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Case definitions ensure standardised criteria for the surveillance of infectious diseases in Germany. Since its last revision in 2007, an update of the complete case definition edition became necessary due to new scientific insights, changes in legislature, terminology and classification systems. At the same time, the case definition should be further standardised and work at local public health authorities should be simplified. The department for infectious disease epidemiology at the Robert Koch Institute (RKI) coordinated the revision of the case definitions. During several feedback sessions, internal RKI experts and external experts from different levels of the German public health system, as well as from medical associations and laboratories, were involved in the revision process. The new edition and an annotated version are published on the RKI website (www.rki.de/falldefinitionen). The new case definitions will become effective on 1st January 2015. The most important changes are summarised in this article.

In the German Reich, smallpox vaccinations were organized by the state. A mandatory vaccination throughout the empire was introduced in 1874, which was continued in the Federal Republic of Germany (FRG) and the German Democratic Republic (GDR) until 1982/1983. From 1935, health departments were responsible for vaccinations. In the GDR, immunization was tightly organized: The state made great efforts to achieve high vaccination rates. Responsibilities were clearly defined at all levels and for all ages. While vaccination was initially mandatory only at the regional level, the legally mandated immunization schedule later contained compulsory vaccinations, e.g., against measles. In the beginning there were mandatory vaccinations in the FRG at the Länder level. Since 1961, the Federal Epidemics Act has impeded obligatory vaccinations. Instead, voluntary vaccinations based on recommendations were stressed. Since the 1980s, vaccinations have been shifted from the public health service sector to office-based physicians. Today, public health authorities offer mainly supplementary vaccinations. In 2007, protective immunizations were introduced as compulsory benefits of the statutory health insurance (SHI). Recently, the German federal states developed a National Vaccination Plan to support immunization strategies.

Chikungunya virus (CHIKV) has been previously reported in many African and Asian areas, but it recently reemerged strongly in countries bordering the Indian Ocean as well as caused an outbreak in northern Italy. In Germany, where potential CHIKV vectors are not yet established, CHIKV infection is mandatorily notifiable. Cases reported from 2006 through 2009 were analyzed for travel characteristics and demographic factors. 152 cases of symptomatic CHIKV infection were notified. Both sexes were affected, with a median age of 46 years. Over the years, countries of infection largely followed the outbreaks reported from various travel destinations. India and the Maldives were the countries of infection most frequently named. In Sri Lanka, India, and Thailand, which are also frequently named countries of infection for dengue virus, the median age of CHIKV-affected patients was higher than that of dengue fever patients. Taking traveler numbers into consideration, risk of CHIKV infection was higher in the Seychelles and Mauritius than in Thailand and India. Even though substantial underdiagnosis is suspected, this assessment of CHIKV importation to Germany offers valuable information about the details of travel-associated cases. Between 17 and 53 notified cases per year signify that CHIKV would be occasionally available for local transmission in Germany once a vector becomes present. Although CHIKV most often causes a comparatively mild disease, the high median age of notified cases and the higher age than dengue patients support more severe disease courses in older adults. Travelers to all CHIKV endemic areas should protect against mosquito bites. In Germany, CHIKV surveillance will be continued to monitor ongoing importation of the virus and to detect early potential autochthonous cases.

Background: Several countries have reported a decline in malaria cases imported by travelers returning from India., Methods: We collected data on imported malaria for the period 1992 to 2005 from nine countries. Traveler statistics denominator data were obtained from the Indian Ministry of Tourism., Results: The malaria case numbers declined from 93 cases per 100,000 travelers in 1992 to 19 cases per 100,000 travelers in 2005. The proportion of Plasmodium falciparum decreased steadily throughout the years. The proportion of Plasmodium vivax accounts for more than 80% of all cases of malaria in travelers to India. Deaths due to malaria were rare; only the UK and the United States reported deaths, a total of 16, between 1992 and 2005. The high-risk areas for malaria in India can be clearly identified using endemic malaria data. High-risk states are Chhattisgarh, Orissa, Jharkhand, West Bengal, Goa (mainly P vivax), and the states east of Bangladesh., Conclusions: The decreasing incidence of malaria in travelers to India and the high proportion of P vivax support the current change in guidelines in some European countries advocating the use of the standby emergency self-treatment strategy or bite precautions plus awareness of risk instead of chemoprophylaxis. Otherwise in high-risk states, chemoprophylaxis should still be considered particularly in high-transmission seasons.

We estimated the total number of human alveolar echinococcosis cases in Germany from 2003 through 2005 using the multiple source capture-recapture method. We found a 3-fold higher incidence of the disease than that shown by national surveillance data. We propose a revision of the reporting system to increase case ascertainment.

Rare infectious diseases are of great importance in Germany: Some of them require special measures and precautions to prevent spreading (e.g. virus caused hemorrhagic fevers). For others, e.g. infectious diseases that can be prevented by vaccination, the prevention aspects are important. Summarizing descriptions for several rare diseases which together describe the situation in Germany are only possible on the basis of the notification requirements. The legal obligation for notification represents a good prerequisite to register diseases occurring in Germany. With the introduction of the Protection against Infection Act in 2001 the quality of the available data was improved by using case definitions. The evaluation of existing information indicates: On the basis of the available data there is no evidence that in the foreseeable future a noticeable increase of isolated rare diseases could pose a threat in Germany.

From 1993 to 2007, a total of 11,605 malaria cases were reported to the Robert Koch-Institut. For 9 593 of these cases information on the possible country of infection is available. Analysis of the data indicates that the malaria cases were imported to Germany from 96 countries. The majority of the malaria cases were acquired in Africa, followed by distinctly fewer cases from Asian countries. More than half of all cases were imported from only 6 countries (Ghana, Kenya, Nigeria, Cameroon, Gambia, and India). The number of cases imported from, e.g., Kenya and India has declined, whereas infections from Ghana, Nigeria, and Cameroon have increased during the last years. For more than two-thirds of all infections the predominant parasite species was P. falciparum; this is consistent with the predominance of the African continent as the main source of infection.

The epidemiology of trichinellosis in Germany was investigated by analyzing national surveillance data from 1996-2006. During this period, 95 laboratory-confirmed infections and 12 outbreaks were reported. The highest mean annual incidence was found in immigrants from southeast European countries (0.3 cases/100,000 vs. 0.01 cases/100,000 in the German population) with an incidence rate ratio of 26.0 (95% confidence interval 11.6-51.8). The predominant clinical symptom was muscle pain in 79 patients (83%). Mean diagnostic delay was 49 days. Among patients with reported source of infection (85%; n = 81), the consumption of pork (mostly originating from endemic countries) represented the most frequent exposure (93%; n = 75). In addition, trichinellosis cases were associated with both indigenous (n = 1) and imported (n = 5) wild boar meat. Although domestic pigs in Germany are practically free from Trichinella spp., the parasite was found in German wild animals such as wild boars, foxes, and racoon dogs. We conclude that trichinellosis still remains a public health issue in Germany, especially among individuals with a migrational background. Immigrants from endemic countries need to be educated about the risks of consuming raw or inadequately cooked pork and wild boar products from their homeland. In addition, German healthcare providers need to be aware of trichinellosis, especially in areas with a large immigrant population.

Trends in the epidemiology of human brucellosis in Germany were investigated by analyzing national surveillance data (1962-2005) complemented by a questionnaire-based survey (1995-2000). After a steady decrease in brucellosis incidence from 1962 to the 1980s, a persistent number of cases has been reported in recent years, with the highest incidence in Turkish immigrants (0.3/100,000 Turks vs. 0.01/100,000 in the German population; incidence rate ratio 29). Among cases with reported exposure risks, 59% were related to the consumption of unpasteurized cheese from brucellosis-endemic countries. The mean diagnostic delay was 2.5 months. Case fatality rates increased from 0.4% (1978-1981) to a maximum of 6.5% (1998-2001). The epidemiology of brucellosis in Germany has evolved from an endemic occupational disease among the German population into a travel-associated foodborne zoonosis, primarily affecting Turkish immigrants. Prolonged diagnostic delays and high case fatality call for targeted public health measures.

Background: Although the majority of patients with reported leptospirosis are male, several seroepidemiologic studies demonstrated that leptospirosis seroprevalences are at least identical between both sexes. To study the effect of sex on the severity--and possibly, recognition--of leptospirosis, we conducted a sex-specific analysis of the clinical manifestations of the disease among patients with reported leptospirosis in Germany during 1997-2005., Methods: Data on demographic characteristics, symptoms, place of infection and place of residence when infection occurred, possible exposure risks, infecting serovars, and mortality were evaluated for patients with laboratory-confirmed leptospirosis reported in Germany during 1997-2005. Mantel-Haenszel odds ratios (OR(MH)), adjusted for age, were used to determine the association between sex and the frequency of reported symptoms., Results: Among 338 patients with leptospirosis (263 male patients and 75 female patients) reported in Germany during 1997-2005, male patients were more likely than female patients to be hospitalized (OR, 2.6; P<.01) and to exhibit symptoms of severe leptospirosis with jaundice (OR(MH), 3.7; P<.01), renal impairment (OR(MH), 3.4; P<.01), and hemorrhage (OR(MH), 7.8; P<.05). These sex-related differences were not associated with differences in exposure risks, presumptive infecting serogroups, or health-seeking behavior., Conclusions: Our results indicate that male sex is associated with a higher severity of clinical leptospirosis. Reports on male predominance in leptospirosis may thus reflect sex-related variability in the incidence of severe disease, rather than different infection rates. In clinical practice, sex differences in the manifestation of leptospirosis may cause systematic underinvestigation and undertreatment of the disease in female patients.

To determine the effect of chemoprophylaxis on the case-fatality rate of malaria, we analyzed all cases of Plasmodium falciparum malaria in nonimmune persons reported from 1993 to 2004 in Germany. In univariate and multivariate logistic regression analysis, we determined the effect of age, sex, chemoprophylaxis, chemoprophylactic regimen, compliance for chemoprophylactic regimen, exposure prophylaxis, country of infection, and year of reporting on the outcome. Of 3,935 case-patients, 116 (3%) died of malaria. Univariate analysis showed significant associations with death for chemoprophylaxis with chloroquine plus proguanil compared to no chemoprophylaxis. The multivariate model showed that patients who had taken chemoprophylaxis were less likely to die compared to those who had not taken chemoprophylaxis, adjusted for patient age and reporting year. The study demonstrated that chemoprophylaxis significantly reduced fatality rates among nonimmune malaria patients and supports the importance of existing guidelines for malaria prevention.

Epidemiologic trends of human leptospirosis in Germany were investigated by analyzing national surveillance data from 1962 to 2003 and by conducting a questionnaire-based survey from 1997 to 2000. After a steady decrease of leptospirosis incidence from 1962 to 1997, surveillance data indicate an increase in disease incidence to 0.06 per 100,000 (1998-2003). Of 102 laboratory-confirmed cases in humans from 1997 to 2000, 30% were related to occupational exposures. Recreational exposures were reported in 30% (including traveling abroad in 16%), whereas residential exposure accounted for 37% of the cases. Direct contact with animals, mostly rats and dogs, was observed in 31% of the cases. We conclude that recent changes in transmission patterns of leptospirosis, partially caused by an expanding rat population and the resurgence of canine leptospirosis, may facilitate the spread of the disease in temperate countries like Germany. Preventive measures should be adapted to the changing epidemiology of leptospirosis.

Background and Objective: In Germany, malaria is a major imported disease. The national surveillance data from 1993 to 2003 were analysed to assess epidemiologic trends in imported malaria., Methods: Malaria is a notifiable disease in Germany. Laboratory and epidemiologic data are obtained for each malaria case in a standardised way and reported to the Robert Koch-Institut where the central database exists for statistical analysis., Results: From 1993 to 2003, a total of 9148 malaria cases were reported to the Robert Koch-Institut. The annual cases ranged from 598 (1993) to 1045 (2001). No clear trend over the years was observed. The proportion of malaria cases of German origin declined significantly over the years to 50 % in 2003. The proportion of cases aged 40 to 49 years increased over time. However, in each year the highest malaria incidence was found in the age group 20 to 39 years. Case fatality decreased substantially in recent years. In about 25 % of patients malaria diagnosis and treatment start were delayed. This is of great concern since 70 to 80 % of all cases were caused by Plasmodium falciparum. In recent years atovaquone + proguanil as well as arthemether + lumefantrin were increasingly used for treatment (both combination therapies made up for 35 % of treatments in 2003)., Conclusions: Further improvements in counselling and adequate use of malaria prophylaxis in travelers and in timely malaria diagnosis and treatment are necessary.

Dengue fever is a reportable disease in Germany. Surveillance data from 2001 and 2002 were analyzed and compared to travel patterns. Imported dengue fever increased strongly in this time. Most infections were acquired in Southeast Asia, specifically Thailand. The 2002 epidemic in Brazil was also reflected in these data.

In Germany, malaria is one of the most frequently imported infectious diseases. In January 2001, the newly implemented Infektionsschutzgesetz (Law for Protection Against Infectious Diseases) brought some important changes in surveillance case notification procedures. After one year, experience shows that the changes did not affect the continuity and representative nature of malaria reporting in Germany. In the years 2000 and 2001, 836 and 1,040 malaria cases, respectively, were reported. In both years, most of the patients were between 30 and 49 years old. 82 % of the infections had been acquired in Africa, and 11 % in Asia. The predominant parasite species was P. falciparum (70 %), followed by P. vivax (12 % in 2000, and 16 % in 2001, respectively). The majority of infections occurred among tourists, fewer in immigrants or business travellers. About two thirds of all patients had not taken any chemoprophylactics. Compared to previous years a decrease in the number of fatal cases was observed (1998: 21, 1999: 18, 2000: 8, 2001: 8). To ameliorate the situation of imported malaria intensified prevention activities are necessary, including efforts to improve choice and compliance of chemoprophylaxis and to facilitate timely diagnosis and treatment.

The number of cases of typhoid fever has decreased in recent years in Germany. In 2000 77 cases were reported (in 1999:111). Most of the cases (84%) were imported from abroad. Travellers can contract the infection when travelling under conditions of poor hygiene in endemic regions. The risk of contracting typhoid fever is high on the Indian subcontinent. Adequate prophylactic measures are the only way to reduce the importation of typhoid fever to Germany.

Malaria is a common imported infectious disease in Germany. A total of 931 cases of malaria were reported in Germany in 1999 (1998: 1,008 cases). Most of the infected patients were 24-45 years of age. Eighty per cent of the cases acquired infection in Africa, in Asia (8.5%) and in Central and South America (5%). Plasmodium falciparum accounted for the largest number of cases (80%) followed by Plasmodium vivax (12%). In 1999 60% of all malaria cases were Germans. Most of them travelled for holidays or study purposes. 20 deaths, all attributed to falciparum malaria, were notified in 1999, most of them (19) were German citizens. In 1999 61% of the patients had not taken chemoprophylaxis at all while travelling abroad. Improving prophylactic measures is the only way to reduce the incidence of malaria cases in Germany.

We report on malaria acquired by German tourists to formerly non-endemic tourist resorts in the Dominican Republic between July 1999 and March 2000. Falciparum malaria is endemic in the western provinces and the hinterland of the Dominican Republic. By contrast, the risk of contracting malaria has always been considered so low in the main tourist resorts in the eastern part of the country that antimalarial chemoprophylaxis was not recommended.

Worldwide incidence of malaria has increased. This may result in an increasing risk for tourists in different areas of the world. Malaria is an important travellers' disease in Germany. Most cases imported to Germany originated from Africa (77%). Plasmodium falciparum caused 67% of all malaria cases. 63% of all cases were Germans, 76% of whom travelled for holidays or study trips. From 1993 to 1996 89 people died from malaria in Germany. Most cases of fatal malaria were reported among German citizens. The case fatality rate increases with age. About 50% of all patients had not undergone sufficient prophylaxis against malaria. Only 22% of the patients who started prophylactic treatment took chemoprophylactics regularly while travelling abroad. Adequate prophylaxis against malaria is the only way to reduce the incidence of imported cases of malaria.

Adequate prophylaxis should always be the order of the day if anyone plans to visit a foreign country where he may be at risk of being exposed to infectious diseases. Numerous protective vaccinations are available for this purpose in Germany. Basing on the incidence of recorded damage caused by such vaccinations 1971-1990 we must conclude that the risk of damage to health as a result of such vaccinations is very remote. Hence, the protective vaccinations carried out in Germany are of vital importance in respect of keeping down the number of infections.

Hospital-acquired infections are a worldwide problem especially in hospitals for the treatment of acute cases. These infections are among the leading causes of death. Certificates of death of 4656 patients who died in hospitals were analysed. Of these, 564 deaths were caused by nosocomial infections (12.1%). It was estimated that annually around 40,000 deaths in the Federal Republic of Germany are attributable to infections acquired in the hospital.

Malaria was in 1989/90 the most important imported disease in Germany. Most of all cases were imported by German tourists (about 75%). Africa was the most prominently represented geographic region (about 75%). Kenia and Ghana represented there the biggest share. About 33% of all patients had not done a sufficient prophylaxis against malaria. An adequate prophylaxis against malaria taking into consideration the recommendations for medicaments for different geographical areas is imperative before the number of importations of malaria into Germany can be reduced.

73 cases of leprosy were imported into the Federal Republic of Germany between 1981 and 1992. A large number of imported cases came from Asian countries (32 cases). 61 patients were male, 12 female. 30 patients had the tuberculoid type of leprosy, 29 the lepromatous. From the total of 73 leprosy patients 7 were German nationals. Early diagnosis and efficient treatment play an important role in ensuring a good prognosis.

The results of an inquiry about the personnel and organisation of the hospital hygiene in 657 German rehabilitation centres and psychiatric hospitals demonstrate that 24% of these hospitals have a hospital epidemiologist, 44% have infection control nurses and 74% infection control physicians. Infection control committees are present in 64% of these hospitals. 78% of the hospitals use the guideline of the Federal Public Health Office "On the Identification, Prevention and Control of Hospital Infections" as a basis for all decisions on hospital hygiene.

Analysis of the outbreaks of food-borne infections and intoxications with a total of 2,610 patients in 1991 demonstrates that these cases were caused in 67.4% by Salmonella species. Eggs were mainly responsible for the outbreaks, whereas poor kitchen hygiene played also a main part in promoting disease.

Malaria continues to be an important travellers' disease in Germany. In 1988 885 cases of malaria were imported into the Federal Republic of Germany. German tourists to far-away countries represented the biggest share (about 80%). Africa was the most prominently represented continent with 76%. Differentiation according to species of pathogens showed that 68% of the diseases were caused by Plasmodium falciparum. 11 patients died of malaria in 1988, in all cases due to P. falciparum infection. The mortality of the patients increases with age. Only in 5 of 11 persons who died there had been a sufficient prophylaxis against malaria, at least as far as the anamnesis revealed. Careful planning of sufficient prophylaxis taking into consideration the partly very marked resistance to a multitude of drugs, as well as competent medical advice to would-be travellers, are imperative before the number of malaria imports into Germany can be reduced.

The results of an inquiry about the hospital hygiene in 2034 German hospitals demonstrate, that 35% of all hospitals have a hospital epidemiologist, 66% have infection control nurses and 86% infection control physicians. Infection control committees are present in 81% of German hospitals. 88% of all hospitals use the guideline of the Federal Public Health Office "On the Identification, Prevention and Control of Hospital Infections" as a basis for all decisions on hospital hygiene.