Covid-19 Protection Guidance for Wastewater Workers
The NADC have contacted the Prime Minister’s Office and have been informed that wastewater contractors are deemed as essential workers. Essential work is considered emergency work and required maintenance works (including essential water company work).
Faecal Matter Transmission (FMT)
In a recent study of coronavirus patients in China, over half of patient’s faecal samples remained positive for Covid-19 for a mean of 11·2 days after respiratory tract samples became negative for the disease, implying that the virus is actively replicating in the patient’s gastrointestinal tract and that faecal–oral transmission could occur after viral clearance in the respiratory tract (Wu et al., 2020).
No cases of transmission via the faecal–oral route have yet been reported, which might suggest that infection via this route is unlikely in quarantine facilities, in hospital, or while under self-isolation. However, potential faecal–oral transmission might pose an increased risk in contained living premises such as hostels, dormitories, trains, buses, and cruise ships.
Respiratory transmission is still the primary route for Covid-19 and evidence is not yet sufficient to develop practical measures for the group of patients with negative respiratory tract sample results but positive faecal samples. Further research into the viability and infectivity of Covid-19 in faeces is required.
Asymptomatic and undiagnosed Covid-19 carriers still shed the virus via respiratory tract and faecal matter. There might be as many as 5 to 10 undetected cases for every known case (Writer, 2020). This means the number of infectious people within the UK is far higher than the confirmed cases statistics.
To conclude, it is known that the Covid-19 virus is shed within faecal matter and that the virus can be present within faecal matter for up to 47 days after first symptom onset. There is no direct evidence of infection via FMT, however it should be considered as a potential route of infection.
As is well known Covid-19 is a respiratory disease. Virus transmission is through the mouth, nose and eyes via contact. This can be by direct contact via water droplets in the air from coughing and sneezing. Faecal Matter Transmission is possible from contaminated water droplets created during drain clearing activities such as jetting or direct splashing. High pressure water jetting is likely to result in aerosol generation of faecal contaminated material.
The other method of transmission is where the virus has been transferred to the hands and then the hands touch eyes, nose or mouth. This type of transfer is normally from surface to hand to face. This will be the case with FMT as well. Any surface contaminated with faecal matter is also potentially contaminated with the virus that produces Covid-19. Potentially with a higher probability of contamination within sewers systems than with private domestic drains. This advice should be used for any work involving contact with faecal matter on private or public drainage systems.
Use safe work practices to protect yourself and limit the spread of infection. The following information is taken from Public Health England guidance for aerosol generated procedures (AGP):
- ensure you are hydrated
- tie hair back
- remove jewellery
- check PPE in the correct size is available
Putting on personal protective equipment (PPE).
The order for putting on is;
- clean hands
- disposable overalls
- respirator (ensure good fit)
- eye protection (either goggles or visor)
- gloves (over cuffs)
- keep hands away from face and PPE being worn
- change gloves when torn or heavily contaminated
- limit surfaces touched in the environment
- always clean hands after removing gloves
PPE should be removed in an order that minimises the potential for cross contamination. This is the suggested order:
- Disposable overalls
- Eye Protection
- Clean hands
Gloves and other disposable PPE should be taken off at the customers property or premises, prior to entering the vehicle and double bagged for disposal. Reusable equipment should be cleaned with soapy water or high alcohol content cleanser.
Hard surfaces within vehicles such as the steering wheel, door handles, handbrake, etc., should be wiped down regularly.
Potentially contaminated equipment should be cleaned on completion of each job.
Risk assessment involves noting all the potential risks and then trying to remove the risk or reduce the risk to reduce the hazard associated with each risk. In all cases the best method of removing a hazard is to remove the risk. This means that non-essential drainage works should not be carried out where possible. Essential drainage works, which should only include emergency blockage clearance or potential, include risks that can not be removed. Because of this it is imperative that these risks are reduced by using awareness, education, correct procedures, personal protective equipment (PPE) and dynamic assessment. It is well known that good safety practice is reliant on an excellent management safety culture.
Drainage workers are likely to be moving from property to property and unless the correct precautions are taken there is a strong potential for spread of the corona-virus, either by direct contact with the customer or with indirect FMT.
It is important that contact with the customer is removed or severely reduced to protect both parties. This includes when dealing with paperwork or payment and communication.
These are hubs for people by their very nature and provide many commonly touched surfaces. Contamination routes are via the pump handles, door handles and other people have higher potential. Be aware of this and make appropriate adjustments by washing hands before and after filling up.
If you have any symptoms you should immediately self-isolate as per government recommendations and report your illness to your employer.
Assets.publishing.service.gov.uk. 2020. [online] Available at: <https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/874328/PHE_COVID-19_Donning_quick_guide.pdf> [Accessed 24 March 2020].
GOV.UK. 2020. COVID-19: Infection Prevention and Control. [online] Available at: <https://www.gov.uk/government/publications/wuhan-novel-coronavirus-infection-prevention-and-control> [Accessed 24 March 2020].
Writer, R., 2020. COVID-19 Spread Is Fueled By ‘Stealth Transmission’. [online] livescience.com. Available at: <https://www.livescience.com/coronavirus-undiagnosed-spread.html> [Accessed 24 March 2020].
Wu, Y., Guo, C., Tang, L., Hong, Z., Zhou, J., Dong, X., Yin, H., Xiao, Q., Tang, Y., Qu, X., Kuang, L., Fang, X., Mishra, N., Lu, J., Shan, H., Jiang, G. and Huang, X., 2020. Prolonged presence of SARS-CoV-2 viral RNA in faecal samples. The Lancet Gastroenterology & Hepatology.
Data gathered from Public Health England and peer-reviewed articles by Ian Cameron, experienced drainage operative, sewer condition classifier, NADC board member and occasional lecturer at the University of Plymouth.