Transmission of respiratory and gastrointestinal infections in German households with children attending child care.

Transmission of acute respiratory infections (ARI) and acute gastroenteritis (AGE) often occurs in households. The aim of this study was to assess which proportion of ARI and AGE is introduced and transmitted by children in German households with children attending child care. We recruited families with children aged 0-6 years in Braunschweig (Germany), for a 4 months prospective cohort study in the winter period 2014/2015. Every household member was included in a health diary and used nasal swabs for pathogen identification in case of ARI. We defined a transmission if two persons had overlapping periods with symptoms and used additional definitions for sensitivity analyses. In total, 77 households participated with 282 persons. We observed 277 transmission events for ARI and 23 for AGE. In most cases, the first infected person in a household was a child (ARI: 63%, AGE: 53%), and the risk of within-household transmission was two times higher when the index case was a child. In 26 ARI-transmission events, pathogens were detected for both cases; hereof in 35% (95% confidence interval (17-56%)) the pathogens were different. Thus, symptomatic infections in household members, apparently linked in time, were in 2/3 associated with the same pathogens.

Estimating vaccine effectiveness against laboratory-confirmed influenza among children and adolescents in Lower Saxony and Saxony-Anhalt, 2012-2016.

Influenza vaccine effectiveness (VE) has to be estimated anew for every season to explore vaccines' protective effect in the population. We report VE estimates against laboratory-confirmed influenza A(H1N1)pdm09, A(H3N2) and influenza B among children aged 2-17 years, using test-negative design. Pooled data from two German federal states' surveillance systems for acute respiratory illness from week 40/2012 to 20/2016 was used, yielding a total of 10 627 specimens. Odds ratios and 95% confidence intervals (95% CIs) for the association between laboratory-confirmed influenza and vaccination status were calculated by multivariate logistic regression adjusting for age, sex, illness onset and federal state. VE was estimated as 1-Odds Ratio. Overall adjusted VE was 33% (95% CI: 24·3-40·7). A strong variation of VE between the seasons and subtypes was observed: highest season- and subtype-specific VE of 86·2% (95% CI: 41·3-96·7) was found against A(H1N1)pdm09 in 7-17-year-olds in 2015/16. Low estimates of VE were observed against A(H3N2) in any season, e.g. 1·5% (95% CI: -39·3-30·3) in 2014/15. Estimates showed a tendency to higher VE among 7-17-year-old children, but differences were not statistically significant. Although our findings are common in studies estimating influenza VE, we discussed several explanations for observed low VE.

Faecal carriage of extended-spectrum ß-lactamase-producing Enterobacteriaceae and Shiga toxin-producing Escherichia coli in asymptomatic nursery children in Lower Saxony (Germany), 2014.

Children may be at higher risk for carriage of antimicrobial-resistant bacteria because of higher usage of antimicrobials. They also have higher rates of Shiga toxin-producing Escherichia coli (STEC) infections than other population groups. Some infections, particularly in children, are asymptomatic, but still lead to the excretion of large numbers of bacteria and viruses that may cause clinical disease in other individuals. That is one reason why, in Lower Saxony as in other German federal states - asymptomatic carriers of STEC are excluded from nurseries and schools until three consecutive stool samples test negative in order to prevent secondary cases. The prevalence of children who are asymptomatic STEC carriers is unknown. But if it is high, this measure would have substantial socioeconomic effects on families. Infections with extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E) are an increasing problem for public health, especially for hospitals. However, there are no reliable estimates of the prevalence of asymptomatic ESBL-E carriers in Lower Saxony, as there is no mandatory requirement to report these carriers. In order to discuss the exclusion policies for children attending nurseries and ascertain a baseline of ESBL-E carriers, we conducted a cross-sectional study. The aim was to determine the prevalence of ESBL-E and STEC and identify risk factors for carriage in nursery children without diarrhoea (asymptomatic) aged 0-6 years in four selected districts in Northern Germany. During April-September 2014, we collected stool specimens with the support of voluntarily participating nurseries. We tested for STEC by PCR and for ESBL-E on chromogenic agar. Questionnaires answered by parents contained data on eating and drinking habits, outdoor activities, prior antibiotic treatment and animal contact for each participating child. We compared the epidemiological characteristics of ESBL-E carriers vs. non-carriers by using univariable analysis (P value, odds ratio and 95% confidence interval). We could not perform a statistical analysis for STEC carriers due to the low numbers of positive STEC specimens. Of 224 asymptomatic nursery children, we found a prevalence of 2·3% for ESBL-E carriage and 0·5% for STEC carriage. Asymptomatic ESBL-E carriers were more likely to have consumed raw milk, have had contact with pet rodents, or to have taken antibiotics during the preceding 6 months. We also found a high proportion of raw milk consumption (11%). We suggest that the low STEC prevalence in asymptomatic children supports the current practice of excluding STEC carriers from nurseries. The association between ESBL-E carriage and raw milk consumption and contact with pet rodents needs further investigation.

Sporadic salmonellosis in Lower Saxony, Germany, 2011-2013: raw ground pork consumption is associated with Salmonella Typhimurium infections and foreign travel with Salmonella Enteritidis infections.

To investigate risk factors for sporadic salmonellosis, for each notified case four randomly selected population controls matched for age, sex and geographical region were interviewed via self-administered questionnaire. Conditional logistic regression analysis of 285 matched pairs revealed significant associations for raw ground pork consumption [odds ratio (OR) 6·0, 95% confidence interval (CI) 1·8-20·1], taking antacids (OR 5·8, 95% CI 1·4-24·5), eating meat outside the home (OR 5·7, 95% CI 2·2-14·6) and daily changing or cleaning of dishcloth (OR 2·1, 95% CI 1·2-3·9). Animal contact and ice cream consumption were negatively associated with salmonellosis (OR 0·5, 95% CI 0·2-1 and OR 0·3, 95% CI 0·1-0·6, respectively). S. Typhimurium infections were significantly associated with raw ground pork consumption (OR 16·7, 95% CI 1·4-194·4) and S. Enteritidis infections with having travelled abroad (OR 9·7, 95% CI 2·0-47·3). Raw egg consumption was not a risk factor, substantiating the success of recently implemented national control programmes in the poultry industry. Unexpectedly, hygienic behaviour was more frequently reported by cases, probably because they overestimated their hygiene precautions retrospectively. Although animal contact might enhance human immunocompetence, underreporting of salmonellosis by pet owners could have occurred. Eating raw pork products is the major risk factor for sporadic human S. Typhimurium infections in Lower Saxony.

Risk factors associated with sporadic salmonellosis in children: a case-control study in Lower Saxony, Germany, 2008-2011.

We conducted a case-control study based on 884 laboratory-confirmed sporadic Salmonella cases reported to the German infectious disease notification system. For controls, we recruited 510 rotavirus cases via the same system. Univariable and multivariable logistic regression analyses were performed separately for children aged 0-3 years and 4-14 years. In both age groups, the highest odds ratios (OR) were found for raw ground pork consumption [0-3 years: OR 8·6, 95% confidence interval (CI) 2·4-30·8; 4-14 years: OR 4·5, 95% CI 1·1-19]. Further risk factors were exposure to animals (OR 1·6, 95% CI 1·1-2·1), consumption of poultry (OR 1·5, 95% CI 1·1-2·1), food items containing eggs (OR 1·5, 95% CI 1·1-2) and black pepper (OR 1·7, 95% CI 1·1-3·5) in children aged 0-3 years, and consumption of uncooked pork sausage (OR 3·6, 95% CI 1·4-9·3) in children aged 4-14 years. This study highlights the significance of raw pork products ('Mett' in German) as risk factors for sporadic salmonellosis in children in Germany.

Foodborne hepatitis A outbreak associated with bakery products in northern Germany, 2012.

In October 2012, a hepatitis A (HA) outbreak with 83 laboratory-confirmed cases occurred in Lower Saxony. We defined primary outbreak cases as people with laboratory-confirmed HA and symptom onset between 8 October and 12 November 2012, residing in or visiting the affected districts. Secondary outbreak cases were persons with symptom onset after 12 November 2012 and close contact with primary cases. We identified 77 primary and six secondary cases. We enrolled 50 primary cases and 52 controls matched for age and sex, and found that 82% of cases and 60% of controls had consumed products from a particular bakery (OR=3.09; 95% CI: 1.15­8.68). Cases were more likely to have eaten sweet pastries (OR=5.74; 95% CI: 1.46­22.42). Viral isolates from five selected cases and three positively tested surfaces in the bakery had identical nucleotide sequences. One additional identical isolate derived from a salesperson of the bakery suffering from a chronic disease that required immunosuppressive treatment. Epidemiological and laboratory findings suggested that the salesperson contaminated products while packing and selling. Future risk assessment should determine whether food handlers with chronic diseases under immunosuppressive treatment could be more at risk of contaminating food and might benefit from HAV immunisation.

Subtype specific risk factor analyses for sporadic human salmonellosis: a case-case comparison in Lower Saxony, Germany.

With the intention to deepen the knowledge of the vertical transmission of particular subtypes of Salmonella enterica from "the stable to the table" a case1-case2 analysis in Lower Saxony, Germany, was conducted. The data collection was based on standardised telephone interviews with 1741 Salmonella case persons. Single-factor-analyses revealed statistically significant associations between S. Typhimurium infections and animal keeping (odds ratio (OR): 1.4; 95%-Confidence-interval (CI): 1.2-1.7), especially rodents (OR 1.5; CI 1.2-2.1), and with consumption of meat (OR 1.9; CI 1.3-2.8), raw ground pork (OR 3.0; CI 2.1-4.2) and uncooked pork sausage (OR 2.1; CI 1.6-2.9). The S. Typhimurium phage type DT 104 was associated most with consumption of uncooked pork sausage (OR 3.6; CI 1.3-8.5). Multiple logistic regression analyses confirmed the associations between S. Typhimurium infection and consumption of raw ground pork and with animal contact. The results circumstantiate the assumption of raw pork products still being a relevant source for S. Typhimurium infections in Germany. Therefore, it is recommended to intensify efforts to reduce salmonella infections caused by raw pork products. S. Enteritidis infection was associated statistically significantly with travelling abroad (OR 2.1; CI 1.6-3.3), consumption of raw tomatoes (OR 1.8; CI 1.5-2.1), dried herbs (OR 2.1; CI 1.0-1.8), and undercooked eggs (OR 1.3; CI 1.1-1.6) compared with other serovars. These results were confirmed in multiple logistic regression analyses, as well.

Risk factors associated with sporadic salmonellosis in adults: a case-control study.

In order to identify and assess recent risk factors for sporadic human infections with Salmonella enterica, we conducted a case-control study in Lower Saxony, Germany. The data collection was based on standardized telephone interviews with 1017 cases and 346 controls aged >14 years. Odds ratios were calculated in single-factor and multi-factor analyses for Salmonella cases and two different control groups, i.e. population controls and controls with rotavirus infection. Multi-factor analysis revealed associations between sporadic Salmonella infections for two exposures by both sets of controls: consumption of raw ground pork [adjusted odds ratio (aOR) 2·38, 95% confidence interval (CI) 1·27-4·44] and foreign travel (aOR 2·12, 95% CI 1·00-4·52). Other exposures included consumption of food items containing eggs (aOR 1·43, 95% CI 0·80-2·54), consumption of chicken meat (aOR 1·77, 95% CI 1·26-2·50), outdoor meals/barbecues (aOR 3·96, 95% CI 1·41-11·12) and taking gastric acidity inhibitors (aOR 2·42, 95% CI 1·19-4·92), all were significantly associated with respect to one of the two control groups. The impact of consuming food items containing eggs or chicken meat was lower than expected from the literature. This might be a consequence of Salmonella control programmes as well as increased public awareness of eggs and chicken products being a risk factor for salmonellosis. Efforts to reduce Salmonella infections due to raw pork products should be intensified.

[Antimicrobial resistance monitoring in Lower Saxony (ARMIN): first trends for MRSA, ESBL-producing Escherichia coli and VRE from 2006 to 2010]. / Antibiotika-Resistenz-Monitoring in Niedersachsen (ARMIN): Erste Trends für MRSA, ESBL-bildende Escherichia coli und VRE in den Jahren 2006-2010.

Antimicrobial resistance is one of the most important health topics of the past few years. To identify regional trends of antimicrobial resistance in inpatient and outpatient care, the Governmental Institute of Public Health of Lower Saxony (Germany) launched the sentinel system ARMIN (Antimicrobial Resistance Monitoring in Lower Saxony). Currently 9 laboratories participate as sentinel sites and contribute single case data of their microbiological results. Data are presented by an interactive data query in the internet. From 2006 to 2010 laboratories reported about 800 000 diagnostic test results. The proportion of MRSA (methicillin-resistant Staphylococcus aureus) among all Staphylococcus aureus increased from 19.5% in 2006 to 23.4% in 2010 for inpatient care in Lower Saxony. During the same period Escherichia coli resistance to cefotaxime for inpatient care increased from 3.0% to 8.8%. Enterococcus faecium resistance to vancomycin decreased from 13.6% to 5.6%. Currently the emphasis of ARMIN is on the description of trends and on the information of prescribing physicians. A quality circle was established to improve standardisation.

[H1N1 pandemic. Measures and experiences on the state level]. / H1N1-Pandemie. Maßnahmen und Erfahrungen auf Landesebene.

In order to establish a joint pandemic strategy, the German states ("Länder") together with the German federal government ("Bund") agreed on joint preparations for pandemic scenarios. This included the description of procedures, such as infection control measures, stockpiling of antiviral drugs, and contracts with vaccine manufacturers to ensure supply of vaccines in the event of a pandemic. The situation during the influenza H1N1 pandemic differed from that planned so that many short-term adjustments were required. It highlighted the need to make pandemic planning more flexible. In spite of several obstacles which had to be overcome during the situation, the states managed to achieve a relatively coordinated procedure and provided the availability of vaccines. In the course of the pandemic, gaps and shortcoming in existing surveillance systems were identified, which should lead to further improvements. A key point for future pandemic events is successful communication between all interested parties, especially with the medical profession, to increase the acceptance of public policies.

Practical usage of computer-supported outbreak detection in five European countries.

This paper discusses computer-supported outbreak detection using routine surveillance data, as implemented at six institutes for infectious disease control in five European countries. We give an overview of the systems used at the Statens Serum Institut (Denmark), Health Protection Agency (England, Wales and Northern Ireland), Robert Koch Institute (Germany), Governmental Institute of Public Health of Lower Saxony (Germany), National Institute for Public Health and the Environment (the Netherlands) and Swedish Institute for Infectious Disease Control (Sweden). Despite the usefulness of the algorithms or the outbreak detection procedure itself, all institutes have experienced certain limitations of the systems. The paper therefore concludes with a list of recommendations for institutes planning to introduce computer-supported outbreak detection, based on experiences on the practical usage of the systems. This list--which concerns usability, standard operating procedures and evaluation--might also inspire improvements of systems in use today.

[Infectious disease emergencies. Responsibility of municipal, state and federal health protection authorities with reference to the international health regulations]. / Kommunen, Länder, Bund und Europäische Gemeinschaft. Zuständigkeiten und Aufgaben bei Seuchennotfällen im Kontext der neuen Internationalen Gesundheitsvorschriften.

Pandemic preparedness has become a catch phrase for politicians, government agencies and communities, both nationally and internationally. This is due to the increasing number of infectious diseases emergencies that are important challenges for health protection authorities, which was shown impressively when SARS emerged as the first pandemic in this millennium. In Germany, effective and efficient infection control is complex, with local health protection authorities having their own responsibilities. In the case of an emergency epidemic, regional health departments are responsible. Having authority over these are authorities on the federal state level as well as on the federal level. For the European Community, the European Centre for Disease Prevention and Control (ECDC) was established. The mission of this agency is to identify, assess and communicate current and emerging threats to human health posed by infectious diseases.

[Synchronising school entry health examinations in Lower-Saxony, Germany]. / Synchronisierung von Schuleingangsuntersuchungen in Niedersachsen.

BACKGROUND: In the German federal state of Lower-Saxony the districts are responsible for conducting school entry health examinations. There exist two different standard protocols for diagnosis and documentation, denoted as Weser-Ems (WE) and SOPHIA. In order to analyse and improve the comparability between these two protocols, a working group was established in 2006. One of the objectives was to adjust the protocols in such a way that in the future the collected data will allow for joint health reporting. METHODS: Each variable was discussed individually by the working group, and if diagnosis or documentation differed between the two protocols, specific modifications were proposed. For certain variables external expert opinions were obtained. For those variables that had to be revised quite generally, specific sub-working groups were established. As prerequisite for implementation, the recommendations of the working group had to be accepted by the user groups through majority votes. RESULTS: Of 88 (WE) or, respectively, 66 (SOPHIA) variables, 39 (WE) or, respectively, 34 variables initially fulfilled the requirements for a joint analysis. As a result of the working group, for more than 20 other variables the requirements for a joint analysis could be achieved. As soon as the sub-working groups have completed their work, also the issues of physical coordination, cognitive abilities and psychological health will be available for joint analysis. DISCUSSION: The synchronisation of school entry health examinations in Lower-Saxony is an example of how different protocols of diagnosis and documentation can be adapted to each other to enable joint data analysis without loosing their individual characteristics.

[Protracted nosocomial outbreak of Salmonella Enteritidis LT 8/7]. / Protrahiert verlaufender nosokomialer Ausbruch von Salmonella Enteritidis LT 8/7.

INTRODUCTION: In spring 2007a cluster of nosocomial salmonellosis cases, culture confirmed for SALMONELLA Enteritidis lysotype (LT) 8/7, occurred in a Wolfsburg hospital. An outbreak investigation was initiated to determine the epidemiology of the outbreak and to identify and control the possible sources. METHODS: A multidisciplinary outbreak team was formed including members from hospital hygiene and local, state and national health and veterinarian authorities. Active surveillance was set up in the hospital to find new cases. A retrospective case control study was conducted to identify possible risk factors for disease. Hospital workers and food samples were tested for the pathogen and positive isolates were typed. RESULTS: Between calendar weeks 4 and 24 of the year 2007, a total of 28 patients with a median age 66 years had nosocomial salmonellosis culture confirmed for SALMONELLA Enteritidis LT 8/7. In food samples from February, the same Salmonella lysotype was isolated in 4 different food samples. SALMONELLA Enteritidis LT 8/7 was also identified in stool samples from 5 kitchen personnel. The case control study indicated antacida therapy (odds ratio: 5.5, 95 % CI 1.2 - 26.0) as a risk factor for nosocomial salmonellosis among patients. No particular diet was associated with an increased risk of disease. DISCUSSION: This nosocomial salmonellosis outbreak was characterised by prolonged duration and a low infection rate among patients. The epidemiological investigation suggests that the origin of the outbreak was food that was probably associated with a contamination in the hospital kitchen. Furthermore, kitchen staff could, as carriers, have contributed to a low-level contamination of various foods for a long period. The intermittent occurrence of the cases is best explained by a low level of contaminated food which primarily led to clinical symptoms among especially vulnerable persons (older patients with antacida therapy). Considering the unusual progression of this outbreak, hospitals should initiate an intensive epidemiological and microbiological investigation, even if only few nosocomial salmonellosis cases occur.

Monitoring of basophil sensitization to antigens of the cat flea (Ctenocephalides felis felis): a new tool for the diagnosis of feline flea bite hypersensitivity?

Suitability of blood basophils for in vitro diagnosis of flea allergy dermatitis (FAD) or flea bite hypersensitivity was studied in cats. A functional in vitro test (FIT) for sensitized type I allergic effector cells was used to evaluate the degree and kinetics of in vivo basophil sensitization against flea antigens in cats under long-term flea exposure. FIT results were compared with intradermal (IDT) and serological testing. Before, during, and after weekly repeated exposure to Ctenocephalides felis; 14 cats were repetitively FIT-assessed for general and flea-specific sensitization. In three cats, flea-specific sensitization was seen before and throughout flea exposure. Five cats, although generally sensitized, never developed a flea-specific sensitization. Six cats initially FIT-negative became sensitized for flea antigen during flea infestation. Induction, upregulation, and binding of C. felis-specific sensitizing antibodies to basophils during flea challenge may explain the developing sensitization in these cats. Strong discrepancies between the levels of flea-specific circulating IgE and basophil sensitization contrasted comparable results for basophil and mast cell sensitization using FIT and IDT, respectively. Hence, the FIT might provide an immunological supplement to the clinical diagnosis of FAD in cats by elucidating the state of basophil-sensitization to flea antigens. And it may be a comfortable alternative to IDT.

[Regionally increased incidence of notified cryptosporidiosis cases due to different laboratory methods]. / Regional erhöhte Inzidenz gemeldeter Kryptosporidiosen durch unterschiedliche Laborroutinen.

INTRODUCTION: In Lower Saxony, during 2001 to 2005, 744 cases of cryptosporidiosis were reported according to the Protection against Infection Act to the Governmental Institute of Public Health of Lower Saxony. The yearly incidence rate of 1.9 notified cases per 100,000 population exceeded the German mean incidence rate of 1.5. Within Lower Saxony, there was a striking heterogeneity of regional incidences with rates greater than 10.0 in several neighbouring districts. METHODS: A retrospective case control study was conducted in cooperation with the health departments of the 5 mostly affected districts to test the hypothesis that diagnostic effects might have caused this regional cluster. Notified cryptosporidiosis cases of the years 2002 and 2003 were analysed with respect to the notifying physicians and laboratories. Notified cases of salmonellosis and campylobacteriosis were taken as controls. Controls were matched to the cases with respect to age, sex, district, and year of notification. RESULTS: Of the 146 cryptosporidiosis cases included in the case control study, 130 (89%) were diagnosed and reported by only one laboratory. In contrast, of the controls only 31% were reported by this laboratory. The matched odds ratio for this laboratory was 43.5 (95% confidence interval: 10.7-177; p<0.001). DISCUSSION: The case control study revealed a significant association of the cryptosporidiosis notifications with one particular laboratory. Confounding by co-variables like age or district could be excluded due to matching. In this laboratory all stool samples submitted for routine microbiological diagnosis were screened for Cryptosporidium parvum. Diagnostic work was done by valid, specific, CE-certified procedures. We conclude that the increased regional incidence rate caused by the broader diagnostic activity of this laboratory rather reflects the real occurrence of this infection. Hence, in other regions with lower incidence rates of notified cases an underestimation can be presumed.

Prevalence of hepatitis C in a German prison for young men in relation to country of birth.

A high prevalence of hepatitis C (HCV) virus infection of up to 80% has been reported for injecting drug users (IDUs) in prison communities. However, there are only very limited data available on the prevalence and course of HCV in young offenders. We performed a study on hepatitis C markers in the largest German Young Offenders' Institution (YOI), a prison for men (aged 16-24 years). In 2002, all 1176 incoming offenders were asked to participate in the study of whom >95% agreed. Ninety-seven inmates (8.6%) tested positive for anti-HCV or HCV RNA, 79% of whom were viraemic. None of the patients had evidence of cirrhosis at presentation. Interestingly, six individuals (6%) tested positive for HCV RNA in the absence of anti-HCV antibodies, four of whom cleared HCV spontaneously during follow-up without either clinical signs of acute hepatitis or developing HCV antibodies. Hepatitis C markers were significantly more prevalent among immigrants from the former Soviet Union (NIS) than among German inmates (31% vs. 6% respectively, P<0.0001). HIV co-infection was found in five individuals, all of whom were German. In contrast, hepatitis B surface antigen (HBsAg) was detected in five NIS immigrants, one Lebanese and one German inmate. HCV genotypes 2 and 3 were more prevalent in immigrants than in German inmates, while biochemical parameters did not differ significantly between the two groups. In conclusion, the prevalence of hepatitis C was relatively low among inmates of German YOIs although there were significant differences in relation to the country of birth. Our data highlight the need for educational programmes for young offenders in order to prevent the further spread of HCV.

Legionnaires' disease outbreak associated with a cruise liner, August 2003: epidemiological and microbiological findings.

Eight cases of Legionnaires' disease were identified among the 215 German passengers after a cruise to the Nordic Sea in August 2003. An unmatched case-control study was conducted to identify risk factors and the source of infection. In total, eight passengers fulfilled the case definition, one of these died. Forty-two passengers served as controls. The attack rate was 4%. The mean age was 60 years for cases and 62 years for controls. Prolonged exposure to the spa pool seemed to be a risk factor of infection (OR 4.85, P=0.09). Legionella pneumophila serogroup 1, monoclonal antibody (mAb) subgroup 'Knoxville' was isolated from clinical and environmental samples. DNA sequence-based typing revealed that these isolates were indistinguishable from each other. The investigation showed the importance of an interdisciplinary approach of microbiology and epidemiology as not all sites on the ship that tested positive for L. pneumophila actually posed a relevant risk for the passengers.

Outbreak of hepatitis B in a nursing home associated with capillary blood sampling.

In 2001, two residents of a nursing home in Lower Saxony, Germany, were diagnosed with acute hepatitis B virus (HBV) infection. A systematic contact investigation of 188 residents yielded 19 confirmed or probable cases of acute or recent HBV infection and three persistent asymptomatic HBsAg carriers. Sequence analysis revealed that one carrier had high viraemia (109 genomes/ml), HBV genotype A2, and the same S gene and/or X gene sequence as 16 acutely infected persons. An unmatched case-control study was conducted with the 17 cases that had sequence identity together with 26 controls. The strongest association was found for treatment by a particular general practitioner (GP) (OR > 11, P < 0.001) and blood sampling for glucose monitoring on a particular day by the GP's staff (OR 13.6, P < 0.001, adjusted OR 8.5, P = 0.017). Control measures were implemented. Serological controls after 6 and 18 months revealed that the outbreak was brought under control.