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Final Issue: Volume 16 Number 51

Published on: 21 December 2006

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Last updated: Volume 14, No.8 (PDF file, KB)

Archives | News Archives 2004: Page 1 | News 23 February 2006

News Archives: | 2006 | 2005 | 2004 | 2003

National case-control study of Salmonella Enteritidis Phage Type (PT) 14b infection implicates eggs used in the catering trade

 

Following a national increase in Salmonella Enteritidis Phage Type 14b in 2003, detected by the Health Protection Agency Laboratory of Enteric Pathogens (1), analysis of the main exposure variables in an initial case-control study, conducted through Local and Regional Services, suggested that food consumed outside the home, and from specific types of catering establishments in particular, was the most likely source of infection. These hypotheses were tested in a second, larger national case-control study, conducted by the Gastrointestinal Diseases Department of the Communicable Disease Surveillance Centre.

An unmatched prospective case-control study was undertaken. Cases were adults, resident in England and Wales and who had not travelled abroad within the incubation period, with laboratory-confirmed S. Enteritidis PT14b infection. Structured interviews were conducted over the telephone. Asymptomatic controls were recruited through systematic sequential dialling, based on the cases’ telephone numbers. Interviews were conducted in the early evenings and at weekends to maximise case response and to ensure that controls accurately represented the population from which the cases arose.

Fifty-five cases and 102 controls were included in the analyses. In the single variable analysis cases were more likely to report travel within the UK (estimated odds ratio (OR)=4.42; 95% confidence intervals (CI)=1.50-13.05; P Value = 0.003), consuming eggs away from home (OR=5.27; 95%CI = 2.12-13.12; P= 0.0001), consuming food from commercial catering premises (OR=2.93; 95%CI=1.39-6.16; P=0.003), consuming sandwiches bought outside the home (OR=3.07; 95%CI=1.39-6.77; P=0.003) and consuming egg sandwiches outside the home (OR=4.09; 95%CI=0.90-18.60; P=0.05). They were more likely to report eating food from Chinese restaurants (OR=3.56; 95%CI=1.19-10.64; P=0.02), eating eggs in Chinese restaurants (OR=3.80; 95%CI=1.17-12.27; P=0.02) and chicken dishes in Chinese restaurants (OR=4.17; 95%CI=1.16-14.95; P=0.02). They were less likely to report consumption of lion-marked eggs (OR=0.35; 95%CI=0.16-0.94; P=0.03), chicken in the home (OR=0.45; 95%CI=0.22-0.93; P=0.03) or to have cooked raw chicken in the home (OR=0.29; 95%CI=0.12-0.72; P=0.005).

Logistic regression analyses were employed to allow for confounding variables such as age and sex. Three models were used to examine the hypotheses concerning egg consumption and types of premises. When the premises type was examined alongside consumption of eggs outside the home, eating eggs away from home was independently associated with being a case of S. Enteritidis PT14b infection (OR=5.02; 95%CI= 2.09-12.05; P<0.001).

Prior to 2001, S. Enteritidis PT14b accounted for less than 200 laboratory-confirmed cases a year. Since 2001 the annual totals have risen sharply, the provisional total for 2003 being 922 cases. In 2002 a large national outbreak of S. Enteritidis PT14b was associated with buying food from local bakers’ shops, eating from sandwich bars and buying food from local butchers’ shops (2). During the investigation of a number of S. Enteritidis outbreaks in 2002 S. Enteritidis PT14b was isolated from eggs originating from Spain (3). Using the molecular typing methods plasmid analysis and pulsed field gel electrophoresis, clinical isolates from outbreak cases of PT14b in 2003 were indistinguishable from outbreak-related clinical and egg isolates of this phage type in 2002. This suggests that the PT14b outbreak in 2003 might have been a continuation of the 2002 situation, probably resulting from the same source.

The Food Standards Agency’s advice to caterers is that raw shell eggs should not be used in any food that will not be cooked (or will only be lightly cooked) (4).

 

References

1.Health Protection Agency. National increases in salmonellosis. Commun Dis Rep CDR Weekly [serial online] 2003 [cited 17 February 2004] 13 (30): news. Available at <http://www.hpa.org.uk/cdr/archives/2003/3003.pdf>.

2.PHLS. National outbreak of Salmonella Enteritidis PT 14b: update. Commun Dis Rep CDR Weekly [serial online] 2002 [cited 17 February 2004] 12 (43):news. Available at <http://wwww.hpa.org.uk/cdr/archives/2002/cdr4502.pdf>.

3.PHLS. Public health investigation of Salmonella Enteritidis in raw shell eggs. Commun Dis Rep CDR Weekly [serial online] 2002 [cited 17 February 2004] 12 (50):news. Available at <http://wwww.hpa.org.uk/cdr/archives/2002/cdr5002.pdf>.

4.Food Standards Agency. Eggs – what caterers need to know. London: FSA, 2002. Available at <http://www.food.gov.uk/multimedia/pdfs/eggleaflet.pdf> [cited 17 February 2004].

 

Avian influenza (H5N1) among poultry in south east and east Asia, and humans in Viet Nam and Thailand - update

 

Outbreaks of avian influenza in poultry
The number of countries reporting outbreaks of avian influenza (H5N1) in poultry has remained stable since beginning of February. The number of confirmed poultry outbreaks in China, Thailand, and Viet Nam continues to increase, due in part to increased case ascertainment. A map of affected areas can be found at:
<http://www.europa.eu.int/comm/health/ph_threats/com/Influenza/images/pathogenic.jpg>

Human cases of avian influenza
Viet Nam and Thailand remain the only countries that have reported human cases of infection by 18 February. Viet Nam has reported 22 cases, 15 of whom have died, and Thailand has reported nine cases, seven of whom have died.

The World Health Organization (WHO) has published the first clinical and epidemiological data on 10 human H5N1 cases in the Viet Nam outbreak at <http://www.who.int/csr/disease/avian_influenza/guidelines/vietnamclinical/en/>, and clinical information on five laboratory-confirmed cases in Thailand at <http://www.who.int/csr/disease/avian_influenza/guidelines/WERAvianinfluenza/en/>. This preliminary clinical report acknowledges that the full spectrum of H5N1 illness is unknown. Milder cases of illness could be occurring, yet fail to reach the attention of health care staff. As a consequence, the current small number of laboratory-confirmed cases cannot be taken as an accurate indication of the magnitude of the present or potential threat to human health

The WHO has published a chronology of key events in the current outbreak. These can be found at: <http://www.who.int/csr/disease/avian_influenza/chronology/en/>

Surveillance of suspected human cases of avian influenza
The Health Protection Agency has published interim guidelines for the surveillance of suspected cases of avian influenza. These can be found at: <http://www.hpa.org.uk/infections/topics_az/avianinfluenza/guidelines.htm>. A case report form can also be found at the same address.

The WHO has published guidelines for the global surveillance of influenza A (H5). These can be found at: <http://www.who.int/csr/disease/avian_influenza/guidelines/globalsurveillance/en/>

 

World Health Organization announce the influenza vaccine composition for the 2004/05

 

The composition of the influenza vaccine for the 2004/05 season (Northern Hemisphere winter) was announced by the World Health Organization in Geneva on 13 February 2004. The vaccine will contain:

 

* The currently used vaccine virus is A/Wyoming/3/2003. A /Kumamoto/102/2002 is also available as a vaccine virus.
† Candidate vaccine viruses include B/Shanghai/361/2002 and B/Jilin/20/2003 which is a B/Shanghai/361/2002-like virus