intermediate or carrier hosts are unknown, or the source of the infection is unknown (or related to an uncontrollable, ongoing, unrelated human activity such as recreational water use or commercial shipping).
Containment. Containment of the disease and pathogen within specified zones with controls in place around infected zones to prevent spread to uninfected populations within the country or straddling neighbouring borders.
Mitigation. Reduction of the impacts of the pathogen by implementing control measures at the farm, or affected population, level that reduce the occurrence and severity of disease. These measures focus on stocks within the infected zone, and concentrate on long-term circumvention of disease losses, either through development of treatments (vaccines, antibiotics as appropriate) or husbandry techniques (selection of resistant broodstock, variation of stocking/harvest times). These measures are based on failed eradication attempts or epidemiological risk assessments indicating that eradication efforts are unfeasible or impractical.