Several recent risk assessments and ranking exercises have considered the public health and safety risk of L. monocytogenes in cold-smoked seafoods. There are some apparent inconsistencies between the findings of these studies.
Ross and Sanderson qualitatively ranked the risk to New South Wales consumers of listeriosis from consumption of ready-to-eat smoked seafood products to be low, relative to other seafood/hazard combinations. However, application of their quantitative ranking tool led to a higher relative ranking, behind only viruses and algal biotoxins in molluscs, and C. botulinum in vacuum-packed seafoods [8]. This higher ranking reflects the greater influence of the severity of outcomes in the ranking tool compared to the qualitative risk ranking. They further estimated that the incidence of listeriosis in the susceptible sub-population in New South Wales would be, at most, a few cases per annum, depending on the degree of adherence to the microbiological limit standard in the Code.
Sumner ranked the public health risk from smoked seafood containing L. monocytogenes as medium (risk ranking 39 for the general population, 47 for the foetus – the extremely susceptible sub-population).
However, he concluded that the estimate of 14 cases per annum due to smoked seafood, as generated by the ranking tool, was not supported by the epidemiological data, and that several factors could account for a lower actual case rate [9]. The average annual reported incidence of listeriosis in Australia (from all food sources) in the period 1991–2002 (inclusive) was 59 cases [56].
The quantitative comparative risk ranking of L. monocytogenes in ready-to-eat foods conducted jointly in the United States by the Food and Drug Administration, United States Department of Agriculture and Centers for Disease Control and Prevention concluded that smoked seafoods had a relatively high risk ranking on a per-serving basis, but only a moderate relative risk ranking on a per-annum basis (estimated 1.3 cases per annum in the whole population) [11]. However, these rankings are for ‘likelihood of illness’ (specifically, invasive Listeriosis) in the total population, and do not take into account a severity factor because the comparisons were made between risks due to a single hazard (L. monocytogenes) in a large number of foods. The report also generated estimates of likelihood of illness in the perinatal and elderly susceptible populations.
FSANZ previously concluded that L. monocytogenes in ready-to-eat finfish (such as cold-smoked salmon) poses a significant public health risk, particularly for vulnerable subgroups, recognising that while the incidence of disease is low in the population, the impact (death) for the infected individual is severe [49]. The assessment led to maintenance of the microbiological limit standard for L. monocytogenes in smoked seafood.