BIOSECURITY BREACHES LEADING CAUSE OF DISEASE TRANSMISSION

In a recent webinar hosted by Pig Progress, Dr. Depner said that ASF has high case fatality and is highly tenacious in the environment, surviving locally in wild pig populations for months or years. While these characteristics make ASF efficient in persistence and transmission, its contagiousness is low, especially in comparison to other disease like Classical Swine Fever and Foot and Mouth Disease. This means that ASF does not have rapid spread in domestic pigs and as a result, can be effectively controlled with good biosecurity.

By considering only the biological aspects of ASF (i.e., its contagiousness, tenacity and high case fatality) but ignoring the human aspects of biosecurity, the disease will not be controlled. Biosecurity can be considered as having two main aspects: hardware (fences, barriers, etc.) and software (management, philosophy, or mindset). Its crucial to include the human aspect when planning prevention, control or eradication measures, says Dr. Depner.

“Humans are the main cause of long-distance transmission and virus introduction into pig farms.”

He goes on to say that “It is always human error that results in the virus entering the barn.” Further, analysis of ASF outbreaks have shown that biosecurity short comings are the most critical element for introduction of the disease. Therefore, reducing human error is critical to protecting domestic swine and keeping the disease out.

Elien Claeys, an expert with CID Lines, underscores this. Claeys emphasises that high risk routes of transmission include vehicles, farming tools and equipment, and on clothing, footwear and hands. She recommends limiting people an animal movement, including clearly marked clean and dirty areas, one way flow, and clear signage for access. Limiting sources of animals to one supplier with a validated health status is highly recommended, as well as limiting deliveries of animals since every delivery poses a risk.

When it comes to entrance hygiene, hand washing remains a critical practice, yet it’s also one that is often not done properly. A 2011 study³ of biosecurity errors made on entering and exiting poultry barns observed via video surveillance found that of 552 visits, 79% made mistakes related to handwashing alone. It was observed that people made an average of four biosecurity errors per farm visit, with a maximum number of 14 errors made by one person in one visit. When people were observed over several visits, the average increased to six errors per visit.

The separation between clean and dirty areas accounted for 67% of errors, and the table shows further detail on the type of delineation, whether a red line, bench, door or footbath. Even when there is a physical barrier such as a door or bench, mistakes occur.

Table 1: Number of visits when the boundary between clean and dirty areas was not respected according to the type of delimitation for eight poultry farms in Quebec based on video surveillance.