Zoonoses
This section contains the following sub-sections:
Defintion of zoonotic diseases
List of Non-Notifiable zoonoses
Defintion of zoonotic diseases
Zoonoses are defined by the World Health Organisation as ‘diseases and infections which are transmitted naturally between vertebrate animals and man’.
Zoonoses cover a broad range of diseases with different clinical and epidemiological features and control measures, because the causative organism may be viral, bacterial, fungal, protozoal, parasitic or any other
communicable agent. Zoonotic infections in man can be transmitted by a variety of routes, which include food, water, person to person, direct contact and through insect vectors. In the United Kingdom, the foodborne source is thought to be the most common (from www.defra.gov.uk)
Defra (2006) report “Zoonoses Report” gives an overview of zoonoses in the United Kingdom (UK) in 2005.
Defra webpage Zoonoses: Diseases lists the more commonly-encountered zoonoses in animals only. A more comprehensive list can be viewed at the OIE website.
Information on the human aspects of zoonoses can be obtained from the Health Protection Agency and the Department of Health websites.
Zoonoses are classified by Defra as Notifiable Zoonoses, Non-Notifiable Zoonoses and Reportable Diseases
From Defra’s Zoonoses pages of www.defra.gov.uk:
A notifiable disease is a disease named in section 88 of the Animal Health Act 1981 or an Order made under that Act. Section 15(1) of the Act says that:
"any person having in their possession or under their charge an animal affected or suspected of having one of these diseases must, with all practicable speed, notify that fact to a police constable."
In practice, if you suspect signs of any of the notifiable diseases in the list below, you must immediately notify a Defra Divisional Veterinary Manager.
Notifiable zoonoses:
· Anthrax
· Equine Viral Encephalomyelitis
· Rabies
Some other notifiable diseases such as Newcastle Disease and Foot and Mouth Disease may, in exceptional circumstances, cause infection in humans. Further information on Notifiable Diseases is available.
List of Non-Notifiable zoonoses
The links below go to the Defra Veterinary Surveillance A-Z of diseases listing.
· E.coli
· Hantavirus*
· Orf *
· Q-Fever
· Ringworm*
· Toxocariasis*
· Yersiniosis*
Two of the diseases listed above are ‘reportable’ - Salmonella and Brucellosis. This means that should they be detected in samples tested in a laboratory, this must be reported to the local Veterinary Laboratories Agency (VLA) laboratory (In England and Wales), and to the local Divisional Veterinary Manager in Scotland.
The EU project Sustaining Animal Health and Food Safety in Organic Farming (SAFO) examined the risks of zoonotic diseases in organic farming and concluded that, although there is only a limited amount of research in this area, many of the risks have not been confirmed by research results or experience. However, it was acknowledged that these risks do exist and should be handled by careful management, for example, proper manure handling, feeding hygiene, reduced movements of animals in flocks or between farms and improved hygiene in general.
In pigs, the risk of Toxoplasma gondii was found to be very low (non-existent) in conventional indoor systems, but present in free range and organic systems.
The incidence of Campylobacter and Salmonella in pigs varies widely within systems, and a clear pattern of risks is difficult to identify, since it also varies between individual animals. Infected animals are not necessarily clinically affected. The incidence varies widely between countries, and some studies show that there are no systematic differences between conventional and organic production systems, and food safety risks are no higher in organic systems compared with conventional ones. The level of hygiene in, for example, outdoor huts is important and the whole processing chain of the products needs to be considered when determining the risk to the consumer.
An important difference between conventional and organic pig and poultry production is the requirement for access to outdoor areas. This implies an increased exposure to microbiological agents, such as Campylobacter (Engvall, 2001; Heuer et al., 2001; Virtala et al., 2005) and Salmonella (Jensen and Baggesen, 2005) that may persist in the environment or is transmitted through wildlife.
In cattle, paratuberculosis was concluded to demand specific attention, as it was widespread and identified as a potential zoonosis, although the incidence seems to be the same in both conventional and organic herds. In poultry, Campylobacter and Salmonella are major challenges.
See also Biosecurity