[Lessons learnt from the German smallpox outbreaks after World War II].

Background: Even though smallpox was declared eradicated by WHO in 1980, it cannot be ruled out that the etiological variola virus could be used as a biological weapon. Undestroyed viruses from biowarfare programmes, virus strains left undetected in a freezer or dangerous recombinant poxvirus constructs could cause dangerous outbreaks in a relatively unprotected population.
Objectives: Despite an abundance of studies performed during the eradication of smallpox, epidemiological data for preparedness planning and outbreak control in modern, industrialized countries are scarce.
Material and Methods: Full-text hand search for the period from 1945 to 1975 in the main German public health journals.
Results: After World War II 12 smallpox outbreaks occurred in Germany. They were studied with the focus on the period of contagiousness, the protective effect of vaccination, booster-effect of revaccination and the place of infection. A total of 95 individuals contracted smallpox, including 10 fatalities. Despite having been previously vaccinated, 81 vaccinated persons came down with smallpox, yet 91% of them developed only mild symptoms. These patients presented a high risk for spreading the infection to contact persons due to misinterpretation of symptoms and the continuing social contacts. Basically, the risk of transmission in the first 2 to 3 days after onset of symptoms was low, thus facilitating antiepidemic measures. The importance of hospital preparedness is emphasized by the fact that most infections occurred in hospitals.
Conclusion: The data analyzed provide valuable information for today's outbreak response planning and counter bioterrorism preparedness.