AIDS-induced decline of the incidence of syphilis in Denmark.

The incidence rate of acquired syphilis per 100 000 total population in Denmark increased by 70% from 6.8 in 1978 to 11.6 in 1982. In 1984 this incidence had decreased by 61.2% to 4.5. The fluctuation of the number of acquired syphilis predominated in the male population with an increase of 71.8% during the five year period 1978-1982 and a decrease of 63.2% during the years 1983 and 1984. In 1978, the incidence of acquired syphilis in males was 11.3 per 100 000 total population increasing to 19.5 in 1982, decreasing to 7.2 in 1984. The decreasing number of acquired syphilis cases during the past two years are correlated to a lower number of sexual contacts among homosexual men because of fear of AIDS.