Despite remarkable advances in human and veterinary medicine over the past century, infectious diseases remain an important cause of morbidity and mortality for both humans and animals around the world1–4. At least 60% of existing human infectious diseases and up to 75% of newly emerging diseases in humans are thought to have an animal origin, underscoring that the health of animals and humans are irrevocably intertwined.5
An estimate of the combined human and animal burdens of specific zoonotic diseases can be calculated to provide tangible evidence of the significant impact of a particular zoonotic disease on a given society6,7. For example, the World Health Organization (WHO) has estimated the annual global cost of cysticercosis, a parasitic infection transmitted through consumption of infected pork, to exceed $760,000 USD in terms of human health considerations and over $2 billion USD in terms of economic losses in livestock production8. Risks associated with spread of infectious diseases from animals are likely only to increase with increasing globalisation and transboundary movement of animals and animal products. The practice of routinely taking into account the health outcomes of humans and animals (and the environment), known as One Health (Figure 1), is essential for continued improvements in animal and human medicine for the future.
There are many areas of consideration for minimising global One Health risks, such as prudent antimicrobial use, competent food inspection authorities, and the use of vaccines to reduce and eliminate key infections. Another significant area of attention is enhancement of biosecurity employed in animal production. In addition to improving animal health and welfare, improved biosecurity practices lead to an increased human health index, because of increased farm stability, better profitability of marketed goods and livestock, and improved food safety, and thus human health. Well defined animal biosecurity programmes are part of sustainable agricultural practices.10 Because of its direct impact on human health outcomes, enhancing biosecurity for food animal production directly targets at least six of the UN’s 17 sustainable development goals (https:// www.un.org/sustainabledevelopment/sustainable-develop- ment-goals/).
Biosecurity – A Definition
In this context, biosecurity refers to the integrated practices and policies applied at a national, regional or local level to minimise and manage the various threats that may contribute to illness or unthriftiness in animals being raised for food or fibre. Biosecurity generally refers to keeping infectious agents out of an animal operation or farm, whereas biocontainment refers to keeping any infectious agent(s) present on a farm or within a region contained to that region.
A better understanding of basic biosecurity principles by farmers and more consistent application of them can significantly reduce the burden of zoonotic disease and pre-empt animal disease outbreaks in a given region or country. Recent epidemiologic modelling of known patterns of pathogen transmission across pig farms in countries with defined biosecurity practices have demonstrated that production efficiency and animal welfare could be improved with more consistent attention to enhanced biosecurity practices11. Further, biosecurity principles may be combined with vaccination or preventative therapeutic administration to reduce or eradicate diseases in a region, such as cysticercosis in swine6. An effective regional biosecurity programme therefore requires training of producers and dissemination of educational resources as well as respectful local support and oversite networks to be sustainable12. In extensive settings, assistance to farmers often can be effectively accomplished through grassroots or peer-to- peer organisations.
Basic Principles of Biosecurity in Animal Production
Implementation of an effective on-farm or livestock management biosecurity programme does not have to be an expensive or complicated undertaking. Several key principles have been shown to be highly effective for promoting biosecurity, regardless of the species being considered, and these are discussed in more detail below10. These principles relate to access management, animal management, and operational management. Even in remote and extensive farming situations, basic biosecurity principles can be practised.
Controlled access to animals, through the use of pens, sheds, barns, and other shelters can minimise intra- and interspecies exposure to animals and transmission of pathogens. Routinely practising good hygiene, such as regular handwashing (particularly before eating or preparing human food), cleaning clothing and footwear heavily soiled with animal waste, and removing or burying human faeces to prevent animals, such as pigs, from contacting or consuming them is important for reducing bioburden and breaking parasitic transmission cycles between animals and humans. Exclusion of pests and vermin is important to reduce disease transmission by arthropod and rodent vectors, and because insects and vermin can infest animal feeds, such as grain, and reduce feed quality. Physical separation of sick and healthy animals, and handling and attending to the needs of healthy animals first will help to reduce disease transmission within a group of animals. These practices also apply when introducing new animals into a herd or flock. A period of quarantine and stabilisation can be helpful to ensure that new stock are healthy and free from disease. Ensuring that animal feed is unspoiled and that water is clean and uncontaminated will help to minimise the spread of disease within a group of animals. Timely and appropriate disposal of deadstock is important as poorly managed disposal of carcasses can lead to persistence of pathogens in the environment and can also attract pests. Similarly, animal wastes and manure need to be appropriately managed to reduce pathogen burden. More sophisticated programmes can incorporate written plans, self-assessment schemes and ongoing monitoring.