• National increase in Salmonella Java infection: England, November 2007

• Norovirus update December 2007

National increase in Salmonella Java infection: England: November 2007

Since 1 November 2007 the Health Protection Agency (HPA) Laboratory of Enteric Pathogens (LEP) have received and provisionally confirmed 23 human cases of Salmonella Paratyhi B variant Java phage type (PT) 3B Var 9 (= S. Java PT 3B var 9) infection in residents of England. Two cases reported recent contact with other individuals with gastrointestinal symptoms and were excluded, leaving 19 primary UK-acquired cases of fully antibiotic sensitive S. Java PT 3B Var 9 infection, and one with the resistance profile (R-type) of GKSSuT (G, gentamicin, K, kanamycin; S, streptomycin; Su, sulphonamides; T, tetracyclines)

Cases ranged in age from 1 to 87 years (median 40 years) and 52% of cases are female. Most were residents of the eastern parts of central England (figure 1). Pulsed-field gel electrophoresis (PFGE) has been conducted on 15 isolates, and 14 were considered to exhibit the outbreak strain PFGE profile designated SPTJXB.0001.

Figure 1. Geographical distribution of cases of Salmonella Paratyhi B variant Java since 1 November 2007 (N=19)

The onset of illness for the majority of cases was between 29 October and 20 November (figure 2)

Figure 2. Epidemic curve (n=18, for whom onset dates are known)

In response to this increase, the HPA conducted epidemiological investigations to generate hypotheses for disease transmission. Twelve cases in England were interviewed between 11 and 15 December to clarify symptoms and develop an hypothesis for disease transmission.

Cases' onset dates ranged from 29 October to 17 November 2007. Diarrhoea (100%), abdominal pain (100%), headaches (86%) and fever (71%) were the most commonly reported symptoms. One case (14%) reported blood in stools and, not everyone who experienced nausea (57%) also experienced vomiting (43%). Illness ranged from four to 47 days (median 25 days) and one case was admitted to hospital (for six days) as a result of their illness.

Eleven of the 12 cases reported the consumption of salad vegetables, however, these were bought from a number of retailing and catering outlets. No single leaf type was clearly identified. The frequencies of consumption of other foods were all markedly lower.

No further cases have been reported to CFI since 11 December. At this point, there are too few cases to perform a case-control study with sufficient statistical power, so there is insufficient evidence to point to one source of the outbreak.

Norovirus update December 2007

Noroviruses frequently cause outbreaks in environments where groups congregate and infection can be rapidly transmitted by both fecal and vomitus routes. Outbreaks affect healthcare facilities worldwide, and may cause massive disruption to providing care, substantial economics loss, and, according to some reports, mortality in vulnerable patient populations.

More than three-quarters of all norovirus outbreaks reported to the HPA Centre for Infections occur in health-care settings (1765/2186 outbreaks reported from 2000 to 2006). We have previously estimated that in epidemic seasons, noroviruses may cost the NHS in excess of £100M per year. Norovirus, like influenza, has strong winter-time seasonality. The 2007 norovirus season has started uncharacteristically early, with a greater number of cases nationally from the first week of November.

The number of cases reported this year surpasses all other recent years, except 2002, which was the most severe season recorded and was associated with the emergence of a new antigenic virus type. These laboratory reports reflect only a tiny fraction (estimated at 1:1500) of all infections that occur in the community and hospitals. The figure below illustrates that the increase in norovirus shows no signs of abatement up to week 48 of 2007. Some caution should, however, be exercised in the interpretation of the 2007 data. This is the first season that sensitive molecular diagnostics have been used in Regional Laboratories. Therefore, the increased numbers may, in part, be a result of improved diagnostic capacity in the regions.

Table. Norovirus laboratory reports from England and Wales at the beginning of the norovirus season

Year	weeks 36 to 48
2000	288
2001	311
2002	1845
2003	313
2004	803
2005	281
2006	685
2007	1325