Sign up now!
Don't show this again
Download the report!Continue to Site >
or wait 7 secs

Thank you for confirming your subscription!

(And remember, if ever you want to change your email preferences or unsubscribe, just click on the links at the bottom of any email.)

We’re glad you’re enjoying Pig Health Today.
Access is free but you’ll need to register to view more content.
Already registered? Sign In
Tap to download the app


Collect articles and features into your own report to read later, print or share with others

Create a New Report


Read Later

Create a new report

Report title (required) Brief description (optional)
follow us

You must be logged in to edit your profile.

Favorites Read Later My Reports PHT Special Reports
Pig Health Today is equipped with some amazing (and free) tools for organizing and sharing content, as well as creating your own magazines and special reports. To access them, please register today.
Sponsored by Zoetis

Pig Health Today | Sponsored by Zoetis


Formula sheds light on disease risk

Understanding the transmission route of a disease pathogen, how long it’s infective, its survivability in the environment and routes of infection all build the foundation for creating effective biosecurity protocols.

Infected animals are the most direct path to introducing diseases into a herd. But as herd health status improves, higher-risk practices are eliminated and other pathogen-exposure routes assume greater relative importance, such as indirect transmission, according to Anna Romagosa, DVM, with PIC Europe.1

While exposure routes vary depending on the pathogen, the more common ones include:

  • Airborne transmission
  • Animal, feed and mortality transports
  • People, including workers, visitors and maintenance staff
  • Equipment
  • Slurry management
  • Pests

When implementing biosecurity procedures, it’s not only important to assess the chance of a disease being brought in through certain routes but also to consider how often the risk occurs.

In her paper submitted to the 2017 American Association of Swine Veterinarians’ meeting, Romagosa offered a predicted-probability formula, provided by Professor Jeroen Dewulf, University of Ghent, Belgium, to assess the combined risk of transmission multiplied by the frequency:

P = 1-(1-P)N

P = the chance of disease transmission per risk occurrence

N = the number of times this risk occurs

For example: If you assume that the chance of a particular route to actually transmit the disease is only one chance in 1,000, but you know that this route occurs 52 times a year (weekly, for example), the chance of disease transmission at the end of the year is 5%.

5.0% =1-(1-0.001) 52

That is already a significant risk, Romagosa noted.

Baseline and low-risk outcomes

Romagosa cited a recent Swedish study that looked at the disease-introduction risk on two different farm scenarios. The infectious agents were Brachyspira hyodysenteriae, causing swine dysentery, and Mycoplasma hyopneumoniae, causing swine enzootic pneumonia. The production examples included a 1,600-head finishing herd and a 484-sow farrow-to-finish, single-site farm. The most common between-farm contacts were considered, including live animals, animal-transport vehicles, mortality collectors and veterinarian visits.

Biosecurity measures included quarantine for new-animal introductions, preventing livestock truckers and mortality collectors from entering buildings and providing protective clothing and boots for all visitors.

The measures were then combined into two scenarios for each herd — baseline and low-risk — used to reflect differences of between-farm contacts. The baseline scenario included the predicted yearly contacts in a typical farm for each type. In the low-risk scenario for the farrow-to-finish herd, the number and sources for live-animal introductions were reduced.

The results of the yearly risk model for introduction of M. hyopneumoniae and B. hyodysenteriae are illustrated in the accompanying table:

Scenario/Model Biosecurity measures Farrow-to-finish herd, % Fattening herd, %
B. hyodysenteriae      
   Baseline No


11.43 (2.88-31.3)

2.33 (0.2-4.92)

45.35 (5.66-70.0)

22.18 (2.69-35.75)

   Low risk No


8.17 (1.88-25.58)

1.18 (0.10-2.52)

26.32 (2.98-45.35)

12.5 (1.37-22.03)

M. hyopneumoniae      
    Baseline No


100 (98.37-100)

53.51 (17.2-85.03)

100 (100-100)

55.86 (18.34-87.56)

   Low risk No


99.99 (98.3-100)

54.24 (17.01-86.46)

100 (99.99-100)

38.12 (15.09-67.61) 

Lewerin, et. al, 2015




1Romagosa A, et al. Applied Review of Evidence-based Biosecurity. Biosecurity Seminar Proceedings of the 48th American Association of Swine Veterinarians’ Annual Meeting. 2017;5-10.


Posted on June 10, 2017

tags: , , ,
  • USDA steps up measures to prevent ASF spread to the US

    As the spread of African swine fever (ASF) across Asia shows no signs of slowing, US pork producers have watched with a nervous eye toward international commerce and travel.

  • Quarantine window for feed ingredients may reduce hog disease risk

    Foreign animal diseases (FAD) are top of mind as the ongoing outbreaks of African swine fever (ASF) in China, Belgium and elsewhere, have raised the stakes to implement new practices designed to minimize disease transmission.

  • Non-thermal plasma reactors can inactivate PRRSV

    Hog-farm biosecurity measures have largely focused on minimizing the transmission of infectious agents on various surfaces. However, it’s been shown that PRRSV — and possibly other respiratory diseases — can be transmitted via air.

  • Tailored biosecurity key to good herd health and profitability

    Tailoring biosecurity strategies to the location, facility and labor of individual hog farms is key to maintaining herd health and profitability, according to a leading veterinarian.

You must be logged in to edit your profile.

Share It
It’s not unrealistic to say that if you checked the nasal cavities or tonsils of any group of pigs, you would find Strep suis. While the strain and impact can vary widely, this commensal bacterium is on virtually every hog farm.

Click an icon to share this information with your industry contacts.
Google Translate is provided on this website as a reference tool. However, Poultry Health Today and its sponsor and affiliates do not guarantee in any way the accuracy of the translated content and are not responsible for any event resulting from the use of the translation provided by Google. By choosing a language other than English from the Google Translate menu, the user agrees to withhold all liability and/or damage that may occur to the user by depending on or using the translation by Google.