Animal Waste, Water Quality and Human Health

50Animal Waste, Water Quality and Human HealthAlthough human infections are confined mostly to direct contact with infectedanimals, contaminated water has also been associated with numerous outbreaks inthe USA (Levett 2001, Fuortes & Nettleman 1994). Cattle, pigs, rats, and dogshave all been suspected sources of various waterborne outbreaks (Levett et al. 2001).The organism survives best in freshwaters and moist terrestrial environments attemperatures above 10 o C. Therefore, leptospirosis is most common in temperateclimates in spring and fall and in tropical climates during the rainy season.Changes in management practices have shifted the serovar distribution amongmany domestic animals; as shown in some cases by decreasing exposure towildlife (e.g. in confined animal feeding operations) and in other cases throughserovar-specific vaccination.Francisella tularensis subsp holarcticas RANK 3 Francisella tularensissubsp tularensis infections are most commonly acquired by contact withinfected wild mammals such as rabbits and deer and also indirectly through anarthropod vectors such as ticks; however, waterborne illness associated with thissubspecies is rare (Petersen & Molins, 2010). In contrast, scattered waterbornedisease outbreaks have recently been reported in Turkey, Georgia, Norway andseveral other parts of Europe and Asia associated with F. tularensis subspholarctica. Drinking of unchlorinated water contaminated by infected water ratsand voles are thought to have been the source of the pathogen. F. tularensissubsp holarctica is associated with a much milder form of human illness thansubsp. tularensis.Antimicrobial resistant bacteria RANK 2 Antimicrobials are not only usedtherapeutically to treat and as a prophylactic to prevent animal diseases, but theyare also used extensively at low doses for growth promotion in livestockproduction all over the world. This long-term administration of antimicrobials toanimals has led to the evolution of bacteria that are not only resistant to singleantimicrobial agents but often to multiple antibiotics. These antimicrobialresistance (AMR) determinants vary considerably in their mechanisms of action.Mutations in the gene encoding the bacterial target protein for example, DNAgyrase mutants, enzymes which chemically modify and inactivateantimicrobials, mechanisms which prevent entry of antimicrobials into cells andthose that promote the active removal of the antimicrobial from the cell.Multiple AMR determinants, frequently reside adjacent to each other as part of agene cluster on transmissible genetic elements such as plasmids, transposonsand frequently as part of smaller elements termed integrons. Antimicrobialresistance and in particular AMR bacteria are of increasing concern in publichealth particularly where resistance has developed to antimicrobial agents usedto treat nosocomial (hospital-associated) infections. Certain organisms are ofparticular concern because few treatments remain for pathogens such as