Biosecurity Risk Factors and Predictive Index for Hepatitis E Virus Serological Status in Belgian Pig Farms: Conventional and Free-Range Systems
Abstract
:1. Introduction
2. Materials and Methods
2.1. Serological Data
2.2. Biosecurity Questionnaire
2.3. Statistical Analysis
2.4. Spatial Visualization
3. Results
3.1. Bio-Exclusion: Piglet Purchase Protects Against Increased HEV Herd Seroprevalence
3.2. Bio-Compartmentalization: Free-Range Systems and Low Boot Hygiene Are Risk Factors for Increased HEV Herd Seroprevalence
3.3. Prediction of the HEV Serological Status of Belgian Pig Farms and Spatial Visualization
4. Discussion
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
Abbreviations
HEV | Hepatitis E virus |
WHO | World Health Organization |
AFSCA/FAVV | Agence Fédérale pour la Sécurité de la Chaîne Alimentaire/Federaal Agentschap voor de Veiligheid van de Voedselketen |
DGZ | Dierengezondheidszorg Vlaanderen |
ARSIA | Animal Health Care Wallonia (Association Régionale de Santé et d’Identification Animales |
SANITEL | Belgian Identification and Registration System |
ELISA | Enzyme-linked immunosorbent assay |
Se | Sensitivity |
Sp | Specificity |
OR | Odds ratio |
BIC | Bayesian information criterion |
PI | Predictive index |
ROC | Receiver operating characteristic |
CO | Cut-off |
SPW | Public Service of Wallonia |
INBO | Instituut voor Natuur- en Bosonderzoek |
Appendix A
Appendix B
Variable | Category |
---|---|
Type | Closed f-to-f herd |
Mixed f-to-f herd | |
Slaughter pig herd | |
Other | |
Size | 101–200 |
201–500 | |
501–1000 | |
1001–2000 | |
2001–4000 | |
>4000 | |
Internal biosecurity score | |
External biosecurity score | |
General biosecurity score | |
Do the pigs have access to free range? | Yes |
No | |
Besides pigs, are there any other livestock animals on your farm? | Yes |
No | |
Are there any cattle on the farm? | Yes |
No | |
Do you purchase breeding pigs (sows/gilts/boars)? | Yes |
No | |
Are piglets purchased? | Yes |
No | |
When purchasing semen, is there proof that the health status and health management of the originating AI center/company are equal to or superior to those of your own farm? | Yes |
No | |
Not known | |
No purchase of semen | |
Is the transport vehicle bringing pigs to the slaughterhouse or other farms empty upon arrival at the farm, and are the animals loaded from an isolated loading dock or directly from the barn/central corridor? | Central corridor and empty vehicle |
Central corridor and not empty vehicle | |
Loading dock or no transport | |
Is the manure/slurry removed through the dirty area of the farm? | Yes |
No | |
Are there specific suction pipes on the farm for removing slurry from the pit (permanent slurry removal pipes on the farm)? | Yes |
No | |
Do the rendering company or the feed supplier handle carcass removal or silo filling without entering the farm buildings? | Yes |
No | |
Does the farmer use a feed supplier that meets specific hygiene requirements (e.g., Salmonella-free, heat treatment)? | Yes |
No or not known | |
Is a bacteriological analysis of the drinking water conducted annually at the source and the storage tank? | Yes |
No | |
Is a bacteriological analysis of the drinking water conducted annually at the main outlets (where the animals drink)? | Yes |
No | |
Are specific measures taken for the supply of equipment (e.g., cleaning and disinfection, quarantine period in a designated area)? | Yes |
No | |
Is a period of no contact with pigs (more than 12 h) required for all visitors before they are allowed to enter the barns? | Yes |
No | |
Is there a hygiene lock available, and is it always used when visitors access the livestock buildings? | Yes |
No | |
Are all livestock buildings accessible to visitors only through the hygiene lock? | Yes |
No | |
No hygiene lock | |
Is vermin (rats, mice, etc.) considered a problem on the farm? | Yes |
No | |
Are the surroundings of the farm (nearby buildings) paved and kept clean (e.g., waste removal, control of weeds) to prevent infestations by rodents/wild animals? | Yes |
No | |
Do pets (dogs or cats) have access to the livestock buildings? | Yes |
No | |
Can birds enter the livestock buildings? | Yes |
No | |
Are there grilles placed at the air inlets? | Yes |
No | |
Is the farm located in an area with low or high pig density? | High |
Low | |
Are there any other pig farms within a 500 m radius of your farm? | Yes |
No | |
Is slurry from other farms spread on neighboring land directly adjacent to the livestock buildings (within a 500 m radius)? | Yes |
No | |
Are vehicles transporting animals from other farms frequently (at least once a day) passing on the road near the farm? | Yes |
No | |
Have wild boars been spotted in the vicinity of the farm (within a 10 km radius)? | Yes |
No | |
Are footbaths present at the entrance of the farm, and are they used? | Yes |
No | |
Are the buildings constructed to prevent wild boars from intruding or coming into contact with the pigs? | Yes |
No |
Variable | Category |
---|---|
Size | 101–200 |
201–500 | |
501–1000 | |
1001–2000 | |
2001–4000 | |
>4000 | |
Internal biosecurity score | |
External biosecurity score | |
General biosecurity score | |
Do the pigs have access to free range? | Yes |
No | |
Are there any cattle on the farm? | Yes |
No | |
Are the animals loaded from an isolated loading dock or directly from the barn/central corridor? | Central corridor or barn |
Loading dock | |
Is the manure/slurry removed through the dirty area of the farm? | Yes |
No | |
Are there specific suction pipes on the farm for removing slurry from the pit (permanent slurry removal pipes on the farm)? | Yes |
No | |
Is the carcass storage site secured to prevent access by dogs, cats, rodents, or wild animals? | Yes |
No | |
Does the farmer wear disposable gloves when handling carcasses or wash and disinfect their hands afterward? | Never |
Sometimes | |
Always | |
Is it required to wash and disinfect hands before entering the livestock buildings? | Yes |
No | |
Is vermin (rats, mice, etc.) considered a problem on the farm? | Yes |
No | |
Are the surroundings of the farm (near the buildings) paved and kept clean (e.g., waste removal, weed control) to prevent infestations by rodents/wild animals? | Yes |
No | |
Do pets (dogs or cats) have access to the livestock buildings? | Yes |
No | |
Can birds enter the livestock buildings? | Yes |
No | |
Are there grilles placed at the air inlets? | Yes |
No | |
Is the health status of the farm (e.g., serology, reasons for seizure at the slaughterhouse, etc.) evaluated regularly (i.e., at least once a year)? | Yes |
No | |
Are sick animals always handled after healthy animals? | Yes |
No | |
Are specific clothing and footwear for each compartment available and changed between compartments? | Never |
Sometimes | |
Always | |
Are hands washed and/or disinfected between livestock compartments? | Never |
Sometimes | |
Always | |
Are footbaths/boot washers placed between different compartments, or are boots changed between compartments? | Yes |
No | |
On the farm, is all work conducted from the youngest pigs to the oldest? | Yes |
No | |
Is the equipment required for a particular group of animals arranged according to the work order to avoid using the same equipment across different groups? | Yes |
No | |
Is there a cleaning and disinfection protocol for equipment (e.g., brooms, shovels) after use, and is this protocol followed? | Yes |
No | |
Is the equipment clearly identified or recognizable (e.g., by color coding) as being reserved for a specific area or age group? | Yes |
No | |
Are syringes (for injections) available and used specifically for each age group? | Yes |
No | |
Are needles (for injections) available and used specifically for each age group? | Yes |
No | |
Are the buildings/rooms cleaned and disinfected after each production cycle? | Yes |
No | |
Are the corridors cleaned and disinfected after moving animals? | Not always |
Always | |
Are footbaths present at the entrance of the farm, and are they used? | Yes |
No | |
Is the liquid in the footbath changed immediately when it becomes visibly contaminated? | Yes |
No | |
No footbath |
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Variable | Category | N | Univariate Model | |
---|---|---|---|---|
OR (95% CI) | p-Value | |||
Piglets’ purchase | Yes | 160 | - | - |
No | 107 | 8.03 (4.51–14.34) | <0.01 *** |
Variable | Category | N | Univariate Model | Multivariate Model | ||
---|---|---|---|---|---|---|
OR (95% CI) | p-Value | OR (95% CI) | p-Value | |||
Availability of a free-range system | Yes | 19 | 1.41 (1.12–1.77) | 0.004 *** | 1.39 (1.10–1.74) | 0.005 *** |
No | 248 | - | - | - | - | |
Presence of a footbath/boot-washer or changing of boots between compartments | Yes | 109 | - | - | - | - |
No | 158 | 1.17 (1.04–1.32) | 0.01 ** | 1.16 (1.03–1.31) | 0.016 ** |
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Wielick, C.; Ludwig-Begall, L.; Ribbens, S.; Thiry, É.; Faes, C.; Saegerman, C. Biosecurity Risk Factors and Predictive Index for Hepatitis E Virus Serological Status in Belgian Pig Farms: Conventional and Free-Range Systems. Viruses 2025, 17, 432. https://doi.org/10.3390/v17030432
Wielick C, Ludwig-Begall L, Ribbens S, Thiry É, Faes C, Saegerman C. Biosecurity Risk Factors and Predictive Index for Hepatitis E Virus Serological Status in Belgian Pig Farms: Conventional and Free-Range Systems. Viruses. 2025; 17(3):432. https://doi.org/10.3390/v17030432
Chicago/Turabian StyleWielick, Constance, Louisa Ludwig-Begall, Stefaan Ribbens, Étienne Thiry, Christel Faes, and Claude Saegerman. 2025. "Biosecurity Risk Factors and Predictive Index for Hepatitis E Virus Serological Status in Belgian Pig Farms: Conventional and Free-Range Systems" Viruses 17, no. 3: 432. https://doi.org/10.3390/v17030432
APA StyleWielick, C., Ludwig-Begall, L., Ribbens, S., Thiry, É., Faes, C., & Saegerman, C. (2025). Biosecurity Risk Factors and Predictive Index for Hepatitis E Virus Serological Status in Belgian Pig Farms: Conventional and Free-Range Systems. Viruses, 17(3), 432. https://doi.org/10.3390/v17030432