No 3 - 2010

Increase in the number of Listeria cases in 2009

After remaining stable at 30-40 for a period of years, the number of notified listeriosis cases has increased every year as from 2003, barring 2008, Figure 1. In 2009, a total of 97 cases were notified, i.e. 2-3 times the previous level.

Listeriosis is a food-borne disease caused by infection with Listeria monocytogenes. The bacterium occurs in many types of raw and processed foods including vegetables, smoked foods, meat and diary pro-ducts. The bacteria reproduce at fridge temperature, but perish when heated.

Listeriosis is typically seen in conjunction with sepsis with or without meningitis, while localised infections are rare.

The condition primarily affects persons above 60 years and immunodeficient individuals. Risk factors include, among others: Cancer, haematological conditions, diabetes, alcoholism, organ transplants and AIDS.

Furthermore, pregnant women are at risk, and L. monocytogenes infection may cause abortion/still birth or cases of congenital sepsis/meningitis. Frequently, these infants are seriously ill at birth, but have a good prognosis when receiving adequate therapy.

L. monocytogenes is susceptible to cephalosporins, but responds to ampicillin. For a more detailed description of listeriosis, please see EPI-NEWS 34/98 (not avaiable online) and 42-43/06.

In Denmark listeriosis cases are notifiable via the laboratory notification system and strains of L. monocytogenes which have been isolated from patients are forwarded to Statens Serum Institut. To identify any outbreaks, methods of serology and molecular biology, including PFGE (pulsed field gel electrophoresis), is used for typing.

Commentary

The reason for the increased number of listeria cases observed in 2009 is unknown. A preliminary revision of patient data has not identified predisposing factors not already known.

Apart from a single outbreak, EPI-NEWS 36/09, in which eight persons were diagnosed with listeriosis after ingesting pre-cooked food from a catering company, no outbreaks were detected in 2009.

In 2009, the clinical microbiology departments have forwarded the isolated strains soon after bacteria growth, and it has therefore been possible to obtain timely typing results. This has been a great advantage in connection with the confirmation/dismissal of outbreak suspicion and also in the process of delimiting the patients forming part of the outbreak. A number of other European countries have experienced increases in the number of patients with listeriosis.

(M. Kemp. Department for Microbiological Monitoring & Research, S. Ethelberg, Department of Epidemiology)

Salmonella concord among adopted ethiopian children

In Denmark, Salmonella Concord is normally a very rare salmonella serotype. It has been isolated 0 - 2 times annually during the latest 10-year-period. In 2009 the infection was observed in eight cases. All patients were adopted children from Ethiopia, seven of whom were infants. The salmonella isolates were all ESBL-producing and multiresistant with resistance to ampicillin, cefotaxime, ceftiofur, chloramphenicol, gentamicine, streptomycine, sulfamethoxazole, tetracycline and trimethoprim and had reduced sensitivity to ciprofloxacin. They were sensitive to apramycin and amoxicillin+clavulanate.

Commentary

International studies have previously shown that multiresistant Salmonella Concord commonly occurs among children adopted from Ethiopia. The 2009 increase shows that this issue remains relevant. When assessing the state of health of adopted Ethiopian children upon arrival to Denmark, salmonella infection should therefore be considered and physicians should include the possibility of multi-resistance. (R. Hendriksen, DTU Food, K. Mølbak, S. Ethelberg, Department of Epidemiology)

Supply situation for Japanese encephalitis vaccine
Unfortunately, we have experienced production and supply problems for the Ixiaro® vaccine against Japanese encephalitis (JE) since the end of December 2009, and the JE vaccine has therefore not been available for all January orders. The next delivery of Ixiaro® is expected by the beginning of February, at which point all orders will be delivered.

(B. Neale, Sales and Business Development)

Counselling of the general public

The SSI continuously receives a number of enquiries from private citizens stating that their GP has referred them for counselling about travel vaccination or the like. SSI does not usually advise private citizens. The counselling should take place via the person’s own GP or other healthcare staff who, in case of doubt or for more detailed questions, may contact the Institute. Further, on the SSI website www.ssi.dk, answers to many questions may be found.

(Department of Epidemiology)

Individually notifiable diseases and selected laboratory diagnosed infections

20 January 2010