gms | German Medical Science

50. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie (gmds)
12. Jahrestagung der Deutschen Arbeitsgemeinschaft für Epidemiologie (dae)

Deutsche Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie
Deutsche Arbeitsgemeinschaft für Epidemiologie

12. bis 15.09.2005, Freiburg im Breisgau

Large multinational outbreak of hepatitis A among German and other European travellers in Hurghada, Egypt

Meeting Abstract

  • Christina Frank - Robert Koch Institute, Berlin
  • Jan Walter - Robert Koch Institute, Berlin
  • Marion Muehlen - Robert Koch Institute, Berlin
  • Andreas Jansen - Robert Koch Institute, Berlin
  • Ulrich van Treeck - Institute of Public Health, State of North-Rhine Westphalia, Münster
  • Anja Hauri - State Health Authority, States of Hesse, Dillenburg
  • Iris Zoellner - State Health Authority, State of Baden-Wuerttemberg, Stuttgart
  • Eckart Schreier - Robert Koch Institute, Berlin
  • Osamah Hamouda - Robert Koch Institute, Berlin
  • Klaus Stark - Robert Koch Institute, Berlin

Deutsche Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie. Deutsche Arbeitsgemeinschaft für Epidemiologie. 50. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie (gmds), 12. Jahrestagung der Deutschen Arbeitsgemeinschaft für Epidemiologie. Freiburg im Breisgau, 12.-15.09.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05gmds167

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Veröffentlicht: 8. September 2005

© 2005 Frank et al.
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Between August and October 2004 Germany’s national infectious disease surveillance system noted a strong increase of hepatitis A virus (HAV) infections among vacationers returning from Hurghada, Egypt [1]. All had stayed in a specific hotel between June 10 and August 7. Altogether 278 infections were associated with this outbreak in Germany: 271 primary infections among hotel guests, among them 263 (97%) with clinical disease, and 7 cases of secondary infections among persons who had not travelled. Additional 59 primary and 13 secondary [2] infections among guests of the same hotel were reported to the RKI from 8 other European countries. The time period between the first infected hotel guest’s last day of vacation and the last infected guest’s first day, i.e. the minimum period of infection in the hotel, was from June 24th to July 23rd. The maximum proportion of infected guests residing in the hotel on any single day during that period was 52%. This and another hepatitis A outbreak within Germany (associated with baked goods) caused the annual number of hepatitis A cases reported in Germany to rise more than 40% in 2004 compared to 2003.


Upon receiving the first reports of associated infections in mid-August, the Robert Koch Institute (RKI) informed the implicated hotel, the Egyptian Health Authorities, the federal states of Germany, and national public health institutes in other European states. An epidemiologic investigation was started. The Egyptian authorities initiated investigations to determine the source of infections on location and took broad measures to curb potentially persisting risk of infection. The respective health authorities of other nationals who had also stayed in the hotel were informed about the outbreak and asked to report additional cases to the RKI. In Germany, hepatitis serum samples of registered cases were collected for molecular typing.

A case-control-study was conducted, enrolling hotel guests >17 years of age, one person per household. 69 registered cases who had stayed at the hotel were compared to control-travellers who were unvaccinated, had remained healthy and had stayed in the hotel at the same time as the cases. After enrolment was completed, the period in which infections had occurred in the hotel had to be corrected somewhat, as data on travel dates became more precise. It was found that a number of the recruited controls had arrived in the hotel only after infections had ceased. As a result this analysis utilizes only those 36 controls, who spent at least one day in the hotel during the four-week minimum period of infection.

Based on information received from the cooperative hotel management, three hypotheses were formulated regarding possible food risk factors: that consumption of ice cream, juices or cold salads were associated with infection. A questionnaire querying these, other food and drink items and various activities was administered via telephone by local, state and federal health authority personnel. In statistical analysis, univariate and multivariate methods were applied.


The German cases’ median age was 34 years, and 54% were male. No fatalities occurred. However, several patients experienced a severe course of disease. Only one patient recalled receiving a complete course of immunization against hepatitis A prior to travel. Hepatitis A viral genome was found in 22 of 42 available serum samples (52%); 13 PCR products sequenced were all identical, belonging to genotype 1B.

In the case-control study the two groups did not differ significantly with regard to age, sex, participation in excursions from the hotel, bathing in the pool, eating ice cream, cold salads and many more of the food and drink items queried. The only significant risk factors were consumption of orange juice and grapefruit juice. More cases (82%) than controls (64%) had consumed orange juice from the breakfast buffet (OR: 2.6, 95% CI: 1.1-6.6) and cases had drunk juice on more days of their vacation (median: 11 days) compared to controls (median: 5 days) (P<0.005). Adjusted for length of stay, risk of infection rose steeply, the more days the cases had consumed the juice, up to an OR of 4.5 (95% CI: 1.4-14.8) for guests who had consumed the juice on 14 days or more (compared to those who had never drunk the juice). Consumption of grapefruit juice also differed substantially between cases (32%) and controls (17%) (p=0.07). Altogether 85% of the cases recalled drinking one of these types of juice for breakfast.

The investigations in Egypt did not identify any recently HAV-infected hotel employees. Independently from the results of the case-control study attention focused on the juices. At the site of their production in Cairo there were also no infected employees found. However, authorities determined that there were hygiene problems associated with production and that the juice was not heat-treated before shipment to consumers.


With 350 recorded cases in 9 European countries this was one of the largest travel-associated hepatitis A outbreaks reported. An even higher number of travellers was exposed to the virus in the hotel but did not develop hepatitis A because of immunity (previous hepatitis A, immunisation). Mild or asymptomatic infections may have gone undiagnosed. The rapid detection of the outbreak and the successful collaborative effort in its investigation demonstrates the efficiency of the national and international infectious disease surveillance systems.

In this outbreak juice, especially orange juice, was the likely vehicle of infection - an unusual vehicle described only once before as having caused an outbreak of hepatitis A [3]. Most likely the juice was already contaminated with hepatitis A virus at the site of production. The high proportion of healthy controls who remember drinking juice may in part be explained by levels of viral contamination of the juice varying over the 4-week period when infections occurred., It is also likely that some controls were sub-clinically infected, or immunity against hepatitis A from unrecognized previous exposure. Regarding Egypt and other countries endemic for hepatitis A, the outbreak strongly underscores the need for adequate pre-travel advice and hepatitis A immunization in travellers [4]. Holiday companies and travel agents should inform travellers about the risk of hepatitis A virus infection and available and recommended immunizations in their catalogues.


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Holzmann, H.: Eine Hepatitis A Epidemie in Ägypten und ihre Folgen in Österreich. Virus-Epidemiologische Information 2004-23. Universität Wien, November 2004 (
Eisenstein AB, Aach RD, Jacobsohn W, Goldman A. An Epidemic of Infectious Hepatitis in a General Hospital. Probable Transmission by Contaminated Orange Juice. JAMA 1963;185:171-4
Robert Koch Institute. Empfehlungen der Ständigen Impfkommission (STIKO). Epid Bull 30/2004, 235.