Control of Zoonotic Diseases in Pigs

By Livestock Knowledge Transfer, UK - This article looks at how to control spread of diseases and methods to reduce the risk of disease.
calendar icon 1 May 2003
clock icon 5 minute read

There are a number of micro-organisms of animals which can cause illness in people. These are called zoonoses. Zoonotic bacteria can be transmitted from animals to people and vice-versa. Some strains do not cause any symptoms in animals but can result in foodborne infections in man. People can pick up infections through contaminated food or through direct contact with animals. The most common causes of foodborne disease in people are Campylobacter and Salmonella.

Foodborne illness in humans

Bacteria exist all around us in the environment and it is not possible to guarantee the complete absence of bacteria in food production. While most bacteria found on meat are harmless, there are some that can cause illness in people. Animals can carry some of these bacteria without showing any signs of illness. If these bacteria are on meat that is not properly cooked they could cause food poisoning.

The Food Standards Agency has set a target to reduce the incidence of foodborne disease by 20% by April 2006. Steps can be taken on farm to help reduce the risk of foodborne disease and protect the wholesome reputation of British pigmeat.

Keep Salmonella out

The best way to avoid problems with Salmonella or any other zoonoses is to avoid introducing the organism on to the farm. Biosecurity is the package of measures that can be taken to prevent this happening through animals, feed, bedding, pests, vehicles, equipment or people coming on to the farm. Strict biosecurity will not only help reduce the risk of zoonotic organisms getting onto a farm but also the risk of introducing organisms that affect animal health.

  • Keep all introduced pigs in isolation for up to 6 weeks
  • Strict visitor and vehicle policies
  • Control pests
  • Source safe feed and clean bedding
  • Do not share equipment

Pig Abattoir survey 99/00

The main results from a survey of the prevalence of zoonotic organisms in pigs sent for slaughter for human consumption in Great Britain are outlined in this table. Salmonella typhimurium is the second most common strain of Salmonella found in people. C. jejuni is by far the most common strain of Campylobacter isolated from people.

% positive
Salmonella spp. (all) 23.0
Salmonella typhimurium 11.1
Campylobacter spp. (all) 94.5
Campylobacter jejuni 3.4
Yersinia enterocolitica 26.1
E. coli O157 1.2
VTEC O157 0.28

Control spread of Salmonella on farm

If Salmonella is detected on a pig farm measures to control the spread of the organism around the unit need to be stepped up.
  • Rats, mice and birds can spread the organisms from pen to pen so a good pest control policy is essential
  • There should be a complete break when pigs are moved to next stage housing, for instance, at weaning
  • Piglets should only be moved to pens that have been completely cleaned and disinfected
  • There should be no mixing with older pigs at any stage
  • “All-in all-out” housing on a room or house basis helps break the cycle of re-infection
  • As far as possible pigs and staff should only move in one direction -from younger pigs to older pigs
It is important that all staff know what needs to be done and why it is being done. Aim to make it easier to do the job the right way than to do it the wrong way.
  • Develop procedures with staff input
  • Provide training
  • Give feedback on progress
  • Provide the necessary equipment

Hygiene, cleaning and disinfection

Good hygiene is essential to limit the spread of organisms through a pig farm. Cleaning and disinfection must be done properly if it is to be effective.
  • Clean all surfaces properly as dirt inactivates disinfectants
  • Use recommended disinfectants at the correct dilution, temperature and time
  • Drying afterwards helps kill bugs
  • Provide footbaths at entrance to buildings
  • Feeders and drinkers should be cleaned and disinfected between batches
In “All in/All out” systems, all pens in a room or house should be emptied and then cleaned and disinfected properly to break the cycle of re-infection before being filled again with pigs.


The best laid plans of mice and men are of no value unless the plans are actually followed. Checks should also be made to make sure the plans are being effective in controlling Salmonella. The farm veterinary surgeon will be able to advise on control strategies for Salmonella and on the results of monitoring.

Source: Livestock Knowledge Transfer - First published 2001. Added to this site 2003.

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