HPS

Norovirus

There were 1306 laboratory reports of norovirus (NV) to HPS in 2014. This is a marked decrease of 609 (31.8%) compared with 2013 when there were 1915 reports, and follows a decrease of 35% between 2012 and 2013. The 1306 total recorded in 2014 is also the lowest number of reports in a single year in the past ten years (Figure 1).

These laboratory reports arise from confirmed infection in the whole population (community and healthcare). Laboratory confirmed cases represent just a small proportion of the true incidence in the community. The second study of infectious intestinal disease in the community (IID2 Study – accessible at http://www.food.gov.uk/science/research/foodborneillness/b14programme/b14pr…) estimated that approximately 290 cases of NV occur in the community for every case reported to national surveillance.

In Scotland the overall rate for reports of NV in 2014 was 24.5 per 100,000 compared with 36.0 per 100,000 the previous year. Rates declined in nine NHS boards and increased in five NHS boards. Rates among NHS boards ranged from 2.1 to 111.5 per 100,000 (Table 1). Some of the differences between NHS boards may be due to differences in clinical or reporting practices. The rates for the island NHS boards should be viewed with caution due to the effect of their small population.

Laboratory reports of NV showed a distinct age distribution affecting the elderly and young, with 57% (742/1306) reported from those aged 65 years and over, 21% (280/1306) from those under five years of age, while none of the other age bands accounted for more than 3% of reports.

Rotavirus

Rotavirus is the most common cause of diarrhoea in young children. An immunisation programme for rotavirus was introduced into the infant immunisation schedule in July 2013, (more information is available in the Chief Medical Officer’s letter CMO9(2013)04 at http://www.sehd.scot.nhs.uk/cmo/CMO(2013)04.pdf). Further information about rotavirus vaccination is also available from the public information website: http://www.immunisationscotland.org.uk/vaccines-and-diseases/rotavirus.aspx.

The introduction of the vaccine programme has had a significant impact on the number of laboratory reports, reducing them from 1301 in 2013 to 346 in 2014 (Figure 2). Of the reports in 2014, 321 (92.5%) were from children under the age of five. Figure 3 shows the impact of the rotavirus programme in eliminating the distinctive historical peak for rotavirus infection in early spring and the size of the reduction in 2014 compared to the average for the previous five years.

Hepatitis A

There were 32 reports of hepatitis A in 2014, an increase of 10 on 2013 when there were 22 such reports, however case numbers remain low and subject to random year-on-year variation.

Hepatitis E

Reports of hepatitis E (HEV) infection in Scotland have increased in recent years, as they have elsewhere in the UK. Since 2011 laboratory reports of HEV in Scotland have increased from 13 in 2011, to 78 in 2012, 95 in 2013 and 161 in 2014. The overall rate of HEV in Scotland in 2014 was 3.0 per 100,000, with a predominance of infection in older males. In 2014, 98 (61%) of reports were from males and, of these, 35 (37.5%) were from males aged 65 years and older.

HEV is emerging as an important new issue in Scotland and while some of the increase in reported cases is likely to be due to increased testing and better ascertainment, it is also believed to reflect a real increase in incidence. HPS is working with colleagues in Food Standards Scotland, the Scottish Government, NHS boards and Public Health England to improve understanding of the epidemiology of HEV, including risk factors and exposures, to inform public health management and control.

Listeria monocytogenes

The importance of L. monocytogenes as a gastro-intestinal pathogen arises not from the number of reported cases, which are relatively low compared to many other pathogens, but rather due to the severity of infection and high mortality. In line with reporting in the rest of the UK and Europe, pregnancy-associated cases are counted as one case, even when both the mother and infant are positive.

Infection with L. monocytogenes can cause an influenza-like illness, septicaemia or a meningo-encephalitis. Pregnant women, newborn infants, the elderly and the immunocompromised are most at risk.

There were 15 cases of L. monocytogenes reported in 2014, the same as reported in 2013 and similar to previous years (Figure 4).

HPS is grateful to all consultants in public health medicine, health protection nurses, microbiologists and environmental health officers who contribute to the enhanced surveillance of Listeria infection in Scotland, the aim of which is to improve our understanding of such infection.

Shigella

Among the species of Shigella reported, the most common was Shigella sonnei. In 2014, 49 cases of Shigella sonnei were reported, a decline of 13 (20.9%) compared to 2013.

Thirty-four cases of Shigella flexneri were reported in 2014, an increase of 15 compared to the 19 reported in 2013. Typing information was available for 32 of the 34 reports in 2014. The most common serotypes were 2a and 3a, responsible for 13 and 11 isolates respectively, while six isolates were of serotype 6 and two of serotype 1a.

Four cases of Shigella boydii and one of Shigella dysenteriae were reported in 2014.

Yersinia

In 2014 there were four reports of Yersinia enterocolitica compared to six in 2013 and ten in 2012.