Documenting the decline of leprosy in Europe: The example of Northern Portugal

Summary Background: There is continued uncertainty over trends of leprosy, including in areas with low incidence, where it may be possible to identify areas where M leprae is no longer transmitted or where it no longer causes disease. WHO has reported data on leprosy in the European Region only since 2015. Methods: Data reported to WHO and published in the Weekly Epidemiological Record were reviewed, Data from five districts in northern Portugal were collected from the National General Directorate of Health and Municipal Health Authorities. Results: Basic information on 133 leprosy cases has been reported to WHO by thirteen of the 54 states in the European Union since 2015. Data on place of birth of the cases were reported by ten states since 2016, implying eleven cases possibly attributable to transmission within Europe. Detailed but incomplete data on 38 leprosy cases notified in northern Portugal 1990–2018 are described and discussed. Of those cases which appear to have been autochthonous, none were born after 1966, none were notified after 2007, and the only three notifications after 2005 were for relapses. Conclusions: Data on leprosy in the European Region are obviously incomplete. The large majority of cases now detected are attributable to infections contracted abroad, but a small number of cases possibly attributable to local transmission are still being identified. Analysis of data from five districts in northern Portugal indicate that this region is no longer endemic for the disease, and that transmission in the area is likely to have ceased at least 40 years ago. The methods illustrated in this paper could be applied to data on leprosy in other regions of Europe, to better define the geographic limits of leprosy today.