Occurrence and Survival of Pathogenic Microorganisms in Irrigation Water

Abstract

The consumption per capita of fresh vegetables has increased in the last years in the USA and other countries, which has contributed to the increase of gastroenteritis outbreaks attributed to contaminated fruits and vegetables. Fresh produce can incorporate pathogenic microorganisms thru the process of irrigation, harvesting, postharvest processing and distribution. Most microorganisms use irrigation water and/or soil as a vehicle of transport (Beuchat, 1995; Bhagwat, 2003). Untreated water is most likely to transmit several microorganisms, which may include pathogenic strains of Escherichia coli, Salmonella, Listeria, protozoa and viruses (Diaz et al., 1999). Studies in different countries indicate that the use of untreated water for irrigation of vegetables is the practice most related to fresh produce safety issues (Mongeet al., 1996; Diaz et al., 1999; Tyrrel y Quinton, 2003). Surface water may pose a risk of contamination if its source is unknown. Water is used for multiple issues in diverse agricultural activities including application of fertilizers, washing and disinfecting produce. Therefore, water has to meet the chemical and microbiological requirements before its use (Siller et al., 2002). The quality of water is based on the amount of indicator microorganisms. The major source of coliform contamination when vegetables are grown is probably the irrigation water (Okafoet al., 2003). There are critical factors that need to be monitored to ensure safe water supply. All water sources must be examined periodically for microbiological determination, the results must be recorded and existing problems corrected, for example bathing and grazing animals nearby water resources which should be prohibited to prevent fecal contamination and reduce risks to human health from consuming contaminated fresh produce. Frequently, contamination is associated with the application of irrigation water and the type of crop. Studies have proved that flooding irrigation represents the greatest possibility of contamination if it’s used on produce having direct contact with the soil while the sprinkler irrigation technique provides a rapid means to contaminate the product if the water is contaminated; On the other hand, the drip irrigation technique has represented the lowest risk of contamination of produce (Siller-Cepeda et al., 2009). Lettuce, radishes, carrots are vegetables most likely to become contaminated due to their direct contact with soil and water which can possibly contain bacteria (Okafoet al., 2003). It is well recognized that fecal indicator bacteria may be transported and be a source of contamination of water sources (Tyrrel and Quinton, 2003).