Burden and characteristics of influenza A and B in Danish intensive care units during the 2009/10 and 2010/11 influenza seasons.

Influenza surveillance in Danish intensive care units (ICUs) was performed during the 2009/10 and 2010/11 influenza seasons to monitor the burden on ICUs. All 44 Danish ICUs reported aggregate data for incidence and point prevalence, and case-based demographical and clinical parameters. Additional data on microbiological testing, vaccination and death were obtained from national registers. Ninety-six patients with influenza A(H1N1)pdm09 were recorded in 2009/10; 106 with influenza A and 42 with influenza B in 2010/11. The mean age of influenza A patients was higher in 2010/11 than in 2009/10, 53 vs. 44 years (P = 0·004). No differences in other demographic and clinical parameters were detected between influenza A and B patients. In conclusion, the number of patients with severe influenza was higher in Denmark during the 2010/11 than the 2009/10 season with a shift towards older age groups in influenza A patients. Influenza B caused severe illness and needs consideration in clinical and public health policy.

High heterogeneity in methods used for the laboratory confirmation of pertussis diagnosis among European countries, 2010: integration of epidemiological and laboratory surveillance must include standardisation of methodologies and quality assurance.

Despite extensive childhood immunisation, pertussis remains one of the world's leading causes of vaccine preventable deaths. The current methods used for laboratory diagnosis of pertussis include bacterial culture, polymerase chain reaction (PCR) and enzyme linked immunosorbent assay (ELISA) serology. We conducted a questionnaire survey to identify variations in the laboratory methods and protocols used among participating countries included in the European surveillance network for vaccine-preventable diseases(EUVAC.NET). In February 2010, we performed the survey using a web-based questionnaire and sent it to the country experts of 25 European Union countries,and two European Economic Area (EEA) countries,Norway and Iceland. The questionnaire consisted of 37 questions which covered both general information on surveillance methods and detailed laboratory methods used. A descriptive analysis was performed.Questionnaires were answered by all 27 contacted countries. Nineteen countries had pertussis reference laboratories at the national level; their functions varied from performing diagnosis to providing technical advice for routine microbiology laboratories. Culture,PCR and serology were used in 17, 18 and 20 countries,respectively. For PCR, nine laboratories used insertion sequence IS481 as the target gene, which is present in multiple copies in the Bordetella pertussis genome and thus has a greater sensitivity over single copy targets, but has been proved not to be specific for B.pertussis. Antibodies directed against pertussis toxin(PT) are specific for B. pertussis infections. For ELISA serology, only 13 countries' laboratories used purified PT as coating antigen and 10 included World Health Organization (WHO) or Food and Drug Administration (FDA) reference sera in their tests. This present survey shows that methods used for laboratory confirmation of pertussis differ widely among European countries and that there is a great heterogeneity of the reference laboratories and functions. To evaluate the effects of different pertussis immunisation programmes in Europe, standardisation and harmonisation of the laboratory methods are needed.

Electronic real-time surveillance for influenza-like illness: experience from the 2009 influenza A(H1N1) pandemic in Denmark.

To enhance surveillance for influenza-like illness (ILI)in Denmark, a year-round electronic reporting system was established in collaboration with the Danish medical on-call service (DMOS). In order to achieve real-time surveillance of ILI, a checkbox for ILI was inserted in the electronic health record and a system for daily transfer of data to the national surveillance centre was implemented. The weekly number of all consultations in DMOS was around 60,000, and activity of ILI peaked in week 46 of 2009 when 9.5% of 73,723 consultations were classified as ILI. The incidence of ILI reached a maximum on 16 November 2009 for individuals between five and 24 years of age, followed by peaks in children under five years, adults aged between 25 and 64 years and on 27 November in senior citizens(65 years old or older). In addition to the established influenza surveillance system, this novel system was useful because it was timelier than the sentinel surveillance system and allowed for a detailed situational analysis including subgroup analysis on a daily basis.

Nosocomial measles cluster in Denmark following an imported case, December 2008-January 2009.

A cluster of six confirmed cases with identical measles virus genotype was reported in Denmark between December 2008 and January 2009. The findings highlight the importance of vaccination before travelling and adherence to the routine vaccination schedule.

Rubella in Denmark.

An average of 20,000 rubella cases were recorded annually in Denmark until 1987. In 1989, however, only 1006 cases were reported, and the true current incidence of rubella infection in Denmark is unknown but considered to be very low and <1 per 100,000 population. The significant decrease in the incidence of rubella mirrors the success of vaccination of rubella seronegative women of childbearing age, which was initiated in Denmark in 1980. From 1982 and onwards the national health security scheme also refunded vaccination of children and the MMR vaccine was introduced in the Danish child-hood vaccination program in 1987. The low incidence has been sustainable due to these interventions, and since 1994 congenital rubella syndrome and rubella in pregnancy have been listed as notifiable infectious diseases in Denmark. Nevertheless, in order to meet the WHO goal of control of rubella in the Region, the introduction of mandatory reporting of all laboratory diagnosed rubella cases is now being considered.

Rubella in Denmark.

An average of 20 000 rubella cases were recorded annually in Denmark until 1987. In 1989, however, only 1006 cases were reported, and the true current incidence of rubella infection in Denmark is unknown but considered to be very low and <1 per 100 000 population. The significant decrease in the inci-dence of rubella mirrors the success of vaccination of rubella seronegative women of childbearing age, which was initiated in Denmark in 1980. From 1982 and onwards the national health security scheme also refunded vaccina-tion of children and the MMR vaccine was introduced in the Danish child-hood vaccination program in 1987. The low incidence has been sustainable due to these interventions, and since 1994 congenital rubella syndrome and rubella in pregnancy have been listed as notifiable infectious diseases in Denmark. Nevertheless, in order to meet the WHO goal of control of rubella in the Region, the introduction of mandatory reporting of all laboratory diagnosed rubella cases is now being considered.

Measles in Europe in 2001-2002.

A total of 17 928 measles cases were reported to EUVAC.NET in 2001-02, with a 41% increase between the 2 years, giving a crude incidence of 2.36 and 3.37 per 100 000 population respectively. Most reported cases were aged 1-9 years. Outbreak related measles cases amounted to 18% of reported cases in 2001 and 20% in 2002. Less than 1% of cases were known to be imported in 2001 and 2002. Encephalitis as a severe complication was reported in 21 in 2001 and 6 cases 2002. One death attributed to measles was reported in 2001. The proportion of reported cases with known vaccination status increased from 56% of cases in 2001 to 72% in 2002. Overall, the proportion of reported measles cases that were unvaccinated rose from 50% in 2001 to 66% in 2002.

The EUVAC-NET project: creation and operation of a surveillance community network for vaccine preventable infectious diseases.

The EUVAC-NET network is in charge of the epidemiological surveillance and control of vaccine preventable diseases. It is coordinated by the SSI in Denmark, in collaboration with the ISS in Italy. The two main diseases targeted by the network are measles and pertussis. A collaboration is planned with the PHLS for the monitoring of Haemophilus influenzae b. EUVAC-NET includes the Member States of the European Union, and Iceland, Norway and Switzerland.

The EUVAC-NET survey: national measles surveillance systems in the EU, Switzerland, Norway, and Iceland.

The EUVAC-NET network undertook a questionnaire study on measles surveillance systems in EU member countries, Switzerland, Norway and Iceland. All questionnaires were completed. Surveillance systems for measles are implemented in 16 of the 18 countries. Most countries have some case based data and in all countries the shift is towards case based surveillance for measles, though there are differences between countries concerning case definitions and classifications. A two-dose MMR vaccination schedule is implemented in all the EUVAC-NET countries but methods used for estimation of vaccination coverage are diverse.

The EUVAC-NET survey: national pertussis surveillance systems in the European Union, Switzerland, Norway, and Iceland.

A questionnaire was mailed out to member states of the European Union (EU) plus Switzerland, Norway, and Iceland, to inquire about the type of information routinely recorded in national pertussis surveillance systems. Information was requested on surveillance methods, type of information recorded for cases of pertussis, vaccination schedule, type of vaccine used, and methods for estimating vaccination coverage. Local surveillance methods, vaccination strategies, and methods to estimate vaccination coverage were found to differ widely across the participating countries. The results of the questionnaire survey show, however, that there are comparable subsets of variables common to many countries. Future activities of the EUVAC-NET project will include defining the homogeneous elements in national systems and to group appropriately those countries with common surveillance features.

[Resistant tuberculosis in Denmark]. / Resistent tuberkulose i Danmark.

INTRODUCTION: Increased rates of multidrug-resistant (MDR) tuberculosis (TB) has been reported from countries close to Denmark. We evaluated the incidence of drug resistance in Denmark in order to determine the magnitude of the problem. MATERIALS AND METHODS: Susceptibility testing was performed in isolates from 85.4% of all notified patients during 1991-1998. Epidemiological information was retrieved from the mandatory notification forms. RESULTS: Total drug resistance remained largely constant, although a minor increase was observed in 1997-1998. Monoresistance was observed in 7.3% of the isolates. Among 3.6% polyresistant isolates, resistance to isoniazid and streptomycin accounted for 2.8%, whereas MDR accounted for 0.5%. The MDR strains displayed different restriction fragment length polymorphism (RFLP) patterns, and no matches were identified in the international MDR database. Drug resistance in untreated Danes and foreigners were 5.9% and 14.6%, respectively. Among Danes and foreigners with previous TB, 6.2% and 22.7% had drug resistance, respectively. Increased drug resistance was found among untreated Danes aged 25-54 years mainly due to a single isoniazid- and streptomycin-resistant RFLP-cluster. Among all patients with isoniazid- and streptomycin-resistance, 77.0% had clustered strains. DISCUSSION: In conclusion, although drug resistance among untreated Danes was close to the rate estimated in good national programmes, close monitoring is needed in future years, as active transmission of isoniazid- and streptomycin-resistant Mycobacterium tuberculosis was demonstrated.

Risk of Mycobacterium tuberculosis transmission in a low-incidence country due to immigration from high-incidence areas.

Does immigration from a high-prevalence area contribute to an increased risk of tuberculosis in a low-incidence country? The tuberculosis incidence in Somalia is among the highest ever registered. Due to civil war and starvation, nearly half of all Somalis have been forced from their homes, causing significant migration to low-incidence countries. In Denmark, two-thirds of all tuberculosis patients are immigrants, half from Somalia. To determine the magnitude of Mycobacterium tuberculosis transmission between Somalis and Danes, we analyzed DNA fingerprint patterns of isolates collected in Denmark from 1992 to 1999, comprising >97% of all culture-positive patients (n = 3,320). Of these, 763 were Somalian immigrants, 55.2% of whom shared identical DNA fingerprint patterns; 74.9% of these were most likely infected before their arrival in Denmark, 23.3% were most likely infected in Denmark by other Somalis, and 1.8% were most likely infected by Danes. In the same period, only 0.9% of all Danish tuberculosis patients were most likely infected by Somalis. The Somalian immigrants in Denmark could be distributed into 35 different clusters with possible active transmission, of which 18 were retrieved among Somalis in the Netherlands. This indicated the existence of some internationally predominant Somalian strains causing clustering less likely to represent recent transmission. In conclusion, M. tuberculosis transmission among Somalis in Denmark is limited, and transmission between Somalis and Danes is nearly nonexistent. The higher transmission rates between nationalities found in the Netherlands do not apply to the situation in Denmark and not necessarily elsewhere, since many different factors may influence the magnitude of active transmission.

Results from 8 yrs of susceptibility testing of clinical Mycobacterium tuberculosis isolates in Denmark.

Increased rates of multidrug-resistant (MDR) tuberculosis (TB) has been reported from countries close to Denmark. This study evaluated the incidence of drug resistance in Denmark in order to determine the magnitude of the problem. Susceptibility testing was performed in isolates from 85.4% of all notified patients during 1991-1998. Epidemiological information was retrieved from the mandatory notification forms. Total drug resistance remained largely constant, although a minor increase was observed in 1997-1998. Monoresistance was observed in 7.3%, of the isolates. Among 3.6% polyresistant isolates, resistance to isoniazid and streptomycin accounted for 2.8%, whereas MDR accounted for 0.5%. The MDR strains displayed different restriction fragment length polymorphism (RFLP) patterns, and no matches were identified in the international MDR database. Drug resistance in untreated Danes and foreigners were 5.9% and 14.6%, respectively. Among Danes and foreigners with previous TB, 6.2% and 22.7% had drug resistance, respectively. Increased drug-resistance was found among untreated Danes aged 25-54 yrs mainly due to a single isoniazid and streptomycin-resistant RFLP-cluster. Among all patients with isoniazid and streptomycin-resistance, 77.0% had clustered strains. In conclusion, although drug resistance among untreated Danes was close to the rate estimated in good national programmes, close monitoring is needed in future years, as active transmission of isoniazid- and streptomycin-resistant Mycobacterium tuberculosis was demonstrated.

[An outbreak of Salmonella enteritidis at the New Year celebration of the Copenhagen Medical Association]. / Udbrud af Salmonella enteritidis ved Københavns Laegeforenings nytårskur.

In order to determine the extent and infectious vehicle of an outbreak of Salmonella enteritidis phage type 6 at the New Year celebration of the Copenhagen Medical Association on 15 January 1999, a cohort study including 77 guests (90% of the participants) and 11 staff was carried out. There was little variation in the degree of exposure among the guests, meaning that identification of the probable infectious vehicle was not possible here. However, among the staff, intake of minced raw salmon was associated with increased risk of disease. Uncooked eggs were used in the preparation of this dish and since S. enteritidis phage type 6 is in Denmark almost exclusively found among egg-laying hens, these findings led to the conclusion that the outbreak was most likely caused by the use of raw eggs. The importance of notification of suspected foodborne disease and microbiological examination of people thereby exposed is stressed.