Let’s look at what zoonotic diseases are, how they can be transmitted from wild animals to humans and, above all, how they can be prevented.
Zoonoses are “infections or diseases that can be transmitted directly or indirectly between animals and humans” (EFSA, the European Food Safety Authority). The most common routes of transmission are the consumption of contaminated food and contact with infected animals, especially wildlife.
The spread of zoonotic diseases involves three main elements: the pathogen, the vector and the animals on which that vector feeds. The most common vectors are mosquitoes and ticks, both of which can be effectively avoided by following a few simple precautions.
Other zoonoses, however, may be invisible to the naked eye and require particular care, as well as specific laboratory testing. This is the case with trichinellosis, caused by nematodes of the genus Trichinella, which are found mainly in the muscles of wild animals such as wild boar.
Which parasites and pathogens of public health concern can wildlife carry?
As we have seen, zoonotic agents can be transmitted to humans in several ways.
Vector-borne transmission occurs through mosquitoes, ticks, lice and fleas, which can act as intermediaries between wild animals and humans for certain zoonotic agents.
Transmission can also occur through contaminated water or food. For example, food products from infected animals may be contaminated if they have not passed through the official, controlled supply chain.
The zoonoses considered a priority for surveillance, because of their spread and potential severity, include:
- Campylobacteriosis
- Salmonellosis
- Listeriosis
- Shiga toxin-producing E. coli infections — STEC
- Brucellosis
- Tuberculosis caused by Mycobacterium bovis and M. caprae
- Trichinellosis
- Echinococcosis
Preventing zoonotic diseases is essential. For this reason, the Med-Vet-Net project was launched in 2004 as “the first EU-funded cross-sector network dedicated to zoonoses, now transformed into the Med-Vet-Net Association, bringing together institutes working in public health, veterinary medicine and food safety”.
The objective is clear: through a multidisciplinary and cross-sector approach, all professional figures who can contribute to prevention activities are brought into the process.
Are there times of year when zoonotic risk is higher?
Interactions between different animal species and vectors, such as ticks and mosquitoes, are closely linked to the natural habitats in which they live.
The incidence of zoonotic diseases can therefore be influenced by several factors, including:
- Climate conditions: rising temperatures and higher humidity can encourage the spread of vectors such as mosquitoes and ticks, which transmit diseases including malaria, dengue and Lyme disease.
- Human behaviour: during spring and summer, outdoor activities increase, bringing people into closer contact with vectors and wild animals that may transmit zoonotic diseases.
- Natural or human-induced changes to habitats.
All these factors should be taken into account, especially when adopting active protection measures against vectors in certain conditions and at specific times of year.
How to protect yourself from zoonotic diseases carried by wildlife
Active prevention is essential. To prevent zoonotic diseases, it is important to avoid contact with vectors such as mosquitoes and ticks, which may transmit diseases from animals to humans.
Some good practices include:
- Wearing suitable clothing, such as closed shoes, long-sleeved tops and long trousers.
- Using insect repellents on skin and clothing where appropriate, always following the manufacturer’s instructions.
- Avoiding areas with tall grass and not sitting directly on the grass.
- Avoiding direct contact with wild animals.
It is also important to remember that zoonotic diseases can be transmitted through the consumption of raw meat from wild animals. This is the case with infections caused by bacteria of the genus Campylobacter or by salmonella. Hunters, as the people most likely to come into contact with wild animal carcasses, need to take particular care.
Fortunately, training courses aimed at hunters are becoming increasingly common. One example is the “Persona formata in materia di sanità” course, first developed in Emilia-Romagna and now widely adopted in Tuscany as well. The course is designed to teach hunters how to handle harvested animals correctly.
By following protocols set out by the relevant local veterinary authorities, the risk of contracting zoonotic diseases can be greatly reduced. At the same time, as shown by our Wild and Good project, this approach also helps make the most of the intrinsic qualities of these valuable meats.
Bibliography:
EFSA – Autorità Europea per la sicurezza alimentare
World Health Organisation (WHO). Zoonotic disease: emerging public health threats in the Region. www.emro.who.int/…
Zinsstag J, Schelling E, Waltner-Toews D, Tanner M. From “one medicine” to “one health” and systemic approaches to health and well-being. Prev Vet Med 2011;101:148–56. doi.org/10.1016…
Directive 2003/99/EC of the European Parliament and of the Council of 17 November 2003 on the monitoring of zoonoses and zoonotic agents, amending Council Decision 90/424/EEC and repealing Council Directive 92/117/EEC. Off J Eur Union 2003;2001:65-71.
