The number of listeriosis cases in 2017 in England and Wales dropped to its lowest level for at least a decade, according to Public Health England (PHE).

A total of 135 Listeria infections were reported which represented a 17.7 percent decline compared to the average number (164) in the previous six years (2010-2016). The highest number of cases based on data from 2008 onwards was 209 in 2009 while 179 were reported in 2016.

PHE officials said that while listeriosis remains a rarely reported disease, as a predominantly foodborne infection, it is largely preventable.

“It remains imperative that sporadic cases of illness and clusters of disease continue to be monitored and investigated to inform the continued risk assessment of the food chain,” according to the report.

In 2017, there were 33 reported deaths among 109 non-pregnancy cases. This represented a 2.1 percent decline in deaths compared to the average number (46) in the preceding six years (2010-2016).

There were four outbreaks of listeriosis in England in 2017. The first had five clinical cases and was associated with a cooked chicken firm and the second had two cases and was traced to a sandwich producer where the same strain of Listeria monocytogenes was recovered from patient specimens and food samples.

The other two outbreaks were national with one involving three cases in 2017 and the other affecting 14 people from 2012-2017 with the source of infection listed as unknown.

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Two more incidents involved sporadic cases microbiologically linked to food samples by recovering the same strain of Listeria from patient specimens and food samples; one involving pre-prepared sandwiches and the other a raw milk cheese.

The largest proportion of reported listeriosis was in those older than 60, particularly elderly men aged 70 and over. All 13 cases in the 10–19 and 20–29 age groups (range 17-29) were female and associated with pregnancy.

Pregnancy associated infections accounted for nearly a fifth of (26) reported cases and, where known, almost a quarter of pregnancy-associated cases resulted in miscarriage or still birth.

In England, Yorkshire and The Humber had the highest incidence rate of 0.35 cases per 100,000 population whilst the East of England had the lowest rate of 0.08 cases per 100,000 population. In Wales, it was 0.13 cases per 100,000 population.

July was the peak month for listeriosis reporting in 2017, although cases were infected with different subtypes of Listeria monocytogenes and no outbreaks influenced this peak. In the previous two years, case numbers peaked in October.

Listeria data in Europe

Meanwhile, the European Centre for Disease Prevention and Control (ECDC) recently released 2016 data for Listeria in Europe. It is based on data retrieved from The European Surveillance System (TESSy).

In 2016, 2,555 confirmed cases of listeriosis were reported by 30 EU/EEA countries. Germany and France had the highest numbers of infections with 697 and 375 respectively, making up 42 percent of all cases reported in Europe. The highest incidence rates were in Belgium and Finland.

Five Listeria outbreaks were reported to the European Food Safety Authority (EFSA) with 25 cases.

Reported listeriosis cases at EU/EEA level show an increasing trend. Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Poland, Romania, Slovenia, Spain and Sweden have had a significant increasing trend of confirmed cases since 2008. No member state has seen decreasing trends between 2008–2016 or 2012–2016.

The ECDC said this increasing trend was “worrying” and called for more attention to be placed on the prevention and control of the disease and outbreaks.

In 2016, cases of listeriosis showed a seasonal pattern similar to previous years, but at a higher level throughout the year. The highest numbers of cases were reported in July, August and September.

Gender distribution of confirmed cases for which information was provided (2,551 cases) was 52.9 percent males and 47.1 percent females. The most affected age groups were infants under one year with 74 cases and those over 64 years with 1,665 cases. The majority of listeriosis cases were reported in people over 64 years, especially males.

Almost all reported listeriosis cases were hospitalized (97.7 percent) and 247 were fatal.

The case rate has steadily increased in recent years among those more than 75 years old, as well as females between 25 and 44 years, which is likely pregnancy-related. For the elderly population, the increase could be linked to the growing proportion of people aged over 45 with underlying health conditions.

The rise in consumption of ready-to-eat foods and an improved listeriosis surveillance system in certain member states may have also contributed to the rising trend.

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