Because infectious diseases may evolve over time, scientists do not know whether strains of tuberculosis or TB from the past (including those appearing in Europe when it was most deadly) are related to the strains we see today. A new study suggests mixed and therefore more dangerous infections may have been common during a time when TB was near peak prevalence in Europe. Mummified bodies found in an 18th century crypt in Hungary yielded 14 separate genomic sequences of M. tuberculosis, say University College London researchers.