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Volume 3 No 42; 23 October 2009

HPR Home | Archives | 2009 news

• National increase in Salmonella Enteritidis Phage Type 14b infections in England
  
  
• Gastroenteritis associated with travel to Turkey
  
  
• Pandemic influenza: UK situation at 22 October 2009
  

National increase in Salmonella Enteritidis Phage Type 14b infections in England

This report outlines an upsurge that has been noted since mid August in the number of non-travel human isolates of Salmonella Enteritidis PT14b. Most non typhoidal salmonella infections, of which there are over 2500 serotypes that cause gastroenteritis, are caused by S. Enteritidis, and S. Enteritidis accounted for 43% of all salmonella infections in England and Wales during 2008.

Illness normally occurs 12-48 hours (range 5-72 hours) after the ingestion of this bacterium and is characterised by non-bloody diarrhoea, nausea, vomiting, fever and abdominal pain.  Diagnosis is by the isolation of the bacterium from samples of faeces, usually taken during the symptomatic period, and also from blood or other body fluids where systemic illness has occurred.  Carriage and shedding of the organisms may occur for up to one year in children under five (median 10 weeks) and for up to 12 weeks (median 4 weeks) in older patients.

Antimicrobial chemotherapy is recommended for invasive disease but not in uncomplicated gastroenteritis and treatment may prolong carriage of this bacterium.  Some strains of this bacterium have outstanding properties for acquiring resistance to antimicrobial agents which are used in both human and veterinary medicine as well as in animal husbandry. Increased resistance to antimicrobial agents in salmonella has reduced the effective therapeutic options for human medicine for treating systemic infections.

Transmission occurs by eating contaminated food, mainly of animal origin, or by faecal contamination from an infected person or animal. Risk factors for S. Enteritidis infection include the consumption of contaminated poultry meat and eggs, and from the handling of contaminated raw poultry meat and eggs and cross-contamination to other ready-to-eat food products. About 45% of cases are associated with overseas travel.

Current situation

The upsurge that is currently being investigated has been dominated by an antibiotic resistance profile, with 259 of those cases reported by the Laboratory of Gastrointestinal Pathogens in 2009 having resistance to naladixic acid and low level resistance to ciprofloxacin (NxCpl) compared to 136 cases in 2008.

Eight S. Enteritidis PT 14b NxCpl outbreaks have also been reported to the HPA during August and September in England, and one has occurred in Wales in late September. The earliest date of onset for these outbreaks was 17 August 2009. Five of the nine outbreaks have been linked to oriental restaurants, three were linked to other restaurant establishments, and one took place in a care home. These nine outbreaks are also above the level that might be expected, and this would appear to indicate significant exposure to this bacterium through a widespread common food source across several parts of the country. There are also other foodborne outbreaks of S. Enteritidis of different phage types that are being concurrently investigated to determine if these are linked or not to the PT 14b NxCpl outbreaks.

A total of 130 cases have been associated with the nine outbreaks, which have ranged in size from two to 68 cases. Seventy seven of the 130 cases have been confirmed as having S. Enteritidis PT 14b, and three have been hospitalized. In one outbreak (in a care home), deaths have been reported in two elderly people infected with S. Enteritidis PT 14b. Post mortem investigations have been conducted and the results inconclusive. Inquests have been ordered into both deaths.

Cumulative incidence (weekly) of non-travel related NxCpl resistant Salmonella Enteritidis PT14b by year, 2007-2009

Actions taken

All of the outbreaks have been investigated by the HPA or, in one instance, by Wales NPHS. Preliminary investigations have suggested putative links to chicken and/or eggs in some outbreaks, and this is being actively tested through analytical epidemiological studies and appropriate investigation of supply chains

A standard national protocol and guidance for the management and investigation of S. Enteritidis PT 14b outbreaks by the HPA National Outbreak Control Team (led by the Centre for Infections) has been prepared, disseminated and is in use across the Agency, ie by the Centre for Infections, Local and Regional Services Division, and the Regional Microbiology Network. Both local point source outbreaks and sporadic human cases of infection are being investigated. Investigation of sporadic human cases of infection started on 12 October 2009.The Food Standards Agency, Department for Environment, Food and Rural Affairs, Department of Health, and the Local Authorities Co-ordinators of Regulatory Services have been informed.

Gastroenteritis associated with travel to Turkey

During the summer of 2009, a large cluster of cases of gastroenteritis, of mixed aetiology, has been detected in travellers returning from a hotel complex in the resort of Sarigerme, south west Turkey. Active surveillance was initiated in mid-September following a series of ad hoc reports of cases received from late August onwards.

As of 21 October 2009, a total of 87 cases of gastroenteritis have been detected in England and Wales with onset dates in May (two cases) June (one), July (13), August (34), September (32), and October (five). Sixty-six of the cases (76%) are children aged 14 years and under. Both Salmonella Enteritidis and Cryptosporidium spp have been isolated in most cases, with many (28%) infected with both organisms. The breakdown of organisms isolated is detailed in table 1.

Table 1. Organisms isolated from cases of gastroenteritis associated with staying at a hotel complex in Turkey (onset dates May to October 2009)

Organism	Infection with single organism	Co-infection with Cryptosporidium	Co-infection with Campylobacter	Total
S. Enteritidis PT6	13	14	1	28
S . Enteritidis PT 21	8	8	-	16
S. Enteritidis PT 14B	1	-	-	1
S. Enteritidis untyped	1	1	-	2
S . Enteritidis subtotal	23	23	1	47
Salmonella sp (untyped)	6	1	-	7
Campylobacter	2	-	-	2
Cryptosporidium	31	-	-	31
Total	62	24	1	87

There were a number of anecdotal reports of gastrointestinal illness in travellers returning from the same resort during the summer of 2008 [1]. At that time 15 confirmed cases of S. Enteritidis PT6 were reported.

There has been an increase in laboratory reports of Salmonella Enteritidis (in particular S. Enteritidis PT 6) associated with recent travel to Turkey as a whole [figure 1] as well as a slight increase in the incidence of S. Enteritidis per 100,000 visits to Turkey up to 2008. The number of reports of Cryptosporidium spp associated with travel to Turkey has also increased slightly in 2008 and 2009. However, it must be noted that travel history for Cryptosporidium spp is very under reported, making interpretation of these data problematic.

Figure 1. Laboratory reports of Salmonella Enteritidis in England, Wales and Northern Ireland associated with recent travel to Turkey: 1999 to 15 October 2009

An independent environmental health consultancy, on behalf of the associated tour operator, conducted an audit of the hotel in August 2009 and no major breakdowns in hotel hygiene practices were reported. There are two further independent environmental audits taking place at the hotel to try to ascertain possible sources of infection (one on behalf of the BBC Watchdog programme, and one on behalf of the tour operator). The mixed aetiology of the cases reported is suggestive of a water source (although a foodborne source, such as washed salad, cannot be ruled out). Hotel outbreaks of gastrointestinal illness have sometimes been associated with swimming pool contamination [2], however, no evidence has yet been found to confirm or deny this as a source in this cluster.

The Health Protection Agency has shared available data about cases in returning travellers with the Federation of Tour Operators, the World Health Organization Regional Office for Europe, and the Turkish health authorities. There have been no similar increases in gastroenteritis observed within the general Turkish population, either nationally or in the region where the hotel is located. The Turkish health authorities are continuing to investigate the situation.

As the source of infection has not yet been determined, there is currently no specific advice for travellers to Turkey over and above general prevention measures. Gastroenteritis is a very common illness in travellers to many countries, and all travellers should ensure they practise food and water hygiene precautions particularly after going to the toilet and before eating. Information about general food and water hygiene is available from the NaTHNaC website. Travellers should observe hygiene notices displayed in hotels and around swimming pools and ensure that their children do not go in pools if they are suffering from diarrhoea. The use of appropriate swim wear for babies and very young children will minimise the risk of faecal accidents. Swimmers should take care to avoid swallowing water.

References

1. HPA. Imported infections, England and Wales: July to September 2008. Health Protection Report [HPR] Weekly 2008; 2(51). Available online at http://www.hpa.org.uk/h p r/archives/2009/hpr0109.pdf

2. Galmes A, Nicolau A, Gomis E, Guma M, Hernandez-Pezzi G, and Soler P. Cryptosporidiosis outbreak in British tourists who stayed at a hotel in Majorca, Spain. Eurosurveillance 2003; 7(33). Available online at http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=2275.

Pandemic influenza: UK situation at 22 October 2009

The Health Protection Agency's Weekly National Influenza Report of 22 October (week 43) [1] further described the UK (and international) situation as follows:

• Pandemic influenza activity increased across the UK, the main burden of disease remaining in school-aged children and young adults;
• In week 42 (week-ending 18 October), the weekly influenza/ILI consultation rates increased, and were above the winter baseline thresholds in England, Wales and Northern Ireland;
• The National Pandemic Flu Service (NPFS) continued to issue antiviral drugs to people in England with an influenza-like illness who called or logged on to the internet site. The number of assessments and antiviral collections has continued to increase gradually over the past week;
• At least 85 schools throughout England have reported outbreaks of ILI, since the beginning of the autumn term, with virological confirmation of pandemic influenza in at least one case in 65 of the schools. School outbreaks have also been reported from Scotland, Wales and Northern Ireland;
• Interpretation of data to produce estimates on the number of new cases continued to be subject to a considerable amount of uncertainty with the move to NPFS. HPA modelling gave an estimate of 53,000 (range 27,000 – 115,000) new cases in England in week 42. The estimated number of new cases increased in all regions and age groups;
• The main influenza virus circulating in the UK continued to be the pandemic (H1N1) 2009 strain, with few influenza H1 (non-pandemic), H3 and B viruses detected. Three of 1733 pandemic viruses tested have been confirmed to carry a mutation which confers resistance to the antiviral drugs oseltamivir; both have been shown phenotypically to be resistant to the drug but retain sensitivity to zanamivir and a third is undergoing further testing;
• The majority of pandemic influenza cases continued to be mild. The cumulative number of deaths reported due to pandemic (H1N1) 2009 in the UK was 119. There was a total of 884 new patients hospitalised with suspected pandemic influenza in the week 15 to 21 October, an increase from 667 in the previous week. The highest hospitalisation rates have consistently been in the under-5-year age group and have increased in all age groups recently;
• According to the European Centre for Disease Prevention and Control (ECDC), by 21 October, 5303 deaths due to pandemic influenza had been reported globally;
• According to the World Health Organisation (16 October), influenza activity is low in temperate southern hemisphere regions, is increasing in the temperate northern hemisphere regions and remains variable in tropical areas.
  

References
1. HPA. Weekly National Influenza Report: week 43 (22 September 2009, PDF 367 KB), HPA website: www.hpa.org.uk/swineflu/surveillance&epidemiology.