1.1.1 Zoonoses

Many pathogens are specific to humans and some specific to animals; however, there are pathogens that are capable of transmitting disease to both humans and animals. A pathogen capable of causing disease from an animal to a human is known as a zoonosis. Knowledge of these pathogens and the diseases that they cause is essential in order to prevent the transmission of disease between the animals we look after and ourselves.

Ringworm is one example of a zoonotic disease. The disease is caused by a fungus and is common in many species, including dogs, cats, horses and cattle. Many animals that are infected show no clinical signs of the disease. People will become exposed by direct contact with the infected areas on the animal and will then show clinical signs (e.g. small circular areas of reddened, inflamed skin that itch) on exposed areas (i.e. hands, neck, lower arms and face). This is prevented by careful observation of the animals that you are in direct contact with and also good personal hygiene.

There are many other examples of zoonotic diseases but it is not the intention of this chapter to provide details on these. What is important is that handlers of animals have a good basic knowledge of some of the more common zoonotic diseases that they are at risk of being exposed to when working with different species. Some of the common zoonotic diseases that handlers should be aware of are outlined in Table 1.2.

In all cases, the risk of disease transmission can be reduced by using a good handwashing technique with soap and water after handling any animal. Wearing the correct personal protective equipment (PPE) is also important.

1.1.2 Carriers

With some pathogens the host does not always show obvious clinical signs of disease. In these cases, the host acts as a ‘carrier’ for the pathogen and will be capable of spreading the disease to susceptible animals.

Strangles is one example of a disease that has a ‘carrier’ status. The disease is caused by bacteria and is common in horses. It is important to note that with this disease there is no risk to humans becoming infected. However, strangles easily transmitted to other horses and, therefore, if you are in contact with an infected horse you must ensure that all necessary precautions are taken with regards to reducing the transmission of the disease. This will include isolation of the horse and putting biosecurity and barrier nursing protocols in place.

1.2.1 Biosecurity

Whereas biocontainment aims to reduce/prevent the movement of infectious diseases within a facility, biosecurity aims to reduce/prevent the introduction of new diseases into a facility from an outside source.

There are four basic principles to biosecurity:

1. selection of animals from known sources with a known health status – of particular relevance to farm animals;
2. isolation of new animals on arrival at the facility;
3. movement control within the facility;
4. sanitation using disinfection of materials and equipment and good personal hygiene.

It should be remembered that biosecurity is not just about protecting the health of the animals in your care but also about protecting your own personal health. It must also be noted that disease in animals does not always show obvious clinical signs, for example animals in the early stage of a disease or carrier animals.

1.2.2 Effective Cleaning and Disinfection

It is important when working with animals that we do so in as clean an environment as possible. Obviously, the degree to which this is done will depend to some extent on the species that we are working with and also the environment in which we are handling the animal. There are some general points to note (Dvorak and Petersen, 2009).

• Faeces: try to limit the amount of faecal contamination that surrounds the animal you are working with, for example always pick up faeces as soon as the dog defecates (if on a walk) or if noted in the kennels. Obviously, in a farm environment this is much harder to achieve; however, cleaning protocols should be in place and heavily soiled bedding should be removed on a regular basis.
• Physical cleaning: the physical removal of visible organic debris in the environment or on surfaces that you are handling an animal on is important. This may involve sweeping, brushing and scraping, depending on the organic material that you are dealing with. For example, sweeping the floor of the area where you are going to examine a horse if in a yard.
• Sanitation: this involves the use of hot water and some kind of detergent. These help to remove organic debris that can prevent disinfectants being effective. This has been shown to remove over 90% of bacteria from surfaces. Particular attention should be paid to floor drains and corners, as these are where debris can accumulate. A mop and bucket or bucket and washcloth with hot soapy water can be used for small areas and it is important that the water is changed several times during the process. For larger areas, mechanical washers that will remove organic debris can be used. Some of these work under high pressure to physically remove debris, whilst others produce steam to aid with removal. Care needs to be taken with high pressure machines as this method can aerosolize, and thus potentially spread pathogens. All surfaces should be rinsed with clean water, as some disinfectants will be inactivated by detergents. Personnel should also ensure that they are wearing the correct PPE when undertaking cleaning; what is worn will depend, to some extent, on the environment in which you are working.
• Disinfection: which disinfectant to use will very much depend on the microorganism involved, as each varies in its ability to persist in the environment as well as in its susceptibility to a particular disinfectant (Table 1.3)

When working with any kind of chemicals you will need to ensure that relevant legislation is followed. In the United Kingdom, the Control of Substances Hazardous to Health (COSHH) 2002 is the law that requires employers to control substances that are hazardous to health (HSE, 2016a). Many of the disinfectants that are available fall under COSHH guidance and it is important that risk assessments and disinfection protocols are produced. The legislation also governs that staff are provided with training and instruction on their use and that staff health is monitored.

1.3.1 Standard Operating Procedures

In addition to risk assessments it is good practice to have a standard operating procedure (SOP). This is a detailed list of written instructions that can be used to satisfy compliance requirements and are recommended for all procedures that pose a potential risk to the health and safety of personnel. They should also be used as the base for everyday training of staff.

1.4.1 Handwashing

Hands should be washed to prevent spread of disease between animals and to humans. Hot water and soap should always be used and a good handwashing protocol such as the World Health Organisation (WHO) handwashing protocol should ideally be followed. Hands should be washed at the following times:

• before and after handling animals and leaving the facility between different animals or species;
• before and after toilet or lunch break periods;
• after glove removal and handling chemicals.

NB: Hand gel or rub may be used, unless hands are visibly soiled.

Gloves should be worn for the following procedures:

• handling or cleaning any bodily fluids or excreta;
• using chemicals or disinfectants.

Ideally, a glove removal technique should be used and hands should be washed following the removal of gloves.

1.4.2 Signs

Where possible, signs (Figure 1.3) should be placed in strategic places around animal handling facilities to remind personnel of the procedures and protocols in place. This is also very useful for new staff or visitors to the facility.

1.5.1 General Points

• PPE must be worn to reduce the transfer of hair, allergens and excreta on clothing, to reduce transfer of zoonotic disease and to reduce the risk to the handler from injury.
• An animal that feels threatened is far more likely to attempt to defend itself when handled.
• Long sleeved clothing should be worn to prevent scratches on arms from sharp claws.
• Flat, enclosed toe, non-slip shoes (Figure 1.4) should be worn with companion animals and animals housed indoors to prevent trips and falls during handling or husbandry procedures.
• Stressed animals are more likely to shed potential disease agents in their faeces and other excretions. Therefore, taking steps to keep the animal as calm as possible prior to and during handling can help mitigate any risks to the handler.
• Where animals appear unwell, or are known to be carriers of disease, handlers should consider wearing gloves as extra protection, though this should not be used as a replacement for good hygiene measures and handwashing should always take place regardless after handling an animal.
• Leather gauntlets (Figure 1.5) can provide protection, but often at the expense of dexterity when handling. For large birds of prey, a leather arm guard may also be necessary.
• Steel toe-capped safety boots should be worn when handling horses and donkeys, and steel toe-capped wellington boots should be worn when working with farm animals (especially cattle).
• Eye protection is strongly recommended when handling birds with sharp pointed beaks, or other wading birds with long necks capable of reaching a handler's face.
• There are some diseases that can be transmitted to people through inhalation of small feathers or feather dust. Wearing a suitable facemask when working in aviaries, particularly those with large numbers of birds, or where ventilation is reduced, will help reduce the risk of disease transmission via this route.
• It is important when handling rodents that no perfume or scented hand cream is worn due to their sensitivity to smell.

1.5.2 Working with Horses

In recent years, more attention has been focused on the safety of people who are working on the ground with horses. This has been in light of recent studies (BEVA, 2014; Riley et al., 2015) that have looked at the risk of injury to veterinarians in the United Kingdom, and veterinary and animal science students in Australia.

Veterinarians are more at risk due to the nature of their work, as they will often be carrying out procedures that are invasive, for example endoscopy of the upper respiratory tract. Also, due to the fact that veterinarians only visit horses to ‘do something’ to the horse, horses often will react to the presence of the veterinarian and, thus, behavioural issues (i.e. rearing) can occur. In addition, whilst veterinarians can use sedation to try to ‘calm’ the horse and make it easier to handle, a horse can still bite and kick whilst sedated. A large percentage of horses kept in the United Kingdom are what are known as ‘pleasure’ horses. They are generally owned by people who will have a varying ability in being able to handle horses, as well as knowledge of behaviour and training of horses. The study conducted by BEVA in 2014 found that a large percentage of injuries to veterinarians occurred when pleasure horses were being treated and the owner of the horse was the handler. It needs to be remembered that it is the responsibility of everyone involved with handling of the horse to ensure that safety is the main priority and to take every possible step to ensure that risk of injury is minimal. To this end, more emphasis has been placed in recent years with the use of PPE by handlers of horses on the ground, in particular with regards to the wearing of steel toe-capped boots, safety helmets and gloves.