Judith Koch

Phylogenetic and case-control study on hepatitis E virus infection in Germany.

BACKGROUND Hepatitis E is a classic water-borne disease in developing countries. In Germany, hepatitis E virus (HEV) infections are notifiable. The number of non-travel-associated infections has increased in recent years, but the route of transmission in most is unknown. Our objective was to determine risk factors for autochthonous HEV infections in Germany. METHODS Cases of HEV met clinical definitions and were confirmed by laboratory analysis (defined as detection of HEV by polymerase chain reaction [PCR] or immunoglobulin M by serologic testing). PCR products from blood or stool samples were genotyped for phylogenetic analysis. A case-control study included case subjects with autochthonous HEV infection and matched control subjects who were randomly recruited from a population-based telephone list. RESULTS From May 2006 through August 2007, 76 of 96 persons for whom HEV infection had been reported to the routine surveillance system were interviewed. Sixty-six persons had disease that fulfilled the inclusion criteria: 45 (68%) had autochthonous infection, and 21 (32%) had travel-associated disease. Genotypes 3 or 4 were present in 15 of 15 persons with autochthonous infection, and genotype 1 was present in 8 of 9 persons with travel-associated infection. In conditional logistic regression involving 45 case subjects and 135 control subjects, consumption of offal (41% vs. 19%; odds ratio [OR], 2.7; 95% confidence interval [CI], 1.2-6.2) and wild-boar meat (20% vs. 7%; OR, 4.3; 95% CI, 1.2-15.9) were independently associated with autochthonous HEV infection. CONCLUSION Hepatitis E is endemic in Germany and likely exists as a food-borne zoonosis. Implicated meat products should be investigated to provide recommendations for preventive measures.

Analysis of Integrated Virological and Epidemiological Reports of Norovirus Outbreaks Collected within the Foodborne Viruses in Europe Network from 1 July 2001 to 30 June 2006

ABSTRACT The Foodborne Viruses in Europe network has developed integrated epidemiological and virological outbreak reporting with aggregation and sharing of data through a joint database. We analyzed data from reported outbreaks of norovirus (NoV)-caused gastroenteritis from 13 European countries (July 2001 to July 2006) for trends in time and indications of different epidemiology of genotypes and variants. Of the 13 countries participating in this surveillance network, 11 were capable of collecting integrated epidemiological and virological surveillance data and 10 countries reported outbreaks throughout the entire period. Large differences in the numbers and rates of reported outbreaks per country were observed, reflecting the differences in the focus and coverage of national surveillance systems. GII.4 strains predominated throughout the 5-year surveillance period, but the proportion of outbreaks associated with GII.4 rose remarkably during years in which NoV activity was particularly high. Spring and summer peaks indicated the emergence of genetically distinct variants within GII.4 across Europe and were followed by increased NoV activity during the 2002-2003 and 2004-2005 winter seasons. GII.4 viruses predominated in health care settings and in person-to-person transmission. The consecutive emergence of new GII.4 variants is highly indicative of immune-driven selection. Their predominance in health care settings suggests properties that facilitate transmission in settings with a high concentration of people such as higher virus loads in excreta or a higher incidence of vomiting. Understanding the mechanisms driving the changes in epidemiology and clinical impact of these rapidly evolving RNA viruses is essential to design effective intervention and prevention measures.

Large listeriosis outbreak linked to cheese made from pasteurized milk, Germany, 2006-2007.

A commercial cheese (acid curd) made from pasteurized milk caused a large listeriosis outbreak in Germany from October 2006 through February 2007. The Listeria monocytogenes outbreak strain was identified in humans and in cheese samples from a patients home and from the production plant. During the outbreak period, 189 patients were affected, which was 97% above the mean case number for the respective time period of the years 2002 to 2005. Of patients with available detailed information on cheese consumption (n=47), 70% reported to have consumed the incriminated cheese product. Recent European food safety alerts due to Listeria-contaminated cheeses more often concerned products made from pasteurized or heat-treated milk than from raw milk. The findings should be considered in prevention guidelines addressing vulnerable populations.

A new Puumala hantavirus subtype in rodents associated with an outbreak of Nephropathia epidemica in South-East Germany in 2004

A micro-epidemic of hantavirus infections occurred in Lower Bavaria, South-East Germany, starting in April 2004. While only three cases were registered from 2001 to 2003, a dramatically increased number of clinically apparent human hantavirus infections (n=38) was observed in 2004, plus seven additional cases by June 2005. To determine the reservoir responsible for the infections, a total of 43 rodents were trapped in Lower Bavaria. Serological and genetic investigations revealed that Puumala virus (PUUV) is dominant in the local population of bank voles. Partial PUUV S segment nucleotide sequences originating from bank voles at four different trapping sites in Lower Bavaria showed a low divergence (up to 3.1%). This is contrasted by a nucleotide sequence divergence of 14-16% to PUUV strains detected in Belgium, France, Slovakia or North-Western Germany. PUUV sequences from bank voles in Lower Bavaria represent a new PUUV subtype which seems to be responsible for the observed increase of human hantavirus infections in 2004-2005.

Significant increase of listeriosis in Germany--epidemiological patterns 2001-2005.

Listeriosis has been a mandatorily notifiable disease in Germany since January 2001. Clinical cases with isolation of Listeria monocytogenes from sterile specimens or neonates are reported to the Robert Koch-Institut. Listeriosis incidence significantly increased from 0.26 per 100 000 inhabitants (217 cases) in 2001 to 0.62 per 100 000 (519 cases) in 2005.

Network “Rodent-borne pathogens” in Germany: longitudinal studies on the geographical distribution and prevalence of hantavirus infections

Hantavirus infections are known in Germany since the 1980s. While the overall antibody prevalence against hantaviruses in the general human population was estimated to be about 1–2%, an average of 100–200 clinical cases are recorded annually. In the years 2005 and 2007 in particular, a large increase of the number of human hantavirus infections in Germany was observed. The most affected regions were located in the federal states of Baden-Wuerttemberg, Bavaria, North Rhine Westphalia, and Lower Saxony. In contrast to the well-documented situation in humans, the knowledge of the geographical distribution and frequency of hantavirus infections in their rodent reservoirs as well as any changes thereof was very limited. Hence, the network “Rodent-borne pathogens” was established in Germany allowing synergistic investigations of the rodent population dynamics, the prevalence and evolution of hantaviruses and other rodent-associated pathogens as well as their underlying mechanisms in order to understand their impact on the frequency of human infections. A monitoring of hantaviruses in rodents from endemic regions (Baden-Wuerttemberg, Bavaria, North Rhine Westphalia, Lower Saxony) and regions with a low number of human cases (Mecklenburg Western-Pomerania, Brandenburg, Saxony, Saxony-Anhalt) was initiated. Within outbreak regions, a high prevalence of Puumala virus (PUUV) was detected in bank voles. Initial longitudinal studies in North Rhine Westphalia (city of Cologne), Bavaria (Lower Bavaria), and Lower Saxony (rural region close to Osnabrück) demonstrated a continuing presence of PUUV in the bank vole populations. These longitudinal studies will allow conclusions about the evolution of hantaviruses and other rodent-borne pathogens and changes in their distribution, which can be used for a risk assessment of human infections. This may become very important in order to evaluate changes in the epidemiology of rodent-borne pathogens in the light of expected global climate changes in the future.

Sorbitol-fermenting enterohaemorrhagic Escherichia coli O157:H- causes another outbreak of haemolytic uraemic syndrome in children.

An outbreak of haemolytic uraemic syndrome (HUS) among children caused by infection with sorbitol-fermenting enterohaemorrhagic Escherichia coli O157:H- (SF EHEC O157:H-) occurred in Germany in 2002. This pathogen has caused several outbreaks so far, yet its reservoir and routes of transmission remain unknown. SF EHEC O157:H- is easily missed as most laboratory protocols target the more common sorbitol non-fermenting strains. We performed active case-finding, extensive exploratory interviews and a case-control study. Clinical and environmental samples were screened for SF EHEC O157:H- and the isolates were subtyped by pulsed-field gel electrophoresis. We identified 38 case-patients in 11 federal states. Four case-patients died during the acute phase (case-fatality ratio 11%). The case-control study could not identify a single vehicle or source. Further studies are necessary to identify the pathogens reservoir(s). Stool samples of patients with HUS should be tested with an adequate microbiological set-up to quickly identify SF EHEC O157:H-.

Salmonella Agona Outbreak from Contaminated Aniseed, Germany

A nationwide outbreak of Salmonella Agona caused by aniseed-containing herbal tea occurred from October 2002 through July 2003 among infants in Germany. Consumers should adhere strictly to brewing instructions, although in exceptional cases this precaution may not be protective, particularly when preparing tea for vulnerable age groups.

Rotavirus vaccine effectiveness and case-control study on risk factors for breakthrough infections in Germany, 2010-2011.

Background: In the German federal state Mecklenburg-Western Pomerania, routine rotavirus (RV) vaccination in infants has been recommended since 2009. The effectiveness of RV vaccination was investigated after an unexpectedly high number of RV infections in fully vaccinated children occurred. Methods: Intensified RV surveillance was performed in Mecklenburg-Western Pomerania between 2010 and 2011. The screening method was applied to assess vaccine effectiveness (VE) in children up to 24 months after vaccination. To identify risk factors for breakthrough infections, a case-control study and genotyping were conducted in vaccinated and unvaccinated RV-infected children. Results: VE for the prevention of RV infection requiring medical attention or hospitalization was 68% (95% confidence interval [CI]: 61–71) and 80% (95% CI: 77–83), respectively. VE for preventing hospitalization but not medical attention remained stable over 2 years. Vaccinated were less often hospitalized (23%) than unvaccinated RV-infected children (61%; P < 0.001). Breastfeeding (odds ratio, 3.99; 95% CI: 1.92–8.27) and attending daycare (odds ratio, 3.42; 95% CI: 1.64–7.12) were independently associated with breakthrough infections. Genotype G1P[8] was detected more frequently in RotaTeq-vaccinated (44% versus 11%; P < 0.03) and G2P[4] in Rotarix-vaccinated children (42% versus 6%; P < 0.02). Conclusions: RV vaccination protects young children effectively from RV disease and can reduce disease severity. Breastfeeding might impair VE, but further research is needed to identify the critical time window for this interference and to develop appropriate recommendations.

Risk Factors for Hantavirus Infection in Germany, 2005

In 2005, a marked increase in hantavirus infections was observed in Germany. Large cities and areas where hantaviruses were not known to be endemic were affected. A case-control study identified the following independent risk factors for infection: occupational exposure for construction workers, living <100 meter from forested areas, and exposure to mice.