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Covid-19 protection guidance for wastewater workers
Essential Workers
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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.
Transmission Routes
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 on sewers systems than on private domestic drains, although this advise should be used for any work involving contact with faecal matter on private drainage systems.
PPE
Use safe work practices to protect yourself and limit the spread of infection. The following information is taken from Public Health
66 drain TRADER | November 2020 |
www.draintraderltd.com
England guidance for aerosol generated procedures (AGP):
Pre-donning instructions. 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; 1. clean hands 2. disposable overalls 3. respirator (ensure good fit) 4. eye protection (either goggles or visor) 5. gloves (over cuffs)
During process
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
Removal order
PPE should be removed in an order that minimises the potential for cross contamination. This is suggested practice:
1. Gloves 2. Disposable overalls 3. Eye Protection 4. Respirator 5. Clean hands
Gloves and other disposable PPE should be taken off at the customers property or premises, prior to entering the vehicle and
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