Role of water and water line biofilms in swine farm biosecurityRole of water and water line biofilms in swine farm biosecurity

Biofilms degrade water quality and can harbor pathogens that can decrease the health of pigs.

Iowa State University

February 4, 2025

7 Min Read
Person checking equipment in pig barn
National Pork Board

By Gabrielle E. Doughan and Locke A. Karriker

Water biology is a critical yet often overlooked component of swine biosecurity. While water treatment and disinfection are not traditionally prioritized in biosecurity plans, the reality is that pigs consume nearly twice as much water as feed[1], leading to the intake of large volumes of potentially untreated water daily. This untreated water can introduce pathogens and aid in the creation of biofilms, which are complex communities of microorganisms that adhere to surfaces within water lines. These biofilms can pose a biosecurity risk by serving as reservoirs for pathogens, potentially facilitating their transmission within swine farms. Understanding and mitigating the risks associated with water and water line biofilms is essential for improving overall farm biosecurity and ensuring pig health[2, 3].

Evidence for contamination of the water source

Water can serve as a vector and reservoir for many bacterial, viral and protozoal pathogens. Many farms are supplied by more vulnerable water sources such as well water or surface water with fewer supplied by rural water. Well water and surface water sources are more vulnerable to contamination from pathogens and other contaminants due to their interface with the environment (and passage through macropores in soil)[2-4] and influences from agricultural activities. A few reports have suspected waterborne transmission or demonstrated the presence of pathogens in water sources supplying livestock farms such as a suspected case of African swine fever infecting a Romanian swine breeding herd via the Danube River[5, 6]. In addition, avian influenza was detected in wells from affected poultry farms in the midwestern U.S. in 2015[7]. Other studies have found livestock pathogens or fecal associated bacteria in wells or surface water[8-10] such as porcine circovirus 2 (PCV2)[11], rotaviruses[10], Escherichia coli, Salmonella[12], Cryptosporidium spp. [13]. Additional livestock pathogens may be present, however they have not been a primary focus until recently.

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Not only are pathogens found in water sources, but in certain circumstances water can preserve their viability in the environment and in aquifers[10]. For example, porcine reproductive and respiratory syndrome is an enveloped virus and theoretically should be more readily inactivated in the environment. However, there have been multiple reports of PRRSV surviving in water for up to nine to 11 days depending on the water source [14, 15]. Others have documented its recovery from soil demonstrating plausibility of percolation through soil and maintaining viability[16]. More research is needed on estimating the frequency and viability of livestock specific pathogens in water sources.

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Current knowledge of water line biofilms in swine farms

Potential pathogen inoculation into swine water lines can be derived from two sources; through external water sources via contaminated water (as discussed previously), or through access points within the water distribution system inside the barn. Swine water distribution systems are open, low-pressure systems with terminal water lines or water lines with “dead-ends,” which provide an environment that is optimal for biofilm development. Organisms can be introduced into the system through the water medicator, from poorly cleaned stock buckets, potentially from the pigs themselves as they utilize drinking water apparatuses (Figure 1.) (cup waterers, wet-to dry feeders, etc.), or from environmental contamination. The water distribution system characteristics paired with water quality parameters from farms that often include hard water, which is an elevation in calcium and magnesium, elevated iron, sulfates, nitrates and other nutrients allows biofilms to form and grow. (Figure 2.).

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Furthermore, water-administered treatments such as electrolytes, probiotics, live attenuated oral vaccines and others provide additional nutrient sources for biofilms to develop inside water lines. These factors can influence the water microbial quality as it enters the farm as mature biofilm development can shed into the water running through the system.

A recent study completed by Iowa State University’s Swine Medicine Education Center team found that water quality decreased from the water collected from the water source (well) to water samples collected in rooms in six wean-to-finish farms in Iowa. They evaluated the presence of coliforms and E. coli in each water sample. Although not all coliforms are pathogens, they indicate livability conditions for potential pathogens. Preliminary water results demonstrated that water samples taken from rooms of the sites had much higher average coliform counts than those present from samples taken at the source water (well) (Figure 3.). This indicates that biofilms are shedding organisms into the room water sources and further degrading water quality. Taking only well samples for water quality may underestimate the impacts to the water quality that the pigs truly experience. Average E. coli counts in water samples were more variable and in many cases were site dependent. When biofilm was directly analyzed, a hemolytic F18 E. coli with PAA and EAST1 toxins was cultured in at least one site.

ISU_Fig_3_020425.png

Conclusion

Water and water line biofilms can pose a threat to biosecurity on farms and should be more thoroughly accounted for in biosecurity planning. Not only can pathogens enter swine farms from the water source, but the design of current swine water distribution systems provides areas for potential contamination within the farm leading to the formation of biofilms. Biofilms degrade water quality and can harbor pathogens that can decrease the health of pigs. Without implementing water line disinfection between, biosecurity may be limited within and between groups of pigs.

Resources

  1. Guthrie, T. Water needs of pigs. 2011; Available from: https://www.canr.msu.edu/news/water_needs_of_pigs.

  2. Doughan, G., L. Karriker, and K. Mou, Water Biology: Implications for Pig Health, Production and Biosecurity, in ISU James D. McKean Swine Disease Conference. 2022: Ames, Iowa. p. 66-71.

  3. Doughan, G., L. Karriker, and K. Mou, Water biology: The next frontier for biosecurity, in 54th Annual meeting of the American Association of Swine Veterinarians. 2023: Aurora, Colorado. p. 346-350.

  4. Olsen, P.C.S., Steven J., Groundwater & livestock production and husbandry, part 1, biosecurity, in 51st Annual Meeting of the American Association of Swine Veterinarians. 2020, AASV: Atlanta, GA. p. 384-398.

  5. Boklund, A., et al., Epidemiological analyses of African swine fever in the European Union (November 2017 until November 2018). EFSA Journal, 2018. 16(11): p. e05494.

  6. Niederwerder, M.C., et al., Infectious Dose of African Swine Fever Virus When Consumed Naturally in Liquid or Feed. Emerging Infectious Diseases, 2019. 25(5): p. 891-897.

  7. Borchardt, M.A., et al., Avian Influenza Virus RNA in Groundwater Wells Supplying Poultry Farms Affected by the 2015 Influenza Outbreak. Environmental Science & Technology Letters, 2017. 4(7): p. 268-272.

  8. Borchardt, M.A., et al., Sources and Risk Factors for Nitrate and Microbial Contamination of Private Household Wells in the Fractured Dolomite Aquifer of Northeastern Wisconsin. Environmental Health Perspectives, 2021. 129(6): p. 067004.

  9. Demoliner, M., et al., Microbial Source Tracking in Small Farms: Use of Different Methods for Adenovirus Detection. Water, Air, & Soil Pollution, 2021. 232(2): p. 63.

  10. Pang, X., et al., The prevalence and levels of enteric viruses in groundwater of private wells in rural Alberta, Canada. Water Res, 2021. 202: p. 117425.

  11. Garcia, L.A., et al., Surveillance of human and swine adenovirus, human norovirus and swine circovirus in water samples in Santa Catarina, Brazil. J Water Health, 2012. 10(3): p. 445-52.

  12. Stokdyk, J.P., et al., Viral, bacterial, and protozoan pathogens and fecal markers in wells supplying groundwater to public water systems in Minnesota, USA. Water Research, 2020. 178: p. 115814.

  13. Stokdyk, J.P., et al., Viral, bacterial, and protozoan pathogens and fecal markers in wells supplying groundwater to public water systems in Minnesota, USA. Water Research, 2020. 178.

  14. Eugene C. Pirtle, G.W.B., Stability of porcine reproductive and respiratory syndrome virus in the presence of fomites commonly found on farms. Javma-Journal of the American Veterinary Medical Association, 1996. 208(3): p. 390-392.

  15. Lugo Mesa, V., et al., Survival of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in the Environment. Veterinary Sciences, 2024. 11(1): p. 22.

  16. Alvarez-Norambuena, J., et al. Adsorption of PRRS virus strains to Minnesota soils, a possible transmission route. in 54th Annual meeting of the American Association of Swine Veterinarians. 2023. Aurora, Colorado.

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