Health and Safety Implications of Avian Influenza and Newcastle Disease in Poultry
UK - This note provides Health and Safety information to people who may be involved in working with poultry that may be affected with Avian Influenza or Newcastle Disease.
30 October 2003
7 minute read
Background
The information is provided to assist you with fulfilling your obligations under Health & Safety legislation to carry out risk assessments and introduce any controls or precautions you deem to be necessary.
It gives information on the respiratory hazards and risks associated with these zoonotic infections of poultry i.e. a disease that can spread between humans and animals, and lists the precautions Defra/SVS staff will take to reduce the risk of infection.
You should consider the risk to your staff and apply some or all of these precautions to them also. If you are unsure about how any of the precautions should be applied you should seek advice from your own H&S advisors or the Health & Safety Executive.
In addition, other infectious, physical and chemical hazards may be encountered. You are advised to seek appropriate advice on these.
Hazards
- Avian Influenza (AI)
Avian Influenza infection in humans is rare but when it does occur, usually presents as a mild to moderate conjunctivitis with, more rarely, mild to moderate flu-like symptoms.
In exceptional cases the disease may be more serious and the virus has been implicated in the death of a vet in Holland. The Dutch authorities believe this was a ‘unique, one – off event’ where the AI infection may have been a factor. It is also not clear what, if any, precautions the vet had taken to reduce the risk while working with poultry.
There is also some very limited evidence of human-to-human transmission to immediate family members.
Newcastle Disease (ND)
- Newcastle Disease infections in humans occur rarely and would usually be in the form of a mild to moderate and sometimes painful conjunctivitis.
- Very rarely have respiratory symptoms been reported.
Routes of Infection
In diseases caused by these agents, the eyes are particularly vulnerable to infection from airborne infective particles or rubbing eyes with hands after handling infective material.
Infection of other systems, e.g. lungs, is most likely to occur through inhalation of dust from faecal material.
Risks
Highly Pathogenic Avian Influenza and Newcastle Disease are not present in the UK and current veterinary advice is that the risk of these diseases entering the UK is considered to be low.
Avian Influenza. Should AI be confirmed in the UK, there could be a significant risk of exposure among those dealing with cases. The risk varies depending on the strain of virus. Not all strains are infectious for humans whilst others could be more infectious than those previously experienced.
Newcastle Disease. The risk of human infection following exposure to ND is likely to be very low. While it is possible for humans to become infected by the routes described, such infections are very unusual. There is no evidence of any cases among SVS staff, or others, involved in dealing with the disease in recent outbreaks in the UK or elsewhere.
People at Risk
Where there is an infectious agent present, the following may be at risk:
- farmer / owner / occupier and their staff and families
- private veterinary surgeons
- others required to undertake inspection of poultry or their products
- veterinary inspector and others investigating and taking samples from suspect cases
- staff handling samples
- valuers
- catchers and killers
- contractors
- staff handling carcases for disposal
- veterinary inspectors and others involved in epidemiological inquiries, tracings and surveillance.
Factors affecting Risk
The risk is related to the species, husbandry and housing system of the flock and to the weight of infection. The greatest risk will be from large numbers of infected birds in enclosed, intensive accommodation especially if inadequate ventilation.
The risk is lower where there are fewer infected birds, good ventilation and open accommodation, e.g. backyard or free-range flocks.
Any work that stirs up litter or dust e.g. culling or cleaning and disinfection of poultry sheds will increase the risk of infection by inhalation or ingestion.
Following slaughter of infected birds the weight of infective material in places where poultry were present will decline.
Carcasses and blood are likely to be infective at the time of sampling though the risk will be low and can be reduced further if high standards of personal hygiene are followed during sample handling.
The highest risk of exposure is to those working in the same environment as live, infected birds and risk of infection will increase with time spent in this environment. The risk from residual infection after depopulation is immediately reduced by preliminary C&D and should be negligible after effective secondary C&D.
Measures to Reduce Risk
Each premises will be different so there should be an assessment of the risk, based on the information above. Depending on the level of risk, the precautions to be taken by Defra/SVS staff will include some or all of the following:
Limiting Exposure - Measures will be taken to minimise the exposure to potentially contaminated environments, infected birds and materials.
Hygiene - High standards of personal hygiene will help prevent ingestion and inhalation of infective material and reduce the risk of transmission to others. The use of anti-viral hand wash / wipes following effective washing may aid this.
Personal Protective Equipment (PPE)
If exposure to a contaminated environment is necessary, consideration must be given to the use of appropriate PPE.
To reduce the respiratory risks from the agents involved, suitable and appropriate Respiratory Protective Equipment (RPE) and eye protection should be worn.
- Respiratory protection / Eye protection
Disposable FFP 3 face piece respirator, with exhalation valve in conjunction with close fitting goggles or a powered respirator (e.g. airstream type helmet – but see paragraph 32).
Other equipment which gives similar levels of protection includes half-mask reusable respirators fitted with a P3 filter in conjunction with close fitting goggles full-face reusable respirator fitted with a P3 filter.
Hand protection - Disposable surgical type rubber/vinyl gloves should be worn. Where available, the toughened, tear resistant brands are preferred. Lightweight, cut resistant gloves, worn under industrial weight rubber gloves is a good combination for handling / necking birds.
- Whole body protection - Lightweight disposable overalls with hoods
- Footwear. Normal wellington boots which can be effectively cleansed and disinfected should be suitable in most circumstances.
- Hair protection. Mob cap or hair net.
PPE must be in working order and fit correctly and appropriate training given on the fitting, use and maintenance of RPE. Where a good seal cannot be achieved with other respirators e.g. because of facial hair, an airstream helmet will be the only possibility.
None of the above equipment will give protection from other hazards that may be encountered in poultry houses, e.g. toxic or irritant fumes or gases such as ammonia. Additional, appropriate PPE may be required in such circumstances.
If goggles are worn they must be good quality, comply with EN standards and be the anti-mist type to allow prolonged periods of use.
Selection of PPE
PPE must be of good quality, properly maintained and issued individually. Where appropriate, a range of sizes should be available. The ‘one size fits all’ principle is not advised. Badly fitting PPE is at best, inconvenient and at worst, ineffective and potentially dangerous.
PPE required for biosecurity purposes must also be compatible with the H&S requirements.
Anti – viral treatment (AI only)
In addition to the measures described above you may also consider seeking medical advice on the use of an anti-viral.
Persons who are concerned about their medical fitness to work in such situations must seek medical advice.
Anybody who experiences symptoms of infection must seek early medical attention.
