Epidemic diphtheria in the 1990s: Azerbaijan.

The diphtheria epidemic in the former Soviet Union reached Azerbaijan in 1991, when 66 cases of diphtheria were reported, a number that compared with 4 cases in 1990. From 1990-1996, 2182 cases of diphtheria and 286 diphtheria fatalities (case fatality rate: 13.1%) were reported in Azerbaijan, primarily among persons 5-39 years of age. Almost 45% of cases and 61% of deaths occurred among children 5-14 years of age. The high burden of severe disease among children and young adults suggested a different pattern of preexisting immunity against diphtheria in the Azerbaijani population than was observed in the concurrent diphtheria epidemic in Russia. Because resources were limited in Azerbaijan, mass immunization of the population was carried out in stages, focusing initially on school-aged children. Mass immunization campaigns targeting children were moderately successful in stabilizing the epidemic; mass immunization campaigns targeting both adults and children were eventually needed to fully stop the epidemic.