequate training for the sanitation workers at the 30 ecosan toilet facility can be ensured, it would be difficult to make this happen amongst a larger population.
5. Risk of public wrath: Hospital staff often face public wrath as they are seen as people spreading the infection (which is also fairly true given the risk of nosocomial spread despite it being unavoidable given the resource-scarce settings). Sanitation workers already face considerable social stigma and adding the tag of "possible carriers of disease" to them is unlikely to make their lives easier. It is high time that sanitation workers are given the respect due to them and our solutions should predict and negate all risks of stigma.
6. Ebola survival time outside the host and implications for sanitation: Please see quotes below from pathogen safety factsheets of the Public Health Agency of Canada (PHAC) regarding Ebola survival rate and physical inactivation time.
   

   Susceptibility to disinfectants: Ebolavirus is susceptible to 3% acetic acid, 1% glutaraldehyde, alcohol-based products, and dilutions (1:10-1:100 for ≥10 minutes) of 5.25% household bleach (sodium hypochlorite), and calcium hypochlorite (bleach powder). The WHO recommendations for cleaning up spills of blood or body fluids suggest flooding the area with a 1:10 dilutions of 5.25% household bleach for 10 minutes for surfaces that can tolerate stronger bleach solutions (e.g., cement, metal). For surfaces that may corrode or discolour, they recommend careful cleaning to remove visible stains followed by contact with a 1:100 dilution of 5.25% household bleach for more than 10 minutes.
   

   Physical inactivation: Ebola are moderately thermolabile and can be inactivated by heating for 30 minutes to 60 minutes at 60°C, boiling for 5 minutes, or gamma irradiation (1.2 x106 rads to 1.27 x106 rads) combined with 1% glutaraldehyde. Ebolavirus has also been determined to be moderately sensitive to UVC radiation.
   

   Survival outside the host: Filoviruses have been reported capable to survive for weeks in blood and can also survive on contaminated surfaces, particularly at low temperatures (4°C). One study could not recover any Ebolavirus from experimentally contaminated surfaces (plastic, metal or glass) at room temperature. In another study, Ebolavirus dried onto glass, polymeric silicone rubber, or painted aluminum alloy is able to survive in the dark for several hours under ambient conditions (between 20 and 250C and 30–40% relative humidity) (amount of virus reduced to 37% after 15.4 hours), but is less stable than some other viral hemorrhagic fevers (Lassa). When dried in tissue culture media onto glass and stored at 4 °C, Zaire ebolavirus survived for over 50 days. This information is based on experimental findings only and not based on observations in nature. This information is intended to be used to support local risk assessments in a laboratory setting.
   

   Therefore, composting and dehydration could technically work. However, it is difficult to enumerate all possible field conditions for a more detailed assessment, particularly considering the lack of adequate information regarding the virus. In community-led composting (eg., woodrows), vermiculture and storage of feces (in UDDTs), is it possible to always prevent both human and animal contact?
   We do not know (a) the natural reservoir for this virus, (b) whether human-to-animal transmission is possible (at least for the key 3 subtypes of the virus), (c) any other type of animal-to-animal transmission is possible, (d) how do these transmission patterns evolve, (e) why herbivores (but not all) are susceptible but carnivores (except humans) are not susceptible and there are probably other questions as well which would be relevant to make an assessment.
   Further, the Ebola virus genome has been discovered in two species of rodents raising the possibility that they may be intermediate hosts (please refer
   PHAC factsheet ). Rodents, which are one of the most adaptive species and known carriers of several diseases (including the plague), are common pests associated with toilets.
   
   Therefore, determining the effectiveness of inactivating Ebola virus in the sanitation chain needs further information to do a proper evaluation.
7. Reducing defecation-related risk of Ebola spread: The Ebola virus is spread easily and it would be practically very difficult to enumerate all the household / community practices that can result in disease spread and then train communities everywhere on all these practices. Therefore, where there are no toilets (ie., open defecation / equivalent method is practiced), the best option would be for the feces to be collected in (preferably, biodegradable and, if not available, plastic) bags and immediately burned. Further, while human urine is generally held to be pathogen-free, Ebola is transmitted through urine also. Therefore, making urine pathogen-free is also necessary. Additionally, while it might be highly preferable to immediately burn feces, this might be difficult in situations where households use firewood for incineration. There are communities where the women have to travel long distances to fetch firewood also. It also takes a lot of time to start a wood fire (you have to keep blowing - hardly something we would require of a patient coughing so much and this can also result in spread). Therefore, the recommendation could be to collect feces in a plastic bag --> tie it --> wash hands & follow proper hand hygiene --> drop the plastic bag into another cover bag and tie it --> drop the cover bag into the incinerator or other container and burn the feces once a day or once in few days depending upon the household's ability to fetch adequate firewood.

Dear Barbara and Krischan,

We all agree that handling fresh feces is too dangerous, esp if users may have Ebola, but switching out the containers of a single-chambered UDDT or digging out 6+-month-old decomposed feces (in the Tropics), by trained staff with gloves, etc., would be much, much safer than having just one person in the county applying open defecation.

Best wishes,
Chris

Dear Chris,

When I mentioned shutting down the process due to Ebola, I didn´t mean closing the UDDTs but stopping the collection of fresh feaces by hand. This is a risk I wouldn´t want the workers to take. Our UDDTs can also be used "normally" as double vaults, which is what will happened in the near futur.

And I am suprised, too, that there is not more discussion in this forum on Ebola! Isn´t it relevant??

Cheers,
Barbara

@Chris: While you are theoretically right, the problem is probably to find people still willing to work under the risk of getting Ebola. IMHO the fear of Ebola is probably what is causing more issues that Ebola itself (so far at least and I don't want to downplay the seriousness of this disease either).

But it might be a good time to get people to think about their habit of open defecation by distributing urea containing peepoo bags or something like that.