Biosecurity

San Miguel Animal Health Care Corner

 

 

 

 


Biosecurity: A Critical Review of Today’s Practices

 

Eugene P. Mende DVM MSc

Veterinary Services Manager

San Miguel Foods Inc., Feeds and Animal Health Care Business

 

“How did I get this outbreak?”, fumed the owner of a farm when a suspected viral diarrhea killed most of his suckling pigs in a week’s time. I could have told him the nature and complexities of the viral diarrhea outbreak but I wanted to convey a message that will have longer and more stable effect for his production.

 

Simple. The farm’s biosecurity failed.

 

In this issue, I am going to discuss a critical swine production program that producers and farm owners now, even with the influx of new diseases and syndromes, still find futile and insignificant. Biosecurity program failures can not be solely blamed on poor execution but also on the lack of understanding regarding routes of disease transmission. So how can our biosecurity system outwit disease outbreaks?

 First, we should know all the routes of pathogen transmission. Second, we need to analyze farm movements and assess details of daily events to come up with a working protocol. Third, we need to continually identify and update risk factors to challenge and reevaluate existing biosecurity protocols.

Now that we already have some scientific data, we will evaluate seven (7) commonly practiced biosecurity protocols and hope that veterinarians and producers develop and practice critical thinking when considering the implementation of biosecurity programs.

 

1. Quarantine and Testing

            Live animals entering the herd have always been the major risk factor in the farm’s health status. Furthermore, the rapid adaptation of Artificial Insemination (AI) in the Philippines has raised the risk of the introduction of pathogens such as Porcine Reproductive and Respiratory Syndrome virus (PRRSV), Pseudorabies virus (PRV) and Hog Cholera virus (HCV) into farms. The recent increase of PRRSV and Circovirus-related infections in Philippine commercial farms has emphasized the need for serological (ELISA) and even PCR testing of newly-purchased replacement pigs and even of semen prior to its release from AI centers.

Application:

Strict quarantine before entering the herd and testing incoming breeding/replacement stocks using statistically valid random sampling protocol.

 

2.    Shower in – shower out protocols

            Basic sanitation appears to be very effective at ridding personnel downtime of swine pathogens from the human body and eliminating the role of pathogens as mechanical vectors. With regards to PRRSV and Transmissible Gastroenteritis Virus (TGEV), a single hand wash and clothing/footwear change appears to equal the efficacy of showering. Unfortunately, due to the nature of workers to take shortcuts in hand washing and clothing/footwear change, forced showering becomes a necessary biosecurity protocol especially for commonly-transmitted contaminants like E. coli and Mycoplasma hyopneumonia. However, a newly recognized weakness even with showering is the anteroom area, located just prior to the entry to the actual shower facility. The anteroom is the section of the farm encountered immediately upon entry through the main door. Here, shoes, boots and clothing are removed and stored throughout the day. Recent biosecurity work indicated that the anteroom could serve as a site of PRRSV, E. coli and Salmonella sp. survival and a contamination point for shipping parcels that frequently enter swine farms, including styrofoam semen coolers, toolboxes, cardboard containers for pharmaceutical shipments and lunchboxes.

            Another area of concern identified by the new biosecurity studies was the common “pass-through window”, usually a sliding pane of glass or door that separates the office area (clean area) from the anteroom (contaminated area). This opening is frequently abused and is left open, allowing for shaking of hands of visitors with farm personnel and the introduction of equipment from the potentially contaminated anteroom floor.

Application: 

Establish a neutral (off-farm) receiving point for all containers and shipping parcels. All sides of these items should be disinfected with San Miguel Animal Health Glutaraldehyde-Quaternary Ammonium spray and allowed to air dry prior to entry into the farm.

 

3. Personnel Downtime

            Today, personnel including veterinarians are forced to follow downtime policies of 48-72 hours that are based on little scientific foundation. The “48-hour rule” was based on some very old publications assessing the ability of people to harbor Foot and Mouth Disease (FMD) virus and Mycoplasma hyopneumonia. However, recent researches indicated shorter recovery times of FMDV from people and the inability of personnel to spread Mycoplasma hyopneumonia from infected to naïve herds, despite multiple attempts over extended periods of time. Finally, latest researches also demonstrated the inability of personnel to harbor or transmit PRRSV and TGEV respectively, following completion of basic sanitation protocols.

Application:

Evaluate all downtime regulations that exceed 24 hours as long as basic sanitation protocols are applied.

Apply Basic Sanitation Protocols:

  1. Require that plastic boots (preferably disposable) should be used by personnel prior to setting foot in the anteroom. Footwear should then be placed on elevated shelves or perforated plastic flooring to prevent pooling of debris and liquids from soles of boots and shoes.
  2. Require that all personnel must shower in and out of each facility using scientifically sound shower standard operating protocols (SOP’s).
  3. Eliminate “pass through windows”. It helps to install intercoms for communication from offices to production rooms.
  4. Establish efficient foot baths at all building entrances.

 

 

4.    Vehicle/Truck cleanliness

Actinobacillus pleuropneumonia (APP) and Streptococcus suis have already been confirmed to be transmitted by contaminated trucks and vehicles. E. coli and Salmonella sp. have been recovered from bedding and truck floors even after a regular washing program (but no scientific disinfection protocol and drying) after transport of pigs. Furthermore, trucks also played important roles in spreading PRRSV from a contaminated premise to a simulated farm. Not only could truck-wash serve as a site for contamination of personnel footwear, but also the interior of the trucks could harbor infectious PRRSV over a 50 km distance. Fortunately, it appeared that the simple application of spray disinfectant to floor mats and soles of boots followed by sufficient time to allow the surface to air dry resulted in the inability to detect PRRSV in 10/10 replicates.

Application:

  1. Ensure efficient truck wash facilities of all trucks with efficient system of disinfecting and complete drying before use.
  2. Best to use disposable plastic boots when washing vehicles.
  3. Thoroughly clean interior of trucks by disinfecting all mats and allow sufficient time to dry.
  4. Ensure no re-entry of personnel from marketing/truck area back into the herd.

 

5. Rodent Control

  Rodents have been documented to transmit many pathogens including Brachyspira hyodysenteriea (causing swine dysentery), Salmonella sp., E. coli, Bordetella bronchiseptica, Leptospira sp., EMC virus and Toxoplasma gondii. In contrast, field and experimental studies have documented their inability to harbor PRRSV and Pseudorabies virus (PRV). Furthermore, rodents damage pig facilities, the feeds they consume and their rapid rate of replication forces the need for population control.

Application:

Make a monthly program to exterminate rodents.

 

6. Bird proofing of facilities

            Natural transmission of swine pathogens from birds to pigs has not been demonstrated. However, a single study on TGEV having been documented experimentally to be transmitted by starlings up to 32 hours following feeding on a suspension of TGE virus has been the foundation of keeping birds out of pig facilities. One laboratory report also suggested the role of Mallard ducks as biological vectors of PRRSV. In contrast, several pathogens including PRRSV, TGEV, Streptococcus suis, Pseudorabies virus, and Hog Cholera virus have been recovered from insects (houseflies, mosquitoes and ticks) and can be transmitted to pigs.

      Application:

      Install insect screens on sidewall openings of existing facilities.

 

7. Fomite management

            The role of fomites (boots, coveralls and shipping parcels) in the transmission of PRRSV and TGEV is well-documented. While some farms may possess fumigation rooms to disinfect fomites, the efficacy of these protocols is unknown, particularly if the base surfaces of the fomites are contaminated and does not come in contact with the aerosolized disinfectant. Fomites that enter the animal air space must be considered a risk, for it is contaminated and allowed to contact the hands of personnel. Particularly, PRRSV and TGEV can be “hand-delivered” to the pig population.