Eurosurveillance - Volume 12, Issue 4, 01 April 2007

This paper examines influenza vaccine coverage rates (VCR) in Poland and Sweden during the 2003/4 and 2004/5 influenza seasons. An average sample of 2,500 persons was interviewed in each country and each season. Questions regarded age and possible chronic diseases, as well as information on whether they had had an influenza vaccination in the given season. Those who had not received the vaccine were also asked to give reasons for non-vaccination. About one in four (Sweden) to one in three (Poland) of the persons surveyed belonged to high-risk groups (>=65 years of age or suffering from chronic diseases). In the 2004/5 season, 17% (CI 12-19%) of the Polish elderly and 45% (CI 39-50%) of the Swedish elderly were vaccinated. In Poland, 9% (CI 7-12%) of respondents younger than 65 years of age with a chronic condition were vaccinated, whereas in Sweden the corresponding rate was 12% (CI 9-16%). In both countries, the VCR did not change significantly from the previous season. Personal invitations resulted in a higher VCR. In Sweden, the most frequently mentioned reasons for not being vaccinated were the assumption of not qualifying for a vaccination and perceived resistance. In Poland in both years, perceived resistance to flu and the cost of the vaccination were the most often mentioned reasons. The influenza vaccination rates in Poland and Sweden remain far below World Health Organization (WHO) recommendations for the high-risk population. No increase in VCR as demonstrated in this study may indicate that these two countries will not be able to meet the 2010 WHO target, if no further action is taken concerning vaccine uptake.

Sentinel surveillance systems offer advantages over passive surveillance which is known to have limitations due to incomplete reporting. Sentinel surveillance gathering data from selected sources was piloted as an option for surveillance of infectious intestinal disease (IID) in Malta. Between October 2004 and May 2005, 22 general practitioners (GPs) voluntarily participated in the study and reported on the number of IID cases (by age and sex) and all primary care encounters in their practice. The GPs' reporting activity lasted for 35 weeks, covering a total of 55,425 primary care encounters, of which 1.95% concerned IID. For every case reported via the routine passive notification system, seven cases would be picked up by this enhanced sentinel surveillance. .

Due to the influenza pandemic threat, many countries are stockpiling antivirals in the hope of limiting the impact of a future pandemic virus. Since resistance to antiviral drugs would probably significantly alter the effectiveness of antivirals, surveillance programmes to monitor the emergence of resistance are of considerable importance. During the 2006/2007 influenza season, an inventory was conducted by the European Surveillance Network for Vigilance against Viral Resistance (VIRGIL) in collaboration with the European Influenza Surveillance Scheme (EISS) to evaluate antiviral susceptibility testing by the National Influenza Reference Laboratories (NIRL) in relation to the national antiviral stockpile in 30 European countries that are members of EISS. All countries except Ukraine had a stockpile of the neuraminidase inhibitor (NAI) oseltamivir. Additionally, four countries had a stockpile of the NAI zanamivir and three of the M2 ion channel inhibitor rimantadine. Of 29 countries with a NAI stockpile, six countries'; NIRLs could determine virus susceptibility by 50% inhibitory concentration (IC50) and in 13 countries it could be done by sequencing. Only in one of the three countries with a rimantadine stockpile could the NIRL determine virus susceptibility, by sequencing only. However, including the 18 countries that had plans to introduce or extend antiviral susceptibility testing, the NIRLs of 21 of the 29 countries with a stockpile would be capable of susceptibility testing appropriate to the stockpiled drug by the end of the 2007/2008 influenza season. Although most European countries in this study have stockpiles of influenza antivirals, susceptibility surveillance capability by the NIRLs appropriate to the stockpiled antivirals is limited.

A Chlamydia trachomatis variant that contains a 377 bp deletion in the cryptic plasmid was recently reported in Sweden. This deletion includes the targets for Cobas Amplicor, Cobas TaqMan48, and Abbott m2000. We examined the proportion and characteristics of this variant in Örebro county, Sweden and developed an effective diagnostic solution. In total, 2,401 consecutive C. trachomatis culture samples and 536 PCR samples from symptomatic and asymptomatic patients and screened females were included. Culture, Cobas Amplicor, and LightMix 480HT were used for diagnosis. A mutant-specific PCR, plasmid sequencing, omp1 sequencing and multilocus sequence typing (MLST) were used to identify and characterise mutants. In total, 162 (6.7%) of the cultured samples were positive for C. trachomatis. However, 61 (38%) of those were negative when using Cobas Amplicor, and 60 of these were subsequently confirmed as the new variant. 13 of these mutant isolates were further characterised genetically, and all were of identical genotype E and the unique MLST sequence type: 21, 19, 1, 2, 1. Of all culture-positive samples, 161 of 162 were positive in the LightMix 480HT assay. The single negative sample was only weakly positive in culture, and negative in all PCRs. Of the 536 PCR samples, 37 were positive in both Cobas Amplicor and LightMix 480HT, 13 were only positive in LightMix 480HT (mutants), and two were only positive in Cobas Amplicor. Mutated C. trachomatis were prevalent in Örebro county in the period from October 2006 to February 2007, and it appeared to be a single clone. LightMix 480HT seemed sensitive, specific, and enabled high throughput diagnostics. However, rare low positive samples may be false-negative. Frequent surveillance and evaluations of diagnostic methods worldwide are crucial. .

In April 2005, a case of reactivation of hepatitis B virus (HBV) infection occurred in a patient undergoing haemodialysis in an Irish hospital. This incident potentially affected patients attending hospitals throughout the country, so a national incident team was set up coordinate the response to the incident. A total of 306 dialysis patients, attending 17 different dialysis centres (14 in Ireland), were identified as having been potentially exposed to HBV as a result of this incident. A programme of HBV serological testing and HBV vaccination was instituted. There was no evidence that any patient acquired HBV infection as a result of cross-infection from the index patient, although 11 patients (3.6%) had evidence of past infection (anti-HBc positive, HBsAg negative). The majority of patients in this cohort were of unknown HBV vaccination status (62.7%), 13.4% were fully vaccinated, 4.6% partially vaccinated and 15.7% unvaccinated. Of 239 tested for anti-HBs, 183 (76.6%) had a titre <10 mIU/ml. Local incidents in dialysis units can have national implications due to the frequent patient transfer between units. This incident highlighted serious deficiencies in current structures and practices, and a lack of appropriate guidelines. However, there were positive outcomes from this incident. The majority of Irish dialysis patients have now been vaccinated against HBV, and lessons learned have been used to develop national guidelines on HBV vaccination and testing and on the management of incidents of blood-borne viral infections in dialysis units.

In early September 2006, the Norwegian Institute of Public Health was alerted to an outbreak of Shigella sonnei infections (shigellosis) among 23 Norwegian passengers who had taken a bus tour from Kirkenes, Norway to Murmansk, Russia. The trip lasted from 27 to 31 August, and the group stayed in various hotels and visited several restaurants in both Kirkenes and Murmansk during this period. Stool samples from three ill passengers yielded S. sonnei; an additional 10 passengers had gastrointestinal symptoms with diarrhoea or loose stools with abdominal pain. An investigation was initiated in collaboration with the department of epidemiological surveillance in Murmansk. We sent a questionnaire to the work e-mail addresses of all passengers asking about symptoms and exposures. Two restaurants and a hotel visited by the Norwegian tourists in Murmansk were inspected and sampled. Of all the food and beverage items mentioned in the questionnaire, only cured meat consumed in restaurant A in Murmansk on 28 August was associated with the risk of developing illness. Inspections of the restaurants in Murmansk identified some hygienic shortcomings and inadequate routines. However, S. sonnei could not be isolated from food samples or the personnel. Improved routines were implemented.

Salmonella enterica is a common cause of gastrointestinal illness in Italy. S. Typhimurium accounts for approximately 40% of isolates, and most of these strains belong to the phage type DT104. We describe the investigation of an outbreak of S. Typhimurium DT104A, a subtype never observed before in Italy, which occurred in Rome during spring 2004. We conducted a matched case control study between 24 July and 9 September 2004. Controls were matched for age and area of residence. Each case had between one and four controls. Odds of exposure to potential risk factors and vehicles for the outbreak were compared between cases and controls. A multivariate analysis was conducted to estimate adjusted Odds Ratios. Sixty-three cases of S. Typhimurium DT 104A infection with onset between 1 April and 5 May 2004 were identified. Sixty-one were residents of Rome and two were residents of a neighbouring region. Twenty-six cases (43%) were enrolled in the study. Their median age was 7.5 years. Fourteen of 26 cases and 16 of 62 controls had eaten pork salami (OR= 25.5; 95% CI 1.6- 416.8). No food samples were available for testing. In northern Italy, two months prior to the outbreak, the veterinary surveillance system identified the first isolation of S. Typhimurium DT104A in a pig isolate. Both human and pig isolates showed indistinguishable PFGE patterns. It was not possible to trace the pig after the sample was taken at slaughter. The epidemiological evidence on the implication of pork salami in this outbreak suggests that pork products can also be a vehicle for salmonella in Italy and underlines the importance of good manufacturing practices for ready-to-eat foods. This investigation highlights the value of laboratory-based surveillance in identifying community-wide outbreaks of uncommon pathogens. It also underlines the need to improve surveillance timeliness, for promptly detecting outbreaks, undergoing field investigation, and implementing control measures. Moreover, our study shows the usefulness of integrated human and animal surveillance in tracing the possible source of infection.