About animals and human health

This section gives background information about how animals affect our health.

There are many indirect links between animals and human health. 

Animals have both positive and negative impacts on human health

Animals can have both positive and negative impacts on our health.

Positive health impacts include:

• reducing depression, anxiety and social isolation
• aiding independence (assistance animals) eg, dogs for blind people
• encouraging exercise
• protecting against development of asthma and allergies in farm children [1,2]
• protecting our safety eg, search and rescue dogs, detector dogs (of biosecurity risk items to prevent introducing pests and diseases of plants and animals into New Zealand, drugs and explosives).

Pet ownership has a number of health benefits such as reducing stress and social isolation. Evidence suggests pets help to improve mental and physical health. Even looking at animals has a relaxing effect [3].  People form strong attachments to their pets. Many people consider their pet to be part of the family such that its loss can mean as much to them as the loss of a family member.

Animal-assisted therapy and activities have been shown to improve mental health and quality of life for people with developmental, neurological and psychological disorders [4].

Negative health impacts include:

• bites and other injuries
• zoonotic diseases eg, ringworm, campylobacteriosis
• allergies
• antimicrobial resistance.

Some occupational groups including veterinarians, farmers and other agricultural workers, horse racing industry workers (eg, stable hands, riders), animal handlers and animal transporters are at greater risk of negative health impacts from animals. This greater risk is due to more contact with animals, including large and sick animals, and their waste. Non-occupational groups with high animal exposure, and therefore greater risk of injury or illness, include horse riders, bird fanciers and pet owners.

Dogs were implicated in 87% of animal bite injuries and cats in 7% of animal bite injuries in people attending an Australian emergency department. About a third of dog bite victims were children [5].

Zoonotic diseases are infectious diseases that can be passed from animals to humans. Most emerging and re-emerging infectious diseases in the world are zoonotic [6]. In New Zealand the number of different zoonotic diseases regularly found (endemic) are relatively few compared to other countries.

Current micro-organisms causing important zoonotic diseases include the bacteria Campylobacter, some strains of Escherichia coli, Salmonella, Yersinia, and Leptospira, and the protozoaGiardia and Cryptosporidium.  Leptospirosis is the commonest occupationally-acquired infectious disease in New Zealand [7]. Several zoonotic diseases have been eliminated (eg, hydatid disease) and strict quarantine prevents the introduction of others [8].

Changes in environmental factors such as rainfall and land use may lead to changes in the incidence and characteristics of zoonotic diseases. For example, outbreaks of leptospirosis have been reported overseas following flooding [9]. Flooding is expected to become more common in New Zealand due to climate change.  For more information, please visit our Climate Change domain. 

Allergies and triggering of asthma may result from exposure to some animals such as cats or dogs.

Antimicrobials (eg, antibiotics) used to treat various infectious diseases in animals may be the same or similar to those used in humans. Resistant micro-organisms (eg, bacteria) arising in animals, humans or the environment from antimicrobial use may spread from one to the other [10]. Evidence suggests restrictions on antibiotic use in animals used for food reduce the prevalence of antibiotic-resistant bacteria in these animals and in humans, in particular those people directly exposed to food-producing animals [11]. 

Animals and human health are interconnected

An international collaborative approach between veterinary science and human health called One Health began in 2008 in response to avian (bird) influenza and the threat of a global human influenza pandemic. The One Health approach recognises that the health of humans, animals and their environments are interconnected. It has largely focused on zoonotic diseases.

The New Zealand Antimicrobial Resistance Action Plan uses a One Health approach to manage antimicrobial use in both humans and animals to keep antimicrobials available and effective to treat human and animal diseases [12].

One Welfare extends the One Health concept beyond physical health to include wellbeing and looks at the interconnectedness between animal welfare and human health [13].

Poor animal welfare is linked to domestic abuse and violence, animal physical ill-health (eg, zoonotic diseases) and compromised food safety. For example, stressed animals shed more disease-causing bacteria in their faeces leading to potentially more contamination of carcasses during slaughter. While animal wellbeing may enhance human wellbeing, human (eg, farmer) wellbeing may also improve animal welfare [13].

To read about the collaboration between the Environmental Health Indicators programme and Massey University veterinary researchers in the EpiCentre, for public health surveillance of vulnerable human and animal populations, see PAWS (people • animals • wellbeing • surveillance ). 

References

1. Braun-Fahrlander C. 2001. The role of the farm environment and animal contact for the development of asthma and allergies. Clinical and Experimental Allergy 31:1799-1803. URL:https://onlinelibrary.wiley.com/doi/epdf/10.1046/j.1365-2222.2001.01269.x (accessed 15 August 2018).

2. Genuneit J. 2012. Exposure to farming environments in childhood and asthma and wheeze in rural populations: a systematic review with meta-analysis. Pediatric Allergy and Immunology 23: 509–518.

3. Wells DL. 2009. The effects of animals on human health and well-being. Journal of Social Issues 65:523-543. DOI: 10.1111/j.1540-4560.2009.01612.x (accessed 15 August 2018).

4. O’Haire M. 2010. Companion animals and human health: Benefits, challenges, and the road ahead. Journal of Veterinary Behavior: Clinical Applications and Research 5:226-234. DOI: 10.1111/10.1016/j.jveb.2010.02.002 (accessed 15 August 2018).

5. MacBean CE, Taylor DMcD, Ashby K. 2007. Animal and human bite injuries in Victoria, 1998-2004. Medical Journal of Australia 186:38-40.URL:https://www.mja.com.au/system/files/issues/186_01_010107/mac10709_fm.pdf (accessed 23 August 2018).

6. Woolhouse M, Gowtage-Sequeria S. 2005. Host range and emerging and reemerging pathogens. Emerging Infectious Diseases 11:1842-1847. DOI:  10.3201/eid1112.050997 (accessed 12 September 2018).

7. WorkSafe New Zealand. 2015. Prevention and Control of Leptospirosis. Wellington: WorkSafe New Zealand. URL:https://worksafe.govt.nz/topic-and-industry/working-with-animals/prevention-and-control-of-leptospirosis/gpg/ (accessed 7 November 2018).

8. Crump JA, Murdoch DR, Baker MG. 2001. Emerging infectious diseases in an island ecosystem: the New Zealand perspective. Emerging Infectious Diseases 7:767-772. DOI:10.3201/eid0705.017501 (accessed 13 September 2018).

9. Levett PN. 2001. Leptospirosis. Clinical Microbiology Reviews 14(2):296-326.

10. WHO. 2018. Antimicrobial resistance. URL: www.who.int/en/news-room/fact-sheets/detail/antimicrobial-resistance (accessed 4 September 2018).

11. Tang KL, Caffrey NP, Nobrega DB, et al. 2017. Restriction in the use of antibiotics in food-producing animals and its associations with antibiotic resistance in food-producing animals and human beings: a systematic review and meta-analysis. The Lancet Planetary Health 1:e316-e327 (accessed 4 September 2018).

12. Ministry of Health and Ministry for Primary Industries. 2017. New Zealand Antimicrobial Resistance Action Plan. Wellington: Ministry of Health. URL: www.mpi.govt.nz/dmsdocument/19391

13. Garcia Pinillos R, Appleby M, Manteca X, et al. 2016. One Welfare – a platform for improving human and animal welfare Veterinary Record 179:412-413. URL: vetreci5470supp_data.pdf (accessed 15 August 2018).