Disease-prevention considerations for people and supplies

“The success of any biosecurity program rests with compliance,” said Anna Romagosa, DVM, with PIC Europe.

In a paper submitted to the 2017 American Association of Swine Veterinarians’ meeting, Romagosa pointed to human traffic, vehicles and fomites as reoccurring challenges to disease-prevention measures.¹

“People can act as a mechanical vector if they have been in contact with infected animals and subsequently have contact with susceptible animals,” she noted. “This has been proven for such pathogens as transmissible gastroenteritis virus, E. coli and porcine reproductive and respiratory syndrome (PRRS) virus, mainly through infected animal excreta on footwear and clothing.”

Less is known about the risk of biological transmission of various swine-related pathogens between people and pigs. Influenza viruses are zoonotic. Therefore, the mechanical transmission aspects and the biology related to human infection should be considered.

Evidence of direct transmission

“Although there is no established evidence of humans acting as vectors of influenza-A virus (IAV) from infected to susceptible herds, there is evidence of direct transmission of IAV from pigs to humans and from humans to pigs,” Romagosa told Pig Health Today.

It can take 48 hours for a person infected with the influenza virus to present clinical signs, which would flag a biosecurity alert. However, nasal shedding of the virus can occur before clinical signs appear.

“Therefore, preclinical infected people present a potential risk for introducing influenza into pig farms,” she pointed out.  Moreover, that risk can run as long as seven days post-infection.

Using disposable masks and gloves might be prudent, especially during flu season. The recommended masks for influenza viruses are N-95, N-99 and N-100. Of course, getting workers to comply can be another challenge.

Other considerations for people

Of course, controlling human traffic is important to minimize pathogen exposure within a hog operation. Limiting human traffic, sanitation protocols — showers, changing clothes, clean/dirty lines, Danish entrance — and downtime between site visits are all common procedures today.

Shower-in/shower-out has been proven to help reduce pathogen-transmission risks, and the complete change of barn-specific clothes is key. Another vital part is a clear separation between the “dirty” entrance side and “clean” exit side of the shower, Romagosa said.  Having a workable flow to this area and keeping it clean is critical to its effectiveness.

Providing hand sanitizers throughout a facility and ensuring their use is highly recommended. Make it a practice to wash hands with soap and then sanitize before entering the main production unit.

Downtime between farm visits has become standard practice, but the length of downtime is less uniform. “Like all biosecurity interventions, downtime has inherent costs,” Romagosa said, “most notably the constraints on working schedules for staff, service personnel and veterinarians.”

How much downtime?

To determine the appropriate downtime, consider the nature of the enterprise, the costs of restricted human traffic, the specific pathogens of concern and the probable costs associated with disease introduction.

“Downtime may be unwarranted and unnecessary in some farms due to existing health status, flaws in biosecurity, multiple pig sources, and the like,” Romagosa noted. She cited a PRRSV study that demonstrated basic sanitary interventions such as showering, changing footwear and clothing could prevent mechanical spread of PRRSV, irrespective of downtime.

A more recent study showed that downtime of one night (14 to 16 hours), along with sanitary interventions (showering, clothing and boot change, footwear disinfection), prevented the spread of PRRSV and Mycoplasma hyopneumoniae by personnel and fomites between infected and susceptible populations.

“The costs of extended downtimes may be acceptable to high-health enterprises such as nucleus breeding herds and boar studs,” she added.

However, extended downtimes for any operation would be prudent following a disease outbreak.

Don’t overlook supplies

Controlling people traffic includes products or supplies that they might bring into the hog facility. This can be a particular challenge with service personnel, but providers in rural areas should be more used to swine-related requirements these days.

“The farm’s biosecurity program must provide for mandatory cleaning and disinfection of any equipment,” Romagosa said. This might also include quarantine time before supplies or equipment can be brought near the animals.

A disinfection room should be set up as the only entry point for supplies or contractor tools. Training one or two people on how to operate the room decreases the risk of human error. Inform vendors about the disinfection requirements before arriving at the farm. Plan to further train vendors by reviewing the required steps and document their understanding of the protocols.

The farm’s exact protocols can vary widely. A micro-diffuser and a cold disinfection system can be applied automatically from outside the disinfection room. Allow for the recommended contact time, plus the safety period. Gluteraldehyde mixtures and oxidizing disinfectants can be used for a cold disinfection system, Romagosa noted.

Double-packaging options, such as bag-in-a-box containers or the box-in-a-box system, can be useful to prevent pathogen exposure as well.  Think of these methods as presenting sort of a micro clean/dirty line.

For the farm’s own tools, consider having a complete set designated for each hog barn on a site.

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